 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
71.136.68.224
...the technically oriented members might find this interesting.
Follow Ups:
"But a serious problem remains. “It can happen that an amplifier measures well and just sounds bad,” admits TI’s Belnap. This statement does not in any way side with what many engineers consider to be a delusional movement among high-end audiophiles—the sort that demagnetizes vinyl records and seeks out hand-braided, gold-plated unobtainium speaker cable. It is rather to admit that the human ear is sufficiently sensitive and adaptable that there is no one quantitative test that can predict how a given DAC, amplifier, and speaker combination will sound to experienced listeners."The market will force behavior change, but not admission of error. Cognitive incompetence prevents that.
x
As Dan B said below, the audibility was measurable in these tests. It also shows that, in these cases at least, sometimes when we think we've measured it all, we haven't. I'm certain their are measurements that correlate to what we hear in amps, cables, etc. I can't prove it, of course - but hopefully someone who can will attempt to do so.
If you read the article carefully they do find the measurements that correlates to what people are hearing. There is no mystery.
Objectivists score again, dysfunctional illiterate subjectivists lose another.
d.b.
Once again you miss the point. The point is that it is LISTENING that pointed the way to the correct metrics and not the metrics that directly led to the good sound. Without the listening they would not have known that the result was anything less than "perfect". After all with their standard tests that is what they got, right? "Perfect"?As I have advocated for a long time now, the metrics must follow and correlate with the listening and not the other way around.
"As I have advocated for a long time now, the metrics must follow and correlate with the listening and not the other way around"Let's remind everyone here what exactly it is you advocate.
You advocate no negative feedback and tubes. By definition you advocate high audible distortion, high output impedance that not only effects FR but bass response, and poor S/N ratios, which by definition decreases the dynamic range of digital audio. Let's sum it up as you prefer gross non linearities and high noise in your playback.
Good thing the rest of the world has rejected you "view" and for good reason. The facts speak for themselves.
Face it: you are just another dysfunctional, illiterate, critic with an agenda that is as bankrupt as the spam I get from Nigerian bankers.
Have a nice day;
d.b.
"Let's remind everyone here what exactly it is you advocate.
You advocate no negative feedback and tubes."Wrong Dano. I have made it clear that I don't have a bias against transistors per se and also made it clear that both of the amps I own are in fact hybrids and not pure tube or transistor. Where does that leave your statement? Also, while from experience I have found that non-negative feedback designs sound better I have owned in the past amps that had feedback (even recently), which sounded pretty good (they had only 10 db of it though).
"By definition you advocate high audible distortion,"
This statement is simply not true Dan and I challenge you to prove it. Low order harmonic distortion is far less audible than high order distortion and you know it (you even claim it on your website for chrissakes!). High output impedance only affects the FR significantly if the speaker has an outrageous impedance curve. Many tube and hybrid amps have very good S/N ratios (I have stated that my amp is dead quiet into 103 db speakers, can yours claim the same?) and a wide bandwidth (-3 db at 80Khz as MEASURED by a Dutch magazine).
So, no high noise, no bandwidth restrictions, no S/N problems and a very pure sound. The fact that you are not even aware that these kinds of amps exist is a sad telling fact to your blindspots. I find it funny that you think one needs negative feedback to design an amp with good measurements in these areas. At 1 watt my amp has less than 0.1% THD and nearly all of it is 2nd harmonic. The next harmonic is 20db further down and the 4th and 5th are 20 db more below that. There is nothing above the 5th and the noise floor is low low low and more importantly not signal correlated as stated by Crowhurst for high feedback amps.
"The facts speak for themselves."
Yes they do. Many high end designers have rejected negative feedback or at least reduced it in their designs because it sounds better when an amp is designed more linearly to begin with and using less feedback simply sounds better in most cases. Again, who cares about mass market electronics, Dan? As if Johnny and Sussie teenager give a rat's ass about sound quality. The electronics industry wants cheap and fast so they can sell millions of items. Small and portable is also good to them. Specs are easy to achieve, good sound is not. I find it telling that this is your benchmark for "good" audio engineering.
The ironic thing is that you think they do it as a marketing ploy and don't really believe in what they do. HOwever; by your own admission this is killing the industry, if that were so then it would be a pretty bad idea to go down that road, wouldn't it? So clearly most of them believe it results in better sound to get the feedback out whenever possible.
:This statement is simply not true Dan and I challenge you to prove it. Low order harmonic distortion is far less audible than high order distortion and you know it (you even claim it on your website for chrissakes!). High output impedance only affects the FR significantly if the speaker has an outrageous impedance curve. Many tube and hybrid amps have very good S/N ratios (I have stated that my amp is dead quiet into 103 db speakers, can yours claim the same?) and a wide bandwidth (-3 db at 80Khz as MEASURED by a Dutch magazine). "YourS/N ratios are at full scale, and they still are terrible. I designed and built one so it measures -104 db at one watt, at full scale it is 120 db. Once again because you refuse to understand that db is a relative measurement, and becasue you misunderstand you misinform others, due to your own either ignorance or political agaenda.
I have informed you of this in the past and you still refuse to even begin to understand.
The audible distortion of units without negative feedback is well known and already well characterized, measured, and the measurements speak for them selves. This one of the reasons why the rest of the world uses negative feedback.
Audio perverts who are demonstrably ingnorant, illiterate and dysfunctional, continue to insist they are right. Well so do the mental patients in locked wards.The rest of the world has spoken.
Seek professional help; your propaganda is based on total and utter falsehoods. In the rest of the world's opinion, you are at best misinformed, and at worst a propagandist for outrageous lies.
d.b.
"YourS/N ratios are at full scale, and they still are terrible. I designed and built one so it measures -104 db at one watt, at full scale it is 120 db. Once again because you refuse to understand that db is a relative measurement, and becasue you misunderstand you misinform others, due to your own either ignorance or political agaenda. "Dead silent into a 103 db speaker is dead silent into a 103 db speaker and needs no apologies. If you hear no noise, whatsoever at with a speaker like this then you can hardly call it a noisy amp can you Dan? Are we after pure specsmanship or are we talking about audibility? Have you ever had your amp strapped to a 100+ db speaker and heard NOTHING, not even the faintest hiss? I understand perfectly that db is a relative measurement but I also know that most amps will fail the test of hearing no noise into such a sensitive speaker...with or without negative feedback.
"The audible distortion of units without negative feedback is well known and already well characterized, measured, and the measurements speak for them selves."
References please, otherwise this is a baseless claim.
"The rest of the world has spoken" Again, the rest of the world listens through shit ipods and shit headphones...if that is who you cast your lot with for good sound then maybe its best your company went out of business. The much of the hifi industry has retreated from high feedback designs in the pursuit of better SOUND. Maybe you have heard of this? The rest of the industry has different goals than absolute best sound so your claim to the industry is a red herring."Seek professional help; your propaganda is based on total and utter falsehoods."
