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This will be a subjective evaluation since most of you don't give a crap about any meaningful spec's.
I have had the misfortune recently to listen to two units that had no negative feedback. One was a CD player which has been well reviewed and praised, the other a switching amplifier.
Both of these units had much in common: they both clouded up when the music got dense, and both had objectionable and very audible noise.
Some folks may appear to like these characteristics, I find it takes away valid and important musical information that I would like to hear.
I will assume at this point considering my experience, that folks who think negative feedback is the curse of audio, prefer the noise and lack of information units without negative feedback give.
d.b.
Follow Ups:
then feedback can only hurt. Some build with devices that are so non-linear that feedback is a must. That is, if you want to listen to it.Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Your measurements for this Panasonic amp don't seem terribly different than what I have seen with other Class D amps with or without negative feedback (I believe nearly all of them use negative feedback but if you say this one doesn't then I guess it doesn't). For example:http://stereophile.com/solidpoweramps/406halcro/index4.html
http://stereophile.com/solidpoweramps/805cia/index4.html
http://stereophile.com/solidpoweramps/405yamaha/index4.html
http://stereophile.com/solidpoweramps/729/index8.html
http://stereophile.com/solidpoweramps/729/index9.html
http://stereophile.com/solidpoweramps/442/index5.html
http://stereophile.com/solidpoweramps/442/index6.html
http://stereophile.com/integratedamps/106ps/index4.html
http://stereophile.com/integratedamps/253/index6.html
http://stereophile.com/integratedamps/253/index7.html
As you can see, they all act a bit wonky and most have tons of out-of-band noise that is riding on JA's squarewave measurements.FWIW, I have big problems with how nearly all Class D amps sound, regardless of implementation. The expensive Sharp is the only one I have heard that really performed well sonically. I think it has a lot to do with the HF noise of the amps and their apparent large increase in distortion at HF. I would not be surprised also if the problems with grounding is an issue due to all the RFI.
However; to blame the sonics on the amp being a non-global feedback design is just silly when 1st it is a cheap as hell product and 2nd even these rather expensive items I posted here all have similar if not identical problems with noise. I find it funny in many of the links JA makes it a point of saying he hates to measure Class D amps because it is hard to tell what is distortion and what is noise.
Picked the wrong amp to try to prove whatever dubious point you were trying to make. Why are you protecting the cd player manufacturer? You didn't spare Panasonic.
After reading through the first two links, I find major differences between the articles. First and foremost, the article that appeared in Audioholics was NOT a review of the Panasonic unit. Secondly, it was to make people aware of the out of band artifacts at the speaker outputs, thirdly, a discussion on the importance of grounding and PCB layout as it applies, fourthly, a brief discussion on the reactive output impedance of this unit and units like this.
Once again, you missed the point(s).
d.b.
1st; I only posted links to the measurements and ignored the subjective review thus making your first point invalid.2nd; Your post on this forum (not the article in Audioholics) is a SUBJECTIVE post by definition and is not about out of band artifacts, grounding, etc. but your opinion of the sound and what you thought its cause was. SHEESh, can't you read your own post? So your second point is invalid as well.
I decided to point out to you that your subjective impression is fine but your assumptions as to its cause were potentially misplaced. That is why I show that plenty of Class D amps with negative feedback have the same problems as the ones you bash for sound because they have no feedback.
I don't think you are willing to admit that this post was nothing more than a troll and to show off your new article, which says nothing subjective really other than you feel the measurements suck.
Hi.No doubt Dan is not prepared in his posts re class D amps without loop feedbacks sounded lousy to him. Apparently he knows very very little how switching amps work. Of coure, he is not alone.
Class D (pulse width modulation) is a 50-year-young concept. Not new at all. It's being not popular mainly due to no active devices to perform the required high speed switching at high frequencies (100KHz & up up) with mininum loss untill the birth of TMOS power MOSFETs in recent years.
Vaccuum tubes can switch pretty fast, but cause too much voltage drop due to their inherent high internal resistance. Bipolar power transistors can handle low frequencies properly but fail to deliver
at high frequencies due to excessive losses & large bias current complexity.Nothing is perfect. Class D PWM power amp gets its downsides, e.g. its switch mode power supply tends to emit RFI; & pretty sensitive to various reactive speaker load due to its low pass filters.
The low pass filter, a must to remove all higher frequency square wave contamination out the audio signals at the exit of the switching amp to drive the loudspeakers.
It is built of capacitors, inductors & resistors, designed to work on a nominal fixed resistive speaker load, say 8R. But the reactive impedance of any loudspeaker swings up & down like a roller coaster.
An inadequately designed switching amp & its low pass fitler can get lousy sound, possibly due to resonances of the RCL filter circuits on the reactive speaker loads not catered for.
Back to the loop feedback issues. Unlike analogue amps where loop feedback is a gravy to the steak. All class D switch mode amps NEED
feedback loops to maintain the various proper functions of the amp, e.g. switch controller for the switching amp.Through loop feedbacks, it controls & keeps the output duty cycle
from 5% to max 95% per the error voltage input, & safeguard the switching amp from blowing by monitoring the current sense I/P.I have just seen class T switching audio amp in the marketplace which claims to beat class D & deliver much better sound.
You said Sharp sounds good, IMO, via digital input saving the A-D convertion error. Considering its USD4,500 vs its lowly 2x50W, it better sounds good. Or who would buy it.
c-J
"You said Sharp sounds good, IMO, via digital input saving the A-D convertion error. Considering its USD4,500 vs its lowly 2x50W, it better sounds good. Or who would buy it."Actually he SX-100 was something closer to $20k when new so yes for the money it had better sound very good!
"All class D switch mode amps NEED
feedback loops to maintain the various proper functions of the amp, e.g. switch controller for the switching amp.Through loop feedbacks, it controls & keeps the output duty cycle
from 5% to max 95% per the error voltage input, & safeguard the switching amp from blowing by monitoring the current sense I/P."Are you saying then that this Panasonic he is going on about must have loop feedback and that Dan is wrong that it is no feedback? I am curious because my understanding was that feedback was a simple fact of life to make Class D work properly.
Hi.Since I don't know which model of Panasonic switch mode amp is it,
I can only assume it is a delta-sigma modulator with 1-bit quantizer, similar to what Sharp is using.If my assumption is correct, then there is definitely feedbacks looping from the exit of the switching amps back to the delta-sigma modulators to to generate an error voltage.
The feedback voltage is used to compensate the nonlinear behaviour in the switching power stage, e.g. non-overlap time, mismatched rise/fall time, & propagation time. It also help to reduce sensitivity to both DC & transient changes of the power supply voltage.
Yes and no, many do not have any correction after the filter.
d.b.
Hi.In switching amps, the low pass filter can cure or kill the sonic performance of the amp. It plays the crucial role of removing the triangle high frequency carrier (say switching frequency of 100KHz & up up), plus its multi high order harmonics & permitting uncontaminated continuous music sine wave signals to pass to the loudspeaker load.
We are talking about some 1A no-signal current & full load currents of many amperes at over 100KHz, depending on the rated O/P power of the amp.
Wires of large size & of very low skin effect material must be used in the inductors to prevent high frequency loss along with high permeability large ferrite cores adequately gapped to prevent core saturation & for linear B/H operation.
Unlike linear/analolgue amps handling only audio signals, momentary no load, like loudspeaker wires detached, can generate large enough voltage monentarilly at the junction of the filter inductors to push the cores into saturation, blowing the filter caps, & could even blow the switching power transistors.
The choice of the inductor leads to receive the input signals is critical to reduce capacitance induced RFI. So effective RF layout of the low pass filter is very helpful.
The filter capacitors must be high voltage (up to 100VDC) for the reason above, & high Q to handle min 100KHz. So non-polar multi-layer film caps should be used.
Again, design of the low pass filter is normally based on a fixed norminal resistive dummy load of say 8R. The reative impedance of any loudspeakers swing up & down like a yo-yo. This makes the design of a proper low pass filter more complex.
To anwer your question, anywhere upstream of the low pass filter is digital where loop feedbacks should be executted for data correction & control.
c-J
.
My impression is the opposent of yours. A way more open, revealing sound. For instance on a track where before there was a single voice, I can discern 2 voices singing together. (this circuit does have some local degenerative feedback but no global)
Try varying the power input voltage to a non feedback amplifier, especially one of those miserable little SET units with direct filament heaters and no regulated power supply with a Variac from 110 volts to 125 volts and see if you don't get about 30% more power output from it...and god knows how much shorter a lifespan.
There are so many other variables involved. Not that I object to well impemented feedback...
The switching amp was the Panasonic SA-XR50 receiver. There is no feedback from the output of the filter back to the input. See link below. The CD player will remain unamed.
d.b.
- http://www.audioholics.com/techtips/audioprinciples/amplifiers/SwitchingAmplifierIssues.php (Open in New Window)
Hi Dan, allSome thoughts about switching, for a PWM or Phase Modulator, neither of these function as a Voltage or current amplifier without a feedback loop.
The PWM or PM is a duty cycle modulator, what happens on the output is largely a function of the load.
Servomotors have been driven by switchers for ages, I built a few for the Servodrive speakers back in the 80’s. Making one go to > 20KHz is possible because of a 10 or more times higher switch rate (typically) than was possible with that current level back then.
Also, since the minimum on time thresholds for output switch devices are finite and are somewhat nonlinear as a function of control voltage or shift , this is another reason a loop is always employed somewhere.
As such I am not sure IF one could even have a switching amplifier that didn’t have feedback to linearize it and make it into a Voltage input = Voltage output amplifier.So far as damping, it may be worth pointing out that so far as its operation, a direct radiator speaker operating well above its Fb, will in fact be current driven so damping factor is not important (or have an impact on the measured result). Keeping in mind it is an R/C filter and the current drive is the voltage across Rdc acting against a C which has a tiny voltage (radiator velocity back emf) across it.
It is control at resonance where damping factor matters and then above say 20 - 50 its irrelevant.
On the other hand, a lowish source Z above is a good idea because the crossover can impose impedance changes that you do not want reflected into the amplitude.
Best,
"On the other hand, a lowish source Z above is a good idea because the crossover can impose impedance changes that you do not want reflected into the amplitude."
I'll add low output reactance/impedance to that. The general idea is to get out the way. Many of us figure that if the output impedance stays below 0.1 ohm at all power levels and from 20 Hz to 20kHz that should do it for 99.9% of the speakers.
d.b.
"I'll add low output reactance/impedance to that"
Difficult with a Class D amp as it has an output filter to clean up all that HF hash. What about those high feedback SS amps that use an output inductor to keep them stable with reactive loads?
I think it is time for you to define just what exactly high feedback is, and I am going to hold your feet to the fire so to speak, until I am satisfied that you have a clue of just what high feedback is.
The typically 2uH to 10uH inductor will dominate the reactivity of the output impedance, if the amp uses one.
Not all of them do.
d.b.
Well said, tomservo!
No wonder. Sorry Dan but I thought we were talking about a high fidelity design not one that costs like $300 retail.
nt
Dan, are you stupid? You pick one of the cheapest "hifi" amps on the market and blame its noise on lack of negative feedback, even though it is a Class D design where noise of the sort you measured is par for the course feedback or not.You also blame its sonic character on the fact that it has no feedback, ignoring the other more obvious factors that would make an amp sound bad when the going gets tough; namely a cheap ass underpowered and underspecified power supply.
From this HIGHLY FLAWED example you draw conclusions about all negative feedback amps as if they all behave like a cheap ass Class D amp that should have been left driving cheap ass subwoofers for hometheater-in-a-box.
If you look at the links I gave you above you will see that nearly ALL Class D amps measure like the Panasonic. Most have plenty of negative feedback.
Your point was blantantly obvious. You wanted to "prove" that subjectively a no feedback amp can't sound good and must be contaminated with tons of noise (in band or out of band). The fact is that I know of SET amps (of course with no feedback) that are so quite they don't even make a whisper with 100+db/watt speakers. And at low power measure better than most SS amps at the same low power.
Think I'm wrong about your point?
"I have had the misfortune recently to listen to two units that had no negative feedback" This sets the tone."Both of these units had much in common: they both clouded up when the music got dense, and both had objectionable and very audible noise" Implication: bad sound must be due to lack of feedback.
"Some folks may appear to like these characteristics, I find it takes away valid and important musical information that I would like to hear." Assumption: These pieces sound bad so all non-feedback gear sounds bad and people must love it for these charactertistics.
"I will assume at this point considering my experience, that folks who think negative feedback is the curse of audio, prefer the noise and lack of information units without negative feedback give."
Assumption: People prefer noise not music and I am the only one who knows the difference. Nevermind if these units are not representative of non-feedback gear as a whole.Jesus, Dan! A non-feedback Class D amp is not representative of ANYTHING. In fact it is the only one I know of. It certainly doesn't relate to all those non-feedback linear amp designs (which have little to no noise out of band for starters).
I will grant you that the noise is probably affecting the sound quality because I have heard problems with every Class D amp I have auditioned.
"Dan, are you stupid? You pick one of the cheapest "hifi" amps on the market and blame its noise on lack of negative feedback, even though it is a Class D design where noise of the sort you measured is par for the course feedback or not. "
There is a bunch of Audiophiles on various forums who praise this/these units to the skies and call it a giant killer.
Take it to them, I was done with this months ago.
d.b.
So, what's the CD player - an Emerson combo?
"There is a bunch of Audiophiles on various forums who praise this/these units to the skies and call it a giant killer"Most of us dismiss this for what it is, Dan, people happy that something so cheap doesn't sound like complete crap. I thought we were talking about serious amp design here not mass market garbage. I am note even sure it sounds better than the usual so-called "linear" amplifier available at this price.
I haven't heard a Class D amp yet that sounds anything close to what real music sounds like with the exception of the (very expensive) Sharp. This one sounds like a very good SS amp with soft high frequencies (soft as in not grating to the ears). All the rest I have heard fail in the HF (no surprise there is it?) and just generally have a funny overall tonal balance. I have heard many types, ICE, tripath, hypex, Ucd, proprietary, etc. There are definite differences but none sounds right and I think the HF noise is a major culprit as is the overall harmonic distortion spectrum these amps produce.
