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Hello. After having an extensive debate over the audibility of amplifiers on another messageboard, I was asked to come here and post my beliefs and have them critiqued. So, here I am! The poster on the other messageboard asked that I ask Mr. Curl about his experience with amplifier design and the audibility of its components.So, I ask this, what about two properly designed amplifiers would make an audible difference in their reproduction of sound? Obviously several factors come up. At higher power levels, one amplifier is better designed so that it indeed can put out more power than another. Also, amplifiers of the tube class A variaty and transistor based amplifiers will sound differnt, but because the tube amplifier has more distortion, correct? But what of two amplifiers both within their linear operating range would cause them to sound different? I certainly am not saying that the waveform is not being altered by each amplifier differently, but the true question here is whether or not those changes are audible. Anyone with comments? In the past, I have found that the only people claiming that amplifiers within their linear operating ranges sounding the same are engineers - people who actually understand how the devices work. I have found those that say there are differences in amplifiers to be subjectivists, who have no engineering background and cannot explain logically the differences they are hearing. I hope that some of you who can hear a difference between amplifiers, and do infact have an engineering background could inform me as to why the amplifiers do sound different.
Follow Ups:
Before we tire of beating this dead horse, one more link may help explain how challenging it is to measure amplifier performance, and why listening may be the best test.This is from a 1959 Audio magazine, prior to the solid state era, but it deals with yet another reason why two seemingly similar amplifiers can sound different.
rtbarr
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Below is a copy of a post I made over at the Madisound board, in response to a question about how an amplifier can sound different, re PRAT.I think this illustrates just one aspect of amplifier performnance that is not typically measured or in some cases, even thought about.
Now, one could always come back and say something along the lines that an amplifier that distorts the waveform envelope is not properly designed. This would be true. It would also indicate an awful lot of "improper design" must be going on.
PRAT in Amplifiers
Just as with audio cables, many of the subtle things that might get lost in a lesser cable, can get through with a good one.What does an amplifier DO to a signal?
It is not JUST passing it along, no, it is actually amplifying it, making it 'bigger and stronger' than it was.
It would seem that if we measured the THD and the FR, that that this would satify any requirement for linearity. Unfortunately, as many have discovered, these measurements, or even a dozen more traditional review measurements, do not fully characterize what the amp is doing with a dynamic, almost constantly changing musical signal.
An amp that preserves PRAT will not lose that almost indefinable sense of continuity to the music, a sense that the players are all together, and 'in the groove'. If you have never been a musician, then perhaps this will not make very much sense to you, the phrase "in the groove' will have very little meaning for you.
If we look at what exactly constitutes an amp that preserves PRAT, I think we will find that it has excellent dynamic behavior, it does not allow the waveform to be corrupted in the time domain.
How might this occur you ask? Well, rather than look at the square wave response leading edge, or to the amp's HF transient abilities, my personal feeling (hey, there ARE no meters that currently exist to measure PRAT, no agreed upon tests, no measurements from a textbook, just as there are no such measurements for imaging depth, or measurements for a sense of space around each instrument, etc.) is that it relates to the low frequency transient response of the amp, and how well behaved the unit is in terms of preserving the musical envelope.
If you examine an amplifier's LF transient response, you can do so in several ways.
One is to use a very low frequency square wave, say 1 Hz. This will show you what the time constants of all the coupling caps or servo loops is. Some amps have terrible response on this type of signal, the wavefrom exhibits a huge amount of overshoot and ringing at LF's, due to stacked coupling poles or poor servo design.This might seem to be a clue, and indeed, it is for an amplifier's sense of bass impact and 'punch'. Where the signal crosses the zero line (translated into the FR domain), is generally where we will hear the amp as having solid bass response down to. I have seen some amps that have this occur at 40 or 50 Hz, even though the sine wave response -3 dB point is infrasonic. The amps tend to sound like they do not have good bass response down below this, you never seem to get a sense of bass 'pressure waves' on speaker systems that are capable of such a presentation. If there is a lot of ringing, this can cause a sense of bloated or boomy bass response, the amplifier equivalent of a poorly tuned vented cabinet.
