So what about the tests done by Richard Clark? 
http://www.tom-morrow-land.com/tests/ampchall/index.htm
http://www.tom-morrow-land.com/tests/ampchall/index.htm
Clark Challenge
More or less uninteresting. It's already well-established that listeners can't distinguish one amp from another in ABX testing under level-matched, non-clipping, matched frequency response conditions. So why issue a challenge which gives exactly the results expected? Dull.
There are two possible explanations to this insensitivity: there are factors not evident in ABX and a different double-blind format should be used, or indeed the claimed differences are as real as psychic spoon-bending.
More or less uninteresting. It's already well-established that listeners can't distinguish one amp from another in ABX testing under level-matched, non-clipping, matched frequency response conditions. So why issue a challenge which gives exactly the results expected? Dull.
There are two possible explanations to this insensitivity: there are factors not evident in ABX and a different double-blind format should be used, or indeed the claimed differences are as real as psychic spoon-bending.
C.W. sorry 'bout that...... changed email addresses and forgot to update my user profile here...... try again pse,,,,
there are major and minor differences between amplifier output characteristics. the major ones are usually audible (amplifier A has a damping factor of 100 and amplifier B's is 2000). the minor ones are usually below the threshold of hearing, but can be measured (amplifier X has a 3rd harmonic at -75 db, and amplifier Y has one at -85 db). sometimes minor ones can add up to a barely audible difference, in which case the amplifiers will have a different sound, but it would be difficult to pin down in a listening test exactly what is being heard differently. test equipment would reveal the differences. if two amps are very close in specifications, they wouldn't sound different at all even though they have some minor differences in their output characteristics. Bob Carver proved that an amplifier's characteristics can be mimicked accurately enough to fool the eardrums and brain, and even get close in the test realm. and this is with a completely different topology than the original amplifiers. all Bob carver was allowed to do was connect test equipment to the amplifiers and treat them as "black boxes".
there are major and minor differences between amplifier output characteristics. the major ones are usually audible (amplifier A has a damping factor of 100 and amplifier B's is 2000). the minor ones are usually below the threshold of hearing, but can be measured (amplifier X has a 3rd harmonic at -75 db, and amplifier Y has one at -85 db). sometimes minor ones can add up to a barely audible difference, in which case the amplifiers will have a different sound, but it would be difficult to pin down in a listening test exactly what is being heard differently. test equipment would reveal the differences. if two amps are very close in specifications, they wouldn't sound different at all even though they have some minor differences in their output characteristics. Bob Carver proved that an amplifier's characteristics can be mimicked accurately enough to fool the eardrums and brain, and even get close in the test realm. and this is with a completely different topology than the original amplifiers. all Bob carver was allowed to do was connect test equipment to the amplifiers and treat them as "black boxes".
IMO, when people talk "measurements" they think of THD. THD is a wonderful tool for amplifier development, but it predicts absolutely nothing about the way an amp will sound.
That statement is every bit as wrong as saying frequency response measurements predict absolutely nothing about how an amplifier will sound.
A lot of amplifiers with improperly applied miller compensation (for example) may test wonderfully WRT to THD at 6.3kHz (which was a standard, but inadequate HF test in the 70's and 80's), but fall in an absolute heap (input stage overload due to current demands of Cdom) at 20kHz. In that case, the THD measurements will reveal a lot – as would a frequency response measurement that reveals –6dB at 10KHz on any amplifier.
Suppose the THD measures impeccably out to 20kHz and the frequency response is flat to within 0.1dB 20Hz to 20kHz, then that would be great and any potential design flaws / design limitations (clipping characheristics, harmonic spectrum if the THD is moderately high, etc) will require more in depth measurement techniques to weed out.
There is no single measurement that will tell everything, but that fact doesn’t mean that any common individual measurement technique is worthless. Also, importantly, all performance aspects of an amplifier are interrelated (to varying degrees). Some important points WRT to THD and other parameters:
If substantially low THD (<0.01%) is measured, loaded at full rated power at 20kHz that amplifier will be virtually free of TIM (a definite no-no for sound quality). An amplifier with very low THD throughout the audio frequency spectrum will also have very low IMD.