"the other a switching amplifier."If you don't start with linear devices then you need feedback.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
(nt)
nt
The most valuable posting I ever read on the internet about cables was authored several years ago by John Curl. He said he measuered noise from the 7th harmonic of 5 khz down -120 db for the cheapest $1 Radio Shack interconnect cable (the worst he could find) and down -135 db for the best cable he could find. This dispelled any lingering doubts I might have had about inexpensive interconnect cables being far more than adequate for use in ANY sound system. This hardly came as a surprise to me though since every test I tried where a 7 mhz video signal with over 350 times the bandwidth of a high fidelity audio signal appeared indistinguishable from the same signal sent to the same TV set as an RF signal for decoding by the TV set's own tuner. (The TV was Sony 36" Wega XBR extra bright and the source was cable TV feed to a VCR.) This is testimony to the dead flat FR of the cable and its immunity to noise at least in that application on that day. It is also in perfect agreement with my own A/B audo tests in which they are alternately inserted in the signal path an shunted by a preamp's tape monitor switch. Inexpensive cables have also never failed to sound indistinguishable to me from the shunt. Since I don't consider a cable a control element and I think most electrical engineers would agree, I consider any cable which performs differently from this to be defective and any cable more expensive that this to be an unnecessary waste of money. Nope, whatever the cause of the poor performance in Dan's setup, it wasn't the cable...unless of course he was foolish enough to use audiophile cables (sound's instead like he used Belden which is excellent.)
When you compare a Yugo to a Pinto, you compare red delicious apples to red delicious apples. You need to throw some braeburn, granny smith, fuji and golden delicious into the mix to better understand the differences in flavor. And to do so, you must taste them. Don't dismiss them based on the way they look.BTW, did you ever get around to compiling that list of recordings adored by audiophiles and the ic's/cables used in the studio to record them with?
Until then, what you have to say about it is gibberish to me.
You may have problems with your Sony or your vcr.
Every video cable I have tried had visible differences and I have used TV sets ranging from 20 inchers to large 60 inchers. On the samller sets the differences tended to be smaller, but not so on the larger sets, including a Sony 34" set I tried various cables on. The RS cables sucked: picture was grainy and edge definition was not very clear with poorer color saturation. Geez, I can see the difference with RG-59 and RG-6 using the cable TV ends....
Stu
I have four of these KV-36XBR250s I bought in 2000 and every one of them has performed flawlessly from the day I got them. BTW, they work beautifully with DVDs too. Never experienced any of the problems others reported with this and similar models on Audio Review's site. Very pleased with both their picture quality and reliability.
(nt)
.
"7th harmonic of 5 khz "Could you hear the 7th harmonic of 5Khz anyway even if it was full scale? lets see fundamental is 5Khz
2nd harmonic 10Khz
3rd 15Khz
4th 20Khz
5th 25Khz
6th 30Khz
7th 35Khz!!Gee, Soundmind, you are right it doesn't matter if one is at -120db or -135db at 35Khz!! You are just brilliant!
Now if it was the 7th harmonic of 500Hz it might be a different story because this would be smack in the middle of one of the most sensitive regions of your hearing.
The first harmonic of 5 khz is 10 khz, 5 khz is called the fundimental but what difference does it make. If you don't like it, don't blame me, take it up with Mr. Curl, it was his posting. BTW, even if it was the 7th harmonic of 500 hz, it would still be at 7khz and -120 down is good enough for government work as they say and it's good enough for me. That's much better than most electronic equipment.
Morricab, I measure at 5KHz, BECAUSE it is convenient for me to do so, especially when I am looking for xover distorion in power amps. 500 Hz would be OK, but my test equipment today is finely tuned for 5KHz and it works best there with the settings inside my test equipment. It would measure the same amount in level. I have checked this, but I do not use it for normal measurements. I also have IM from the same tester, and it is better at measuring low frequency garbage.
Hi John,
I wasn't criticizing your measurements as they seem fine for whatever purpose you had for them. I was criticizing soundmind's use of this as a reason why cables all sound the same and that the frequency of the 7th harmonic of 5Khz is so high that he wouldn't hear it regardless of level.
" I was criticizing soundmind's use of this as a reason why cables all sound the same and that the frequency of the 7th harmonic of 5Khz is so high that he wouldn't hear it regardless of level."I clearly didn't say all cables sound the same. Quite the opposite, I have complete faith in the ability of tinkerers who don't know what they are doing to find endlessy ingenious ways screw up anything and then find people they can convince that their inferior product is actually better than the far cheaper alternative which functions perfectly. In audio, this has been turned into an entire industry. I also said that insofar as the only legitimate function of an audio interconnect cable for a consumer audio system, the inexpensive interconnects function as perfectly as can be desired and any problems with the performance of a sound system would be far better off resolved by investigating and changing other areas than to experiment with expensive, unpredictible, uncontrollable audiophile type cables.
You said, "He said he measuered noise from the 7th harmonic of 5 khz down -120 db for the cheapest $1 Radio Shack interconnect cable (the worst he could find) and down -135 db for the best cable he could find. This dispelled any lingering doubts I might have had about inexpensive interconnect cables being far more than adequate for use in ANY sound system."If this isn't another way to say, "they all sound the same look at how low the distortion is on even the cheapest cable" then please by all means tell me what you mean.
"I also said that insofar as the only legitimate function of an audio interconnect cable for a consumer audio system, the inexpensive interconnects function as perfectly as can be desired and any problems with the performance of a sound system would be far better off resolved by investigating and changing other areas than to experiment with expensive, unpredictible, uncontrollable audiophile type cables. "
Sorry but this is just a very roundabout way of saying that "all cables sound the same and even if they don't the expensive ones that sound different to the cheap ones must be F*(ç/*" up". How do you know the inexpensive cables are designed properly?? Have you tested them yourself? Has anyone bothered to actually test the giveaway cables or cheap radio shack ones?
a
John Curl's test of the ic's had some validity. It is the interpretation of the results that is in conflict.John pointed out differences between cables as they were tested on a specific machine....his
The AP sports much better specifications than JC's rig, and therein lies the distinction. Having been designed to more rigorous specs, issues which affect JC were eliminated via engineering in the AP rig, whereas John attempted to better his old rig without baselining it.
I certainly can believe John found repeatable differences, but Bruno's results prove that it is a cable/rig interaction, not some nefarious diode/zero-crossing distortion.
THAT needs to be researched, as it is that interaction that is far worse in the home environment.
A shame it was not continued, as it is a good avenue of research.
Reactive loading of the output driver. What's your guess?
d.b.
Dumb guess, Dan. If you had the schematics you would see that the oscillator and its output driver are completely resistively buffered from the cable itself. Also I deliberately put a relatively large capacitor (.033uf) to ground designed to attenuate anything over 5KHz on the oscillator and therefore improve both the S/N of the oscillator and its residual distortion, as well as to have a predictable cap load buffering any changes in cable capacitance. The distorion itself still looks and measures like mini back paralled diodes in series with the wire. It is most probably PIM distortion in the return shield interface with the rca connectors. This could probably have been ignored by the Audio Precision, but important with the ST. I also wish to say that the examples provided to me were very well soldered, when they were custom made, and in general measured better than other examples on my workbench.
We've been through this already, if you wnat to continue, be my guest. I'm still not convinced that your resistive buffer is the total answer on this.
Have a nice day;
d.b.
jc: ""
If you had the schematics you would see that the oscillator and its output driver are completely resistively buffered from the cable itself.""
Since he doesn't have the schematics, it can't be called a "dumb guess", silly..:-)jc: ""
Also I deliberately put a relatively large capacitor (.033uf) to ground designed to attenuate anything over 5KHz on the oscillator and therefore improve both the S/N of the oscillator and its residual distortion, as well as to have a predictable cap load buffering any changes in cable capacitance.""Hmmm, new point of info..
When you say "ground", where are these bad currents going? Since ground is not an infinite sink that forever removes electrons, perhaps the ground currents were indeed coupling to the cable loop via some chassis path....an interesting thing to look at..
My concern is more that the physical loop caused by the cable and the test widgit had an interaction with chassis currents of the drive signal.John noted that cleaning the contacts of the ic's changed the results, and he got more consistent readings when he cleaned them.
A shield interaction would do that.
So, I do not think it was a reactive loading issue, simply because the load would not change that much when the contacts were cleaned.
Yes it's been done, and all that was found for distortion was the residual distortion of the analyzer.
d.b.
HowdyRemember when he was hearing "Hyper Compression cause[ing] gross distortion" on "the Tierny[sic] Sutton CD Dancing in the Dark, track one and track 10": http://www.audioasylum.com/audio/general/messages/434708.html
You have to wonder what his system sounds like.
-Ted
Well Ted, possibly you are unaware of the level differences between the SACD version and the CD version. The CD version had the level cranked to where a rather laid back jazz trio was clipping. I have the scope shots to prove it.
Personally I was pretty disappointed that Telarc, a label known for high quality recording would allow something like this to be released, but the times are changing aren't they.
I have a few other CD's from Telarc and they are generally superbly done, although I must admit I didn't think they did justice to McCoy Tyner.
d.b.
HowdySince all I had was the (hybrid SACD) I asked you for times into the tracks and you didn't answer. Instead you started talking about other discs.
Since you "have the scope shots to prove it" could you tell me the times?
I do not think I have the times into the tracks, but I will look and get back to you.
d.b.
HowdyThe squares in the image are the samples. They are connected by the line which would be produced by a correct reconstruction filter.
Here's the worst clipping I found on track 10:
There were about six others clippings I noticed in tract 10 but most were where the tops were already near rounded and were only a few samples long.
Also the worst I noted in track one ("What'll I Do?") was a (roughly) 15 sample clip in the right channel at about 4:04.7:
On the other hand none of these clips are nearly as bad as some discs I've seen, I don't think I'd go as far as saying that Telarc screwed them up.
I should have a chance this evening to e mail you the scope shots and hopefully, if I can find the list, where on the tracks these occurred.
I was going to do an article on this but it got sidetracked along with other things.
d.b.
HowdyThe clipping sections I found are actually a lot rarer than they look till you zoom in. Also it looks like they are only a fraction of a dB most of the time. This disc sounds fine both on my expensive and my cheaper DACs.
FWIW I've seen some ASRC upsampling DACs fail with signals which never even reached 0dB (but came close). They either didn't use saturation math or the programmers didn't take into account the expected overflow when the input signal was near the limits.
If your system has an upsampler you can turn off or bypass perhaps you can see if that changes or eliminates the problems you hear with this disc.
Just to be clear I agree that there are discs out there which are horribly clipped and also that there are discs out there which have copy protection measures which have sections of crap in them, but I don't think this disc is nearly that bad (tho clearly it would be better if it never quite reached the limits.)
...about audio, never list their systems?
Why criticize someone who would prefer alternative approaches to design??
You wrote:Why criticize someone who would prefer alternative approaches to design??Who does Dan criticize in his post? Below the parts of his post talking about people:
This will be a subjective evaluation since most of you don't give a crap about any meaningful spec's.../...
Some folks may appear to like these characteristics, I find it takes away valid and important musical information that I would like to hear.
I will assume at this point considering my experience, that folks who think negative feedback is the curse of audio, prefer the noise and lack of information units without negative feedback give.
d.b.
If you were to like to be seen on a public forum behaving like a young imp throwing poo to another, laughing when I gotcha you, both of them being soiled to the bone, that would be your choice.
Just don't take for granted many other people would enjoy such a smelly spectacle.
"Who does Dan criticize in his post?"When he stated: I will assume at this point considering my experience, that folks who think negative feedback is the curse of audio, prefer the noise and lack of information units without negative feedback give.
First of all, Dan cited a CD player and switching amp that both had no feedback and to him sounded awful. Call me ignorant, but I personally think *most* CD players and switching amps sound awful, regardless of whether or not they have feedback. What he heard that was awful may have been due to the lack of feedback, but it could have been a variety of other things as well.
But my point is he hears sonic anomalies which he *thinks* are attributable to the lack of feedback in the design, and then presumes those who prefer less feedback in essence prefer having such anomalies in the sound. If he merely stated he hears those sonic anomalies without having to go as far as stating that others prefer such anomalies, that would have been fine. I've personally heard sonic anomalies in products which others like, yet it should be taken as a different perspective, not as the opposing perspective being questionable.
Hi.On the contrary, I read rave sonic reports on excellent sounding
class D switching power amp using tons & tons loop feedbacks.Let me quote the designer of this brandname 2x500W power amp using
pulse width modulation (PWM) technology, super 90% high power efficiency (only tagged for lowly USD3,496.00):-"It is the slowness of analogue circuitry that diminishes the benefits of loop feedback, resulting in an undesirable effect on the sound".
This amp switches 500,000 times a second to deliver intime error corrrection.
"Ok, so maybe both of us were abducted by audiophile aliens, but I don't think so. I think we were both shanghaied by one of the finest audio amp that we have ever heard, and through it, transported to a
new universe of listening pleasure."This is taken out from a free online audio journal. So commercial agenda should not be there.
c-J
I've auditioned products from the SI Sonic T to the Red Wine Clari-T to the Teac 700P to the Nu-Force 8 monos.... They all sound nice at first listen, then about half an hour later, I realize that there's something strange going on with the music. It's not really unlistenable like a bad digital source, but the music has no soul. It hit me between the eyes several months ago, when I switched to a SEP tube amp, and I perceived the music totally differently. The human element of the performance was restored with the tube amp.
Hi.Many die hard tube fans can't take any SS sounds let alone switching amp sound. May be tube harmonic distortions sound more musical to the ears.
I know Red Wine amp used linear OP chips which get quite some rave appraisal from end-users using tube amps before.
To me, I still love my direct current power amp built of all discrete bi-polars along with my tube trioded PP power amp.
Despite I love my all transistor phonostage along with my tube phonostage, I am sonically skeptical about any audio amps using
linear OP chips.
Umm...well, all of them so far with the exception of TACT and Sharp (both of which truly convert PCM directly to PWM). My understanding is that basically all of the Class D amps used negative feedback so I wonder which one he is going on about?
And don't take it the wrong way, please. ;-) And a definitional note: when I use the term "zero feedback," I'm talking about loops, not single stage degeneration.Your description sounds (uff!) very much to me like my subjective impressions of zero feedback SE triode amps (and, to an extent, the zero feedback stuff like the Pass diy designs). But the distortion spectra correlate very nicely to that impression- it gets pretty ugly when any power is actually demanded. Now, that disclaimer made, do you get the same impression from zero feedback stuff that keeps the distortion low up to a reasonable power and has reasonably low source impedance?
I ask this because I've played with amps and preamps that have zero feedback and hold their distortion down, and in those cases, I get none of that congestion.
