Comments made by Richard Clark about the Amp Challenge.

These comments were taken from a post made by "Mouser" on the talkaudio web forum, dated 10/18/2002. The comments are believed to have been made by Richard Clark.

Before reading these comments you might want to read the summary and FAQ of the challenge, and the challenge rules.

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of course my challenge includes tube amps---thats what got it started to begin with----while most tube amps have more distortion than transistor amps it is still usually below the audible level of a couple percent---the biggest audible difference is like Big T said---the higher output impedance created by the transformer windings causes a slight frequency dependant amplitude difference---while this is usually less than a db or so except in the worst designs (the "super" amps without negative feedback really have this problem big time)the effect is subtle but audible-----and since it naturally happens at the resonant places of the speaker it is sometimes very pronounced----it is easily duplicated with a small value resistor in series with the speaker-----RC-

and just to show you how people misunderstand my challenge someone recently told me he could pass the test if he didn't have to be "blindfolded"----thats what his understanding of a "double blind" test was---so much for scientific understanding.....

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guys my testing procedures are more than fair--and they are set up to help the listener--all you have to do to get the details is to e-mail me at a2000rich@aol.com [EDITOR'S NOTE: that email no longer works as of 6/2006] and request the amp challenge rules--you can provide any CD player--any speakers you want--you can do the switching--you can provide the CD's and on and on and on---i want to see somebody do it--i will be happy to write the check--it will bring back a new realm of audio to me--and remember it is not a bet--you don't lose 10K if you lose--that is why i call it a challenge--a bet would require you to put up an equal amount--there are conditions i am willing to accept if you only want to do it 6 out of 6 times but because it increases the odds of guessing i require it to be a bet at that level--now before you continue to mis-quote me FIRST read the challenge rules!!!!!!!!!!!!!!!!--and if you think you can do it then come on and prove it and stop talking about it

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I wil not disagree with that assumption as I have found it to be true--thats why I exclude that condition from the testing conditions--but the real issue is that there are no amps that really sound better than others unless you drive them into a condition where they all sound bad--and the difference comes down to which sounds the "LEAST WORSE"--and remember that it is the "sound quality" that is supposed to be the reason to pay large sums of money for those "sweet sounding amps"--well the simple fact is that a modestly priced amp with more power than an overpriced "exotic" amp will surely sound the best under those important "real world conditions with dynamic music" so the bottom line is still what I have been saying all along---when buying an amp buy reliability and POWER--forget about the nonsense of "sound quality"

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guys--it always circles back to the same old thing--i have never said or even inferred that there is no meaningful difference in amps--of course there are differences--some amps cost more because they are built better--perhaps they will last longer--or play longer without overheating--or have better resale value because they have more "brand appeal" or do more because they have more features--all I ever said was that WHEN THEY ARE COMPARED EVENLY THE SONIC DIFFERENCES BETWEEN AMPLIFIERS IS BELOW THE AUDIBLE THRESHOLD OF HUMAN HEARING-- as for what we actually hear consider that if we compare two identical amps but turn the bass boost up on one and leave the other flat we will be able to hear the difference between two identical amps that have consecutive serial numbers--read my challenge rules--it should make sense

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i don't have a power limit for the test--the rules just say that the listening cannot exceed the clipping limit of the smallest amp of the pair being compared--i don't care if you compare a 500 watt amp with a 50 watt amp--you would just have to keep the listening below whatever caused the smallest amp to clip

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Blkout---tube amps are a serious waste of money--an obsolete technology like wooden wheels and horse drawn buggys-i can make any good quality solid state amp sound exactly like a tube amp with less than 5 dollars worth of parts---i have done it on many ocaasions for my amp challenge---but why would anyone want to degrade a good solid state amp to make it sound like a tube unit??? sure confuses me...........RC

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the actual components depend on each amp but rarely does it involve more than a resistor or couple of small caps-----90% of the time all it takes is a small value resistor in series with the output----the faults of tube amps are pretty much the same regardless of price---some are just worse than others-----but i have to have the amps to do an actual measurement.........RC

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guys---an L pad is designed so it presents the smallest possible resistance in series to the load for a given amount of loss-----that is why there are L pads and not just resistors----do they have an effect??----of course they do BUT THE EFFECT IS MINIMAL----is the effect the same as having a high source impedance (ie low damping factor) ----yes it is but as i have always said---the negative effects of low damping are overstated as well as the benefits of tube amps--------its all just audio nonsense........RC

