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Is there a noticeably audible difference between two level matched solid state amps under controlled

  • Yes... I believe a notable difference can be heard.

    Votes: 139 48.6%
  • No... I do not believe there is any audibly significant difference.

    Votes: 147 51.4%

Can we really hear a difference between amps?

179K views 835 replies 96 participants last post by  jonathonsmith 
#1 ·
Can we really hear a difference between two amps?

More specifically... between two amps that have been level matched in a controlled listening test. We are not talking about amps that have been modified or are driven beyond their reasonable limits.

What a crazy and completely worn out question... I know, I know, but I figured why not have a bit of fun with it anyway.

Naturally our ZERO TOLERANCE FORUM RULES are going to apply as they ALWAYS do! So... if you are one of those who simply cannot have a sensible discussion on a hot and debated topic... STAY FAR AWAY from this thread. :D

Consider the following link and quoted articles:

LINK: Science and Subjectivism in Audio

Any amplifier, regardless of topology, can be treated as a “black box” for the purpose of listening comparisons. If amplifiers A and B both have flat frequency response, low noise floor, reasonably low distortion, high input impedance, low output impedance, and are not clipped, they will be indistinguishable in sound at matched levels no matter what’s inside them. Of course, some of the new “alphabet soup” topologies do not necessarily satisfy those conditions.

I really believe that all this soul-searching, wondering, questioning, agonizing about amplifiers is basically unproductive and would be much more rewarding if applied to loudspeakers instead. For various reasons that I have discussed in the past, people are more willing to change amplifiers than loudspeakers. That’s most unfortunate because a new and better loudspeaker will change your audio life but a new amplifier will not.

—Peter Aczel, Editor & Publisher, The Audio Critic
There has been a lot of hot chatter on the E-mail circuit over the past couple of months about the Steve Maki and Steve Zipser challenge in Miami. I thought you would appreciate a complete recount of the events. Zipser, a high-end salon owner, had issued a challenge that he would pay the airplane fare of any interested party who wanted to see him prove he could hear the differences between amplifiers.

On Sunday afternoon, August 25th, Maki and I arrived at Zipser's house, which is also Sunshine Stereo. Maki brought his own control unit, a Yamaha AX-700 100-watt integrated amplifier for the challenge. In a straight 10-trial hard-wired comparison, Zipser was only able to identify correctly 3 times out of 10 whether the Yamaha unit or his pair of Pass Laboratories Aleph 1.2 monoblock 200-watt amplifiers was powering his Duntech Marquis speakers. A Pass Labs preamplifier, Zip's personal wiring, and a full Audio Alchemy CD playback system completed the playback chain. No device except the Yamaha integrated amplifier was ever placed in the system. Maki inserted one or the other amplifier into the system and covered them with a thin black cloth to hide identities. Zipser used his own playback material and had as long as he wanted to decide which unit was driving the speakers.

I had matched the playback levels of the amplifiers to within 0.1 dB at 1 kHz, using the Yamaha balance and volume controls. Playback levels were adjusted with the system preamplifier by Zipser. I also determined that the two devices had frequency response differences of 0.4 dB at 16 kHz, but both were perfectly flat from 20 Hz to 8 kHz. In addition to me, Zipser, and Maki, one of Zip's friends, his wife, and another person unknown to me were sometimes in the room during the test, but no one was disruptive and conditions were perfectly quiet.

As far as I was concerned, the test was over. However, Zipser complained that he had stayed out late the night before and this reduced his sensitivity. At dinner, purchased by Zipser, we offered to give him another chance on Monday morning before our flight back North. On Monday at 9 a.m., I installed an ABX comparator in the system, complete with baling-wire lead to the Yamaha. Zipser improved his score to 5 out of 10. However, my switchpad did develop a hang-up problem, meaning that occasionally one had to verify the amplifier in the circuit with a visual confirmation of an LED. Zipser has claimed he scored better prior to the problem, but in fact he only scored 4 out of 6 before any difficulties occurred.

His wife also conducted a 16-trial ABX comparison, using a 30-second phrase of a particular CD for all the trials. In this sequence I sat next to her at the main listening position and performed all the amplifier switching functions according to her verbal commands. She scored 9 out of 16 correct. Later another of Zip's friends scored 4 out of 10 correct. All listening was done with single listeners.