How can you hear the distortion with a noise levels that high? I would hazard an edumacated guess that the high noise levels mask the distortion. This would not surprise me as it appears to me that high noise levels in this end of the business is considered "more musical" As far as the source impedance goes the unit in question is coming to my bench in the near future.
To tell you the truth: I never thought the lack of negative feedback would increase the noise levels to the absurbly high level that I appear to be hearing. I need to ask a few questions to some of the folks who are more knowledgeable than my self. Does the error correction of negative feedback also reduce noise? It wouldn't surprise me.
d.b.
In this book, the chapter on noise and feedback concludes that the total equivalent input noise eni ("n" and "i" should be subscripts here) is unchanged with feedback, except for a possible very slight increase in noise with feedback due to the thermal noise of the feedback resistors.
Does the book compare no negative feedbck circuits vs. feedback circuits for noise? In addition, negtive feedback helps with power supply rejection and DC stability. If I remember all this correctly, what effect would that have on noise? I suspect that it would have some effect, but the incredibly high noise floors I have heard out of these units and in some cases measured from these units make me wonder.
In any case the quote you gave is esentially correct.
d.b.
Dan, you don't know what you are talking about. My Vendetta phono input stage has no loop feedback, but it has a noise floor of 0.4nV/rt Hz. By the way, I have had Mochenbacher and Fitchen's book by my side for almost 1/3 of a century, and I knew most of it before I even read the book. You people are arguing with experts in the audio field, and you are amazingly unprepared.
They were comparing a circuit having no feedback with the exact same circuit with feedback. The equivalent input noise (squared per Hertz) parameter basically takes the mean-square Volts per Hertz (voltage spectral density) value at the output and divides it by the magnitude squared of the voltage gain. This reflects the output noise back to the input, giving a mean-square Volts per Hertz equivalent input noise.So with no feedback, you have a high output noise, but also a high gain. With feedback applied, the output noise is lower because the gain is correspondingly lower. But when you divide the output noise by the gain, it all comes out in the wash to the same equivalent input noise, assuming the contribution of the feedback resistors to the total noise is negligible.
So if the non-feedback circuit had high noise, it was probably a topology-related issue rather than the absence of feedback per se that was causing the problem.
Low-Noise DesignI use a figure-of-merit of 5, meaning if the preamplifier has a gain of five then the noise contributed by the next stage is low enough to disregard. I got this from a Tektronix salesman who pointed out that if an oscilloscope has a bandwidth five times the signal bandwidth, then the scope signal amplitude is 0.1% accurate.
I use series-shunt feedback since this is the most stable. For example, if the input is a JFet, I pass the feedback to the source of the Fet. The secret of this amp is that the feedback is not applied to the input, so it has desirable features of both open-loop and feedback and is rock-solid.
In X-Ray preamps they always mount the JFet right next to the detector (microphone) and then run a cable to the rest of the amplifier.
I typically use the AD797 op amp if the input impedance is on the order if 1K or less. The AD797 input noise is only 50nV p-p between DC and 10Hz.
For a low-noise Fet amp, check out the Magnicon amps. They have very low noise Fet inputs - I would love to find out what Fet they are using. If you don't care about LF noise, then check out the MOXTEK (X-Ray Preamp) JFets, these are from Area 51. These will achieve 500MHz bandwidth at 1nV/Rt-Hz!
For affordable JFets see American Microsystems LSK170A.
"So if the non-feedback circuit had high noise, it was probably a topology-related issue rather than the absence of feedback per se that was causing the problem. "
This I'll believe. Thanks;
d.b.
I was sloppy earlier in my statement about noise (failed to consider input noise, indistinguishable from signal, thanks for the correction), but I do believe that noise introduced after the input is attenuated by the feedback factor. Am I also mistaken in this? Or is it true but just a trivial consequence of the gain reduction?
This does get a bit confusing :-). But basically, the noisy circuit is modeled as a noiseless one with a noise voltage source in series with the open-circuit input signal voltage all the way back at the input. That noise source is eni, and is the figure of merit for the noise performance. It's computed by taking the output noise voltage and dividing by the gain from the open-circuit input signal voltage to the output voltage.If I understand your question correctly, you're referring to the output noise contribution from a noise source at a certain point in the circuit. But the way the equivalent input noise figure of merit is formulated, the effect when that contribution is reflected back to the input (by dividing by the amp's gain) is independent of whether there is feedback or not. Feedback reduces the output noise contribution, but the gain is correspondingly lower too. So it comes out the same when reflected back to the input.
Anyhoo, I hope I've answered the question you asked and not a different one :-).
No, that was exactly it. The answer was, "yes, but it's a trivial consequence of the gain reduction." I had only remembered the "yes" part. Many thanks!
Of course, negative feedback can help to reduce external noise from the power supply, but if you keep your forward gain low, and don't throw it away with high amounts of local feedback, then open loop design CAN be quieter than feedback design, because you don't have to add a feedback resistor in series (noisewise) with the input stage.
Your post makes me think about a common problem in many PA implementation: the feedback resistors (wired as a divider).
Noise coming from thess resistors is in serial with the feedback path, and so adds its noise without possible reduction by the FB loop.So, it's a good idea to keep them low, in the 100 ohm range. Furthermore, it helps to maintain good high-frequency characteristics.
As a result, current flow and dissipation won't be insignifiant.
For a well-designed PA, 100 to 200mW at 100W PA power is common.Here comes the issue:
To avoid thermally-induced distorsion at low frequencies, these resistors should be oversized types, at least 10 times the peak dissipation.
And on a real musical program, which most of its power in the bass range, you will have only peaks of dissipation.
So a resistor with high peak-to-average power tolerance is required.
Which bans metal-film resistors.
Since it has to be the less inductive possible, standard wirewound resistor is banned.
So, the FB resistor of choice should be:
- bulk metal resistors (manganin is the better alloy in this matter): the best choice or
- crenelled-wound wire resistor (much less inductive than standard wirewound,
- mounted on an heatsink, or it will be a high spot (best is TO220 shaped resistors)
Unhappily, I scarcely saw these refinements used in so-called high-end equipment.
Often, this resistor goes hot when the PA is used at full power. To avoid burning the PCB, the manufacturer often lifts the resistor a few centimeters above the PCB, on standoff if he's serious, or with the resistors' wires if he's clueless about mechanical vibration tolerance. But anyway the open area under the resistor's body creates a loop, in which any induced voltage will be ...in serial with the feedback...Jeeeezzz. Often, this loop is vertical, so that it can get flux from the Earth's magnetic field if the PA is "correctly" set. So, any vibration will translate into a signal.
(btw that's not the only issue that makes an equipment microphonic. Other issues exist too, but they are O.T on this thread. All these issues can be solved, and a SS equipment should not be microphonic at all if correctly designed )
Well, it makes the life easier for vibration control manufacturers, but, wouldn't it be easier and more respectful of the customer to have the equipment correctly designed from the beginning?So, as you see (and John C knows), many issues are intermixed.
FB resistors can act as a noise generator, a distorsion generator at low frequencies, and can make the PA microphonic.
But you can avoid it. Just a question of knowledgeable and serious design.
Jacques, I think that I would rescale the resistors to be a higher value. Power amps are at the end of the amplifiying chain and the difference between a 100 ohm resistor and a 1K resistor would usually be unimportant. At a moving coil input stage, however, even 100 ohms would be too much, but then there is no signal output either.
For my power amps, I generally use a 47K 1/2W Holco (old) feedback resistor with perhaps 1.8K to ground. I might use a 1-2W Resista, if I had to sacale it down to 10K and 330 ohms or so. I would most likely never use a 100 ohm resistor, because of the problem of dynamic overheating, that could be fixed with a heatsinked power resistor, but then you develop other problems such as capacitive coupling to the chassis, etc.
Jacques, of course you meant the 100 ohm resistor as the resistor that goes to ground, but if you raised the value of that resistor to 1K or so, the noise in the power amp would still be very low, The main feedback resistor that swings almost all the voltage would then be about 25 times larger or more with modern power amps. This is the resistor that will overheat, if you are not careful.
...was the resistor to ground.
So, the FB resistor itself would be in the <1,000 ohms.
which would suck several watts up to tens of watts... For sure.
sorry for the misunderstanding.
Just to make it perfectly clear: You can use a somewhat higher series resistor in series with the input stage of a power amp, because it operates at a much higher voltage level than a preamp phono stage, or microphone input stage. A 1 Kohm feedback resistor to ground for a PA amp should be OK. Then the main feedback resistor would be 28.2K for a normal home theater power amp, and maybe more or less for some other amplifiers. If you use +/- 100 Volt supplies and presume a full square wave as a worst case output, then the main feedback resistor must have a rating of 100 squared =10000 divided by 28.2K. This is less than 1W, but it is always best to use the largest resistor that is practical in order to keep changes in temperature of the resistor to modulate the output voltage. Still, a 1W resistor can be compact enough to be board mounted and not require an external heatsink. Even a 1/2W resistor (what we use) is good enough with a good resistor and normal operation.
jacques: ""
To avoid burning the PCB, the manufacturer often lifts the resistor a few centimeters above the PCB, on standoff if he's serious, or with the resistors' wires if he's clueless about mechanical vibration tolerance.""
Tis an unfortunate move. Most axial resistors are rated to dissipate power through the leads onto the pc traces. A typical rating for an axial diode, for example, has 3/8 inch long leads, with a specific pad size. It would be better to just dedicate a larger pad for the resistor connections.Jacques: ""
But anyway the open area under the resistor's body creates a loop, in which any induced voltage will be ...in serial with the feedback...Jeeeezzz. Often, this loop is vertical, so that it can get flux from the Earth's magnetic field if the PA is "correctly" set. So, any vibration will translate into a signal. ""Loop, whatsa loop? :-)
I would also be concerned with the magnetic fields that are being generated internally within the chassis, by the xfmr, the power leads, and all the high current leads around the zistors, the output binding posts, everything. I do not see good poweramp wiring design practices much, and the magnetic hash within the chassis will indeed be coupling to the FB loop, especially where it will do the most damage. The half gauss of the earth's magnetic field is small taters.
Cheers, John
The half gauss of the earth's magnetic field is small taters.Yes, but appreciable anyway: Lorentz induction through an area of several cm2 varying about one thousandth by mechanical vibration at 1,000Hz in a field of 0.5gauss would give something in the tens of microvolts, so less than -100dB.
OK, just appreciable ;-)
Jacques: ""
Yes, but appreciable anyway: Lorentz induction through an area of several cm2 varying about one thousandth by mechanical vibration at 1,000Hz in a field of 0.5gauss would give something in the tens of microvolts, so less than -100dB.
OK, just appreciable ;-) ""500 Wrms into 4 ohms, sqr(500/4) = sqr(125) = 11.18 ampsRMS.
Peak I 11.18 * 1.414 = 15.8 amperes peak.
B(tesla) = (μ 0 I)/(2 pi r)
μ 0 = 4 pi 10 -7
1 Tesla = 10000 gauss = 10 4 gaussB = 2 10 -7 10 4 I / r
B = 2 10 -3 I / r Gauss
at 500 wrms into 4 ohms,B = 2 10 -3 15.8 / r Gauss
at the wire surface (r =1mm, or .001 meters 10 -3 meters ):
B = 31.6 10 -3 / 10 -3
B = 31.6 Gauss.
at 1cm, B = 3.16 gauss.
at 10 cm, B =.316 gauss.
Mind you, this field it time varying, and proportional to the output current. AND, if the pos and neg rails or output devices are not equidistant, they will couple differently..meaning, feedback error coupling will be dependent on the quadrant of operation of the amplifier/load.
And, also? The haversine charging of the supply caps. The output current I used? The charging currents through the bridge are a lower duty cycle..at 10% duty cycle, your talking 3 Gauss fields at 10 cm...and they will also depend on which cap is being pulled.
Cheers, John
Haversine = ripple in this case.
nt
jc: ""
Haversine = ripple in this case.""Hi John
Two points of concern..the first, the primary currents of the xfmr, odd order harmonics which are indeed haversines..the second, the FWR current pulses, even harmonics in the secondary loop.
What is never worried about is the fact that the ripple currents within a capacitor, externally, are just a wire. External to the cap case, the difference between a wire carrying the ripple current, and the capacitor itself doing the same, is zero..If the cap is carrying 15 amps of 1khz ripple, the equations I gave here model correctly.
It should be possible to spot the difference between primary and secondary coupling, but that requires test methods I use here but have not seen externally..
Cheers, John
meaning, feedback error coupling will be dependent on the quadrant of operation of the amplifier/load.which brings us back to the previous thread about how the amp behaves under the voice coil back-emf induction.
And, also? The haversine charging of the supply caps.../...
and also the eddy currents induced in the chassis by the above, and their own induction. (should act to mitigate all those sneaky inductions).
Anyway, all these issues are manageable. Twelve years ago, I designed an airborne equipment half analog in the audio band, half digital, which is set in helicopters just beneath the magnetic compass with its exquisite sensitivity, and just above the radar pulses generator...
It worked the first time with those neighbours, and is now certified.
No heavy shields, just a light aluminium enclosure.
But careful layout.
They're fun...:-)Now, take that 500 w amp, and go a bit more:
EMF = -N δΦ/δt N is turns..
Φ = BA = magnetic flux...A is area in meters.
At 10 cm from the wire, BA per cm 2 is:
.316 gauss times 10 -4 T/gauss = 3.1610 -5 Tesla
As a 1 Khz signal 10 cm away, B = 3.16 * 10 -5 sin(ωt) Tesla
Rate of change of B is it's derivative.
ω = 2 pi f, or 6.283 10 3
so B = 6.283 10 3 * 3.16 * 10 -5 sin(ωt) Tesla
= 19.84 * 10 -2 sin(ωt)
If the feedback loop encompasses 1 cm 2 , 10 cm away from a current lead, then..1cm = 10 -2 meters, 1 cm 2 = 10 -4 meters 2
EMF = - 1 * 19.84 * 10 -2 sin(ωt) * 10 -4= 19.84 * 10 -6 sin(ωt) volts....20 μvolts per square cm area.
Now, keep in mind star grounding techniques. They do not consider a time varying magnetic flux environment..It is not inconceivable to imagine 10 square centimeters of loop in a poweramp chassis in the grounding system. So, perhaps 200 μvolts??
And god forbid, some kind of inductor in the output..what, 10 turns? 2 millivolts?
Is that a worry??