Your the bitter old fool who had to dump his company, not me. I find it funny that you now try to bite the hand that fed you (at least partially, no?).
Other professional engineers have changed their views in light of experimental and listening data. Crowhurst warned of the problems with negative feedback all the way back in the 1950s (even before transistors were a real product) and we are talking about modest amounts compared to what is used with SS amps. Otala shows how back EMF can have serious audible consequences with high feedback amps. Boyk and Sussman show how in many cases negative feedback has a serious effect on the harmonic distribution. Cheever shows how with his metric amps with negative feedback give a worse result and with listening tests as well. There are other sources as well. So where is your evidence that non-feedback amps sound like shit? References???
One of the things that Boyk and Sussman do is to look at a common-source FET amp with source degeneration, using an idealized FET model. In this model, the device by itself has only second-order distortion. They evaluate three different configurations, corresponding to three different levels of feedback. Yet they only show data for two of the three configurations. The data for amplifier c, with the highest amount of feedback, is not shown. They state, " The spectrum of amplifier c is not shown. Its additional feedback compared to b makes for a distortion spectrum which is similar except that all of the products are pushed down in level ". I'll return to this idea in a moment.Cheever makes his point in a way that's easier to visualize than Boyk and Sussman's approach. He deals with harmonic distortion only. Using the same approach of assuming the open-loop amplifier has only second-order distortion, he shows the relative values of fundamental and various orders of harmonics as a continuous function of the amount of feedback applied. He shows that the relative values of the higher harmonics rise as the amount of feedback is increased from zero, then decrease again as feedback is increased further and further. Of course, the higher-order products were assumed to be zero without feedback, so in this case feedback cannot improve higher-order harmonics by the definition of the problem itself.
But this raises a practical question, and that is, "What practical device has only second-order distortion when no feedback is applied?". The answer to this question is "None". The quadratic equation used by Boyk and Sussman to model the JFET is an empirical curve fit, chosen for ease of hand computation. A more accurate equation relating drain current to gate-source voltage based on the device physics is more complex than a simple quadratic (Ref: Massobrio and Antognetti, equations 3-11 and 3-12 ). This is also borne out by measurement.
This raises yet another question, and that is, "Has anyone done actual measurements of a JFET amplifier with varying amounts of feedback to determine the harmonic levels as a function of the amount of feedback applied?". The answer to this question is "Yes!". Peter Baxandall, in his series in Wireless World from 1978 to 1979 does exactly this. In fact, if you look at the graph of harmonic levels vs. feedback in the Cheever thesis, this was taken from these very articles by Baxandall. They are not Cheever's own work. But Baxandall overlays the actual measured data from a JFET amplifier on top of these theoretical plots, allowing one to see the effects of feedback on a practical amplifier.
Quoting Baxandall, here are some of his results for the JFET amp. "...referring again to Fig. 7, 16.5 dB of negative feedback is sufficient to reduce the third harmonic to the same level as it has without feedback, whereas about 35 dB is required for reducing the sixth harmonic to its no-feedback level" . He also goes on to say, "The magnitude of harmonics of extremely high order will be increased by the application of negative feedback, no matter what practical amount of feedback is employed. But this is of no consequence if, when thus increased, they are, say, 120 dB below the fundamental ".
I have a PDF of these documents. The first four articles in the series would be an excellent introduction to feedback for those with a scientific background, but no formal EE introduction to the subject. If anyone is interested, just shoot me an email through the forum system. It's a 3.4 MB file, so keep that in mind.
Thanks very much Andy. Many years ago I saw part 5, but not part 6, and there are many facts that are brought out in this series of articles.
In part 5, it is interesting that Baxandall proves that the parabolic approximation cannot hold up at low currents with a fet, and higher order distortion is inevitable when fets are operating well below their normal working current.
Another factor, new to me, was the curve in fig 3 of part six on p.69. In 1973, I had asked Dr. R.G. Meyer, a professor at UCB whether there was a distortion minimum for higher order harmonics such as 5th. Dr. Meyer already knew about the 3rd harmonic cancellation with 3dB of feedback and derived the fundamental equations in class. I was curious about the higher order harmonics as well. He apparently had not considered this as important at the time, but I certainly did. Baxandall also pointed out the polarity of the harmonics in part 6. This is something that most people do not know about, but it can be important in serious audio design. This is the sort of thing that we should be talking about and even debating, rather than the usual.
Many years ago I saw part 5, but not part 6, and there are many facts that are brought out in this series of articles.
In part 5, it is interesting that Baxandall proves that the parabolic approximation cannot hold up at low currents with a fet, and higher order distortion is inevitable when fets are operating well below their normal working current.I think this sequence of articles is about the best out there on this subject. Regarding the FET characteristics, I was coming at it from the angle of the Massobrio and Antognetti device modeling book I referenced above. Though it's nominally a text about SPICE modeling, a major portion of the book is concerned with deriving equations relating the terminal currents and voltages of the device based purely on considerations of device physics. The formula they get for a FET is pretty messy, involving, among other things, a square root term with Vgs cubed inside the square root. Then they show the usual quadratic approximation with a graph comparing the two. The graph shows them to be very close. What I took home from this was that the simple quadratic approximation was not based on device physics at all. Rather, it just happens to be a pretty accurate and much more convenient approximation to the formula obtained from device physics. I could scan these pages from the book and send them to you if you're interested.
This is the sort of thing that we should be talking about and even debating, rather than the usual.
Amen! Technical discussions are what this forum is all about. I don't know how it turned into the nightmare it did. I think people realized that it was essentially unmoderated, so they know they can come here and create havoc.
I was looking at part 6 with the BJT results. It seems to me that with BJT amps in particular, typical feedback levels are usually over 20db to adequately reduce the gain. Is this correct? If you look at the graph it is clear that for higher harmonics, up to about 40 db of feedback the 6th harmonic (and presummably it gets even worse for the harmonics higher than the 6th) is significantly higher than with no feedback. However; aren't there stability issues if you use so much feedback? At 20db, other than a lower 2nd and 3rd harmonic, all other harmonics are higher in level than with no feedback.The nulls created by phase of the distortion are interesting but notice that they don't occur at the same amount of feedback for each harmonic. So it doesn't seem like it would be possible to design an amp with feedback to "catch" all of these null points, thus minimizing feedback and lowering distortion.
Hi Brad,I think John answered your question above. But there are a few things I want to add.
First, these distortion percentages (and also the relationship of higher-order terms to the fundamental and lower-order terms) are not a fixed quantity for a given level of feedback! They vary with signal level. This is discussed by Basandall, but I'll summarize the results below. In order to get the numbers he got, Baxandall had to assume some value of AC current swing relative to the DC (bias) value. So "signal level" in this context represents the variation in device current relative to the DC current value. He chose those values both to simplify the theoretical distortion computation, and also to induce plenty of measured distortion so the effect of feedback could be assessed easily.