In sum, no matter what you may have heard elsewhere, audio store owner Steve Zipser was unable to tell reliably, based on sound alone, when his $14,000 pair of class A monoblock amplifiers was replaced by a ten-year old Japanese integrated amplifier in his personal reference system, in his own listening room, using program material selected personally by him as being especially revealing of differences. He failed the test under hardwired no-switching conditions, as well as with a high-resolution fast-comparison switching mode. As I have said before, when the answers aren't shared in advance, "Amps Is Amps" even for the Goldenest of Ears.

Tom Nousaine
Cary, IL
Richard Clark $10,000 Amplifier Challenge FAQ

by Tom Morrow

Written 6/2006


The Richard Clark Amp Challenge is a listening test intended to show that as long as a modern audio amplifier is operated within its linear range (below clipping), the differences between amps are inaudible to the human ear. Because thousands of people have taken the test, the test is significant to the audiophile debate over audibility of amplifier differences. This document was written to summarize what the test is, and answer common questions about the test. Richard Clark was not involved in writing this document.

The challenge


Richard Clark is an audio professional. Like many audiophiles, he originally believed the magazines and marketing materials that different amplifier topologies and components colored the sound in unique, clearly audible ways. He later did experiments to quantify and qualify these effects, and was surprised to find them inaudible when volume and other factors were matched.

His challenge is an offer of $10,000 of his own money to anyone who could identify which of two amplifiers was which, by listening only, under a set of rules that he conceived to make sure they both measure “good enough” and are set up the same. Reports are that thousands of people have taken the test, and none has passed the test. Nobody has been able to show an audible difference between two amps under the test rules.
This article will attempt to summarize the important rules and ramifications of the test, but for clarity and brevity some uncontroversial, obvious, or inconsequential rules are left out of this article. The full rules, from which much of this article was derived, are available here and a collection of Richard's comments are available here.

Testing procedure


The testing uses an ABX test device where the listener can switch between hearing amplifier A, amplifier B, and a randomly generated amplifier X which is either A or B. The listener's job is to decide whether source X sounds like A or B. The listener inputs their guess into a computerized scoring system, and they go on to the next identification. The listener can control the volume, within the linear (non-clipped) range of the amps. The listener has full control over the CD player as well. The listener can take as long as they want to switch back and forth between A, B, and X at will.

Passing the test requires two sets of 12 correct identifications, for a total of 24 correct identifications. To speed things up, a preliminary round of 8 identifications, sometimes done without levels or other parameters perfectly matched, is a prerequisite.

Richard Clark normally has CD source, amplifiers, high quality home audio speakers, and listening environment set up in advance. But if the listener requests, they can substitute whatever source, source material, amplifiers, speakers (even headphones), and listening environment they prefer, within stipulated practical limits. The source material must be commercially available music, not test signals. Richard Clark stipulates that the amplifiers must be brand name, standard production, linear voltage amplifiers, and they must not fail (e.g. thermal shutdown) during the test.

Amplifier requirements


The amplifiers in the test must be operated within their linear power capacity. Power capacity is defined as clipping or 2% THD 20Hz to 10kHz, whichever is less. This means that if one amplifier has more power (Watts) than the other, the amplifiers will be judged within the power range of the least powerful amplifier.

The levels of both left and right channels will be adjusted to match to within .05 dB. Polarity of connections must be maintained so that the signal is not inverted. Left and Right cannot be reversed. Neither amplifier can exhibit excessive noise. Channel separation of the amps must be at least 30 dB from 20Hz to 20kHz.

All signal processing circuitry (e.g. bass boost, filters) must be turned off, and if the amplifier still exhibits nonlinear frequency response, an equalizer will be set by Richard Clark and inserted inline with one of the amps so that they both exhibit identical frequency response. The listener can choose which amplifier gets the equalizer.


FAQs:


How many people have taken the challenge?

Richard Clark says over a couple thousand people have taken the test, and nobody has passed. He used to do the test for large groups of people at various audio seminars, and didn't charge individuals to do the test, which accounted for the vast majority of the people who did the test. Around 1996 was the last of the big tests, and since then he has done the test for small numbers of people on request, for a charge ($200 for unaffiliated individuals, $500 for people representing companies).

When did the challenge start?


Sometime around the year 1990. Richard Clark says in a post on 7/2004 that the test with the $10,000 prize started about 15 years ago.

What were the results of the test?


Nobody has ever successfully passed the test. Richard Clark says that generally the number of correct responses was about the same as the number of incorrect responses, which would be consistent with random guessing. He says in large groups he never observed variation more than 51/49%, but for smaller groups it might vary as much as 60/40%. He doesn't keep detailed logs of the responses because he said they always show random responses.

Is two sets of 12 correct responses a stringent requirement?