Cheers, John
That calculation is of the error voltage after the divider, not before.If it's before, then the error is divided down also. If it is before, it is pure error introduced into the front end.
If it were caused by the secondary haversines, then...it can be somewhat masked by the power output.
If one tries to measure this output current to input error, what would one expect? If it's the output lines, it'll just be a phase shift. If it were one of the rails, it gets more complicated, based on quadrant of operation.
Many good points here; Although I think the resistor effects could well be swamped by the compression and distortion of the loudspeaker.
Low noise is NOT an attribute that high end wants as far as I can tell, and this includes both measurements and listening. It appears that they desire high levels of noise for masking, and the "appearance" of greater dispersion in the loudspeaker. That's my impression of what's going on.
d.b.
Yes, it does, assuming you don't introduce noise through an incompetent implementation of feedback. But the zero feedback amps I'm talking about have S/N in the -100dB or better range.So, it's not noise. the congestion I've heard in SETs and similar designs is pure and simple distortion, and plenty of it; some like it, claiming it gives the music "emotion." I don't; I expect the emotion to come from the musicians, not the preamp.
> Both of these units had much in common: they both clouded up when the music got dense, and both had objectionable and very audible noise.>How can you be certain that what you were hearing was due to the lack of negative feedback?
I'll use your famous line:
"Observational Listening"Isn't that what you consider superior? Isn't that the "ultimate" for absolute sound?
d.b.
..."observational listening" is merely reporting what we hear.Attributing something like negative feedback to any of the deficiencies you heard goes way beyond the normal speculation of any rational equipment reviewer.
Suggesting this might be the case and asking for more testing or information is rational.
"Attributing something like negative feedback to any of the deficiencies you heard goes way beyond the normal speculation of any rational equipment reviewer."
Rational equipment reviewer? ROTFLMAO
d.b.
I really should qualify that; the pro audio folks generally have a lot more on the ball than just about any of the "high end critics"
d.b.
(nt)
Perhaps you should start with LINEAR examples. Class D is very problematic, and so is CD reproduction.
BTW: this fancy shmancy well reviewed CD player appeared to have trouble driving a line level jensen transformer. A Sony unit did one heckuva lot better.
Pitiful John, absolutely pitiful. Remember the good old days when real performance mean't something? Now it doesn't mean diddly squat.
d.b.
Sounds to me that the high output impedance of the open loop CD player distorted the transformer, that is normally not used in most hi fi equipment. Did you check on this?
Far more likely the relatively low input impedence of the transformer which should be no problem for an emitter follower or cathode follower output (it was intended to be used with) relative to the high output impedence of the cd player loaded down its pathetic little output stage. I can hardly believe this conversation.
Of course, cathode, fet, or bipolar followers would have a low enough impedance to easily drive an INPUT TRANSFORMER. But I don't normally use input transformers, so why design followers into the design, if you can get away with just a resistive load? It has been found that followers can be problematic, in that they can ring and oscillate with difficult loads. I once built a line driver for the Grateful Dead sound system. I avoided followers for this very reason. I used transconductance amps instead, which, even with negative feedback, can drive difficult loads more easily. The only place where I find followers mandatory is with power amps, BECAUSE they spit back EMF from the loudspeakers, and can create IIM distortion.
"It has been found that followers can be problematic, in that they can ring and oscillate with difficult loads."Patient; "Doctor, it hurts when I do this."
Doctor: "Then don't do THIS."There's a challenge for you, improve something which can work and has potential instead of wasting time on an idea which doesn't.
"I once built a line driver for the Grateful Dead sound system."
Some people will do anything for money. (A friend of mine was once asked to design a sound system for the Peppermint Twist Lounge which would achieve an SPL of 150 db. He turned the offer down. I guess he had a conscience....or maybe he was just worried about the legal liability of it.)
Don't be stupid. The Grateful Dead was one of the most popular groups in the USA for decades, and they played venues up to 1/2 million people at a time. They put a lot of time and money into making the best sound system that was practical and possible for their performances, for decades. The challenge of this line driver and why I was specifically asked to do it was that it drove one of the most difficult cable loads possible, that could be perhaps 50 yards long. IC's and normal line drivers just could not do it without being troublesome.
Having heard their execrable sound....I'd have been a lot more grateful if they really were dead. However I can see your point of view. A job's a job. Of course, there was always the possibility of a wireless connection. Too late now."They put a lot of time and money into making the best sound system that was practical and possible for their performances"
Given their sound, how would anyone know? Now I know how you judge audio equipment and why we disagree so vehemently. And here I thought you were the one who took clients to SF Symphony performances. My mistake. Don't feel bad, having met PQ in person, he told me he also attends live rock concerts. BTW, how long does it take for your ears to stop ringing after you've been one of them or do you wear ear protection?
Wow! Guess they must have had a bad night, the day you went!
For the record, Jon Meyer and I,( Jon probably designed the loudspeakers for the PA the night that you might have attended, since my speakers were only used up through 1975, were both faculty members of 'The Institute for Advanced Musical Studies, in Montreux Switzerland in 1974-1975. This was a graduate school for classical musicians, and they didn't need me to design them a line driver, since they were loud enough without amplification. I just happened to marry one of the students there, who happened to be a violinist. We measured their output level peaks to about 115 dB. Is this what you call acceptable sound level?
"We measured their output level peaks to about 115 dB. Is this what you call acceptable sound level?"
Well, feel sorry for the classical musicians then. The Institute did a concert version of 'Alexander Nevsky' by Sergei Prokofiev and I'm sure that they exceeded 115dB at that time. Learn and grow, life is more than just saying no, but it does make sense to protect your ears from too much SPL on a continuing basis.
The studies I've seen say classical music rarely gets over 100 db even at the conductor's podium but hearing loss is an occupational hazard among classical musicians. Now, even risk from the auditory impact of noises from electric razors is being questioned. I cannot take anyone seriously when they talk about audio if they attended live rock concerts for a multitude of reasons. I know a guy who has no sense of smell. He wants to sample my wine cellar. Fat chance. The most valuable audio component many baby boomers and others who attended live rock concerts can buy today is often a good hearing aid. Exposing yourself to loud noise needlessly is a very stupid way to injure yourself permanently, right up there with smoking tobacco but then a lot of people don't heed the warning until it's too late. It's the auditory equivalent of staring straight into the sun. I've still got excellent hearing as verified in audiometry tests about a year ago, have you still got most of yours?
It was pretty damn loud the last time I heard Shostakovich's 11th symphony in Tonhalle 2 months ago. Even towards the back where we sat it got uncomfortably loud in a couple of parts. It was the first time I had experienced such a volume level unamplified.
Look kid, I am 64 1/2 years old and I still hear pretty well. Perfect? NO! BUT better than most people my age. Can I still tell sound differences? You bet that I can! In fact, I run into my old friend who was the mixing engineer for the Grateful Dead for about 25 years. He doesn't wear or need a hearing aid. You have your head in an uptight space, sort of like 'second hand smoke' or floride in the water supply.
It makes about as much sense to me to take subjective advice about the sound quality of audio equipment from someone who has been repeatedly exposed to sound at literally ear shattering levels as to take advice on what wine to buy from a guy who regularly smokes cigars. I also find it inconceivable that anyone would suggest they can assess the relative inaccuracies in the reproduction of recordings of subtle nuances in the sounds of the worlds most prized musical instruments when their proclivities leads them towards mediocre music makers performing through electronically amplified sound systems to begin with. I posted once before that I felt you were putting me on but now this new information puts that in a whole new light.
I'm sorry, but when you learn what audio quality is, you always seem to know the difference. I doubt that you even know what it is, as yet. FYI, I ALWAYS depend on the listening input of others, because I might just like a product that I have designed, just because I designed it. It's possible. So far, I have been fortunate that this isn't so.
"FYI, I ALWAYS depend on the listening input of others"Have they also been exposed repeatedly and for prolonged periods to loud rock? Do they also prefer to listen to music which is performed through electronically amplified instruments? Why would their opinions be any more reliable?
"I'm sorry, but when you learn what audio quality is, you always seem to know the difference."
What a self serving, and pretentious statement. For someone who makes judgements ultimately based on audible evaluations alone, not only don't you keep your ears calibrated by constantly feeding them a diet of unamplified musical instruments, not only is the accuity of your hearing in question if due to nothing else than your age, but you have a self admitted history of having exposed it to abuse which might have led to permanent impairment. Your listening instruments are hardly of the caliber of your electronic instruments yet these are what you rely on. And then you ask me to trust your hearing and that of your acquaintenances who for all I know are in exactly the same boat you are in.
" I doubt that you even know what it is, as yet."
There's hardly a day that goes by when I don't listen to or play my 1927 Steinway, or hear live violin music. Sometimes I'll even sit at my Baldwin. That's the quality of sound I have the good fortune to listen to and use and use as a reference. And I must say that at the VTV show as in most other consumer audio shows I've ever been to and at most retailers I've ever been to, ALL of the audio equipment on display is invariably demonstrated using types of music which will tell me absolutely nothing about the equipment's relative merits and shortcomings and the other people who frequent them don't even bother to bring their own recordings. If I don't take this industry or the people who work in it seriously, perhaps this partly explains why.
Soundmind, I perhaps should have said to you: " Appreciation of reproduced sound quality" as you obviously know what real musical instruments sound like, BUT is virtually every example of reproduced sound to your liking? That is my problem and challenge. By the way, what do you know about Strads?
As each individual instrument has its own characteristic sound, you can only generalize but of course there are exceptions. The greatest violin whose sound I am most familiar with is a Guanari del Jesu. It's power is absoultely phenomenal. It is hard to believe you are hearing a violin which sounds as loud as a trumpet. I have heard this instrument in my own home, in other homes, and in concert halls including Carnegie Hall. And like all such instruments, it has a well documented history of its former owners. I am not going to mention the owner's name. Generally Strads have a reputation as being sweeter sounding but less powerful. They are therefore preferred in smaller venues or when playing with smaller groups or solo recitals. The Guanaris are preferred for their big sound when the performance calls for a major concerto with a symphony orchestra in a large hall. They usually have a greater ability to "cut through" and give people in the cheap seats up in the clouds their money's worth. The secrets of the great violin makers of Cremona died with them. Violin makers ever since have been trying to figure out how they did it but to this day, nobody knows for sure. Sadly, many of them are reaching the end of their lives and we will probably never see their like again.BTW, there is a recording made by Rugerio Ricci called "The Glory of Cremona" on Decca which showcases many different great violins. On a companion disc, he plays the opening of the Bruch concerto on each one. When asked to comment about this recording, an artist I knew well said what difference does it make, his playing style tends to mask their differences.
Thanks for the input, Soundmind. Personally, I prefer Strads to Guranari, but I don't think that I ever listened to the 'Guranari del Jesu'. Have you ever been to Cremona see and hear what is there, especially how they build violins?
"Have you ever been to Cremona see and hear what is there, especially how they build violins?"No, the year I wanted to go to Italy, fall of 1973 just before returning to school in Bordeaux France after a summer break....Italy had a cholera epidemic. I got a cholera shot and went to Spain and Portugal instead.
I've known a few violin makers in the US and have seen at least one workshop on several occasions.
"Generally Strads have a reputation as being sweeter sounding but less powerful"This is not mine nor my girlfriend's impression when we DIRECTLY compared a Guarneri del Gesu to a Strad. The strad sounded sweeter, brighter, and most definitely more powerful. The Guarneri sounded darker and still powerful. Her sister also played a Guarneri for some time and the one she had was also darker in character. The prettiest sounding violin she had was the Guadagnini but it was less powerful and more suitable for chamber concerts. The Strad she had sounded absolutely wonderful in Tonhalle's smaller concert hall (still pretty big for a solo violin). In my apartment it could make your ears pulsate (literally). No violin is as loud as a trumpet or trombone.
That being said it varies greatly from instrument to instrument as one would expect for such handmade devices.
"By the way, what do you know about Strads? "My girlfriend had one on loan for a year. Amazing sound and unbelieveable acoustic power. When she played in our apartment I could feel the pressure waves from the instrument inside my ears. Like eardrums Flapping!! And the tone! WOW! She has had other really nice instruments to play(Guarneri del Gesu, Guadagnini, Kappa, and Rocca) but none of them could sound like this one. She was fortunate to have it when she did a concert tour last year playing all 24 Paganini caprices solo in concert. At Tonhalle (smaller auditorium) she needed an instrument with this kind of projection of sound. A lesser violin would not have had the same awe factor.
Well Morricab, since you've heard that violin in both small rooms and presumably when she performed at a concert in a hall, you know that the sound is very different. In a small room, the power of that instrument expresses itself in being very loud but when you are sitting farther away than you could in your apartment or a practice room, while the instrument is softer, it sounds every bit as powerful because it fills a vast space in time, a second or more for each note to die out. And the tone is different too, it's just as clear but mellower. That's the effect of the acoustics of the hall. And if you had a sound system capable of it, and most are not, you might get it to sound like you heard it in an apartment but I assure you with our current technology, you will NEVER get it to sound like it does in the concert hall. That's because unless and until you can duplicate the acoustics, you will not duplicate the tone. I've been working on that problem on and off for 32 years and it is a far more interesting one than which cable or how much feedback sounds better or whether tubes or transistors are better. I can tell you this much from data on about 200 concert halls, the integrated ILG fan response for just about all of them starts falling off at about 2 to 4 khz and is down about 7 to 10 db by 10 khz. Put another way, the RT at 10 khz often runs about 1.2 seconds but at 1 khz it's often 1.8 to 2.5 seconds. Until you can duplicate that, you won't duplicte the tone and until you can duplicate the sense of space and the insturment filling it up in time, you won't duplicate the power of a live performance either, especially a large instrument or group like a symphony orchestra, a chorus, or a pipe organ. If you want to hear that sound, you'll have to hear it live.
I agree with most of what you are saying here except for this:"And if you had a sound system capable of it, and most are not, you might get it to sound like you heard it in an apartment but I assure you with our current technology, you will NEVER get it to sound like it does in the concert hall"
From my experience it is possible to get a sound very close to what is heard in a concert hall AND what would be heard in a small room. The key to the concert hall is low level resolution of the entire reproduction chain. This means speakers that are extremely responsive to small signal input (like an electrostat or horn)and source in electronics that TRULY delve deep into the recordings. IMO, typical mid to low sensitivty speakers will never achieve the resolution of very small input signals due to mechanical resistance and losses in the cones and cabinets. Also, the low level resolution needed to get everything from the electronics is muddied by crossover distortion, which is most problematic at low levels) and feedback smearing over these subtleties (I know you don't believe this but it can clearly be heard when one knows what to listen for). I can tell you from plenty of experience (I grew up with gear similar to what you have) the kind of gear you live with will not dig deep enough to recreate the ambience that is recorded ON THE CD with the right recording.