Yet even this signal is NOT going to fully explain PRAT, as the signal is symmetrical.
If we look at the LF transient response in terms of a LF tone burst of moderate length, then we may begin to see some effects due to poor interstage operating point shift, and other related issues. The tone burst may end with a small tail or DC offset.
But again, this is basically a symmetrical signal.
BUT, if we look at the response to a medium length LF tone burst that has been offset so that the negative peaks are at the zero line, and examine the amps behavior with this kind of input, in many cases you would be shocked at what you see!
The amp may slowly 'center' the burst, and then, when it ends, there is a transient generated when the tone burst stops, AS IT IS NO LONGER AT THE ZERO POINT WHEN IT ENDS. This transient will USUALLY take the same general shape as the VLF square wave decay, but not always.What is also very interesting, is that this effect may extend up into the midrange, even a 1 kHz offset toneburst will exhibit this effect! Yes, it is related to the DC coupling (and the stability of DC operating points within the amp), or lack thereof, but the fact remains, that the amplifier has now added some very serious waveform distortion that will not show up on a steady state THD measurement at all!
This alteration of the waveforms envelope is going to be continually adding spurious transients to the music, that are related initially to the dynamic nature of the music, BUT, also have the LF time constant/s signature of the amp superimposed over the music's envelope.
This directly affects the way we percieve the rhythm and timing of the music, as well as how much of this the speaker is exposed to, and ends up with the woofer offset from it's proper position, and the consequent added distortion as the woofer tries to reproduce it's upper range correctly.
Perfectly linear woofers will not suffer much, other than to loose effective dynamic range, but poor woofers will modulate the HF content due to displacement from nominal VC centering.
I once heard a system SO BAD on an offset tone burst, that an offset 1 kHz burst was clearly modulating the 1 kHz amplitude as each burst progressed from start to finish! The combination of the amp and speaker was clearly not able to handle this kind of signal properly, and it was intruding to a very large extent on the perception of the music.
There have been several AES papers on related matters, most notably, Lavardin's work, but these may only touch on the surface of what is going on with envelope distortions in audio systems.
Unfortunately, these kinds of papers have been looked upon as having been the work of 'fringe audio kooks' by the mainstream engineering establishment, and have not received the attention they deserve.
Some amps might seem to be inherently immune to such effects, such as a DC coupled amp. However, there are DC bias points and if these shift, they can also bring in secondary effects on the amplifier, some of which may affect mostly HF content as the bandwidth swings all over the place.
Literally, the rise time of the amp is modulated by the music's envelope content! Again, none of this shows up on traditional measurements usintg steady state sine waves.Most Class A DC coupled amps seem to be immune (Gee, I KNEW there was a reason that Class A sounded good!), and so, if they do not commit any of the other numerous errors of design that can plague audio amplifiers, they tend to sound very good in terms of PRAT.
DC servo circuits are NOT a panacea in this regard, they too have time constants, and some poorly designed servo's will exhibit similar envelope distortions, or harbor such at somewhat lower frequencies than more conventional AC coupled amps.
So Yes, Virginia, there is amplifier PRAT, and some amps have it, and some don't.
Of course, all of the above is my personal take on all of this, and I am not saying that I have the whole answer, or that this is the only or primary problem, just that it illustrates one aspect of amplifier performance that is seldom, if ever, measured or looked at, sometimes even by the designer!
Whoever discussed this issue with you, obviously used a lot of technical jargon and quotes. Didnt the bottom line comedown to ABX?Well, when I change my listening habbit to max. of 30 secs at a time, I might entertain ABX.
> .Also, amplifiers of the tube class A variaty and transistor based amplifiers will sound differnt, but because the tube amplifier has more distortion, correct?
Not true.
Tubes are more accurate than SS anyday. These guys simply put all distortions in the same basked and gloat about it.