Yes. Richard Clark intentionally made the requirements strict because with thousands of people taking the test, even random guessing would eventually cause someone to pass the test if the bar was set low. Since he is offering his own $10,000 to anyone who will pass the test, he wants to protect against the possibility of losing it to random guessing.

However, if the listener is willing to put up their own money for the test as a bet, he will lower the requirements from 12 correct down to as low as 6 correct.

Richard Clark has said “22 out of 24 would be statistically significant. In fact it would prove that the results were audible. Any AVERAGE score more than 65% would do so. But no one has even done that”.”

Do most commercially available amplifiers qualify for this test, even tube amplifiers and class D amplifiers?


Yes. Nearly all currently available amplifiers have specs better than what are required for the test. Tube amplifiers generally qualify, as do full range class D amplifiers. It is not clear whether Richard Clark would allow sub amplifiers with a limited frequency response.

Besides taking Richard Clark's word, how can the results of the test be verified?


Many car audio professionals have taken the test and/or witnessed the test being taken in audio seminars, so there isn't much doubt that the test actually existed and was taken by many people. One respected professional who has taken and witnessed the test is Mark Eldridge. Because the test has been discussed widely on audio internet forums, if there were people who passed the test it seems likely that we would have heard about it. Sometimes there are reports of people who believe they passed the test, but upon further examination it turns out that they only passed the preliminary round of 8 tests, where levels were not matched as closely as for the final test.

How can audio consumers use the results of this test?


When purchasing an amplifier, they can ignore the subjective sound quality claims of marketers. Many amplifier marketers will claim or imply that their amplifiers have some special topology, materials, or magic that makes the sound clearly superior to other amps at all volume levels. Many consumers pay several times more than they otherwise would for that intangible sound quality they think they are getting. This test indicates that the main determinant of sound quality is the amount of power the amplifier can deliver. When played at 150W, an expensive 100W measured amplifier will clip and sound worse than a cheap 200W measured amp.

Does this mean all amps sound the same in a normal install?


No. Richard Clark is very careful to say that amps usually do not sound the same in the real world. The gain setting of an amplifier can make huge differences in how an amplifier sounds, as can details like how crossovers or other filters are set. When played very loud (into clipping), the amplifier with more power will generally sound better than a lower powered amp.

Most people perceive slight differences in amplitude as quality differences rather than loudness. The louder component sounds “faster, more detailed, more full”, not just louder. This perceptual phenomenon is responsible for many people thinking they liked the sound of a component when really they just liked the way it was set up.

I changed amps in my system to another one with the same measured power and I hear a sound quality difference. Does this show that the test results are invalid?


No. Installing a new amplifier involves setting the gains and crossovers, and any slight change you make to those settings is going to affect how things sound.

Is adding an equalizer just a way of “dumbing down” the better amplifier ?


Richard Clark allows the equalizer to be added to whichever amplifier the listener wants. It can be added to the amplifier that the listener perceives as the weaker amplifier . The EQ is most likely to be used when comparing a tube amplifier (which exhibits slight high frequency rolloff) to a solid state amplifier . In that case Richard Clark says he can usually fashion an equalizer out of just a resistor and/or capacitor which for just a few dollars makes the solid state amplifier exhibit the same rolloff as the tube amplifier, and therefore sound the same. If the tube amplifier really sounded better, then modifying the solid state amplifier to sound indistinguishable from it for a few bucks should be a great improvement.

How might allowing clipping in the test affect the results?


It's impossible to know for sure because that would be a different test that has not been done. But Richard Clark seems to think that in clipping, conventional amplifiers would sound about the same, and tube amplifiers would sound different from solid state amplifiers.

Richard Clark reported that he did some preliminary experiments to determine how clipping sounds on different amplifiers . He recorded the amplifier output using special equipment at clipping, 12db over clipping, 18db over clipping, and 24db over clipping. Then he normalized the levels and listened. His perception was that with the same amount of overdrive, the conventional amplifiers sounded the same. With the same amount of overdrive the tube amplifiers sounded worse than the conventional amplifiers . On the basis of that experiment, he said “I believe I am willing to modify my amplifier challenge to allow any amount of clipping as long as the amplifiers have power ratings (actual not advertised) within 10% of each other. This would have to exclude tube amplifiers as they seem to sound much worse and it is obvious”.

If a manufacturer reports false power ratings, will that interfere with the test?


No. The test is based on measured power, not rated power .

Does this mean that there is no audible difference between sources, or between speakers?