So how do the distortion components vary with signal (current) swing? Per Baxandall, and provided gross distortion is not occurring, the following relationships apply:
1) Percent second harmonic distortion is proportional to signal level
2) Percent third harmonic distortion is proportional to the square of the signal level
3) Percent fourth harmonic distortion is proportional to the cube of the signal level
4) Percent fifth harmonic distortion is proportional to the fourth power of the signal level
...and so on.These relationships describe the so-called "weakly nonlinear" behavior of class A circuits. They are a direct result of the Taylor series representation of the circuit's nonlinear transfer characteristic with a sine wave input. It should be noted that with topologies for which transistor switching occurs, such as power amp class AB output stages, these relationships do not apply. Let's temporarily ignore the class AB case so we can focus on what Baxandall's results show.
One could view the relationships listed above as a "glass half empty" or a "glass half full" situation. For the "half empty" perspective, one can see that as signal level (current) increases, the higher-order terms will rise very fast. For the "half full" perspective, you could say that the higher-order terms go down very fast as current swing is reduced.
Is there a way to take advantage of the "half full" perspective? Yes! The key (for class A stages) is that the quantity we're interested in is voltage , not current. For the type of gain stages normally used (common-base, common-emitter, common-source and common-gate), the voltage gain is proportional to the load impedance of the stage. If we make this impedance larger and larger, then for a fixed voltage swing at the output (what we want), the current swing required gets smaller and smaller. Because the required current swing for a fixed voltage swing gets smaller and smaller as the load impedance increases, the higher-order harmonics go down and down at a very fast rate. But now, because of the high load impedance, we have this high voltage gain. But the needs of the circuit are for only moderate gain. What do we do with the extra gain? It's used to provide high feedback. I hope you can see the cycle here. The increased load impedance makes the current swing less for a given voltage swing, reducing the distortion for a given voltage swing requirement. But the increased voltage gain also results in increased feedback, further reducing the distortion. So we get a double benefit here. Of course, the amount of feedback has to be limited because of stability considerations, but that's a separate topic. But this is the general idea of high-feedback amplifiers. Note that this situation does not fit the false dichotomy often mentioned in connection with the low-feedback vs. high feedback debate. That false dichotomy is "Have high distortion in the open-loop amplifier and cover it up with high feedback" vs. "Make the open-loop amplifier as linear as possible and use low feedback". The example above clearly shows the open-loop amplifier is getting more linear as the amount of feedback goes up.
So here's something to think about. Because of the points (1)-(4) above, what can you say about the applicability of Cheever's distortion formula?
Thanks for clarifying a few things for me. I already had the jist of most of what you were saying but the explanation regarding load impedance and using feedback to an advantage there is interesting.However; you said, "Of course, the amount of feedback has to be limited because of stability considerations, but that's a separate topic. "
But this is pertinent to the situation because it is a limit as to how much feedback you can apply to a given circuit. This also then would have an effect on where on these distortion curves you end up.
I see the exponential increase in high order harmonics with level as a big no no in general and that it largely negates the advantages of reducing lower order distortion. Audibility of distortion is for me one of the major issues and underplayed by many engineers.
I assume when you say Class AB is different you mean that it is more strongly non-linear? Crossover distortion being one serious issue (and not fixed with negative feedback). What are some others?
"The example above clearly shows the open-loop amplifier is getting more linear as the amount of feedback goes up."
Linear in terms of total distortion yes, but at what price to audible harmonics?
From Cheever's thesis he seems to focus not so much on the amp mechanics but on the resulting distortion PATTERNS that are coming out of them. He has derived an audibility pattern (he calls Aural harmonics) that is level dependent (he has dbA in exponential term) and gives strong weighting for audibility towards high order harmonics (the n11 term in the denominator).
Unless very large amounts of feedback are used, the higher order harmonics will increase significantly when feedback is applied. Cheever claims that these will be much more likely to be audible than relatively high levels of low order harmonics (although already the third must be a small fraction of the 2nd to be inaudible according to his aural harmonic sequence). However, stability is an issue limiting most amps in the application of feedback. I don't say his metric is right but if he is right about the audibility of these harmonics (ie. his aural harmonic series) then it seems clear to me that amp design should focus on making a pattern that is similar or lower at each harmonic than this pattern. In the real measurements I have seen, I don't see this happening.
Brad, I'll get back to you a bit later tomorrow. You raise some very interesting points, and it's clear to me that I should explain my position better. It's much easier for me to talk about mathematical things than it is to express my views about the Cheever thesis (which I also hope to do briefly in your thread at the top of the page). Stay tuned, I haven't forgotten you.
Sometimes.
One cannot easily use the nulls in the distortion, but you can see the trend, and avoid worst case.
I would very much appreciate any input on a more accurate fet model. Also, device manufacturing techniques, such as diffused or ion implantation many change the transfer function also. It is sometimes obvious when changing manufacturers of the same part number fet.
Hi John,
Do you think more modern Fets will have the same behavior as the ones measured by Baxandall? The question then would be, do they fit more closely to a quadratic relationship or do they deviate further?
FET's MUST deviate from their quadratic relationship as they drop further away from their normal operating current, or they would exceed the physics limit of Gm/I =40, because the change in Gm in fets is normally slower than that of bipolar transistors with lower current.
Okay, I'll scan the relevant pages and email them to you. Device physics is not my thing, so I couldn't follow it in detail.There may be multiple emails, as I can't zip them together because of the Mac/PC thing.
Andy, I appreciate anything that you can do. It is difficult to get real insight on these design problems. Of course, you can 'cover' them up with negative feedback, BUT if Boyk is correct, then we are not doing ourselves any favors.
I was attending engineering classes when Spice circuit analysis was first introduced. I was there to hear the active circuit models explained. However, my classmates and I knew that it was only an approximation of the real thing.
When I first worked with Mark Levinson we made complementary differential fet input stages. However, we found a different distortion spectrum when we used National Semi fets instead of Siliconix fets, yet they had the same part number. I know that the amount of higher order harmonics is very important, so I try almost anything to get lower. I don't worry too much about 2'nd or 3rd harmonic. It is just too much part of the music to make me concerned with .01% or less, BUT a little 5th, or worse: 7th or 9th harmonic, at listening levels, and I know that I have failed to make a truly successful product. This is why I measure individual harmonics down to .0001% with noise averaging to resolve xover artifacts that MUST reside in a typical IC op amp's distortion spectrum.
Based on the specifics of the manufacturing, such as layer thickness and uniformity, I could imagine the actual behavior to vary from fet to fet. That being the case, I would guess then that it would be necessary to obtain an actual transfer function for the exact transistor you are using in order to model it adequately. That would be a big PITA I guess.
We usually just build and test a prototype. Excessive reliance on modeling can give only partial results.