The next thing it relies upon is naturally recorded ambience and that the microphone wasn't shoved in the f hold of the violin. If they close miked the violin or piano and sections of the orchestra then all bets are off unless the Tonmeister is exceptionally gifted and even then it won't be the real acoustic signature of the hall the recording was made in but the Tonmeister's memory of that venue.
Now I have a few recordings of this caliber and they do sound impressively like hearing the music live up to a medium loud level with my system. Naturally recorded chamber music (Beethoven quartet I recorded of my girlfriend's old quartet) can sound spookily real. I made some other recordings of her and a pianist and a cellist (two separate occasions) in a medium/small concert hall that was empty during the recordings. The reproduced sound is very close to what I heard when standing by the microphones some 4 meters from where she stood on stage and the tonal balance is spot on with proper echoes from the walls and hall decay. Very natural. Is it perfect? No because for sure the room is convoluting and polluting this hall information. But it is still audibly quite close.
"From my experience it is possible to get a sound very close to what is heard in a concert hall AND what would be heard in a small room. The key to the concert hall is low level resolution of the entire reproduction chain."The key to reproducing what the concert hall does is duplicating hundreds of reflections resulting from each note arriving at you uniformly from many different directions in rapid succession over a period of a second, two seconds, or more where the high overtones die out nearly twice as fast as the lower and mid range tones. There are few if any sound systems in the world other than highly experimental ones which can do that. I have one such system. It is extremely difficult to set up, calibrate, and operate properly especially with different recordings. Try a binaural recording instead of a stereophonic recording made around Row "M" or Row "R". Listen to it through headphones. You'll hear two scalar fields so you won't get the spatial aspects of a true vector field but you will get the right musical tone of the instruments at least. That's better than what you normally get from other recordings.
"The key to reproducing what the concert hall does is duplicating hundreds of reflections resulting from each note arriving at you uniformly from many different directions in rapid succession over a period of a second, two seconds, or more where the high overtones die out nearly twice as fast as the lower and mid range tones"Yes this is why low level resolution is of the utmost importance because each successive reflection from a single event gets lower and lower in level, especially in higher frequencies which provide more spatial clues.
In addition, it requires an electronics chain that will not smear the time information of that low level signal. As you noted implicitly it is not just frequency repsonse but timing and low level resolution.
"I have one such system. It is extremely difficult to set up, calibrate, and operate properly especially with different recordings. ... but you will get the right musical tone of the instruments at least."
I simply don't believe you sounndmind. I don't think your system will do a credible job, not with the speakers you have and not with the electronic you are using. I can't put it any plainer than this. As to instrument tone, my system sounds very right to me, my fellow audiophiles and my girlfriend and her musician friends all seem to think so as well. Since I can't get to hear yours nor you mine then I guess we will have just not believe each other.
First of all, the sound associated with the acoustics is NOT on the recording.Secondly, there is no known and likely no possible way to record it if for no other reason than the sound due to the acoustics cannot be separated from the sound directly from the source instruments at the microphones.
Third, it would require at least 4 more channels in addition to the two stereophonic channels to record them if it could be recorded at all, channels only multitrack recorders have.
Today, the only method avialable is to process the existing channels through electronics based on mathematical algorithms designed to emulate the physical relationships of the acoustic itself in order to recreate the kind of field the listener hears at a live concert. This takes many speakers strategically placed around a listening room. This is not the same as quadraphonic or home theater systems and it doesn't sound like them.
There are no special requirements in the sense of "low level resolution" whatever that means for these "auxilliary" sound channels. You can believe whatever you like to believe and fool yourself into whatever you want to fool yourself into but to anyone with normal hearing who is honest, there isn't even a remote comparison between what you hear at a live concert and what you hear from a stero system....any stereo system. While fools waste their time tweaking amplifier circuits, wires, cd players deluding themselves that they are actually doing something valuable, acousticians are tweaking the architectural shape, materials, and baffles in concert halls to mold sound to their conception of ideal. Their supporters contribute millions, even tens of millions of dollars on often dubious expectations of improvement while the audiophile tweakers proclaim every change as a major breakthrough. I've offered this link in the past but nobody has taken me up on it even once, however if you want to actually learn something instead of just your usual yammering and what you get from ad copy, listen to Leo Beranek's lecture on the link below. He was a founder of Bolt Beranek and Newman, the leading architectural consultant in the US, probably the world and his lecture deals specifically with concert hall acoustics.
"I simply don't believe you sounndmind. I don't think your system will do a credible job, not with the speakers you have and not with the electronic you are using."
What do you know about it? You never saw it, you don't understand it, and you aren't really interested in it anyway. OTOH, the US Patent office was interested enough to grant me a patent and at least one company was interested enough to steal it. Funny, even though it offers real hope, few have even bothered to explore what possibliities it offers.
Here's the link to real knowledge nobody will use anyway. Go back to your ad copy, your stereo system, and your delusions.
"First of all, the sound associated with the acoustics is NOT on the recording."Can you actually be serious?? The acoustics and decay of instruments in a real space is easily heard on recordings. How is possible that this information is NOT on the recording?? This information comes to the microphone in the same manner as the direct sound, just softer and shifted in frequency balance. The microphone doesn't care when it arrives nor does the recorder. On the playback if your gear and speakers preserve the phase realtionships between direct and reflected sound and preserves the lowest level signals then your brain does the same thing to separate the reflected from direct just as it would in a real concert hall. I can clearly hear reflected sounds in the hall as well as the settling of instrument decay. It is a pity that you don't even reailze this information exists on the recording.
"There are no special requirements in the sense of "low level resolution" "
Of course there is. Do you deny that reflected sound and room decay are not much lower in level than the main signal? Sometimes more than 50db below the main signal. Information retrieval is crucial to creating an accurate acoustic space of the original recording, whether you have 2 or 10 speakers.
"acousticians are tweaking the architectural shape, materials, and baffles in concert halls to mold sound to their conception of ideal."
Again and again you are confusing the real thing with reproduction. No one here is doubting the benefit of a properly prepared room, whether for listening live or listening reproduced. The only way to have a truly correct reproduction of a venues acoustic is to have zero contribution from the room you put the stereo system into. IMO, puttnig more speakers all around the room could possibly exaccerbate the problem by exciting more room modes and generating even a greater contribution of the listening rooms own acoustical properties. Either way you haven't taken the listening room out of the equation so the soundfield is still a convolution of the recorded space and the actual listening room space. Nobody follows up your link because it is simply irrelevant to reproduced music. It is great if one wants to make their own music hall for live concerts but the criteria are most certainly different.
"What do you know about it? You never saw it, you don't understand it, and you aren't really interested in it anyway."
I know AR speakers from the past (and they were off the pace even in the 1970s with the exception of good bass). So you tinkered and added a better tweeter. I bet the integration between the drivers is less than ideal. Did you at least use a good active crossover? It might interest you though to know that I find 90+% of the things I heard at shows to be less than convincing. Many designers have crap for ears or don't really care about sound. That doesn't mean that the SOTA hasn't improved, it has in many ways, especially in electronics (I too have older speakers...from the late 80s early 90s).
"Funny, even though it offers real hope, few have even bothered to explore what possibliities it offers."
Well, soundmind it can mean only two things: 1) it was ahead of its time and maybe if you are lucky it will be rediscovered and used or 2) No one cares because it is not all you think it is and others dismiss it. Care to give the patent number so I can look it up?
"The acoustics and decay of instruments in a real space is easily heard on recordings. How is possible that this information is NOT on the recording??"Only a small percentage of the reverberation heard in the audience gets on the recording, what is there is inseparable from the direct sound from the instruments and, very importantly it is missing at least one of its most critical aspects, vectorization. In the audience, 90% of the field or more comes from the acoustics. On a recording it's usually far less than 50%, even far less than 25%. This is because the microphones are much closer to the instruments than the audience sits in a live performance and are often highly directional having a cardiod pattern and pointed directly at the musicians. If this weren't true, playing a recording which actually had that much reverberation such as a binaural recording made in the audience through one pair of speakers would make it sound like the performers are inside a tunnel. Most important of all, the recording contains reverberation in two scalar fields, the real reverberation is a vector field. My experiments show that humans are relatively but not completely insensitive to percepion of vertical differences in direction as opposed to horizontal differences to which they are very sensitive. If this were not true, the minimum criteria for reproducing reverberant fields would be eight auxilliary channels, not four and the minimum number of speakers would be 16, not 8. My current setup uses 16 auxilliary speakers in 4 lateral quadrant channels, a previous prototype used 20. The radiating patterns for the reverberant field are very different from the direct field in order that their source be undetectable. (Your friends can't help you out on this one, I literally wrote the book on this problem...so far only a small part of it has been published as part of my patent.)
"Information retrieval is crucial to creating an accurate acoustic space of the original recording, whether you have 2 or 10 speakers."
Most of the information just isn't there on the recording, there's nothing to retrieve. As for playing sound softly, most audio systems can do that. That's not the hard part.
"Again and again you are confusing the real thing with reproduction"
And again and again you are clueless.
"The only way to have a truly correct reproduction of a venues acoustic is to have zero contribution from the room you put the stereo system into. "
That's not possible...unless you live in an anechoic chamber. NOBODY DOES.
"IMO, puttnig more speakers all around the room could possibly exaccerbate the problem by exciting more room modes and generating even a greater contribution of the listening rooms own acoustical properties"
Wrong again and if you don't, you cannot duplicate the concert hall's critical function of directing multiple reflections at the listener from different directions. This is so critical that special architectural techniques are used to diffuse them by providing many convex surfaces as one example of many critical aspects of good acoustics.
"Nobody follows up your link because it is simply irrelevant to reproduced music"
Nobody here listens to Leo Beranek's lecture because they are morons. They have the opportunity to actually learn something from one of the greatest acousticians in the world who studied and designed concert halls over a lifetime and they pass it up preferring instead to yammer on about their imbecillic nonsense about wires and vacuum tubes. They reveal not only their ignorance but their determination to stay that way. Me? I've heard this lecture at least 10 times and learned something new about concert halls every single time.
"I know AR speakers from the past...."
This is a non sequetor. This has nothing to do with AR speakers or anyone elses. In fact this invention was born, experimented with, and patented many years before I even owned an AR speaker.
"it was ahead of its time and maybe if you are lucky it will be rediscovered"
Yes it was far ahead of its time. When I discovered the principles behind it and invented it, the technology to fully exploit it was beyond the cutting edge of technology as digital audio processing was still far too primitive and expensive to take advantage of it. The earliest prototypes used multiple tape delays and analog mixers. At this time, nobody is particulary really interested in it anymore. This is an industry which has died not only from lack of any new ideas but from a loss of interest in and knowledge of music itself. It will likely remain nothing more than a curiousity for those who know me personally and get a demo of whatever prototype I care to show them. I've decided that's the way I want it to stay, at least for the time being. There is a certain satisfaction in having something in this world than nobody else can have.
"Most of the information just isn't there on the recording, there's nothing to retrieve. As for playing sound softly, most audio systems can do that. That's not the hard part."Completely false and it is at the soft end of the spectrum where most systems fail utterly. This is why there is so much talk about having to turn up the volume in order to "wake up" the speakers. There is plenty of low level ambient and acoustic field information on better classical recordings. Most systems play well only in a very small loudness window, usually between about 70-90 db. Below that they lose the ability to keep complicated passages clear and above they start to suffer audbile compression and/or distortion. The better a system can play soft often the more realistic it sounds.
An example:
I have a recording made with a single stereo ribbon microphone (from Royer labs) that uses a blumlein configuration. The recording is of a full orcehstra playing Prokofiev's Romeo and Juliet. The microphone was placed 6 meters from the front of the stage. It sounds very similar to live in a very good system and a disaster in most systems. It has TONS of acoustic information and has such a wide dynamic range that unless your system excels at low levels you have to turn it up way too loud for the peaks (classic problem in a car with classical music). It does not sound like its in a tunnel, it sounds like a concert hall. I would argue that until you have made or heard recordings of this sort yourself then you are merely speculating about the result. I can hear the results and to me it sounds much more realistic than a multimiked session.
The nominal input impedance of the Jensen transformer in question is 10 K ohms. A nothing load for just about any competently designed solid state unit. The Jensen app notes recommend lower than 2.5 kohms output impedance to drive the transformer.
d.b.
Sign over your house and you get an empty box. But man does that box ever sound good. I've got a great little Sony 1 bit car discman 808DK I bought in 1992 for $300 which can drive at least three sets of MDR V6 headphones to very high volume. I'll bet it beats the pants off that so called high end player too.
You'd be the manufacturer:
- Fire the designer, or better have him/her work several years for hi-rel industrial or (better) airborne analog equipment so that he/she learns his/her job.
- Also fire the marketeer who couldn't say: "we cannot sell this crap until we respect enough our would-be customers as to provide them equipment that fits other equipment in the system).
- Have a big party for the founder's requirement, who wasn't able to detect that an high ouput impedance on a line output is a childish no-no. Don't forget to offer him a painting.
High output impedance simply means one has to be careful what he mates the source or preamp to. Long cable runs or reactive input loads are out of the question. But if one stays within the requirements of short cable runs and a resistive high-impedance load, some of the better source and preamp designs happen to have high output impedance (between 300 and 1500 ohms).
Virtually all zero feedback designs have higher impedance than normal. What about a passive preamp?
Virtually all zero feedback designs have higher impedance than normal.Output impedance higher than grossly one kiloohm will strongly react down to the audio band with the interconnect's reactance to shape the frequency and phase response.
It would jeopardize equipment interoperability.
That's why I do think this concept is not respectful of the customer (who should be clueless about these issues).
Anyway, and even without global FB dividing the output impedance, one can design stages with correct output impedance. It just has to be done this way.
What about a passive preamp?
A passive preamp is not really a preamp. The wording "preamp" is excessive here.
It's just an attenuator and/or switch.
Which BTW has better to be fed by low output impedance sources!
Anyway, you must admit that, while it's not possible to design an attenuator with constant small output impedance without strong attenuation, it's perfectly possible to design a no-global FB preamp with correct output impedance.