No. There are listening tests that show small but significant differences among some sources (for instance early CD players versus modern CD players). And speakers typically have 25% or more harmonic distortion. Most everyone agrees that differences among speakers are audible.

Does the phrase "a watt is a watt" convey what this test is about?


Not quite but close. Richard Clark has stated that some amplifiers (such as tubes) have nonlinear frequency response, so a watt from them would not be the same as a watt from an amplifier with flat frequency response.

Do the results indicate I should buy the cheapest amp?


No. You should buy the best amplifier for your purpose. Some of the factors to consider are: reliability, build quality, cooling performance, flexibility, quality of mechanical connections, reputation of manufacturer, special features, size, weight, aesthetics, and cost. Buying the cheapest amplifier will likely get you an unreliable amplifier that is difficult to use and might not have the needed features. The only factor that this test indicates you can ignore is sound quality below clipping.

If you have a choice between a well built reliable low cost amp, and an expensive amplifier that isn't reliable but has a better reputation for sound quality, it can be inferred from this test that you would get more sound for your money by choosing the former.

Do home audio amps qualify for the test?


Yes. In the 2005 version of the test rules, Richard explicitly allows 120V amplifiers in a note at the end.

How can people take the test?


They should contact Richard Clark for the details. As of 2006 Richard Clark is reported to not have a public email account, and David Navone handles technical inquiries for him. Most likely they will need to pay a testing fee and get themselves to his east coast facility.

Is this test still ongoing?


As of early 2006 , there have not been any recent reports of people taking the test, but it appears to still be open to people who take the initiative to get tested.

Do the results prove inaudibility of amplifier differences below clipping?


It's impossible to scientifically prove the lack of something. You cannot prove that there is no Bigfoot monster, because no matter how hard you look, it is always possible that Bigfoot is in the place you didn't look. Similarly, there could always be a amplifier combination or listener for which the test would show an audible difference. So from a scientific point of view, the word “prove” should not be used in reference to the results of this test.

What the test does do is give a degree of certainty that such an audible difference does not exist.

What do people who disagree with the test say?


Some objections that have been raised about the test:

  • Richard Clark has a strong opinion on this issue and therefore might bias his reports.
  • In the real world people use amps in the clipping zone, and the test does not cover that situation.
  • Some audible artifacts are undetectable individually, but when combined with other artifacts they may become audible as a whole. For instance cutting a single graphic EQ level by one db may not be audible, but cutting lots of different EQ levels by the same amount may be audible. Maybe the amps have defects that are only audible when combined with the defects from a particular source, speaker, or system.
  • Some listeners feel that they can't relax enough to notice subtle differences when they have to make a large number of choices such as in this test.
  • There is a lack of organized results. Richard Clark only reports his general impressions of the results, but did not keep track of all the scores. He does not know exactly how many people have taken the test, or how many of the people scored “better than average”.
  • If someone scored significantly better than average, which might mean that they heard audible differences, it is not clear whether Richard Clark followed up and repeated the test enough times with them to verify that the score was not statistically significant.
Is there one sentence that can describe what the test is designed to show?

When compared evenly, the sonic differences between amplifiers operated below clipping are below the audible threshold of human hearing.

Links


Note from the author

I wrote this Summary/FAQ because I found that many of the people who disagreed with Richard Clark about the challenge simply didn't have the whole story on the challenge. I originally thought the challenge was flawed even after I read the rules a few times, but after reading lots of comments from Richard Clark, my objections were answered and now I believe that understanding the challenge is a very useful tool for learning what is audible and what isn't. I have no relationship with Richard Clark and have never communicated with him except that I've read his public postings about the challenge. If anyone finds typos or factual errors in this document please contact me.
I have leaned towards the camp of not being able to hear any significant difference between almost any two amps out there when played at moderate levels on the typical speaker system, unless there is something wrong with one or the other amp that might cause it to color the sound.

Granted... a low-end receiver may well have an issue driving a system of certain electrostatic speakers... or speakers with low sensitivity, especially if pushed to higher levels. There are going to be exceptions, but for the sake of this discussion, let's say we are using a pair of Klipsch RF-62 II speakers with a sensitivity of 97dB @ 2.83V / 1m ... or perhaps the Duntech Marquis speakers that Zipser was using above at 92db.