A true testiment to any system is the lister satisfaction, and nearly all the people who tried tubes never go to sS again.
Well, this won't cover all the bases by any means.....Some amplifier designs put a small RL circuit in their output to reduce the possibility of the amp oscillating outside the audio band.
This can react with the dynamic load that a speaker presents to actually alter the in-band frequency response of the amplifier as measured at it's output terminals.
you know either their dragger is drawn, they're trolling, or they're inappropriately courtly. All likely trouble, imo.
- This signature is two channel only -
This thread has erupted into a flame war. I came here hoping that this would not happen. At any rate I have done amplifier comparisions, and sadly I have not heard a difference. Perhaps my hearing is truly poor? The ironic thing was I switched between my normal Technics reciever and a cheap Sony boombox. I would have expected a difference, but did not notice anything, except on transiants and at high volumes, which is to be expected since I was comparing a cheap amplifier vs a midrange one - the technics reciever allowed for more clean power output. Now, I know my equipment isnt exactly "high end" but I have asked several people if what I was hearing was valid or not, and they said it should. Two of which were electrical engineers and know about amplifier design. Why can't anyone explain to me the differences between two amplifiers? I mean, get as technical as you want, why one will sound better than another - and the difference actually be audible. I have heard no valid reasons as of yet why I should believe there is a sound quality difference at low power between a cheap reciever and a 10 thousand dollar amplifier. I hear over and over, that I should trust my ears. I find that to be extremely arrogant to assume that your ears are better at distinguishing sound than testing equipment. Humans cannot hear a difference between an MP3 file encoded at 256kbits from the original source CD - how are they going to hear the most minute differences between amplifiers?
for this statment.> > I find that to be extremely arrogant to assume that your ears are better at distinguishing sound than testing equipment.
Human ear is the most sensitive sonic detection gadget in existence.
Not meant to be a flame, really.What speakers are you using for this comparison? CD player? cables?
Likely, your other components are introducing such a sonic signature (more like an "X" in purple crayon) that you won't hear the difference between amps.
Take others' advice and walk into a hifi shop and listen. I build interconnects and my girlfriend can pick which pair is which 10x out of 10 on music she is familiar with - you should be able to discern different amps.
Since there is no such thing as a "properly" designed amplifier, it's all a matter of trading one sonic signature for another. Some of us hear beautiful music in what you would call "distortion" or "lies." Apparently our ears pick up on something that matters less to yours, and the test equipment.
Sometimes, I wish I was in your position - it would save a lot of time and money.
Your girlfriend can pick your cables out ten out of ten times? That is impresive. I think it would be interesting if you were to document this in double blind listening tests and show it to the folks who are in the "objectivist" camp. I've never bothered with such tests myself so I understand if you didn't want to bother but if she has such a high acuracy rate in blind identification of your cables I would suspect that you could offer up some good stuff on this issue.Alas it would probably be tarred and feathered if you got positive results. It seems the "objectivist" camp routinely ignore or attack positive results comming from James Boyk's research over at Cal Tech in his double blind tests. Still it might be interesting.
You were comparing a pre-amp and an amplifier together. There are two components in the amplification process, the pre-amplifier, which amplifies line level signals and operates as a volume control, and the amplifier, which takes the output from the pre-amp, amplifies it again and sends it out to the speakers. Both the preamplification stage and the amplification stage change the sound, so if you are strictly interested in hearing the difference between amplifiers, you need to listen to the same, seperate pre-amp and then switch amplifiers.You have to at least have decent equipment to hear the differences. The cheap speakers that come with most main stream mini systems won't allow you to hear the difference. Speaker cables also make a difference in the sound. With cheap speaker cables, it's more difficult to hear the difference between amps b/c less of the source is getting through the cable and it's being colored and distorted more than with a better, more expensive, cable.