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Colin, the output impedance of an amp doesn't have nearly the effect at midrange and high frequencies as it does with bass.

you can compensate for lpads because they just change QES of the speaker. usually letting you get a little more low end out of a speaker at the expense of efficiency.

you see very few setups(outside of guitar) where tubes are driving the woofers. This is not by choice, more necessity. (I dont think you need to worry about this with the butler amps, because if i remember correctly, they just use tubes in the preamp stages)

It is of course better to have all drivers matched to the same efficiency, but if they are unmatched, especially in the mid+high range, the L-pad solution is the lesser of two evils. I dont know if winISD lets you model generator resistance, LspCAD does. The main reason it is better to use Lpads on midranges instead of woofers is the power involved. You may need a 50 or 100W resistor in the woofer setup, where a 5 or 10W will work with midrange.

To obtain new QES and QTS, you simply use the following equation

QES' = (1+Rg/RE)*QES

where Rg is the output impedance of the amp or Lpad
RE is the DC voice coil resistance
QES is electrical Quality Factor

then for new QTS

QTS' = QMS*QES' / (QES'+QMS)

If your midrange is less efficient than your woofer, the best option is to add another midrange.

jt

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RC's amp challenge is the source of much debate but I have found it to be very helpful. The challenge simply proves that 100 (or insert whatever number pleases you) unclipped, unmanipulated watts from a less expensive amp will sound the same as 100 unclipped, unmanipulated watts from an expensive one. Does this mean everyone should run out and buy the cheaper amp? No. If the expensive amp is constructed with a higher quality of parts, is designed with a heat sink that functions better, has a nice crossover with more user functions, a better warranty, etc. then clearly it is more desirable. Furthermore if you only want 100 watts and the expensive amp can produce 130 watts before clipping compared to 105 watts before clipping for the less expensive one, this is an added bonus. I have seen some post on this forum expressing dislike for the challenge because (A) it states the obvious and (B) it doesen't tell you which amp is better for the end user. Both of these statements are true. For those of us who are just learning about car audio, however, RC's challenge serves a good purpose. It helps us to see past the marketing hype that wants us to believe that 100 unclipped, unmanipulated watts will sound different from one amp to the other (like when they compare distortion specs from two amps that are both well beyond the range of human hearing).The amp challenge will not tell you what you should buy, this is not it's intended purpose. It helps to educate consumers like me. The amp challenge helped me to understand what I really need to look at when considering an amp. To me this seems to be it's intended purpose and it serves this purpose well.

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guys---the sound quality issue of amps once again raises its ugly head----i ahve no reservations of including class D amps in my amp challenge and have done so in the past---for years dave and i have been strong proponents of class D as it just makes sense---yes it is harder to do class D at higher frequencies but not impossible---its just not as important as we usually reserve most of our power for the lows anyhow----and as for actual efficiencies i have posted such numbers in earlier threads---they are probably in the archives by now but at full power 70 to 85 is typical for class D and 55 to 60 is normal for class a/b-----at one third power (the most important due to the nature of duty cycle of music) the a/b is usually about 25 to 30% and the class d is about 50 to 60 percent........RC

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spliff--the audio world is full of guys who feel they could beat that challenge with no problem--that particular guy was a very keen listner--i would have to place him in the top 1% of challengers--he aced the qualifying test--very few have ever done that--after passing the qualifying round he was extremely confident--but once we started the real listening test he knew within minutes that he was going to lose---he looked at me with extreme dissapointment and said he wanted to continue just in case he got lucky

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colin----you can't hear less than 3% distortion no matter what kind it is---IM--TIM--THD---and in the amp challenge i don't worry about the 2ond order thing---it means nothing to audibility---the only thing that matters audibly is frequency response-----and for the resistor i just put a small value resistor in series with the speaker---usually one or two tenths of an ohm will make any transistor have the same response errors as a tube amp--------and WASTE if you want an amp with little damping factor use a resistor equal to the nominal impedance of the speaker---such as a 4 ohm with a 4 ohm speaker---you will then have a damping factor of ONE--------yes you will lose half your power but at least you can hear how it sounds------------RC