I have owned processor/amp combos and/or receivers from Sony, Denon, Sunfire, McIntosh, Adcom, NAD, Onkyo, Earthquake, Anthem, Rotel, Lexicon, Emotiva (and probably others I cannot remember) powering Snell B-Minors, Klipsh Forte, PSB Image, SVS, JBL, Boston Acoustics, VMPS RM30's, MartinLogan Ascents, ML Spires and recently the older ML Prodigy mains with a Theater center and Ascent surrounds powered by Emotiva XPA-1's and an Onkyo 906 Receiver. Currently (updated January 2104) I run an Onkyo 5509 with an Emotiva XPR-5 with MartinLogan Montis, Stage X and Motion 12's. The most significant difference I ever heard was moving to the Martin Logan speakers. NOTHING had EVER made anywhere close to a difference in sound as did the MartinLogan speakers. I thought at one time that my NAD receiver had more of a soft sound (maybe "warmer" as some will state the description), but was told (never did verify it with NAD or via measurements) that NAD intentionally setup their receivers with a rolled off high-end. However, I have heard significant differences in speakers. I have also performed A/B testing between several amps and have not found any differences outside of clipping and/or distortion.

Is it not the desire of the audiophile to have electronic equipment which does not alter the sound?

Your thoughts and comments will be interesting.
 
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#124 ·
The anechoic chamber would be the best way forward, not because it would remove the room effects, but because it would remove the tendency to blame such possibilities for the end result, as in failing the test etc. While such a test would be possible in any room, removing any human elements (such as looking for blame in failure situations) would be the ideal IMO.

Thats really what I was trying to get at.
 
#126 ·
IMO, the ideal situation is good experimental design that eliminates as many variables as possible and controls for the rest. What either side argues as bias is not as relevant as using methodology and analysis that is good science and can be used to further knowlege regarding what is audible and under what conditions.

I agree that if one is trying to determine whether claims of being able to detect differences are accurate and one is trying to disprove those claims it make sense to use the conditions that satisfy the claimant. This, however, is not good science. Good science does not try to disprove the beliefs of some in favor of those of others. Good science extends knowledge in an area through experimental manipulation of variables and appropriate analysis of results. No good experimental design sets out to prove that there are no differences. One makes a hypothesis and fails to reject the null if there are no differences.
 
#127 ·
I agree that if one is trying to determine whether claims of being able to detect differences are accurate and one is trying to disprove those claims it make sense to use the conditions that satisfy the claimant. This, however, is not good science. Good science does not try to disprove the beliefs of some in favor of those of others. Good science extends knowledge in an area through experimental manipulation of variables and appropriate analysis of results. No good experimental design sets out to prove that there are no differences. One makes a hypothesis and fails to reject the null if there are no differences.
So if one wants to determine how a wolf pack hunts: it would be bad science to observe a wolf pack hunting in the woods (as this would lack a manipulation of variables) and instead would stick individual wolves in empty rooms with (preferably artificial: as they are more consistent) prey ?!?

By removing the conditions under which people claim to hear differences, you may remove the actual cause of those differences. What if the amp causes the speakers to excite walls differently than another amp?

No. If you want to know if amps are different all you need is a meter.
If you want to know if differences are audible: you use headphones.

If you want to test the claim that people can hear differences: you do it in the setting that it has been claimed in.
 
#128 ·
If you want to do good science you control for as many variables as you can and manipulate the one under test. If you hypothesize an effect due to room acoustics or the interaction with loudspeakers or whatever, you treat that as an experimental variable.

Observation is the start of all science. Some knowledge is gained from observation, some from experimentation. When you are testing a condition such as described here and trying to define the conditions under which differences may exist, it is entirely reasonable, actually expected, to control as many variables other than the one under test as possible. It may be reasonable to use a setting that is similar to that in which subjects who claim to hear a difference are accustomed, but the results may not be as conclusive as many would like to consider if sufficient controls are not in place. I explained above one example of how room acoustics could have an effect that is not controlled for. There are many considerations in any study and generalizing is difficult. One has to consider each on its own merits. The context of a specific experiment needs to be considered, along with the number of trials, source material, subjects, and all of the specific conditions.

If you simply want to determine whether a particular individual can tell the difference between two amps in a given system or not, then what you describe is fine. My point remains that there is much more to be learned from experiments that are more targetted to discovering what is audible and to what degree in more carefully controlled designs.
 
#129 ·
It's still the same problem. You are watching a wolf in captivity and trying to add a tree and bird-call to get wild predation. In theory, theory is the same as practice; but is practice it isn't.

I assert that you are working backwards. You would first need to determine that a difference in experience exists and then attempt to determine the cause. If you don't all you are going to do is a thousand tests to end up right where I suggested you start and know nothing more than if you had skipped ahead.