Thanks, I have sent you an email with addy.TIA
Music making the painting, recording it the photograph
Andy, I think that you will find that fets have very little 3rd harmonic distortion when used without local feedback and not in a diff pair. There is a little, however, and it depends on how the fet is constructed as to how much. Another factor to consider is the polarity of the distortion, e.g. is it additive or subtractive?
In almost every case, adding feedback will move the harmonic series upward. As designers we have to accept that.
With tubes however, it might well be that negative feedback, either local or loop is usually detrimental to the subjective quality of the distortion, by adding higher order distortion products.
I too, would appreciate your packet. My email address is: j_curl@earthlink.net
Thanks in advance.
cool! Please email them to me. thanks.
I can't send binary attachments directly using the AA forum email. But I did a search through my inbox and found I had sent you an Otala paper a few months ago. Anyhoo, I sent the article to that email address (hotmail).
Interesting what he found regarding the fet. However; given that this was written in 1978, isn't it possible that modern fets will give a more nearly ideal quadratic behavior? Perhaps the deviations he noted are related more to imprefections in the devices at that time (weren't they relatively new then?).
Got it, thanks! I will read it and see what to make of it.
"Dead silent into a 103 db speaker is dead silent into a 103 db speaker and needs no apologies. If you hear no noise, whatsoever at with a speaker like this then you can hardly call it a noisy amp can you Dan? Are we after pure specsmanship or are we talking about audibility? Have you ever had your amp strapped to a 100+ db speaker and heard NOTHING, not even the faintest hiss? I understand perfectly that db is a relative measurement but I also know that most amps will fail the test of hearing no noise into such a sensitive speaker...with or without negative feedback."You have jsut claimed that you don't know the difference between noise and music!
Finally a moment of honesty!
d.b.
"You have jsut claimed that you don't know the difference between noise and music!"Are you sure english is your mother tongue?? You sure can't read because I made no such claim.
When you hook an amp to a speaker and turn it on when there is NO music playing you will either hear some noise or not. Got it? This is not with music playing and I never implied anything else.
You don't understand the nature of the S/N ratio which is the relationaship of signal to noise. With no signal there should be little noise, it's with the signal that the measurement applies. You are not differentiating between S/N nad residual noise.
In addition your Apogees are very inefficent so residual noise will not be as audible as S/N.
This is just another example of how ignorant, clueless, illiterate. pompous, propagandists, who don't the meaning of the measurements they speak about claim that apples are really oranges.
Duh!
I AM TALKING ABOUT RESIDUAL NOISE YOU IDIOT!! I know very well what S/N ratio is it is part of basic training for analytical chemistry and used constantly in analytical spectroscopy for determining the LOD of a substance and that is not what I am talking about. It doesn't matter if the data is mass spec or audio data, same same. GOD, why do you insist on being obtuse to try to make points??As to S/N, the measurements I have seen for a 1Khz sine wave at 1 watt show the noise floor at -125db above 1Khz for the distortion spectrum. The power supply noise is all lower than -90db. At 10 watts the noise floor was -130db where the harmonics are present and the power supply still at -90db or better.
"In addition your Apogees are very inefficent so residual noise will not be as audible as S/N"
Did you hear me talking about the noise on my F(*?ing Apogees? I mentioned the review where they used Avantegarde Duo Horn speakers (103 db/watt) and heard nothing. I personally have put the big brother of that amp on my friend's Wilson X1 Grand Slaam speakers, which are 95 db/watt and heard NOTHING, no hiss, no hum, nada. Got it yet, Dano?
"As to S/N, the measurements I have seen for a 1Khz sine wave at 1 watt show the noise floor at -125db above 1Khz for the distortion spectrum.If that is not physically impossible it's damn close. Either you are lying, or you don't know how to make the measurement. Probably both.
Once again; Morricrab: No one else except you claims measurements like that, No One.
Duh!
"If that is not physically impossible it's damn close. Either you are lying, or you don't know how to make the measurement. Probably both.
"I am not lying nor did I make the measurement so actually, wrong again Dano. Like I said if you look at the power supply noise its up around -90db at 1 watt. Its a standard FFT of THD+N residual for 1Khz input at 1 watt power. Obviously 1Khz is notched out for greater clarity. Above 1KHz the noise floor shows -125 db because there is essentially no IM distortion with the power supply harmonics (seen this with a lot of amps both SS and tube), which looks like fuzz around the harmonic peaks. None of that funny business here. Just clean sharp peaks and residual noise.
Its in the magazine, I am just reading the graph. What? Your amp doesn't look as good? Check out that schematic there might be a bug! HA! LOL!
No; you got it wrong. If I remember my analyzer theory, when you do a distortion measurement you divide the bandwidth into very small sections. When bandwidth is decreased the noise gets lower, and as bandwidth increases the noise increases.
You need to do a real S/N with a full bandwidth of 20Hz to 20 kHz, and not interpret that from a distortion measurement. Remember what I said to you: No one has gotten those numbers except you; and you're not very special in that regard.
Stick to Chemistry;
d.b.
Well obviously it was wideband, Dan or else there would not have been the 50Hz (plus harmonics) from the power supply would there? The graph bandwidth is plotted from 20Hz-20Khz. Obviously, if you average all the values over the whole bandwidth you probably end up with something around -100db or so. However; all the information is there, its just not as straightforward to interpret as a single S/N value. You have to have a signal in order to have a S/N ratio, in this case they have a 1khz sine wave at 0db. All the noise and distortion are captured in the FFT from 20-20. The point is that no single component of the noise was above -90 db and no distortion component above -50db (and then only 2nd harmonic with the rest way down).For the record, I never claimed the amp had a signal to noise ratio of -125db. -100 db is probably closer to correct given how quiet it is into even very sensitive speakers. All that you have been blabbing about doesn't at all invalidate mine and other reviewers observations that there is no noise present at all even with extremely sensitive loudspeakers. I have heard plenty of so called low noise amps that cannot pass this obvious test.
Far be it from me to try and correct you. BTW: Do you have your Clever Little Clock yet?
ROTFLMAO;
d.b.
Your other bald faced lie is that tube amps only give low order distortion. It has been well documented that tube amps give significant and audible amounts of even order distortion, 4th, 6th, 8th etc, etc, order. This gives tubes that typical "muddy" sound, that most audio perverts like yourself, call "musical" It's not musical, it's audible distortion. The fact that illiterate pompous propagandists like your self claim otherwises has the rest of the world ignoring your lies.
d.b.
I have test measurements from an independent Dutch magazine that shows that the smaller brother of the amp I am using has at 1 watt only to 5th harmonic above the -125 db level. The 4th and 5th are at -95 db and -105 db the 3rd at -75 db and the 2nd harmonic at -50db.At 10 watts this amp has more harmonics above the -130db level.