If substantially low THD is measured at 20Hz, loaded at full rated power with continuous sine wave input (which is obviously a much more stringent demand than what a music signal would inflict), that amplifier has a beefy enough power supply to deliver large amounts power for sustained durations without clipping or distorting excessively.
I don’t think that anyone would deny that these things contribute something to a prediction on how an amplifier may sound. I really wish that this place could rise above the mindless mantra about THD meaning nothing.
Cheers,
Glen
That statement is every bit as wrong as saying frequency response measurements predict absolutely nothing about how an amplifier will sound.
A lot of amplifiers with improperly applied miller compensation (for example) may test wonderfully WRT to THD at 6.3kHz (which was a standard, but inadequate HF test in the 70's and 80's), but fall in an absolute heap (input stage overload due to current demands of Cdom) at 20kHz. In that case, the THD measurements will reveal a lot – as would a frequency response measurement that reveals –6dB at 10KHz on any amplifier.
Suppose the THD measures impeccably out to 20kHz and the frequency response is flat to within 0.1dB 20Hz to 20kHz, then that would be great and any potential design flaws / design limitations (clipping characheristics, harmonic spectrum if the THD is moderately high, etc) will require more in depth measurement techniques to weed out.
There is no single measurement that will tell everything, but that fact doesn’t mean that any common individual measurement technique is worthless. Also, importantly, all performance aspects of an amplifier are interrelated (to varying degrees). Some important points WRT to THD and other parameters:
If substantially low THD (<0.01%) is measured, loaded at full rated power at 20kHz that amplifier will be virtually free of TIM (a definite no-no for sound quality). An amplifier with very low THD throughout the audio frequency spectrum will also have very low IMD.
If substantially low THD is measured at 20Hz, loaded at full rated power with continuous sine wave input (which is obviously a much more stringent demand than what a music signal would inflict), that amplifier has a beefy enough power supply to deliver large amounts power for sustained durations without clipping or distorting excessively.
I don’t think that anyone would deny that these things contribute something to a prediction on how an amplifier may sound. I really wish that this place could rise above the mindless mantra about THD meaning nothing.
Cheers,
Glen
I don't know why this is so hard for people to accept. Though I'm very interested in measuring differences, I rarely hear them. When I can hear a difference in a component, it's invariably because there's something wrong with it. Either it's got some subtle oscillation problem, it's picking up something from the outside world, it's unstable or it has a significant response or distortion problem from some defective part (or design error on my part). Good designs, working correctly, never show the kinds of differences people describe as "obvious", "incredible", "night and day" or "worth every penny of the $10k I spent", unless they differ in some straightforward fundamental (and measurable) ways.
THere's every reason to believe that the better and better amps get the less and less the differences between them will be.
How could it be otherwise?
The best amp is the one that recreates the sound most accurately.
In the limit (remember your calculus) the reproduction will be perfect.
Two amplifiers of equal power output, but different construction, if perfect, will produce the same output when driven from the same source.
There's no logical escape from the statement, read in context. All amplifiers sound the same.
w
How could it be otherwise?
The best amp is the one that recreates the sound most accurately.
In the limit (remember your calculus) the reproduction will be perfect.
Two amplifiers of equal power output, but different construction, if perfect, will produce the same output when driven from the same source.
There's no logical escape from the statement, read in context. All amplifiers sound the same.
w
Re: An observation
Poor stupid capacitor manufacturers. Since all capacitors are the same, why bother to make so many types (Mylar, Polypropylene, Polystyrene, Ceramic etc)? Think of the fortunes in manufacturing equipment they could save if they just made one kind of capacitor.
Or, wait..... maybe.......?
Sarcasm aside; capacitors are non-ideal devices. Each construction technique has different trade offs as to which parameter is emphasized. ESR, inductance, leakage etc etc. Since they are measurably different it's not a giant leap to image some of those differences are audible.
analog_sa said:
Poor stupid capacitor manufacturers. Since all capacitors are the same, why bother to make so many types (Mylar, Polypropylene, Polystyrene, Ceramic etc)? Think of the fortunes in manufacturing equipment they could save if they just made one kind of capacitor.
Or, wait..... maybe.......?