Is there a good audiophile store in your area? [Not Best Buy, Circuit City, etc, but a small specialized store]. Get a variety of CD's (Jazz, classical, vocal, and whatever you like) and go to a high end shop and tell them you want to audition amplifiers. They will probably ask you what you have at home, just tell them that you are building a system after hearing your friend's setup. You could even tell them that you don't believe that two solid state amplifiers that output the same amount of watts could sound different. Listen to the same pre-amp and speakers and use the same cables. You could even listen to the difference between integrated amplifiers, even though that would include a change in the pre-amp stage, it would be the equivalent of the comparison you made earlier between the receiver and the boom box. You will hear a difference if your hearing isn't damaged, and you might catch the audio bug.
If you don't know of any high end stores in your area, post a message here asking if there are any good audio shops in your area.
Actually, I have heard several high end systems. I have visited a local audio store and they had a pair of 10K B&W speakers on display. I listened to them and was less than impressed. The subwoofer hooked up with them was terrible. They used extremely expensive cables in this installation, but the amplifier looked to be a Adcom or Rotel, I cannot remember, it was almost a year ago.Another experience, I have visited Ultimate Electronics. They had ML electrostat speakers along with Krell electronics driving the whole system. I WAS impressed by this system.
Finally I have heard Wayne Parham's (Owner of Pispeakers) system. It sounded very good as well, but he does not use "audiophile" components - just a crown amplifier and cheap 16awg speaker wire.
As for the system I listen to, it is not a boombox. I have attached a picture.
As for your analysis on speaker cables, I am going to flat out disagree with you. As long as they are of sufficient diameter, you are not going to hear a difference. Listen to what you said, "With cheap speaker cables, it's more difficult to hear the difference between amps b/c less of the source is getting through the cable and it's being colored and distorted more than with a better, more expensive, cable." Do you really believe that the loss of a 14awg cable vs the losses in the voice coil or inductor inside your speakers is going to matter? What about plain copper wire colors the sound? Same with distortion, how can a cable add distortion to the signal? I can believe a phase shift, but distortion?
In reference to your comment about speaker cables, It's not about what I believe, it's about what I hear. I was using monster cable $1/foot cable, and I changed it out for Audioquest Type 4+. There was an immediate and obvious improvement. I'm not an engineer and could only repeat what I've read in rebuttal to your comments, but the bottom line is that I hear a difference, and that's all that matters to me.
Jerry, why should you ask a question like this? Why don't you just go listen to a high end system? What's your problem?
The history of hi fi amplifier design goes back more than 55 years, and significant research was already available before that time. I have in my lab, one of the oldest tube designs (Williamson), several Dyna tube amps, and a whole variety of power amps, from my first effort 35 years ago, to my latest hi end product. ALL amps measure and behave differently. Some are faster, and have higher slew rate, others have only low order distortion. The worst are both slow and have lots of higher order distortion. However, even the best amplifier that I can possibly build will have a sonic signature, but hopefully not much of one.
Your overall attitude is like a high school kid wondering what difference there is between auto tires. Why do some cost so much more than others? How could someone explain that to someone with your lack of understanding?
What you should do is to look up amp design on the internet and learn what you are asking about. I use the internet in this way, and you can too. Don't think that I am being too hard on you, I was once fairly ignorant about tires into my '50's. Then I changed the tires on my old Porsche to better ones, and I was AMAZED at the difference, yet there was no obvious parameter that had been changed significantly. Still, it took a Porsche to show me the difference, I doubt that my Honda would have showed the difference in the same way. The same goes for amps. You HAVE to own a pair of good speakers and a good musical source to hear much difference between many amps.
Well perhaps at least high priced anyways? I have heard a B&W setup, and did not know what amplifier was being used. It honestly did not sound very good to me. I also have heard a ML electrostat setup with Krell amplifiers, preamps and dvd players. It sounded very good, but I have no basis to compare the way the speakers sound with a cheap 200 dollar reciever and the 10K Krell amplifier. Do you really think the salespeople will allow me to do that?Also, I was wondering if you are an engineer yourself? Do you work with amplifier designs?