2nd -40db
3rd -55db
4th -70db
5th -85db
6th -90db
7th -105db
8th -110db
9th -115db
10th -110db
11th -115db
12th -120dbAs you can see the results are not bad at all for any amp of its power rating and most SS amps have higher levels of higher order harmonics at this power (and more damning at lower powers where my amp gets more and more linear...crossover distortion...its a bitch). Also, above 4th harmonic the levels are still very low even at 10 watts (a lot for a typical SET and plenty for most music listening with reasonably sensitive speakers).
Again, bandwidth is 80khz (-3 db) and damping factor is about 5.5 (fine for all but crazy impedance curves). Distortion vs. frequency is nearly flat.
You are right about one thing, Push pull tube amps with negative feedback do indeed often more give higher order harmonics. They also often give predominantly odd order harmonics like most SS amps (due to even order cancellation from being push pull). Also, tube amps with poorly designed output transformers will have high distortion in the bass usually. This is not endemic to the design but indicative of a poor output transformer choice. Finally, a poor driver stage can generate a lot of distortion as well. It is true that a no feedback amp is more sensitive to these things but with careful design and execution the problem is largely solved not doctored with feedback that really doesn't solve the problem of inherent non-linearity.
Just like you would say that most SS amps are likely poorly designed, so too are many tube and hybrid amps. That doesn't mean the whole class of amp is damned it just takes talent to make it work correctly. IMO, the result sounds better because it makes less offensive distortions...and I think this is largely due to the relative absence of negative feedback.
"that most audio perverts like yourself, call "musical" "
I never call muddy sound musical, Dan. I call muddy sound muddy, and grainy sound grainy etc. In fact I believe there are two types of distortion, the kind you can hear and the kind you can't. If you can hear it then it degrades the sound...period. If you can't hear it then its like it isn't there at all. Doesn't matter if it is 0.00001% or 10%, if you hear it you hear it and if you don't then who cares if its there? If a tube amp sounds muddy then it is clearly making audible distortion. I don't abide by this because I know what real instruments should sound like, period. If an SS amp sounds sterile or grainy in the highs then I don't abide by it because that too is distortion. The question then is which type of distortion is less annoying. The amp I have now, at reasonable levels, has to my ears nothing in the way of distortion. It is one of the only ones i have heard this clean without being etched or sterile.
Actually the fact that such amps are on the rise should give you pause to wonder why people are preferring the sound. After all, according to your design philosophy, we have had perfect amps for at least 25 years. Some have thought about this and come up with better sounding designs. Fossils like you are not flexible enough to question your own philosophy so it is no wonder you rage against the wind, which has shifted direction away from your philosophy. There is a backlash for a reason and its not because we are all degenerates and you are somehow the perfect rational human. Rather it is probably the reverse.
The third, fourth and fifth and possibly sixth harmonics are readily audible. You haven't studied much of anything substantial on audibility and upper order hatrmonic distortion have you? Pretty fair amount of upper order distrtion in your example, makes any reasonably designed solid state look damn good.
Duh!
"Duh"No Duh there Dano. I have seen PLENTY of SS amps with high order harmonics much higher in level and also extending well beyond 20kz for a 1Khz signal (so even over 20th harmonic). In addition, they are mostly odd harmonics...the most offensive.
The third, 4th, and 5th are audible but at what levels? Do you know? 2nd is of course inaudible up to quite high levels but we are talking about -75 db, -95 db, and -100 db at 1 watt. Probably not so audible because masking can still occur for these harmonics (ie. the ear still makes distortion at these harmonics). The complete absence of anything 6th or higher (at least they are below -125 db, which is the measured noise floor above 1khz)is the really interesting story.
At 10 watts those were -55db, -70db and -85 db. HOwever, this will likely be less audible because it will be much louder (with a 95db speaker likely too loud) and your ears own distortion may still mask the distortion (see cheever).
The real problem, Dano, is the higher order harmonics present in a complementary, Class AB amp with high feedback at LOW power, where most listening is really done. Found a cure for that crossover distortion and high order harmonics? Didn't think so. Feedback doesn't fix it, Dano. Feedback MAKES high order distortion, while reducing low order distortion. Read Crowhurst or Boyk and Sussmann.
It is also clear from Boyk and Sussmann's triode tube model why my amp has some low level high order harmonics when the power increases. However; it is clear from their work also that for the same input level the tube produces far lower levels of higher order distortion, which is why at 1 watt they are well below the -125 db noise floor. I think we can both agree that below -125 db it is likely to be inaudible, no?
Crowhurst talks about signal correlated noise floor, something that is really only possible with negative feedback. As the so called "noise floor" is really made of multitudes of harmonic components it will increase and decrease and modulate with the input signal. This can't happen with a no feedback design. What about back EMF distortion from highly reactive speakers? He says that although the level is quite low the high order nature of the distortion could possibly be audible and could be why amps can sound so different from speaker to speaker. Care to comment on that or was Otala a quack too?
Cheever found a way to measure a Hafler DH500 without the feedback interferring and found the THD to be 24%!!! Of course with feedback this amp wipes the floor with yours in terms of THD. I doubt either of us would find it particularly good sounding.
If your distortion measurements are anything like your S/N measurements I'll take those with a few grains of salt too."Cheever found a way to measure a Hafler DH500 without the feedback interferring and found the THD to be 24%!!! Of course with feedback this amp wipes the floor with yours in terms of THD. I doubt either of us would find it particularly good sound."
I would not make that assumption if I were you; and you still don't understand the basics of negative feedback, you refuse to learn and you insist on misinforming others. I guess that makes you well qualified to write for a magazine that gives the CLC a design award.
Have nice day;
d.b.
Why don't you get off your lazy butt and read it for yourself? If you then think he did it wrong then explain why you think he was wrong. Otherwise, I will assume that his data is correct and you don't know what you are talking about.
I, too have to confuse the issue by pointing out the facts as well. :)rw
and you still nake me puke; see most recent post to Morricrab, the pompous propagandist.
d.b.
"I imagine nothing"You sound like Sgt Shultz! So you're just delusional. What part of "VTL amps use 15 db of NFB don't you understand?
rw
What part of the 1.5 ohm output impedance don't you understand?
Tubes: they're just great for microwave ovens.
d.b.
You're getting worse. First you couldn't remember what was said in the space of four days. Now, you can't even remember past an hour! Great job!What does source impedance have to do with your inability to understand the difference between 15 db of NFB and zero?
This is getting pathetic.
rw
High output impedance is generally caused by feedback that is too low. Duh! So are the crappy distortion numbers which clearly show a poor open loop linearity. Some idiots keep saying that tubes are more linear than solid state. Your amp, and countless other tube amps prove just the opposite.
you still make me puke;
d.b.
I would like to see the distortion measurements of your amp with no negative feedback!! LOL! Talk about poor open loop linearity. Without negative feedback tubes are FAR more linear than SS, which is why it is possible to make good sounding amps without feedback. Try your amp without it, I dare you, maybe it won't blow up...maybe.
You don't have to see them, you can pretty much figure it out from the amount of negative feedback vs. closed loop distortion.