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guys ---have any of you ever heard cd 103 from autosound----it has tones and music at various distortion levels from .01% to 10%----it is easy to see what you can hear----no one can hear less than 2 or 3% on any kind of music-----but on a reasonable system it is easy to hear fractions of a percent on pure single tones-------check out the cd.........RC

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There is an ABX tester available and tons of clips (# of bits, distortion, etc.) for you to test your ears with. Also has guidelines for doing listening tests.

http://www.pcabx.com/

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as i stated in the tube amp thread i spent the last several nights doing some tests on the "sound" of amps when overdriven or "clipped"--------seems this has become the "best excuse" to surface on why one amp may be sonically superior to another-----i have always excluded overloading the amps in my challenge since the issue started out as a search for what specs really contrubuted to sound quality-------and since it seemed silly to listen to amps producing double digit distortion in a quest for sound quality this requirement made perfect sense to me-----in my first round of tests I compared a JL, a Jensen, and a high quality home/studio tube amp (4 El-34's per channel in a classic push pull output) ------i considered the JL as representative of the best car audio has to offer----the Jensen as a brand that most "sophisticated" audiophiles look down on and the tube amp as a good example of high quality tube design----meaning it is a real honest to goodness tube amp unlike the market driven hybrid nonsense that is sold in the car audio market---------the car amps were powered by a motor driven GM alternator wired to a yellow top battery------the home amp was of course plugged into the wall outlet-------i tested the amps at the following levels-------driven right to the edge of clipping (0 dB overdrive)------6 dB overdrive------12 dB overdrive------18 dB overdrive------and finally 24 dB overdrive-------the amps were connected to a 8 speaker (4 per channel) JL array wired to 4 ohms so the power could be safely absorbed without damaging the speakers------the signal was tapped directly off the speaker lines with a lab grade bridging coil and fed into a digital workstation------the signals were then "normalized" for the same loudness since the amps all had different power outputs-------i then edited the tracks into a single easy to compare CD-------here is my first impression-------the JL and the Jensen sound the same at all drive levels--------ie their distortion is equally bad------the tube amp sounds a little worse at the higher over drive levels-------i don't hear any speacial sonic character from any of the amps and sure can't hear any "tube magic" that is so touted by tube fanatics-------no soft clipping or pleasing harmonics------just nasty distortion-------i was going to do a few more amps in the test but after this i believe it is about as futile as trying to find survivors in the WTC------at this point i believe i am willing to modify my amp challenge to allow any ampunt of clipping as long as the amps have power ratings (actual not advertised) within 10% of each other----this would have to exclude tube amps as they seem to sound much worse and it is obvious-----------anyone want to listen to the CD send me and e-mail and i will send it to you as long as you agree to send it on to someone else that is interested in also hearing the results in a timely manner----when i send it to you you will be given the name and address of the next person to send it to--------the music is copyrighted and i don't want to make lots of copies...........RC

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manville------i don't follow you but here is a try----are you saying to set the overall amp gains the same??? ie --the sensitivity so a given input voltage will achieve a given output voltage????------if so thats what i always do in my amp challenge------but if one amp is more powerful than the other the difference is obvious if one amp clips and the other doesn't--------the unclipped amp will always sound better----somehow i doubt that is what you are asking???????-------what are you getting at by specifying the "cars" charging system-----in my test we actually powered the system from a alternator/battery combo-----and since an amps overall gain is not affected by the supply voltage i don't see the reason for this request------i will send the CD out monday---------i look forward to your comments..........RC