Nobody's required to design the impossible (but audiophile quakeries manufacturers). Just let us required them to design the difficult and better ;-)
I worked with the company Audible Illusions for several years. The output impedance of the preamp was about 1.8K. This is because it was a paralleled open loop triode. No followers were used. It sounded great, and it is still very successful in the audio world.
I first worried about the rather high output impedance, but I found it not very important, so long as it did not change much with frequency.
My own open loop CTC preamp, using open loop design and complementary fet topology has an output resistance of 1Kohm that could potentially effect an input transformer in a power amp, IF someone chose to use one. Interesting problem.
and used a spreadsheet based calculator to determine HF rolloff at various attenuation levels. With my 75 ohm source, 160 pf cables (two meter), and 133k ohm amp, it is virtually non-existent up to well over 100 khz. I would agree, however, that attenuators or high output Z preamps do not work with every system given all the variables.I did, however, have an amusing exchange with SM on this topic a while back. While the images are no longer available due to an ISP change, download the calculator and plug in my values if you wish to see the curves.
The DACT calculator can be found here
I am amazed.The term "high output impedence" is relative. The higher the input impedence of the following stage relative to the output of the previous stage, the better because both the source impedence and transmission line (interconnect) become less of a factor. This is the reason cathode follower and emitter follower output stages are used in the first place. For a power amp with a 10k input, a 1.8k preamp output could be a problem. For a power amp with a 200k inupt, a 1.8k output should not be a problem. The lower the output impedence of the source and the higher the input impedence of the load the less the effect of the impedence of the interconnect has as well. This is straightforward network analysis. The concept of a so called "passive preamp" is a terrible idea as can easily be seen from the way its impedence interacts with both the source and the load not to mention how it is affected by the connecting wire. OTOH, a 50 or 100 meg audio tapered pot buffered between two active gain stages with barely inches of wire connected to it is not a problem.
"The concept of a so called "passive preamp" is a terrible idea as can easily be seen from the way its impedence interacts with both the source and the load not to mention how it is affected by the connecting wire."
That's why many folks like the "passive preamp". Just think how much entertainment they can have with this.
d.b.
... buffered between two active gain stages with barely inches of wire connected to it is not a problem.for the usual mediocre gain stages you seem to think are transparent. Unlike you, loss of resolution is significant to some of us.
rw
"for the usual mediocre gain stages you seem to think are transparent"You mean like the countless ones used in making EVERY single recording you own?
Take a pane of glass and throw some dirt on it. Look through it at some object and see if you are able to discern the difference when not. Now soil another pane of glass equally. This time look through both simultaneously. See any further difference?Maybe not.
Passive can be VERY good. I used passive for years, until I got the CTC preamp. Passive does put some stress on the length and quality of the cables following the pot, but this can be handled. Just make sure you use a REALLY GOOD POT or a tapped transformer for the level control.
I use DACT stepped attenuators, JPS Labs wire, and Cardas connectors in a case you might find familiar.
I remember the JC-2 well from the 70s. BTW, I saw Brian Walsh's Blowtorch on a visit to Chicago in the spring. That thing is massive!
I became a convert to the potential of attenuators after getting the GamuT CD-1. With its 4 volt output, I was struggling to get a useful gain range with the Audio Research preamp. To make a long story short, I initially tried a $15 Radio Shack sourced component DIY attenuator box and found it worked better. More resolution and a wider soundstage. Why did I need a 12 db gain stage to attenuate a 4 volt output source for a 1.3 volt sensitivity amp using 2 meter cables? The answer I arrived at was - I didn't. While the ARC preamp is nice, it is not sonically perfect, despite the claims of others. It serves duty as phono preamp where I do need the gain.
rw
Soundmind points out something that obvious that you just can't seem to accept. Think about all that negative feedback, and "cheap wire" in the recording chain. Think about all the digital EQ, mixdown & mastering decisions to final pressing.
You poor suffering thing, you have audiophile delusions.
Take two Thorazine and call me in the morning.
LMAO
d.b.
rw
Take your window, and lots of noise, even order distortion, rolled off frequency response, and you get your typical high end tube based system.
BORING
d.b.
...is the part where they look you straignt in the eye and tell you that the eight dollars worth of potentiomenter, switches, jacks, and the box they put it in that they normally charge $1800 for will only cost you $1500 if you buy it today due to a special promotional sale...and because you seem like such a nice guy.
The parts cost for Dan's former $2700 preamp couldn't have cost him more than eight, well call it eleven bucks. I'm sure he will corroborate your claim.
The parts cost was about 1/3 the selling price. 40% of that cost was connected to the front panel. Six deck Grayhill sealed rotary switches are not cheap, neither are the Bourns panel mount pots or the Kilo knobs that go on them.
Semi precision analog does cost serious money.
All a moot point now.
d.b.
P.S. Don't forget the RG174 with the copper clad steel center conductor.
Ask SM is he was being facetious as was I.FWIW, I spent about $8 each for the gold plated Cardas connectors, $55 for the Par-Metals anodized chassis, and around $120 each for the DACT stepped attenuators in my attenuator box. I get it.
Soundmind has every reason to say what he said, because there is so much of the business that is a rip, and it goes right on by most of the critics and magazines.
Clever little clocks? designer cables? Tube amps? (obsolete before it was manufactured) Two inch thick face plates? Not to mention those highly/praised reviewed pieces of junk that have come across my bench from time to time.
d.b.
After all, why spend $3,995 on a pair of 80 watt amps when you can get a Big Lots Dynaco amp that sounds every bit as good in his eyes, er ears for $300? Sounds reasonable to me. (this time did you get the sarcasm?)Two inch thick face plates?
I'm curious as to which audio product you are referring. Never seen one of those!
BBC interviewed a guy in china a couple of years ago who claims he is the largest manufacturer of pins, buttons, and badges in the world. He makes a lot of campaign buttons as well as badges for police and fire departments including in the US. I think he manufactures badges for the NYC police dept. too. He was talking about a campaign button he made for some political candidate in California to be sold at a political rally in a stadium in San Diego. His cost to manufature, 2 cents each. His selling price 6 cents each. Cost to the end customer in California 2 dollars each, one hundred times original cost. This is a lot more typical than you'd think. In volume, most electronics parts are very cheap. The more you buy, the lower the cost goes, especially when you start bidding it out. You want something custom made in small quantities to very high quality standards, you'll pay through the nose. But audiophiles are suckers. They'll pay a 250% markup on a fancy front panel which adds nothing to the value of their product. When you have more money than brains, packaging means a lot. As for the $3995 amps, they're a lot closer to the similarly powered $300 pair than you'd think. An awful lot closer. Take them apart and look inside at what you get. There's a lot less than meets the eye. And the manufacturer's justification? He calls his hit and miss tinkering "research." What an insult to real scientists and engineers who actually do.
As for the $3995 amps, they're a lot closer to the similarly powered $300 pair than you'd think. An awful lot closer. Take them apart and look inside at what you get. There's a lot less than meets the eye. And the manufacturer's justification? He calls his hit and miss tinkering "research." What an insult to real scientists and engineers who actually do.Damn straight, SM! Dan is simply a charlatan with his overpriced amps using "hit and miss tinkering 'research'". What an insult indeed! Well you can now take comfort since he decided to cease production.
For mass market electronics, the suggested retail price is often between 5 and 10 times the actual cost to manufacture. If high end manufacturer's products markups differ widely from this, it is because they are extremely ineffecient at minimizing cost and their markups are lower or they price their products because they feel they can achieve a market niche and their markups are higher. One area which is a joke to consumers are fancy panels and enclosures. They are very expensive to buy OEM or make in small quantities. High end speaker manufacturers produce cabinets built to very high fit and finish standards unnecessarily and they invariably get marred, scratched, gouged in use anyway so that's a complete waste of money from the customer's point of view. Most manufacturers of loudspeakers use off the shelf drivers or custom manufactured variants. You can practically identify them going through a Madisound and Parts Express catalogue. I'll bet Audax pulled its Aerogel line off the retail market because of complaints from OEM customers seeing hobbyists buy them to reverse engineer high end designs. Take the retail price of the drivers and knock down at least 40% to 60% off them to get an idea of what manufacturers pay when they buy them OEM in quantity. That $100,000 pair of VS or Wilson speakers probably has less than $5000 worth of drivers in it, perhaps a lot less. If you are clever enough, you can identify the drivers and build the systems yourself. The single most expensive item in an amplifier is the power transformer. You can buy one hell of a transformer for an amplifier for about $200 or less at full retail. OEM made in China they are probaby about a tenth of that or less. Transformer prices are almost all directly related to their volt-amp ratings. Torroidals cost more than other types. The next most expensive components are the enclosure and filter capacitors. The rest is gingerbread. Here's another example of actual retail markup. In a virtual war over a $26,000 UPS I had with Square D about 20 years ago after it failed one month out of warranty, they agreed to supply replacement batteries not at the $200 each normal price but at $37, their actual cost. Even industrial equipment gets marked up heavily.
If high end manufacturer's products markups differ widely from this, it is because they are extremely ineffecient at minimizing cost...Or, choice "B", limited quantity hand-built components do not enjoy benefits of large scale production.
"Or, choice "B", limited quantity hand-built components do not enjoy benefits of large scale production."Among other things which drive up cost for the little guy. BTW, for many, even most products made this way even by large manufacturers no two are exactly identical. Of approximately 1000 JBL Paragon D44000 loudspeaker systems made in a span of about 15 years, no two had cabinets with interchangeable parts. And for small manufacturers with garage type operations, quality control often stinks. This is due not only to cost cutting but to lack of manufacturing technical knowledge and resources. They couldn't possibly get ISO 9000 certification. Not only in terms of uniformity but in consistant quality of build, mass market products made largely by machine in large modern factories are infinitely superior.
Soundmind, you should really stick to violins. Perhaps you can get a large manufacturer to mass produce them, and get really good results. As you know, your simple attitude toward hi fi equipment, won't work with qualitiy musical instruments, not that people have not tried.
I purchased my first classical guitar in 1960. I already had a very good electric guitar, but when I went to the music store to get strings for it, I casually picked up a classical guitar that was displayed on the wall. I fell in love, and though I couldn't afford it, I purchased it anyway. This guitar was made in Sweden and was called an 'Espania' I loved playing this guitar and took it everywhere. Unfortunately, someone stole it out of my car in 1962, and I was at a great loss. I tried to buy another 'Espania' guitar, but it didn't sound the same. I then tried to buy a Goya (made in Sweden also) but I turned it back in to the music store, because I could not live with it. I then bought the best guitar that I could find in Guadalajara, Mexico in 1963, but I ultimately traded it for a voltmeter.
So where does this lead? Well, every guitar that I had purchased at that time was hand made and cost real money, and each had a different personalty. Being fussy at the time, and finding a 12 string Mexican guitar that I came to love, I stopped looking for my classical guitar replacement for several years.
Now to my point:
However, in 1970, I found a bargain classical guitar in a music store that cost retail for about $50. It looked perfect, played in tune, and in every way that I could see, and even first hear, it was acceptable. I bought it, hoping that it would sound even better after a few months or years of playing. Well it was not to be! It just sounded barely OK, and stayed that way. I finally just gave it away in disappointment. How did the Japanese do it? How did they make a beautiful guitar, yet a mediocre one? Was it the wood, the varnish, the glue, the bracing? I couldn't SEE any difference. Still, it was there! I had bought a MIDFI guitar and I came to dislike it.
It is the same between midfi and hi end.
It is very difficult to make the best stuff possible.
It is like making a race car, rather than a family sedan. If you want to compete with the others, you have to use the BEST connectors, wire, parts, topologies.
Where a mid fi manufacturer will use connectors that look good, they are just gold flashed potmetal. That's how we can tell the difference sometimes. We just use a magnet. Visually, they can be perfect, and even better looking than the 'good' connectors. How embarrassing! This is true with wire, circuit boards, parts, everything!
What about something in-between like the equivalent of an expensive Honda, BMW, Mercedes? Well they are limited production, just like Parasound, where I usually design products. Are there sonic compromises for having to use limited mass production, instead of hand crafting? Of course, and I know them well. Yet, the retail price can be 1/3 what an equivalent amp might cost that is truly hand made. This is NOT the fault of the craftspeople who make the custom amps, but the cost of 'keeping the lights on' when you can make only a few components a week or month and the REAL COST of quality passive and active parts. This is hi end, folks!
There are a small minority of craftsmen in many businesses who go to extraordinary lengths to produce the highest quality products possible but even there, one place or another, many of them fall short somewhere along the line. But for the overwhelming majority of small manufacturers with garage style operations, their products are inconsistant in quality at best.I'm reminded of something which happened over 20 years ago. Another engineer dumped a project on me he didn't want to do. The security manager of the large software development site I worked at had purchased a replacement computer room card entry access system from a company in Central NJ which had just been spun off from a world famous British military electronics hardware company. Shortly after I was to see why with my own eyes. The salesmen who sold this system took me to the factory and gave it a big buildup. After the high level meeting with the plant manager and other top level management, I got a tour of the plant...a garage with a few people sitting at tables hand assembling equipment, a fenced parts crib, and a computer for testing. When 14 card readers arrived at my office, I spread them out on a table. Many of them had different parts from each other, some had obvious short circuits, two even had the same serial number, and workmanship uniformly stank. I sent them all back with a message that they were unacceptable and would all have to be completly reworked or replaced. The manufacturer was furious. It came back a few weeks later marginally better but eventually the entire system was scrapped for one built by a major manufacturer. This is typical of my experience with garage style operators. Even if the founder was "passionate" about his work, those who inherit the business usually aren't and are only interested in cutting every possible corner including quality. I have no issue with hand made equipment...if it is well made. BTW, even the AR2as I recently renovated, built to very high consumer standards would not have passed inspection for soldering to military specifications standards. How lucky I was to have a father who was the Quality Control Manager of a famous electronics company for 14 years which built only military gear.
Craftsmen who are dedicated to building the best musical instruments and have learned their craft over a lifetime by being apprenticed and starting out by sweeping the floor as children are not in this category. They are in a special trade. Don't compare them to the garage manufacturers of high end audio equipment. Especially the ones who farm out their work to prison sweatshops in China.
Soundmind, you are very prejudiced against people who make custom audio electronics for a living. I happen to be one of those people, and I have worked with many audio manufacturers who make similar audio products. Many, if not most of these people, have years of academic training and manufacturing experience. Look at Roger West for example. What is wrong with you?