Duh!
It should be the following.
You don't have to see them, you can pretty much figure it out from the amount of negative feedback vs. typical open loop gain. Closed loop distortion vs open loop distortion cna be also pretty figured out pretty much the same way.Now smart ass; if you had bothered to read some of the material I suggested you would know that. It certainly appears that you would rather lie and throw out accusations that can't stand the light of day.
Duh!
Seeing as I don't have the original closed loop measurements I can't really calculate anything from your non-providin' information ass, can I? Its pretty hard to calculate something from nothing. If you give me all your data then I will see for myself. If you don't then be so kind as to give me a ball park figure? 10% THD, 20% THD, more? Is it even stable without negative feedback? Come on Dano, you can at least tell me that, or haven't you tried?
The closed loop measurements are on the web site. 0.1% THD, all second order distortion, and 26db gain. Once again you are proving to me and the rest of the world, that you don't have a clue about how feedback works. Given that you write for a magazine that gives design awards to clever little clocks, I'm not surprised.
d.b.
No, Dan I don't want your "specs". I have seen way too many, shall we say optimistic, specs. Most companies specs don't hold up to even Stereophile or Soundstage measurements. I will believe your specs when I see independent measurements."Once again you are proving to me and the rest of the world, that you don't have a clue about how feedback works."
Oh and how am I proving that? By not believing your specs at face value, sorry Dano been around hifi too long for that. After all you can't even give me a schematic of a working amp how should I trust your specs.
There isn't ONE amplifier on either stereophile or soundstages website that has only 2nd order harmonic distortion. Not one.
How ironic it must be for you that the one of the only real reviews you got was from a magazine that gives awards to clever little clocks!! LOL! Yet you have no problem pointing to your review as valid, right? Did YOU get a CLC yet, Dano?
P.S. The last model number of the VTL amp you said you had claimed no negative feedback. Are you changing model numbers in mid arguement, or do you not know the difference between local feedback and negative feedback?
Given your unsavory reputation, I suspect both.
You make me puke;
d.b.
You make me laugh!rw
"You make me laugh!"
Glad to hear that, I always suspected ignorance was bliss. I also note that you didn't deny my previous post, which is another indication that your ignorance is bliss.
Have a nice day;
d.b.
Still waiting for substantiation to your claims and whatever you were trying to say about the last model #.rw
nt
you are unable to understand the difference between zero and 15.rw
Are you able to understand the difference between local feedback and negative feedback?
Give us the difference between the two, simple english will do fine here, as I'm not expecting much of anything else at this point.
d.b.
My Threshold Stasis, for example, uses zero global NFB between the input and output stages, but does employ some local NFB.The VTL, on the other hand, uses minimal amounts of global to keep the source impedance as low as 1.5 ohms.
Since you will forget this information an hour later, I'll put in some keywords to find this later.
DAN CAN'T REMEMBER $HIT FROM DAY TO DAY
rw
There is a difference between global feedback and negative feedback.
Do you know what it is?
Surprise me for a change. BTW: I'm still waiting for a rudimentary definition of negative feedback and local feedback.
Any time this week bubba;
d.b.
Cite "proof" that my VTL map uses zero feedback.
Cite "proof" that I have spoken about anything other than my MB450s following your wild-assed-guess to the contrary.rw
I can't discuss feedback with someone who doesn't understand the basic rudimentary definitions.
Get a freakin clue!
d.b.
who continues to make false accusations and fails to back them up.Bye.
rw
Well I 'm certainly glad you don't take yourself too seriously, given your level of ignorance I concur that it would be a bad move on your part.
I will try to my best so that in the future I will not take you seriusly either. Given your posts until now, I don't that will be all that difficult.
Have a nice day;
d.b.
P.S. Whenever you decide to learn the differences between negative feedback, global feedback , and local feedback, please let us know.
rw
I'd like to forget you, but the &hit you keep putting on this board makes it tough. You can't tell the difference between your lack of taste vs. accuracy.
Have a nice day;
d.b.
> > As I have advocated for a long time now, the metrics must follow and correlate with the listening and not the other way around. < <Hard to argue with that...except that I would suggest that even standard measurements CAN reveal poor design--and, indeed, poor performance--even if they often are not up to the challenge of characterizing truly excellent sound.
Jim
Not always, your own magazine nixed some of my power amp designs after listening to them, yet they measured very well. Why don't you tell me why?
> > Not always, your own magazine nixed some of my power amp designs after listening to them, yet they measured very well. Why don't you tell me why? < <Hi John,Read my message again and I think you'll conclude that I'm not saying anything your message contradicts--though I'm not sure since I'm not sure I understand your point. Measurements can catch some obvious engineering problems, but the usual suite of measurements don't tell the whole story.
Oh, and I might not have agreed with those reviews of your amplifiers either. Maybe they were wrong--who knows?
Cheers,
Jim
They can also help a company with quality control for obvious failures.
I don't suppose "dysfunctional illiterate subjectivists" need to be discredited. After all, they're disfunctional and illiterate.But, IMO, the only people this article discredits are the mystics, those who believe that things happen in audio that neither have nor require a physical explanation. That's a pretty small group I think.
As for the rest, it suggests that 1. yes, measurements probably CAN ultimately explain everything we really hear, and 2. Just because you can't measure it doesn't mean they don't hear it.
The cautious empiricists win this round. The losers are the mystics and the greedy reductionists.
BTW: Dick, thanks for posting. A nice article.
Cheers,
Jim
As I recall, most of the info in the article is nothing new and may well be over ten years old if not older. This of course does not matter as many audiophiles who post here either have limited attention span, poor reading comprehension, or really just don't give a damn and prefer to rant.
This is old news Jim.
d.b.
I mean, other than to say "I already knew all that. So what?"--which doesn't really seem to be on point.Cheers,
Jim
That's NOT my point! The point is Mr. Austin, is that high end audio is at least 10 to twenty years behind the rest of electronic technology, and going further into retro/antique all the time. AND THAT'S NO SECRET!!!!!! May I suggest a subscriprion to EE Times, or EDN? Can I recommend going through their archives for the past number of years?
d.b.
sorry for offending.There is much that I don't know, but I'm learning all the time. The reason I liked that article, by the way, is not because there's anything in it that I thought was new, but because it was written from an engineering perspective but with respect for what other techy types deride as "audiophile values." It acknowledges from the beginning that high-performance audio is indeed high-performance, rather than acting as if a Circuit City CD player is as good as it gets.
I'm not saying it's new, only that it's uncommon in this world. So it's refreshing.
Best,
Jim
In this case, I will do you a professional favor. A far as the magazines, such as 'EDN', 'Electronics Design', 'Design News' etc, etc are concerned, they would not teach you much more about audio design, with only a few exceptions. Dan is simply in a position to bamboozle you with his slightly better knowledge of electronics design. For the receord, I read virtually all the magazines, and have consistently read them all for the the last 40 years. IF you really want to read something about electronic engineering design, then get a copy of 'The Art of Electronics' by Horowitz and Hill, and keep it on your reference shelf. Unfortunately, even the IEEE or the AES don't do much for audio electronic design, these days. The old stuff from the 60's-80's was very good, however.