Jerry, I have been a member of the IEEE for 38 years. I have been a member of the AES since 1966. I design amplifiers for a living, and am well known for my published designs. You seem completely unresponsive to ANY of my input. What is your math level? Can you do differential equations and vector analysis? Unfortunately, many serious articles on the forefront of amp design require this level of knowledge. However, a simple listening comparison can give you most of what you really need, since you are not designing amps for a living, like I do.
For the record, many 'engineers' don't believe in hi end audio, and go back to their meter reading. I suspect that you are attempting to 'set me up'.
> > I suspect that you are attempting to 'set me up'.finally, figured it out?
He was sent to this board to talk to you specifically, he doesnt respond to any other inmate.....we list is long enough.
I was not sent here to bash John, a user on another board told me to come here and be "schooled" by him. For the record, I am only 19 years old - I have not even graduated college. As for the math, none has been presented, therefore I have no idea whether I can follow it or not.My main questions are, what do in fact make audible sonic differences within amplifiers? Is it the power supply? What about the output transistors or tubes? Can't you even give me a simple explaination? I see it this way. I cannot hear a difference between amplifiers. I questioned this and asked knowledgeable people, some of which post on audioasylum. Everyone up to you has told me that the amplifier should not matter at low power levels. I mean look through my eyes for a minute, I have yet to hear a difference between amplifiers and was told by knowledgeable sources that what I was hearing was normal. Perhaps if you give me any kind of valid reason why I should think otherwise, I will research it further. Otherwise, all I have heard from amplifier supporters is that I should trust my ears, and well frankly that is not a good idea, since I cannot hear a difference anyways. Perhaps my hearing is truly poor, at least at hearing details anyways? I can hear up to 18khz, so upper frequency limits are not the issue, I am not deaf.
Jerry has stepped into a pool of grumpy old men who evidently weren't ever 19 years old in their life. Just how many hours or years of experience do you expect this young man to have in just plain *listening, let alone auditioning systems, attending concerts, learning to play a musical instrument, reading, collecting records, researching, experimenting?Jerry has some terrific qualities; the majority of which are well suited to being an excellent engineer.
Curiosity
Assuming nothing and asking questions.
Questioning Authority.Man, it's *real* hard to pick on a 19 yr. old who dares to ask some questions. No doubt a lot of the responses he's gotten will surely encourage and mentor him to pursue either audio engineering or building up a reasonable home stereo system.
I'll also say I think Jerry is close, since in my experience, discrete amplifier change - within the same power range, and not a 30 yr. old receiver to a pair of modern monoblocks - produces sonic changes that may be subtle. In my case it was a mod'ed Hafler DH200 to a ARC D130. Not terribly earth shattering; or that lameass TAS phrase "jaw-dropping"...
Hang in there Jerry. Not only will you outlive us all, but I expect you will do quite well with your life.
Thank you cdb, for the kind words. Surely I have not done as much experimentation as you all, since I was bit by the audio bug only 3 years ago. Back then I was the typical teenager who only cared about a loud subwoofer in his car, but wow have the circumstances changed.As for pursuing audio engineering, that is doubtfull. I enjoy audio reproduction, and like learning how everything works. But, I also enjoy computers and quite frankly there is more need for computer people than audio engineers. But yes, to get to the point I have gotten to now has taken a considerable amount of research and question asking. Hopefully in 10 years or so I will be able to design my own amplifier and explain to you all why there are no audible differences! :-)
Go back to where you heard the Martin Logans, have them switch out the Krells with the cheapest reciever you can find of equal power rating, listen and then get back to us.
He is not a 'troll', he is not a 'fool', he is a 'sophomore'! Now we understand you.
you are a veteran inmate and yet to master the AA lingo...> > he is a 'sophomore'!
Wow, you are really mature. How old are you? What makes me an uninformed idiot and not yourself? You are just angry that I questioned your beliefs and do not believe what you have to say, I presume if I may be so bold.