This is how it is, folks!
It is difficult to make anything perfectly and consistently. First you can personally make a prototype or two and get it going. Then you might make a limited run of 25 or so. Well, soldering every board yourself, gets really old, and so you usually hire a solderer or two to help you. I have ALWAYS hired good solderers. One was Swiss trained, another worked at cable making at Lawrence Berkeley Labs, a third was NASA trained, etc, etc. They also get tired of soldering and sometimes make mistakes. Then, I have to find their mistakes, (never the same one) to get the unit to work. You can imagine how much fun that is.
Now, what about limited production, like Parasound? Well, here comes the compromises, which are minor, but real. Automated production with pick and place machines also involves wave soldering, that looks good to the eye. However, polystyrene caps are mostly out, because the final cleaning will probably destroy them, if not the soldering process itself. Also, the quality of the solder will be different, because I just can't tell some manufacturer in Taiwan to use SN62 solder, in their production line. They also have to make products for Carver, etc, etc, who demands no such solder quality. A pick and place machine always seems to leave excess leads on the components that will tarnish with time, and probably change the sound. Oh well, that's the price of cost savings. Now, what do the mid-fi guys do? They turn everything that they possibly can into an integrated circuit. Good pots? Goodbye! Good IC's? Too expensive! Use the cheap ones that cost a few 10's of cents each. Sony does this, and so does just about everyone else.
I have the greatest respect for Dan Banquer's selection of components. He was trying to do a good job, that should have been acceptable to most anyone. Bourns pots are good!
Bourns pots are not cheap! Audible Illusions uses Bourns pots, as well, and I have independently measured and listened to them. However, TKD is even better and even more expensive, That's what we used in the CTC preamp, and WE had to pay a minimum of $320/stereo pot set OEM for each preamp. It is now almost impossible to get them, because they are not being imported anymore, due to a price doubling at the wholesale level. NOW what are they going to cost?
It is just like buying quality aged wood from a certain tree to make a guitar or violin. It costs money to do it right. The Yamaha guitar that I bought for $50/ 36 years ago, must have taken a shortcut in the wood department when they made the instrument. I can't blame them, but then I didn't like the results, as the funky 12 string of Mexican origin with a large cigarette burn on the front of it, ran rings around it sonically.
Now, please Soundmind, I am not writing this just for you to pick apart, it is for the silent majority who read this stuff and who are interested in why good audio often costs so much, and also to offset then negative propaganda about audio that you insist on submitting.
"Soundmind, you are very prejudiced against people who make custom audio electronics for a living"NO! I am prejudiced against people who set their own arbitrary subjective standards which cannot be verified independently and who are pretentious about them to the point of declaring them to be beyond what others who have set objective standards which can be verified can achieve. Golden eared wizards, the ultimate determiners of what is good and bad who as it turns out have questionable hearing accuity for a variety of reasons not the least of which is a long history of self abuse. As for the so called objectivist manufacturers, their claims are documented and their products are held in the highest esteem by professionals where cost is a secondary factor to performance and reliability, not hobbyists who can and are sold the moon on the strength of their ignorance every day. Having built many A/V projects as a project manager working with A/V consultants and contractors and having worked for one myself for a short boring stint, I know when Bryston has to compete against Crown to bid a job, all the bullcrap they shovel at consumers goes out the window, prices become very competitive, and there's no room for games. You don't sell a three year no fault warranty to pros on inferior parts, weak design, or poor manufacturing standards.
"It is just like buying quality aged wood from a certain tree to make a guitar or violin"
It's one thing to buy selected wood and age it for 20 years to make a violin. It's another to say you can only make an accurate speaker by building an enclosure using Russian birchwood or using 100 pounds of silver in the crossover network capacitors and that's why they have to cost $125,000 a pair. Not everyone out their is both stupid and inexperienced.
If you were a true engineer/scientist in function as well as in training, you would find out WHY one of your designs sounds better to you than another and use that knowledge to produce consistantly better product, you wouldn't be flailing around with wild theories such as which components of harmonic distortion are irritating and which aren't when the whole of it taken together is less that 0.1% of the signal.
"It is difficult to make anything perfectly and consistently."
Tell it the ISO standards organization, that's what they are all about, production units remaining within specified deviation of the prototype and the manufacturer's documentation subject to audit to prove it. ANSI is similar, so are military specifications and contracts. That's how big money electronics is made and sold today.
"Also, the quality of the solder will be different, because I just can't tell some manufacturer in Taiwan to use SN62 solder, in their production line."
If you can't write contracts to produce to your own exacting specifications and enforce them because you don't have the resources of strong purchasing and legal departments that hardly comes as a surprise. That's typical of garage operations.
"Well, soldering every board yourself, gets really old, and so you usually hire a solderer or two to help you"
"One was Swiss trained, another worked at cable making at Lawrence Berkeley Labs, a third was NASA trained, etc, etc. They also get tired of soldering and sometimes make mistakes. Then, I have to find their mistakes, (never the same one) to get the unit to work. You can imagine how much fun that is."
More garage type operations. Professional solderers and wirers are carefully trained and tested to verify their skills. Their work is 100% inspected. This is the function of a manufacturing engineering department. This is what I am talking about when I refer to small time operators. I've seen countless examples of their crap...and I don't authorize installation or payment for it until they repair it and get it right. This is testimony that I will never buy one of your products no matter what is claimed for it. By your own admission, I would not be satisfied with it."Automated production with pick and place machines also involves wave soldering, that looks good to the eye. However, polystyrene caps are mostly out, because the final cleaning will probably destroy them, if not the soldering process itself"
Do you think IBM and other large elecronics manufacturers have the same problems? How do you suppose they handle them?
The resources of large companies which buy, make, or sell billions of dollars of electronic hardware every year gives them the resources to make whatever they need to make to whatever standards they choose to make them. Compared to that kind of power, the little guy has two and a half strikes against him before he even starts. If these big guys aren't competing against you, it's only because they don't see enough profit in it. Count yourself lucky, they'd eat your lunch if they did.
Oh boloney!
Not the point he wants to make, but does make one nevertheless.I know when Bryston has to compete against Crown to bid a job, all the bullcrap they shovel at consumers goes out the window, prices become very competitive, and there's no room for games.
This is standard audiophile bashing rant #304 which he has used before. He is absolutely correct. Prices dominate the equation and pros couldn't care less about the ultimate sound quality. They are far more concerned about watts per dollar, ability to drive a dozen speaker bins without blowing up and getting thrown around by roadies.
I responded to this rant once before. You'll note he didn't counter my comparison. :)
I can't disagree. Chevy vs Ford, Crown vs Bryston, even low cost Parasound vs Advent or many other similar products. The problem is that I prefer to drive a Porsche, because I enjoy driving it, and I prefer not to own a Chevy or a Ford. Why? Refinement.
Can I own the newest, fastest, or coolest Porsche? No! My car is 22 years old, BUT it still drives well, even though I could only get a few thousand dollars for it in the marketplace. It's the same with audio. Most of my audio is used equipment or products that I have designed. Hi end audio doesn't have to be ourageously expensive, but you have to want what it gives you, over mid-fi. Refinement.
"Chevy vs Ford, Crown vs Bryston, even low cost Parasound vs Advent"
What do you expect in an amplifier for only $4000. For that kind of money you're lucky if it works at all."Can I own the newest, fastest, or coolest Porsche?"
Yes! If I wanted one. My next door neighbor owned a 911 Targa. He washed it every day. He stroked that car more than he stroked his girlfriends. One day it almost became his coffin. What a piece of shit...in an accident. Me, I drive a 96 Mark VIII LSC. It's plenty fast....I've got the speeding tickets to prove it. I was in an accident in a Mark VII LSC which was totaled. It was sent spinning on an interstate on wet pavement by a guy who fell asleep at the wheel of his Dodge Daytona. My car was completely out of control hydroplaning, unable to recover from the skid and unable to slow down even with antilock brakes. It hit the concrete center divider head on at 50 miles per hour. I walked away. In a Porche, I'd have been killed for sure. Drive your Porche...if your back can stand being scrunched up in it.
Soundmind, the more I interact with you, the more I find you to be a clueless mean-spirited guy. AR-2's? They sucked then, and they suck now! Does this help you? I doubt it, but then you may have fallen in with Big B's (you know the guy you love in acoustics) law which states: " If you have chosen a speaker and have even modified it, then it is the speaker that you will like most." I would rather have a Wilson, thank you.
Your choice is cars is OK for YOU, but you would never see me driving one. What a dog to drive! Parking? Gas mileage? Real response to local situations? Please give us a break!
However, I bet it is really nice on the freeway at normal speeds, and that it has a great back seat for your other passengers.
Do you know what his "reference" performance car is? Hint: think AARP.Yeah baby!
Cables aside, the gear I use is built by larger scale (in the relative sense) manufacturers who have been around for at least twenty five years. I have visited the Audio Research facility north of Minneapolis. Here's an online link to the factory tour. This is not a garage operation, yet hand assembly of all components is not cheap.Likewise, VTL, and its offshoot, Manley Labs, have been around for a long time as well. I have met Luke Manley before and have spoken with Bea Lamm. They are passionate music lovers who have translated that love to the business of audio. In Luke's case, he grew up in the audio environment with his father's engineering background and work with the professional industry (where he remains today). Despite your mantra of audiophiles blindly buying based upon advertising (VTL and Audio Research do precious little), it was only after auditioning their products that I later came to purchase those products.
Recently, I had the good fortune of meeting Dr. West of Sound Labs in April for a meeting of the Chicago Audio Society. I was invited to join dinner with him and his wife the night before and assisted setting up the system the next day. He is a soft spoken engineer with a passion for music and his products dating back nearly thirty years.
Sidenote: he's not a midget - the Majestics are nine feet tall.
They do zero advertising, BTW. One of the challenges Dr. West mentioned is that because of his relative small demand, getting custom made adhesives and high voltage coatings from the vendors is a challenge. Unlike conventional speakers that use readily available drivers, he has to perform his own materials research and production. Creating the Pro-Stat family of products intended for the pro market has helped focus on durability and reliability across the line. No problems here with incompatible cabinets (or in the case of my U-1s, 100 pound steel frames). You'll no doubt enjoy the fact that they use a Crown Macro Reference to burn in all their speakers initially for an hour at 800 watts. He finds the amp utterly reliable and well suited for such duty. They use the John Curl designed Parasound JC-1 amps for sonic evaluations.
You tend to focus far too often on the minority of companies who do not do the industry justice.
"You'll no doubt enjoy the fact that they use a Crown Macro Reference to burn in all their speakers initially for an hour at 800 watts. He finds the amp utterly reliable and well suited for such duty. They use the John Curl designed Parasound JC-1 amps for sonic evaluations."I'd have done it the other way around. :> )
"You tend to focus far too often on the minority of companies who do not do the industry justice."
I've been in far more factories in far more industries than I can count. After a while you can get a sense almost as soon as you walk through the door what kind of operation they are running and what quality of product they probably turn out. Besides committment, it takes enormous resourses both technical and financial to build and run a first rate plant. It's just beyond the possiblities of most very small manufacturers to acquire this. When it's a family business run like a pizzeria where the owner gets into everything and works 25 hours a day, 8 days a week, you know he is out of his depth and probably in real trouble one way or another. Many if not most small businesses sooner or later fail. Mismanagement and lack of adequate financial resources are the reason in a large majority of cases.
"I'd have done it the other way around. :> )"That is because you are more impressed with the fact that it can run all day at 800watts than its sound quality. Honestly, if I need a beastly amp to run a shaker table at 30hz all day long then its fine but this has no bearing on its sound quality. Clearly, Dr. West sees the Crown as nothing more than the audio equivalent of workhorse and he sees the JC-1 as thoroughbred. I am sure they listened to both before assigning their respective roles, don't you think?
It was a joke.....sheesh. I know you think JC1 is the greatest thing since sliced bread. Well, to each his own. I've never even heard one, what do you know about that. Or if I did, I didn't know it.
It is a good amp but I wouldn't trade my current one for it. However; I would take it over a crown macro reference in a heartbeat.I don't think it was a joke. Given the choice I am sure you would take the Crown, no?
more than talking about the Crown amp with the 20,000 DF. A quick search found eleven posts. Forget the fact, of course, that even Dan will tell you that anything beyond 100 or so is wasted. Not only that, such a figure (specified only below 400 hz) suggests the massive use of NF. It does, however, sport a dust filter!There is a reason why that amp, like the Edsel, was unique. While SM thinks that Crown discovered some wonderful new approach, the reality is that no other designers are that stupid. Now discontinued, may it rest in peace.
It wasn't a joke, it was an insult against me.
NO! That was my other postings.
You are just being dumb, Soundmind. They chose the JC-1's because they drive the speakers properly. If you don't know, you should not venture an opinion. AR-2a's, are these your reference standard?
"You are just being dumb, Soundmind. They chose the JC-1's because they drive the speakers properly."And nobody else's can? How deaf must the rest of the world be not to see that? BTW, I know another guy who would argue vehemently with you about your amplifiers. He'd claim a Japanese manufactured pair of SETs for a mere $250,000 are far superior sounding and run rings around yours.
"AR-2a's, are these your reference standard?"
NO of course not. But in some ways, their manufacture was outstanding, in others it was awful. As a relative economy model 40 years ago, they still produce remarkable bass and their woofer surrounds are still in tact operating perfectly. And they were built like a tank using steel plate frames instead of the cheaper stamped frames used later on in AR2ax. They were sealed with what may have been the best putty on earth, still soft, complant, and stickier than many glues after all these years. Getting them apart without damaging them was tough. But it was worth it. With some creative tinkering, I have turned them into remarkably fine speakers, surprising even to me. BTW, I may be about to acquire another pair of AR9s, a far better choice and performer after some tinkering than anything I saw at the VTV show in May.
Thirty years ago, I was in a listening test with some AR-2 loudspeakers. I thought they were the worst loudspeakers I had heard for a years, that were pretending to be hi fi.
Don't get me wrong, I owned an AR-1 loudspeaker for many years as a student. It didn't have any high's, so I kept trying different add on tweeters. The AR- X series tweeters made of what looked like ping pong balls for tweeters burnt my ears.