Sarcasm aside; capacitors are non-ideal devices. Each construction technique has different trade offs as to which parameter is emphasized. ESR, inductance, leakage etc etc. Since they are measurably different it's not a giant leap to image some of those differences are audible.
Re: Re: An observation
I think he was referring to the Chinese firms who got bitten hard by a now-infamous round of industrial espionage where they stole their electrolyte formulas from Taiwanese and japanese manufacturers, but unfortunately only made off with part of the recipe. So their caps appeared to work fine and no one was the wiser until their caps started failing about two years later. They'd neglected to steal the parts of the formula needed for electrolyte stability (specifically to suppress hydrogen outgassing).
The reason for all the different types of the caps is mostly because they're each optimized for different behavior in situations where it really matters-- like high ripple currents in a PSU where a high ESR cap will literally overheat and explode. Or the difference between working at 100Hz (any cap) and 10GHz (many fewer) or super-high-Q applications that never appear in audio circuits.
The caps *do* make a difference in an audio circuit, but their contributions are almost entirely harmonic distortion (and fairly slight at that). 'Proper selection' means more taking into account actual ESR, load, working impedence, etc than what the caps are made of. there's more to cap ratings than the '10uF' stamped on the side.
Oh, and there are some caps that are so strongly nonlinear they're recommended against because their THD contributions start reaching into the whole percents-- specifically tantalum and ceramic.
hermanv said:
I think he was referring to the Chinese firms who got bitten hard by a now-infamous round of industrial espionage where they stole their electrolyte formulas from Taiwanese and japanese manufacturers, but unfortunately only made off with part of the recipe. So their caps appeared to work fine and no one was the wiser until their caps started failing about two years later. They'd neglected to steal the parts of the formula needed for electrolyte stability (specifically to suppress hydrogen outgassing).
The reason for all the different types of the caps is mostly because they're each optimized for different behavior in situations where it really matters-- like high ripple currents in a PSU where a high ESR cap will literally overheat and explode. Or the difference between working at 100Hz (any cap) and 10GHz (many fewer) or super-high-Q applications that never appear in audio circuits.
The caps *do* make a difference in an audio circuit, but their contributions are almost entirely harmonic distortion (and fairly slight at that). 'Proper selection' means more taking into account actual ESR, load, working impedence, etc than what the caps are made of. there's more to cap ratings than the '10uF' stamped on the side.
Oh, and there are some caps that are so strongly nonlinear they're recommended against because their THD contributions start reaching into the whole percents-- specifically tantalum and ceramic.
It seems like newer amps do sound more alike, I bet they have similar response curves. IMO older amps have more of a difference. I have some old 80s amps (I think 80s); a Kenwood, an NAD, and a larger Harmon Kardon. I can tell you many times I hooked them up to the same speakers and input and they all sound different. I had a large pioneer amp too, but got rid of it when it sounded so bad compared to the Harmon. I have the same thing with car amps. Of course now you just DSP it to sound the way you want. Maybe the old amps had various 'loudness' or EQ type circuits built in to help sound since EQing was less used then...and it was not the actual amp section but the input, still they were certainly different.
Lol, what is this Richard Clark amplifier test? He will EQ the amps to sound the same??? What is that then, certainly not comparing amps. I say you turn the tone to the center and that is that, just how it is built.
Lol, what is this Richard Clark amplifier test? He will EQ the amps to sound the same??? What is that then, certainly not comparing amps. I say you turn the tone to the center and that is that, just how it is built.
G.Kleinschmidt, I missed your post earlier. You're right of course, but lacking any other information, which seems to be the most common case, a single THD number, assuming it isn't ridiculously high, is in fact, worthless. A full THD curve is better, but it still doesn't predict anything specific about the sound quality- the point of my post. Without knowing the cause, can you say a rising THD at high frequencies is associated with any particular sound quality? IMO, that curve might mean two completely different things, depending on whether you're talking about a typical solid state design, or a tube amp. I do agree that if it's below some threshold across the band, it moves the amp into "blameless" territory, and lacking any other flaws, the amp will be indistinguishable from other blameless amps.
"RICHARD CLARK IS AN IDIOT.."
I would tend to agree, but really, it's more likely that he just can't hear.