Now, perhaps you can return the favor by giving me the title of a definitive book on electrical flow through a wire. No simple approximations, please.
...in college. I'm sure it's a good book, content-wise, but it was absolutely the worst-written textbook I've ever seen. Intolerable. Hope they've hired an editor since then.Cheers,
Jim
Jim, you are missing the point. It is the information that is important, not the way that it is presented in this case.
By the way, once again, what is your recommendation for a reference book defining the most precise quantum model for current flow in a wire?
Expensive though--got a good science library nearby?http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=9780521855129
This is not a first-hand recommendation. It's probably pretty advanced, but the reviewer's comments suggest that it's accessible. Still, at best you'd need to do a lot of work to rigorously extract the implications of the physics to whatever problem you're currently working on.
Cheers,
Jim
This textbook looks very good. I'll check with Jack Bybee to see if he has it already. He picked up something similar a few years ago, and he might want to buy a copy of this book.
This is the sort of book that I have collected over the years, trying to find out why things do what they do.
As you know, I tend to believe my ears first, and then try to understand what I hear, through research papers or through measurement. I have found that this is essentially unappreciated on this website, for the most part.
> > By the way, once again, what is your recommendation for a reference book defining the most precise quantum model for current flow in a wire? < <Hi John. Sorry, I have no recommendation. That was never my area, and it's been 10 years or so since I've seriously studied a solid-state physics book. I would expect that any advanced textbook on the subject would be sufficient for your needs. I recall that Ashcroft and Mermin, a grad-level textbook, did a good job, starting with Drude theory then getting more sophisticated and dealing, in a reasonable way, with electron correlations and phonon effects. It's a slog, however. Took me two semesters to fight my way through it (though I'm pretty sure that metals were covered in the first term), even at a time when I was pretty good with the math.
There are some other folks on this board, I'm sure, that are more up to date than I am.
Cheers,
Jim
Thanks Jim, that is helpful. I have never heard of those authors before, and I have the graduate level version of text that JN likes so much, and some others, but they didn't tell me anything useful. That is why I initially wanted to look into Landau, but unfortunately I bought the wrong volume. If you ever get a copy of 'Electronic Properties of Materials' by Rolf E. Hummel, I think that you will be pleasantly surprised. Drude theory is not exact enough for me at this time.
As far as H&H are concerned, they did make a departure with their teaching style, BUT many of their topics are reasonably up to date, and can be useful. I even gave the late Bob Crump a copy for his reference, since it was readable by semi-technical people as well.
Thanks John. Re: Horowitz and Hill, I was in college at the time--still young--and something of a writing snob. Not that I could have done that much better, but I thought I could, and was appalled that a textbook could be so badly written. Actually, I know now it's not the writing but the editing. You don't necessarily expect electronics experts to be expert writers. But you DO expect publishers to be able to fix up the prose a little.I lost my copy of H&H (and the lab manual that goes with it) my senior year of college. I left my dorm room unlocked all the time, and someone went in and took it (along with some of my favorite records; I forget which ones. And some other things). I can't believe whoever took it really wanted a copy of "The Art of Electronics," but who knows. Anyway, I bet I could pick up a used copy cheap on amazon.com. I'll pick one up.
Best,
Jim
If you ever decide to do some serious investigation into electronic technology, you will probably come to the conclusion that audio is the bastard child of electronics. Marketing pays the bills, as many of us have observed.
d.b.
...but I don't disagree. And I know a lot of people in the industry agree as well.Still, it's great fun, and I've got enough of a rebellious spirit to believe that, though 99% of the work that defies (willingly or unwillingly) scientific orthodoxy is likely to be worse off for it) occasionally the result is something brilliant and special--and something that would be inhibited by too much focus on scientific orthodoxy. I am NOT saying what many of the mystics around here often say: That cutting edge science and technology, beyond what's known by the scientific establishment, is to be found in that Chinese factory where they make the "intelligent chip". I'm just saying that sometimes really smart people can do better work when they don't pay so much attention to the rules, so it's possible for a boutique amp to be special. Not often, but sometimes.
Call me a romantic, I don't care. ;-)
Jim
> But, IMO, the only people this article discredits are the mystics, those who believe that things happen in audio that neither have nor require a physical explanation. That's a pretty small group I think.Personally, I think a sizeable number of those that refer to themselves as audiophiles fall under this category. These boards are littered with comments from folks that allude to such nonsense. Will blind tests ever become popular in the audiophile community, I doubt it as it will reveal a reality that much too uncomfortable many of those engaged in the hobby, as it will show many audiophile staples as fanciful mirages.
Music making the painting, recording it the photograph
"Will blind tests ever become popular in the audiophile community"Unlikely as they are really not much fun as a listening party.
> > Personally, I think a sizeable number of those that refer to themselves as audiophiles fall under this category. < <I admit that I get exasperated sometimes with people on these boards that reject scientific notions outright. But I think it's much more common for people to fail to understand that what they're proposing IS mystical. As I've written before, here and in Stereophile, I don't understand those who would reject what we know and trust only their ears.
> > Will blind tests ever become popular in the audiophile community, I doubt it as it will reveal a reality that much too uncomfortable many of those engaged in the hobby, as it will show many audiophile staples as fanciful mirages. < <
It's interesting to me that, as that article indicates, sometimes things that techy folks think are impossible end up being not just possible but demonstrable via blind tests. In other words, some of those audiophile staples proved to be things that the measurement folks couldn't measure. I think blind tests have problems, but I think we've given up on them too quickly. But clearly we shouldn't be so quick to dismiss something people claim to hear just because 1. we can't measure it, and 2. it hasn't (yet) been demonstrated in a rigorous test.
Jim
"It's interesting to me that, as that article indicates, sometimes things that techy folks think are impossible end up being not just possible but demonstrable via blind tests."Well here's the thing: people assume (including engineers) that numbers like 0.01% distortion or +- 3db Must be irrelevant or relevant, respectively when in fact it might very well be the other way around. The resaoning is that 0.01% is a SMALL number and 3db is a LARGE number but it all depends on its relationship to what we hear.
Engineers tend to see a small number for THD and assume that it must be inaudible because of its perceived smallness. By the same token +- 3 db is often thought of as a large amplitude deviation for a speaker; however in room measurements can vary easily by 10 db or more, especially in the bass, rendering the speakers "native" response to be relatively unimportant.
The point of my post is that unless the numbers are aligned to something meaningful then it is perception that governs people's opinions about their significance.