You can't hear the difference between amplifiers. That way you won't be tempted to spend the money on them.It is an interesting comment on your education that apparently you have been taught, in the first instance, not to trust your own senses but to seek some "expert" validation of an abstract hypothesis.
If you want to experimentally confirm or deny your hypothesis, you should start by changing only one variable -- the amplifier -- and leaving everything else constant. I don't even think you'll have to go nutso on the tweaks and the wires, just have a decent source, playing decent music (acoustic music recorded in a "live" venue is my preference) through decent speakers. I heard the difference between a high-end Japanese receiver from the late 1970s (a Luxman) and Krell's small integrated amplifier on a pair of $400 speakers that had very little bass response below 50 Hz (Snell K-IIs). I think I was using generic interconnects and Monster XP speaker wire.
Just out of curiosity, have you considered the possibility of spending a little time with a couple of different amps? Its pretty hard to know what these things sound like from the schematics.As Yogi Berra might say, "if you want to hear something you have to listen".
I agree. You will have a real time finding out what anything SOUNDS like, and why, here.
Curiously enough, that seems like the most impossible subject to get information about.You would also do yourself well to listen to tube equipment as well as SS.
You seem to have little experience with tubes, and you should hear them before you draw any conclusions about distortion or anything else.Perhaps you will have more success finding useful information at the DIY asylum or the Bottlehead Forum.
I think you will find some very interesting information on this subject at James Boyk's website under current projects. He and two people from MIT are doing a study on the sonic differences between two preamps that are designed "propperly" according to the usual battery of specs on harmonic distortion, signal to noise ratio and all the other things that "objectivists" say are the only things that matter. Not only have they found sonic differences in double blind tests they have found significant differences in null tests when comparing the signals. You might find it interesting.
The link below may be of some help It is one of the resources found on the AA FAQ page. The IEEE is major league electrical engineering organization. (Institute of Electrical and Electronics Engineers, Inc. )I have both tube and solid state amplifiers. Many audiophiles find that both types can be very musical if they are well designed, carefully made, and matched with appropriate sources and speakers.
Measurements and specifications are useful in some ways, but can also be misleading. 36-24-36, 5' 4", 112 lbs, tells you a little about a woman, but probably not enough to make a final decision about marriage.
Listen to many different systems, especially to music you are very familiar with. Trust your ears and intuition, not the measurements.
rtbarr
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Good link!
This is a difficult question. There are 1000's of different amplifier designs. Every one is different, why? Why don't engineers go on to make other components and leave amps alone? If you don't know why this is so, then I can't be very helpful. Sorry.
I would venture to say that new amplifier designs are coming out to increase the efficiency, power output and DSP features. I find it hard to believe that engineers are hard at work trying to find the perfect sound quality. Who knows though.Just a question, has anyone heard of Richard Clark's amplifier challenge? He offers ten thousand dollars to anyone who can properly identify one amplifier from another 12 times out of 12 in a blind test. If one amplifier has equilization on it, he defeats or equilizes it out. He also matches the amplifier gains completely. Many people argue that this is an invalid test since it just strips the amplifier to its power supply and output transistors. But I see it as an objective, non biased test to compare two amplifiers between each other. Clark even admitted that at one point he too thought there were big differences between amplifiers, but later "found the truth". Why doesnt anyone go and win the test? I really do not understand this. I read the rules on the test and they seem completely fair. Why doesn't anyone else agree with his testing methodology?
Where can we take this test? I could use the money.
www.carsound.comGo to the forums, then Richard Clark's. It gets brought up in there about once a day.
Are you referring to David Clark, the inventor of the ABX test box?
Known him for over 20 years. For the record, almost any test can be improvised to make virtually subtle difference between products unrecognizable. I first saw this in action, where a customer at a bar could not tell the difference between 'cola', 7-up, and ginger ale, in a bar bet. It was amazing! The same thing happened when 'new' coke was introduced years ago. Someone actually funded a protest against it. This person was later given a double blind test and he failed it. Can you folks tell the difference between 'new' coke, 'classic' coke, or Pepsi? Well you might think that you can, but someone can create a blind test that will fool you into thinking that there isn't any difference. It's the same with electronic components.