IIRC, his 'test' will not allow for modified equipment, otherwise I would take his money away from him.
I modified a McIntosh amplifier for a recording studio (just cap mods).
After extensive listening, the two music professors (at Cornell) thought that I had 'added too much bass and treble boost'. They could not believe that the amplifier had flat response!
Measurements, of course, proved that it did.
Posted by djk (M ) on May 23, 2003 at 00:44:47
In Reply to: crap about all amps sounding the same??? posted by robber on May 22, 2003 at 21:49:20:
All food tastes the same(if you have a zinc deficency), all women kiss the same(if you're a eunuch), VHS and Beta look the same(to Ray Charles and Stevie Wonder), and all amplifers sound the same(to the deaf old men at Stereo Review).
WHO?
Tell the deaf/dumb/blind kid to go play pinball.
-------------------------------------------------------------
Golden Ear Audiophile hit with a brick "Oww, that
hurts! I'm bleeding!"
Tin Ear Meter Reader hit with a brick "You can't prove
I was hit with a brick! We need to do a double blind
ABX test!"
---------------------------------------------------------------
I would tend to agree, but really, it's more likely that he just can't hear.
IIRC, his 'test' will not allow for modified equipment, otherwise I would take his money away from him.
I modified a McIntosh amplifier for a recording studio (just cap mods).
After extensive listening, the two music professors (at Cornell) thought that I had 'added too much bass and treble boost'. They could not believe that the amplifier had flat response!
Measurements, of course, proved that it did.
Posted by djk (M ) on May 23, 2003 at 00:44:47
In Reply to: crap about all amps sounding the same??? posted by robber on May 22, 2003 at 21:49:20:
All food tastes the same(if you have a zinc deficency), all women kiss the same(if you're a eunuch), VHS and Beta look the same(to Ray Charles and Stevie Wonder), and all amplifers sound the same(to the deaf old men at Stereo Review).
WHO?
Tell the deaf/dumb/blind kid to go play pinball.
-------------------------------------------------------------
Golden Ear Audiophile hit with a brick "Oww, that
hurts! I'm bleeding!"
Tin Ear Meter Reader hit with a brick "You can't prove
I was hit with a brick! We need to do a double blind
ABX test!"
---------------------------------------------------------------
Or just knows how to properly design a test to control for known human perceptual effects? It's really suspicious how many of these "obvious" sonic differences between amplifiers disappear during double blind testing.djk said:
I wish somebody would design an A/B switch box that doesn't hide obvious sonic differences
I think a more pertinent question is how long will it be before they make a microphone that realisticaly captures sound, that reponds equaly well to all frequencies... (kind of like a fullrange speaker in reverse).
To me it is conceiveble that "information" goes missing between the sound source and the point of first recording...(mouth and mic), and that it is possible for some amps to "accidentaly" add some of this inforamtion that went missing (or something that resembles it), to what made it to the recorded data...
I still subscribe to not all hearing is the same, nor is the mental processing of the sound the same, school of thought...
I sometimes think people are plain deaf... especialy when I watch Idols... there is so much more to sound than just sound alone....the very energy sub and above audiable range sound imparts to the body.
Sometimes I think the realy clever guys among us, are those who hang out in the speaker building thread...
I would wager there is more diffirence between loudspeaker boxes and hell, even microphones, than amps...
I base my opinion on a life spend in and around bands... I have baby photos of me in my walkring between band equipment...
To me it is conceiveble that "information" goes missing between the sound source and the point of first recording...(mouth and mic), and that it is possible for some amps to "accidentaly" add some of this inforamtion that went missing (or something that resembles it), to what made it to the recorded data...
I still subscribe to not all hearing is the same, nor is the mental processing of the sound the same, school of thought...
I sometimes think people are plain deaf... especialy when I watch Idols... there is so much more to sound than just sound alone....the very energy sub and above audiable range sound imparts to the body.
Sometimes I think the realy clever guys among us, are those who hang out in the speaker building thread...
I would wager there is more diffirence between loudspeaker boxes and hell, even microphones, than amps...
I base my opinion on a life spend in and around bands... I have baby photos of me in my walkring between band equipment...
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.