Like all speakers of that era. AR2a had a pathetic design for high frequency reproduction. Around 17 years ago, I began tinkering with the problem myself. I copied what other people were doing to see what worked and what didn't. It took me several years to understand the problem. I have come to the conclusion that the issue is definitely not one of cost, it is the very concept used to reproduce high frequency sound fields. The way most speaker designers go about it, there is no single tweeter design possible which can satisfactorily be incorporated to convincingly reproduce the sound of most musical instruments. Given what they do, it's small wonder to me that most of them sound thin and shrill. Unless and until the high frequency problems is solved, a loudspeaker system simply cannot be made to sound like most music, it's that critical. Get it wrong and nothing else can salvage the sound of a speaker system. I have been modifying and revoicing every speaker I own to incorporate my discovery. I'm considering reactivating my AES membership and offering a paper for presentation...if I become sufficiently motivated. BTW, revoicing one usually takes me about 2 to 3 years to get it the way it sounds right to me. So far, original Bose 901 was the hardest because of the direct reflecting principle... 3 years running so far and still struggling with it but results are encouraging. AR2a was relatively easy. I've got a bunch of others people have long ago given up on to rework as well.
Dick Schram was discussing the Parasound philosophy and proud of the fact that they do not engage in frequent updates and incremental releases. Along with the JC-1s (out of sight), you will no doubt recognize the Blowtorch and the newest members of the family, the JC-2 preamp (I think it should have a slightly different name myself) and the unnamed-at-the-time CDP prototypes driving the Majestics.
While the hotel room was far from ideal and really had no treatments, one could get a notion of the performance potential of this setup.
and why should I be. I know what my parts cost is/was, and I know that most audiophiles hear with their eyes. This is nothing new.
d.b.
So, what's the two inch thick front panel audio component?
About 20 odd years ago after a trade show on LI, I bought the demo pair of McIntosh ML-1C speakers they had used for a couple of hundred bucks. I think they actually retailed for about $400 each. In discussing them with a McIntosh rep some years later, he told me that manufacturing the special wood millwork and special extruded plastic piece which constitutes the front grill would have cost more at that time than the whole speaker system retailed for originally. Looking at it, I can believe it. Functionally, it is no better than the 50 cent masonite and linen grillcloth I just removed from an AR2a. Nice to look at but from a user's point of view, needlessly expensive useless gingerbread. A lot of high end audio equipment has that in common. I was amazed at the VTV show how much of that there was, especially those fancy front panels with just two or three knobs on it.As for tinerers (being one at times in audio myself), I am not saying that they cannot come up with superior products, even better than those which are carefully engineered. But that result is usually the product of hit and miss trial and error efforts and because the underlying principles which make them superior are usually not understood even by the tinkerer himself, he cannot generally exptrapolate his success and refine its essence. Each successful model is a "one off" event. OTOH, while lucky unexpected accidents do happen, science and engineering are systematic processes of investigation, determination of concrete facts, and tested results. It is also notable that the products of tinkering are often inferior to mass market products but because of the enthusiasm of the tinkerer himself and his close friends and relatives, they are initially hyped far beyond their actual worth. And of course, hobbyist publications in which they are advertised or those just looking for new products to review and use to maintain interest among their subscribers are not unwilling to show unwarranted enthusiasm for ho hum products as well. Why else would every new monthly issue review equipment which "kills everything else" on the market up to that time.
"science and engineering are systematic processes of investigation, determination of concrete facts, and tested results."WHat about intuition and innovation? These do often do not result from systematic investigation. In fact, many times the most interesting things are learned when an expected result does NOT occur.
I remember once talking to Bill Duddleston, the designer and chief of Legacy Audio, about his (then pretty new) Whisper speaker. In case you don't know, it uses 6 x 15 inch woofers in a compound open baffle dipole configuration. One the back in a damped chamber is one 12 inch woofer. I asked him if this driver was wired out of phase with the main woofers to cancel some of the back wave to minimize cancellation of the front wave. He replied that this is what they had originally intended but had found it didn't work so well until one day suddenly it was working much better. They eventually discovered that the technicians had forgotten to hook them up and they were simply acting as passive radiators and were passively absorbing the back waves off the wall. So in this case an accident resulted in the discovery of a better way to execute the design.
This happens a lot in research labs all over the world but of course its not in any text book. How do you teach someone to be innovative and intuitive? It comes from having a deeply rooted understanding in the fundamentals of your science and then making the proper brain connections when opportunity arises. Unfortunately this simply takes brains, full stop. Some have it and some don't. But it cannot come from raw intelligence with no training (there are notable exceptions of course). The scientific method is a toolbox to allow the innovations to be tested for validity but the innovations rarely come directly from the scientific method.
"WHat about intuition and innovation? These do often do not result from systematic investigation. In fact, many times the most interesting things are learned when an expected result does NOT occur."Science and engineering don't preclude that, in fact they harness it and exploit it to its fullest. Don't you know that science starts with a hypothesis and then sets out to prove or disprove it through carefully conceived and executed experiments and observations? This has nothing to do with blind trial and error. And when someone thinks they've found something new, it gets tested over and over not only by the original inventor but by collegues who are also skilled and can find the merit or flaw in a new idea. Ever heard of cold fusion? It was the joke of the scientific world in the 1990s. Hailed as a revolution in energy, it was refuted by physicists as a mistake made by some chemists. So was the South Korean geneticist who is now in jail for his fraud regarding cloning. By the standards of the high end consumer audio industry, proponents of these invalid concepts and false claims would still be touting their discredited theories as fact to this very day. The difference between science and engineering on the one hand and what golden eared audio equipment tinkerers do on the other is that real technological breakthroughs are built on proven facts, not wishes, dreams, and delusions.
"This has nothing to do with blind trial and error. "Of course it does sometimes! The theory doesn't tell you what you need to know about how to conduct the actual experiment. This is why in science courses they have the classroom studies and the laboratory studies. What you learn in the lab course is NOTHING like what you are learning in the classroom course. Once you get to the Ph.D. level, they take that your classroom background has put you in the top 20% or so of University chemistry graduates. Now it is all lab work and this, quite frankly, is often about trial and error and a feeling for equipment, chemicals and such.
Many very successful students in terms of classwork fail miserably in the laboratory because in many ways it is so unstructured compared to the classroom. Understanding chemistry, physics, or engineering takes discipline and focused study. Actually using it in the laboratory to test interesting hypotheses requires creativity and you find very quickly which of your colleagues have it and which do not.
Since you have never gone through this process of self-discovery and I have, I suggest you have no idea what is involved in the creative process of science. You should stick with quality control. It is good to have people like you who can sweat the details for those who are actually inventing the stuff. How many different light bulbs do you think Edison actually had to make before he hit on the right formulation of wire coating? You think each one was guided by theory? I am sure there was much trial and error. You seem to think things spring forth fully developed, typical of an industrial engineer who has never been on the inventive end of science or engineering.
"Once you get to the Ph.D. level, they take that your classroom background has put you in the top 20% or so of University chemistry graduates. Now it is all lab work and this, quite frankly, is often about trial and error and a feeling for equipment, chemicals and such"I hope I'm not standing anywhere near you....when you reach for that vial of sulfuric acid.
"I suggest you have no idea what is involved in the creative process of science."
You don't have a clue. Besides my own education, in case you missed it in one of my other postings, for twelve years I worked for the largest scientific research consorteum in the world. And that's just one place I've rubbed elbows with scientists daily over my lifetime. I've been in more labs than I can remember...and designed and built many of them around the experiments they were designed to conduct too.
Stick to your chemicals...preferably water. It's not completely safe but it's less dangerous than most of what you probably have access to.
"I hope I'm not standing anywhere near you....when you reach for that vial of sulfuric acid."You have no clue, period! We are not talking about the mundane aspects of lab work. Proper handling of materials is one of the first things taught in any laboratory (at the high school chemistry level no less). If you had a clue you would know this.
"worked for the largest scientific research consorteum in the world"
yeah doing what?"And that's just one place I've rubbed elbows with scientists daily over my lifetime." "I've been in more labs than I can remember"
Rubbing elbows doesn't make their intelligence and insight rub off on you, soundmind. Do you think walking into laboratories makes you a scientist? If so then the cleaning ladies that come into MY laboratories (I have two that I am responsible for) would also qualify, as I am sure they have been in more labs than you even if it is to mop the floor. I have rubbed elbows, performed experiments with, written peer reviewed papers with, and given presentations in front of hundreds of other scientists for the last 15 years, so you will forgive me if I think I know more about what is involved than you.
Please, soundmind, give me a break, you are no scientist and rubbing elbows with them doesn't make you one even if it helps you to parrot their way of speaking. Please point me to one publication where you contributed sufficiently to have your name on it. You claim a patent, show me.
"stick to your chemicals...preferably water. It's not completely safe but it's less dangerous than most of what you probably have access to."
It frightens me to think of anything large in mechanical or electrical that you *might* have had a hand in designing. That is if any such thing exists. FWIW, I have never had a serious chemical burn, poisoning nor have I ever destroyed expensive lab equipment (but I have singlehandedly repaired half-million dollar high energy laser systems). On the other hand, I have designed and built my own analytical instrumentation. I have posted the link to the commercial manufacturer before.
Sorry the Whisper uses 4 x 15 inch woofers per speaker just to get my facts straight.
Nice to look at but from a user's point of view, needlessly expensive useless gingerbread. A lot of high end audio equipment has that in common.Needlessly expensive? That is a relative statement. The front panel on my Audio Research preamp, for example, runs about $120 and the knobs about $15 each. It is both engraved and painted. I replaced the original silver flavor with black for cosmetic reasons. Sold the silver ones on Agon. While the cabinet doesn't affect sound quality or longevity, their mil spec construction does. One can effectively maintain it forever. Like my Omega Flightmaster watch, I like precision built gear. Not expendable made in Taiwan stuff like my Toshiba DVD players or Kenwood receiver.
Other pics found here
$15 each for a $2 knob? Aren't you going to swap them out for those wooden ones for a mere $500 each? Think of the sonic improvement you'd get for only another $2000. As for your front panel, are you intending to rack mount that preamp? The handles will come in handy if you do when you have to insert or remove it from the rack each time. BTW, that circuit board doesn't look like glass epoxy to me. Is it? Looks like there are only two tubes in it. One relatively modest sized torroidal transformer, and a bunch of resistors, capacitors and jacks. How many thousands did you say that set you back? If what John Curl said in his posting is right, how do you suppose they got all of those polypro caps on those PCBs without damaging them. This was not a hand soldered board.
$15 each for a $2 knob?Tell me where you can buy a black anodized aluminum knob with engraved indents for two bucks.
Aren't you going to swap them out for those wooden ones for a mere $500 each?
You confuse me with someone else.
As for your front panel, are you intending to rack mount that preamp?
Nope. Came that way. Handles do make moving it around a bit easier. Especially the 80 lb amps.
BTW, that circuit board doesn't look like glass epoxy to me.
Look again.
Looks like there are only two tubes in it.
Yes. The nine is a hybrid. The phono and line stages each use a dual triode and an FET.
How many thousands did you say that set you back?
Bought it used for $900.
If what John Curl said in his posting is right, how do you suppose they got all of those polypro caps on those PCBs without damaging them. This was not a hand soldered board.
One of the things I like about you is that you love to stick your foot firmly in your mouth. Take a minute and follow the factory tour link I provided. Yes Virginia, all Audio Research circuit boards are hand stuffed and soldered after extensive cleaning.
E-stat, the preamp contains both rel and Wonder caps, probably polypropylene. IF the yellow ones say RT on them, then they are polystyrene (they are the same brand that I use. The resistors appear to be 1 or 2W Resista resistors (my favorate).
Since Audio Research and I compete with each other, it should not be any surprise that we use many of the same parts, just like auto racers might use the same brand of tire.
Any technical reasons for your choice?
d.b.
Since I poached the picture from the Audio Research Database (independently operated website), I took the cover off my unit to take a closer look.You are correct about the REL PPMFs and the Wonder caps. Both are metallized polypropylene. The numerous white Multi-Caps used more prominently in the signal path of both sections, however, are polystyrene.
Being the audio gourmand that he is with his Dynaco and aged H-K components, SM wouldn't know a polystyrene cap if it bit him. He's quite happy with electrolytic coupling caps in the signal. :)
E-stat, apparently Soundmind believes ONLY in ABX testing, rather than just listening for yourself. Trust me, Audio Research picked those caps precisely because of how they worked in that circuit. Part changing at this level would be a real problem. I am familiar with each and every type cap that is used here. I am lucky in that my DC coupled designs do NOT require ANY coupling caps, from MC input to power amp output to the speaker. However, Audio Research is not so fortunate, so they had to evaluate and assign each and every cap in their preamp at its assigned place. I am sure that they assigned the best caps possible, for each location.
If you're so smart, why don't you answer Dan's question about the technical justification for selecting poly capacitors. Do you want to claim you could hear the differences between them in a DBT?
Testing various capacitorsDon't forget to follow link to see the dreadful performance of the electrolytics.
Typically, all gain stages add distortion components to the signal. Do you know of any perfect ones? I find it logical to use additional gain and/or buffer stages only when they are needed. It seems the reviewer from Widescreen published on your website of the SCPA 1 agrees with my first point. And likewise disagrees with your commentary regarding tube equipment finding an Audio Research preamp musically superior to your stuff."As you might expect, the $10,000 vacuum tube ARC preamp sounds harmonically richer and more detailed while presenting a more three-dimensional image".
Indeed, he does give your (former) product a nod for "it seemed to add virtually no objectionable colorations" and does well in the bang-for-the-buck quotient. Well done.
I would quickly acknowledge, however, that if indeed your pre to power amp run were 50 to 100 feet as you indicate was your design criteria, then I would agree that you will need a preamp. In that case, I'm sure my Audio Research unit would have worked out better than the attenuators in my system.
It's coming to my bench in the near future, and if I manage to remember I'll measure that.
That's interesting, I now use a preamp with Zero feedback and I hear exactly the opposite. The dense orchestral passages have better dimensionality, and much more tonal texture, one which is consonantly truer to the sound of a real instrument. I hear no unusual noises, and if anything, s/n ratios seem to have increased over the previous designs which used feeback. That, because of circuit topology changes, is not a true and valid comparison for use or non use of feedback..
That being said I do use an amp which employs feedback, so no technology seems to have a stranglehold on good sound (at least to my taste, speaking subjectively).
One of the most vexing problems I have in assessing sound is trying to find a decent transducer: one which is phase and time aligned. I believe too much wasted time and space are spent trying to correct the problems of the transducers. If we did have a time and phase correct transducer with adequate FR, maybe amplifier and cable designs will converge. It sure would make life easier.
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