Since you are interested in science (thought I'm not sure why): science is the process of creating models which can be used to make accurate predictions about reality. You want to execute a scientific experiment? Then describe your model and show how you are testing a falsifiable prediction. If you do not, then you are tossing around the term "science" rhetorically.

I'm interested in practical reality. It is less an issue of accurate models and more an issue of proving or disproving a claim of fact. As such: burden of proof falls on the positive claim. The positive claim is that a difference can be detected.

Better still is the claim that a difference *is* detected under some set of conditions.

Obviously: if a difference can be detected under some conditions, whether it can be detected under all conditions is not really important to establishing the presence of a difference. (obviously: we must remove non-auditory tester bias... all things must be the same except that which is being tested).

If you simply want to determine whether a particular individual can tell the difference between two amps in a given system or not, then what you describe is fine.
Isn't that exactly the claim being tested?!? It's the title of the thread.

Now if you found a difference and then wanted to understand *why*. THEN I would agree with your proposed methodology to isolate the cause.
 
#130 ·
More precisely controlled experimental designs are desirable in my opionion. If you think otherwise that is your opinion and you are welcome to it. I don't care to batter the corpse any longer. I have made my point and you have a different view. So be it.
 
#132 ·
I tried out a McIntosh first gen solid state amp in the '70s (after my brother repossessed it) and it was truly awful as I believe all first gen transistor amps did. In the '90s I thought a Sony basic stereo amp sounded better than an old Sherwood amp did. These days I don't think that there is a difference in sound between well designed amps with low distortion, certainly those with flat frequency, and low thd and IMd. Measurement of sound equipment has been going on for many decades and today a thorough objective test suite will show what is causing differences in sound. One might like different colorations, I certainly like some, but if the amp tests well it will be neutral.
 
#133 ·
Concerning testing environment.
As long as the amp is the only item changed in the system, it doesn't matter what the environment is. If the sound between amps is different, it has to be the amp itself.
I do believe listening in a controlled environment would make it easier to hear a difference if there is one, because it would minimize outside distractions.
Wolves separated in captivity would act differently than a pack in the wild, but wolves and amps are completely different beasts. The amps have no idea where they are, and do not change their characteristics.
 
#134 ·
You are correct. There is all sorts of non-sense that goes on but at the same time there are measurements that explain all sorts of real differences in sound. One of the problems is people often compare the difference in sound between an inexpensive (or even $2000 one) receiver and a separate power amp. Receivers almost always overstate (lie) their power output and distortion will be much higher because of an insufficient power supply. I therefore doubt that there is a sound to amplifiers that can't be explained through measurement. Perhaps there is but that is for someone with more "golden ears" (read golden pockets) than me. If so they should spend some time coming up with a measurement that quantifies this and not use the subjective "language" (without correlating the word with something that can be measured) that has been developed by those selling and reviewing the very high end.
 
#135 ·
I've got to agree with Jerry on this one.

The room is not a variable. It must stay the same during the tests otherwise it becomes one. Anything that is acting equally on both DUT's is not a variable. That word indicates that there must be some sort of change happening which there would not be otherwise the entire test would be invalidated. On a side note I'd contend that listening to speakers in an anechoic chamber would be a much stranger condition and effect on the listeners perception of sound than any usual acoustics issues present in a much more normal, random, room environment, taking much longer to get acclimated to.

Sure...Ideally you'd want as accurate of a playback system with as wide of a bandwidth as possible and the best environment possible with the lowest noise floor and intimately familiar material to listen to, but all of that doesn't really relate to the real world.

Let's say that you stick big time music producer Rick Rubin who has spent many years critically listening to music and probably knows how to spot minute differences in the sound, in a huge anechoic chamber outfitted with the most neutral set of passive speakers somoeone like Genelec or JBL can engineer coupled with laboratory grade power supply and front end electronics. You lock him in there for a month listening to his music on both amps with them being switched randomly in between songs so he can get used to the system and chamber. Then you do another 14 days of the tests where he guesses which amplifier is on for each of 72 songs a day. We'll get MIT to run the whole deal. At the end of it compile the results. Lets say that he actually got a statistically significant, higher number of guesses right than just chance would suggest.

Does that prove that you can hear the difference in amplifiers? Should you start listening to them before buying to use in your room at home? Personally I'd say no. Others would say yes we have the proof..EAT IT LOSERS!:eek:lddude: Obviously there are real measurable differences between most amplifiers and the way I see it if a test happened like that it would prove conclusively one way or the other whether it is possible to tell the difference reliably with the human senses, but it wouldn't mean much in the real world of inferior: speakers, acoustics, listeners, noise floor, etc. Basically if a scenario like that is what it takes to be able to tell the difference conclusively, a percentage of the time, what chance would there be for Sonnie to do the same in his underground swamp fortress?:D What if Mr. Rubin with Uber system and MIT moderation failed to identify the amps reliably?
 