Actually the person who has the test is Richard clark, he writes for carsound. I dont see why he would try and "fool" people in believing that there is no audible difference in amplifiers. I cannot think of any bias one would have in trying to prove that many different products are the same?As for the Coke and Pepsi test, it is quite ironic that no one can tell the difference in a blind test. Perhaps they are so similar? I honestly like Pepsi better, because it seems sweeter. But, when I was in High school, we had a class where we did a blind test between the two. The results were quite odd. Many people could not tell the difference. This is actually a good test, I will try it later this week to see if I and others can indeed pick one out from the other. But, our tastebuds and ears are vastly different organs....
As some one who has been involved in blind taste tests I can tell you that people can identify differences easily when the test is conducted propperly but one can easily create a double blind taste test that will get false negative results. I know I've done it! Same is true in audio just as John has stated. You can create double blind tests that will net false negatives quite by accident. So no ill will or agenda is needed although it has become clear that many self proclaimed "objectivists" do carry such an agenda and are doing double blind tests in the name of science and objectivity that are neither scientific or objective in nature.
You can be fooled in the same way with listening tests. I'm glad that you at least have some experience with taste tests. I hope you learn something from your retest.
I am sure they seem fair. The issue is, "they" are applying DBT as if IT IS THE ANSWER, which it is not.
What is the "answer"? What would be a fair objective test to compare two amplifiers from each other?I personally think subjective tests do not work well, at least for myself, as I know the ear can easily be tricked
> > What is the "answer"? What would be a fair objective test to compare two amplifiers from each other? < <Is there some new law of nature you've discovered that says it is possible to devise an objective test for anything we'd like? Because one method is clearly flawed (subjective testing) does not mean that the other (ABX testing) is not also flawed.
...I could easily choose my SET tube amplifier in such a comparison against a SS arc-welder (as could virtually anyone, the differences being rather large), but he would say the measurable and audible flaws of my amp allow me to distinguish it (you cannot equalize out harmonic distortion, for example.) I wouldn't refer to the differences as flaws, however, as I've heard some very good SS amps, but my ears still prefer the SET amplifier in virtually every aspect of reproduction except power output.
I suppose it is up to the end user to decide which amplifier sounds best to him or her. But it seems you are saying that you realize that in reproducing the audio signal and amplifying it, the tube amplifier is introducing distortion - but you still like it? If so, that is fine, each person has different tastes and preferences. But, how would that disprove his test of all amplifiers sounding the same? Basically are you not saying that the SET amplifier would fail against a transistor based one, due to its high distortion? I realize that tube amplifiers are loved by many, but if its distortion is higher than a fet based amp, why use one if you are looking for the ultimate in audio REPRODUCTION? I would assume that the least amount of change to the original audio source would be wanted in HI FI.
> > I suppose it is up to the end user to decide which amplifier sounds best to him or her. < <Yes, it is and that is really *all* there is to it. Passing further judgement presumes you know what I hear when I listen to my system. If you choose to make this presumption, I've got two words for you...
> > But it seems you are saying that you realize that in reproducing the audio signal and amplifying it, the tube amplifier is introducing distortion - but you still like it? < <
It is introducing distortion, but I can't hear distortion. I'd hate to say that no one would hear the distortion, but I don't think anyone would. I think I like it in spite of its flaws, not because of them.
> > If so, that is fine, each person has different tastes and preferences. But, how would that disprove his test of all amplifiers sounding the same? Basically are you not saying that the SET amplifier would fail against a transistor based one, due to its high distortion? < <
I'm not saying that. You are saying that and he would say that. To my knowledge absolutely *no one* has taken the time to demonstrate that the reason many people prefer SET amplifiers is specifically due to the measured flaws. They point to the measured flaws and to studies showing that some people prefer 2nd harmonic distortion added to music and the high output impedance interacting with speaker impedance, etc., and then claim the science backs them up and that's as far as it goes. Would you like being put in jail because your description matches a criminal?