In my field I have a similar problem when I report a % of an impurity in a drug product. Not only is the amount an issue but its toxicological relevance must put the number into perspective. Otherwise you have no idea if it is a lot or a little relative to its effect. Dealing with managers who are not technically competent makes this correlation all the more critical so that they don't make silly decisions based on irrelevant data. I think audio suffers a similar problem. If a number looks small everyone (including a lot of engineers) assume that it must not be relevant. If it looks large it is assumed it must be relevant but this is by no means guaranteed.
that in audio there are known numbers that are widely assumed to be the limits of perception. But they're very hard to quantify in a simple way, so they can sometimes be misleading. So, among reasonably knowledgeable folks, it's not just a matter of "big" versus "small". It might, rather, be a result of relying on too-simple metrics in situations where they don't apply. Closely related to what you're saying but not exactly the same thing.Jim
> I think blind tests have problems, but I think we've given up on them too quickly. But clearly we shouldn't be so quick to dismiss something people claim to hear just because 1. we can't measure it, and 2. it hasn't (yet) been demonstrated in a rigorous test.Well, I suppose the challenge will always be how to seperate the wheat from the chaff, how do we identify valid observations? Many audiophile claims do not stand up to any rigorous scrutiny. Ironically, Contrary to current audiophile thinking, I think it is the ear mechanism's much greater supsetibility to various biases not its sensitivity that make this a mammoth task and as such this will continue to make this fodder for mystic claims for years to come.
Music making the painting, recording it the photograph
> > Well, I suppose the challenge will always be how to seperate the wheat from the chaff, how do we identify valid observations? < <In the longterm, science. In the short term...know people with ears you can trust?
> > Many audiophile claims do not stand up to any rigorous scrutiny. Ironically, Contrary to current audiophile thinking, I think it is the ear mechanism's much greater susceptibility to various biases not its sensitivity that make this a mammoth task and as such this will continue to make this fodder for mystic claims for years to come. < <
You won't get any disagreement from me on this. But the problem is made harder still by the fact that sometimes those folks are right and the scientists are wrong. You can't just dismiss 'em (well, some of 'em you can, but not all of 'em).
I just don't quite believe that John Curl is hearing things when he says he hears differences between caps. Or--however kooky it sounds--when Charles Hansen claims to hear differences between cable supports made of different kinds of wood, I don't exactly believe him (that just sounds too crazy), but I don't dismiss it outright either. Call me gullible but it seems to me that these are serious people with obvious technical skills, and the idea that they're faking it just isn't consistent with what I know (or think I know) about their characters (I don't know either personally, beyond our exchanges on the Internet and by email).
Keeping a truly open mind while not being taken in by hucksters is hard. It's a very delicate balance.
Jim
> Keeping a truly open mind while not being taken in by hucksters is hard. It's a very delicate balance.So true... :-)
Music making the painting, recording it the photograph
namely, if a difference is audible, there is a very high possibility that it is measureable. Secondly, it affirms the value of blind tests, the anathema of many pundits of subjective persuasion on this board. A salient issue is that interface jitter is the major problem in digital audio not data dependent jitter or transport jitter.
Music making the painting, recording it the photograph
"A salient issue is that interface jitter is the major problem in digital audio not data dependent jitter or transport jitter."And why I use jitter reduction on both input and output of my jittery but otherwise good performing Behringer DEQ 2496. The audibility of going without is painfully obvious.
MC - ....performing Behringer DEQ 2496. The audibility of going without is painfully obvious.Determined by Blind, Controlled listening, as referenced in the article, like most audiophiles do of course?
cheers,
AJ
The threshold for disproving something is higher than the threshold for saying it, which is a recipe for the accumulation of bullshit - Softky
nt
Music making the painting, recording it the photograph
rw
You're having problems with basic reading comprehension. Is English a second language for you?
d.b.
But a serious problem remains. “It can happen that an amplifier measures well and just sounds bad,” admits TI’s Belnap...It is rather to admit that the human ear is sufficiently sensitive and adaptable that there is no one quantitative test that can predict how a given DAC, amplifier, and speaker combination will sound to experienced listeners.Actually, I find this to be a wonderful wake up call for those who oversimplify the challenges. I have no problem whatsoever with measurements that correlate directly to that which we hear as opposed to those that don't. I used measurements to fine tune the placement of my speakers and bass traps in my listening room.
rw
If you prefer, the noise, distortion, and FR issues of a tube amp with no negative feedback you are entitled to do so. To claim it as superior for the rest of the world is absurd. The rest of the world went solid state with negative feedback years ago. You are among a small and excessively vocal minority. If you claim superiority for that expect to be challenged on a continual basis, or better yet; ridiculed as illiterate and dysfunctional.
You still make me puke;
d.b.
"The rest of the world went solid state with negative feedback years ago"Oooohhhh, so now we are using "the rest of the world" as a valid judge of sound quality?? Get real Dan, the rest of the world walked off with Ipods and MP3 so do you think their opinion in this matter is a good reference? The switch to transistors was primarily for convenience, reliability, heat reduction, and higher profit margins. It had little to do with sound quality, which was simply marketings way of getting people to try a new technology. It has taken SS a long time to get even close to really top tube designs in terms of sound quality (the standard metrics here (like THD) are close to useless). If you can't hear this then you don't hear half as well as your supposed pedigree would suggest.
I find it ironic that your amp doesn't measure particularly good by modern SS standards. You even make claims about distortion content (unverified of course) that put you closer to the subjectivist camp and yet you are so vehment against others who trust their ears.
I also find it ironic that you always point to Lynn Olsen, a bastion of zero feedback tube amps on the web as "good reviewer". Is that just because he liked your amp? Probably. I happen to take his opinion seriously and bought my Monarchy M24 DAC on his recommendation.
As to noise; my hybrid SET amp is dead quiet even into 100+db/watt horn speakers. Dead quiet as in no hiss, no nothing. Would your amp pass that test? Here is a quote from the review of my amps (KR audio VA350i) smaller brother (the KR audio VA340i):
"Even when turning up the volume, the amp proved to be as quiet as a mouse even over our 103dB efficient hornspeakers. No hissing, no humming, no noise at all. Marek has done a great job to further improve the original Antares design."
I have confirmed this with mine using 95db/watt Wilson X1 loudspeakers; no noise, no hiss, no hum, nothing with the gain full up.
The fact is that you are so out of touch with what is possible with the best tube and/or hybrid designs that you are talking from your A** rather than from experience.
If you prefer, the noise, distortion, and FR issues of a tube amp with no negative feedback you are entitled to do so.It was only four days ago when I last corrected you on this canard.
rw
to admit you have a problem. Maybe one day there will be local meetings you can attend.
d.b.
Engineer, heal thyself.I cannot remember back to March 5
rw
Whatever we did to deserve your applause, I thank you on behalf of perverts worldwide. And I have a great URL to show you....email me offline...wink, wink....
> >
The threshold for disproving something is higher than the threshold for saying it, which is a recipe for the accumulation of bullshit - Softky
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