#136 ·
OK, here is something for you to mull over. If a 'real world' room is the test room, and a participant does detect a difference, then in theory, changing the room to one with different effects should still yield the same result should it not. It might even be conceivable to say that the fairest test would be one that is replicated in a few different rooms. If the results vary, the room is to blame, and an anechoic chamber would then be the only logical test facility. Swapping the order of the test questions would further help resolve that issue.

So I ask, why even risk that variable, and not just rule the room out anyway. The fewer variables the better the test, is that not the preference of science.

There are other concerns too, what if you used a pair of 50$ speakers, would that be a fair test :D. Obviously it wouldnt, but what would such a test reveal about amps? I'm with you on this though Ricci, if that is the kind of test required to prove this, then the results probably show its something we really dont have to worry about, meaning that a no vote above would be technically incorrect, but in the real world, actually closer to the real world result truth.
 
#140 ·
Then there should be no problems repeating the test results in several rooms, just to be sure, should there. If it was my 10k, I would be adding that into the mix as well. If I was taking the test, I would specifically ask for an anechoic chamber to try give myself the best chance of winning.
 
#139 ·
I must say that for a Thread that could easily devolve into anarchy and personal attacks that this Thread has gone quite well. Props to all who have taken part.

While I have never heard massive differences in the Amplifiers I have Owned over the years, I do believe in having large Power Transformers and high levels of Capacitance. This is predicated by the Electrostatic Speakers I have been using for over a Decade. Using a 5.1 Electrostatic Surround setup has really made me grateful that I have powerful Amplifiers that are stable down to 2 Ohms.

Electrostats are simply Speakers that are quite demanding of Amplifiers. Not only do they drop below 1 Ohm in the upper registers, but they present a difficult Capacitive Phase Angle. With Sonnie's Prodigies, while little Musical Information is present where Electrostats present their lowest Ohm load, at around 8 khz where there is plenty of action the Ohm load is still 3.55 Ohms with a Capacitive Phase Angle of -58 degrees.

While there might not be great sonic differences between the Amplifiers I use, not all Amplifiers are capable of coping with the demands of Electrostatic Speakers. Interestingly, it is the highs that are rolled off when not using a sufficiently powerful Amplifier.
Cheers,
JJ
 
#141 ·
Not at all... but it would serve no purpose and it is not part of the challenge, therefore it is irrelevant. It is not your 10K anyway... it is his. He gets to set the rules, which are the conditions of the challenge. If you can really hear a difference, it won't make a difference where you hear it at if all other conditions are equal for the amps in question. If you can hear a difference in room A, then you will hear a difference in room B... or an anechoic chamber... it won't matter... PROVIDED all is equal other than the amps. I am not sure how you would ever rationalize that the listening environment (with everything being equal other than the amps) would cause one amp to sound different than another. Oh wait... there's magic in the air! :ponder:
 
#142 ·
You werent reading my earlier posts pertaining to human perception and the way the human brain works were you :D.

Watch this smarty pants, and it will become a little clearer as to the point I am actually trying to make:

http://www.bbc.co.uk/iplayer/episode/b00vhw1d/Horizon_20102011_Is_Seeing_Believing/

Assuming we had one available, I can think of a single reason as to why the tester would refuse an anechoic chamber as the test facility, except of course, unless something was a foot.
 
#144 ·
Figures. Well its basically the science behind the studies of human perception. It details well how the human mind works, and how it combines the information it receives from your senses to result in a best guess result. This happens in everything we do, even when we are aware it happens we cant stop it from happening. Just knowing your in a room thats has factors influencing the result, WILL influence the result like it or not.

Look up the mcgurk effect and ames room. Both are examples of how your senses fool you, and like it or not all the senses work together in pretty much all scenarios and things like this can and do happen, even when you know about them and are aware they are happening.
 
#145 ·
Regardless... I still believe that if all things are equal and you hear a difference in one room, you will hear it in another.

If that philosophy did come in to play with rooms and amp testing, the anechoic chamber is going to have an influence on you as well, it's another room. If you can't stop it, you can't stop it, therefore the anechoic chamber ain't gonna stop it. In your scenario, you would not be taking the influences of the room out of the equation... one) because the anechoic chamber is still going to have a different influence on the sound from that of a non-anechoic chamber... and two) because your implication is that it would be impossible to remove the perception from your mind... why would that be any different by going to an anechoic chamber. Silliness!