Although I've not tried it, all the tests I've heard of that attempted to duplicate the SET sound by adding distortion to a SS amp have failed. Seems it isn't so simple as that.
Have a look here for a different point of view:
http://usuarios.uninet.com.br/~edelima/REASONS.htm
> > I realize that tube amplifiers are loved by many, but if its distortion is higher than a fet based amp, why use one if you are looking for the ultimate in audio REPRODUCTION? < <
Because it sounds more realistic in its reproduction than a FET based amp to my ears in my system. How can you argue with that?
> > I would assume that the least amount of change to the original audio source would be wanted in HI FI. < <
Yes, I'd say that's possibly true at a system level. It isn't so important at a component level because you can't listen to a component in isolation.
realize that tube amplifiers are loved by many, but if its distortion is higher than a fet based amp, why use one if you are looking for the ultimate in audio REPRODUCTION? I would assume that the least amount of change to the original audio source would be wanted in HI FI.
if you're interested in good sound, you'd better listen to John Curl when he said not to believe completely in numbers.
What's a "change"? What's distortion? It's a mistake to believe completely in a few numbers quantized from a mysterious set of attributes, and ignores the true metric: your ear. On the other hand, if one can't tell a tube amp from a solid state amp, then there's no point.
By the way, people who make tube amps are engineers, and do believe in lowering distortions, IMO. It's just a compromise of which to lower.
I do Believe John when he says to not believe completely in numbers, as they can be fudged easily. Take for instance the THD spec on an amplifier, it is meaningless if you ask me. Since I cannot hear anything less than 1% 3rd order or higher unless test tones are being played, I find it to be an irrelevant spec. Not to mention the amplifier's dampining factor, just use a higher impedence load, and the dampinging factor goes up.Distortion is unwanted noise. However, when it comes to my ears, I have given up long ago as I said before. I cannot trust them, as they cannot hear a difference between amplifiers. Perhaps I am just handicapped?
I do know engineers build tube amps, and obviously they want to lower distortion.
You've given up long ago? I thought you said you were Nineteen. You don't have a "long ago" in your life unless you are talking about getting out of diapers.
I doubt that you couldn't physically tell a different between a typical solid state amp, and a tube amp. For one thing, a tube amp likely sounds warmer. But such a difference probably doesn't matter to you, and hence it's effectively indistinguishable. Many people, including musicians or music lovers, are like that. But that doesn't mean they do not physically hear a difference.Listening itself is complicated too; I don't know if I could hear distortions (unless it's obscenely obvious). Most of the time, I can only notice their abscence. And I have seen this happen with my friends too. In one case, a guy said his system doesn't have any distortion, until he listened to mine. So now, when I feel the music is too loud or irritating, then I know it's distortions (which are a dynamic function of power line conditions and how long i've been listening) that are kicking in. That's why I think it's very difficult to capture distortions/fidelity with a simple set of numbers.
As to compromising and unwanted noise, my amp has the loudest 60hz hum that any I've known, but it is much better than many others, solid state or tube. This is due to its design (direct heated, directly coupled single-ended triode with a very simple power supply circuit). The designer could reduce the hum and other means such as a different design. But I doubt they would have resulted in what i'm hearing.
Folks, this is not just for Jerry, but for everyone.
Today, a friend came by with this new amp prototype. It is very fast. He asked me to measure it with my test system. At the time, and to warm up the system, I measured a 40 year old germanium transistor based integrated amp that was impressive (and expensive) in its day. I could measure harmonics out to beyond 50th, within the capability of my system. The other amp was somewhat different. It had 10-100 times lower distortion, and it had less x-over distortion and slowed down at the 9th harmonic.
My usual designs slow down or stop at the 5th harmonic (max) and some tube amps only have 2'nd and / or 3'rd harmonic distortion. This is even better, but the distortion is usually higher in magnitude than my designs. Which is better? Only our ears can tell us that.
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