Either way, it doesn't matter. If 100 people accept the challenge, I believe 100 people will not be able to determine a difference, regardless of where the challenge is conducted. His method eliminate "chance". The end result is the same.
 
#147 ·
I agree I dont think people could hear the difference. My point is simply to eliminate all possible variables as well. An anechoic chamber has the mental effect of most people not knowing what to expect, thus removing preconception and the influence of it, and having that chamber in complete darkness would also aid this experiment as your ears are more sensitive an accurate when the visual sense is removed from the brain. It also serves to make the test as sympathetic to the person taking the test as it does the guy with his 10k on the line. Half the problem is not just the room, its the human being as well, and I think good science would agree with me on these points.

I'm still in agreement with Ricci though, that the fact we are even discussing such extremes, or not, lends itself to the idea the differences are simply too small to make a meaningful difference to 99% of people out there.
 
#146 · (Edited)
I've liked speakers that would probably test badly, such as the Ti Focals and Al Vifas of ten-fifteen years ago. I think its my hearing that was subjected to very loud music concerts in the early '70s. But I have to admit that it is a smooth midrange that attracts me most now. Speaker motors have improved so much. I can hear the difference of 24 bit depth from those that have 16 bit resolution but doubt that I hear any difference between 96kHz and 48kHz. MP3's, especially 128k, sound inferior to me, although I've bought thousands. I wish MP3's were never invented. Dolby Digital (DD, not the HD version) also sounds harsh to me. Even some low-def cd's sound inferior to the best LPs I've heard. I have some 24 bit flacs that I like a lot and I think sound better than a cd. Sometimes technology takes a step backward in order to save on production costs and to appeal to people as the newest "best thing." Solid state was one of those when it was first released, with horrible switching distortion but years later is now neutral sounding (given that better parts are used) and arguably better than tubes (which often color the sound with high 2nd order distortion). I wouldn't mind using a tube amp for the mid-range in a DSP crossed over system, if it had enough power. I am not ready to buy a mid-range receiver as the power supplies are almost universally deficient. What happened to the FTC dictating objective and non-deceptive numbers in ads and specs? I've been to many concerts (folk, classical, jazz (not easy listening or "cool")) and I think my system sounds better better in comparison due to the deficiencies of the sound systems and poor seats/concert hall. Still a live concert is special and highly enjoyable with an energy often not present in recordings. One of my favorite recordings that captured this energy was the LP version of Old & In The Way which sadly was destroyed (mastered by Owsley Stanley, LSD chemist). I also prefer movies on my system because of the deficiencies of sound systems and the 24fps flicker in theaters which for some reason I am highly sensitive to. I have no interest in replicating the sound of a concert hall but rather want something better at home. I do use surround to add a subtle ambiance. Music is a subjective experience but the replication chain does not need to be.
 
#158 ·
As a former nurse and mental health professional I would say that physical (include electro-chemical) differences would tell nothing about the sound of the amps but rather only differences in perception (or how perception is processed). Its not that perceptions are not real but rather they are in a different realm and do not necessarily indicate any non-mental difference.
 
#159 ·
The maple blocks give the sound a leaner and more forward soundstage. If you like a warmer and more intimate experience, I suggest you try the Rosewood blocks. I don't care for the walnut blocks, IMHO they tend to construct the image and I have trouble with depth perception;)
 
#164 ·
This problem is pretty common. AVRs have no ground connections, they use two-wire plugs. Subwoofers often use three-wire plugs, and that can cause a hum problem, because the neutral connection is never at the same potential as the safety ground. Adding a BFD or other pro gear that uses 3-wire power will also cause this. There are several solutions, but balanced output is one good one. rejecting common-mode ground noise is the reason for balanced connections in the first place.
 
#166 ·
This problem is pretty common. AVRs have no ground connections, they use two-wire plugs. Sub woofers often use three-wire plugs, and that can cause a hum problem, because the neutral connection is never at the same potential as the safety ground. Adding a BFD or other pro gear that uses 3-wire power will also cause this. There are several solutions, but balanced output is one good one. rejecting common-mode ground noise is the reason for balanced connections in the first place.
I suppose that is good to know but most manufacturers say that RCA for short runs is the better connection and most AVR's do not have balanced connections but only single RCA outputs, so that can be quite a big issue to some?
 
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