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guys---the first CD will go out to manville today and after he gives it a listen i will send a few more out-------once again i am misunderstood-------i have never said or have i intended to imply that some amps are not better than others----i my personal collection i have all sorts of amps but my favorites are Mcintosh, Western Electric and Altec------its just a PERSONAL PREFERENCE and has nothing to do with SOUND QUALITY------someone asked about headroom----home amps are usually specified at 120 volts with a variac used to maintain line voltage----rarely will a home amp meet specs at 117, 115 or 110 like can be expected under load in a real house------its just life------as for regulation it is a FACT that a amp that has a unregulated supply vs a regulated supply (by regulation i am referring to the secondary voltage rails not the input regulation) will produce more unclipped power reproducing MUSIC than another amp that HAS THE EXACT SAME CONTINUOUS POWER RATING-------on several occasions in A2000 seminars i have shown this by using an amp output stage with the ability to switch the amp to a loosly regulated supply vs a stiff supply--------the difference is dramatic----as far as i am concerned the best design (excepting of course a tracking supply) would be a supply that had very tight input regulation and very loose load regulation------now for the subject of amp price vs quality-----this is perhaps the area where i am most disturbed----THERE IS NO CORRELATION BETWEEN PRICE AND QUALITY OF AMPS ----in many cases there may be a connection but price is no guarantee of quality-----I feel very safe in saying Mcintosh builds some of the best amps in the industry-----the JL amp is really great----and so are a lot of others-----now i am not a liberty to say but we recently tested an amp that seems to be very highly regarded-----in fact from threads on the internet it seems that this amp actually has a cult following as if it were divine-----at our lab we were never able to complete a single test of this amp without it nuking on the bench-------finally when we were pressed to provide a test report we had to compile data from all three amps to come up with a complete set of specs to publish---------the amps are EXTREMELY EXPENSIVE but they are junk and every time i see them endowed with admiration i get sick----it especially makes me sick when i imagine a kid saving up hard earned money to buy "HIS DREAM AMP" when he would have been better off with something more sensible ---but this is audio and we have made a religion of it instead of a science.....................RC

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Here's my view:

1. Sound Quality:
Cheap Amp - Same
Great Amp - Same

2. Power (Wattage):
Cheap Amp - overrated
Great Amp - underrated

3. On/Off Noises:
Cheap Amp - you never know
Great Amp - should be quiet but you still never know

4. Reliability (ie won't break down):
Cheap Amp - wouldn't want it
Great Amp - want it

5. Cosmetics:
Cheap Amp - some look nice
Great Amp - some look nice

6. Prestige in impressing people who listen with their eyes and wallet (some judges):
Cheap Amp - not good
Great amp - good

If you compete, my advice is to spend money on 2 through 6.

If you don't compete and your amp will never be seen once installed, spend money on 2 through 4.
.
.
.

Cheap Amp examples are RadioShack, Rockwood, Kenford, Boss, Kmart etc...

Great Amp examples are Rockford Fosgate, MTX, JL Audio, etc...

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2000-------lets add one more to your list-------#7----resale value when its time to upgrade: good amps=good------cheap amps=zilch----i have in my personal collection some old Mcintosh home amps that are worth more today than when they were sold new---and i have some Western Electric studio amps that are worth 10 times what they cost new-----personally i think this is a real consideration since it is a rare audiophile that is ever satisfied with his system and we always want something better-------------you really drove that nail home------good post.............RC

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420----------i haven't collected the data for several years-------sort of like i haven't noted the location of the north star since i studied it in school----- it was so consistent-------in large groups i have never observed a variation that varied more than 49/51 % -------smaller observations sometimes vary as much as 60/40-------the more samples the more it approaches 50/50------any study of the numbers has only shown random probability.............RC

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phil-----believe it or not the amplifier challenge started out in home audio and pro audio-------i just modified it for car audio several years ago-------and if you have taken the time to notice most home amps are straight gain block designs devoid of crossovers, filters, and signal processors----and the claims from home audio about amp differences are the root of the car audio beliefs------high end home audio folks claim to be able to hear differences in simple gain block amps like they were night and day-----check out mags like stereophile and the like-------and years ago when i first published the car audio amp challenge at least 50% of the car amps did not have any kind of signal processing-----yet the claims still persisted............RC

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europa-----sure i have no problem with one of the amps being a home amp---i have done many "challenges" in the past with one or both home or pro amps-------it is true that the wording of the challenge excludes non 12 volt amps but that was done to keep things in the autosound arena-----i also have no problem with headphones being used...............RC

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yea guys-----not understanding scientific testing brings out the ignorance in a lot of beople---- fact is the people from the ABSOLUTE SOUND mag actually participated in just such a test about ten years ago--- in LA about 87/88 at the annual meeting of the AES (audio engineering society) it was done to their liking and agreed to ahead of time----after the test the excuses were simply amazing--------the guys just continue to make excuses about everything----what they don't know is that i don't control the music or the switching-----the listener does----he can listen as long or as short as he wants----he contols the switch-------he can put the CD player in a "loop" and listen to the same musical segment over and over for the entire test-----the test was not designed to "fool" or "trick" anyone----it was devised to determine if indeed anyone could really hear amp differences and if they could it would make it really easy-----not hard ----but they are too ignorant to even see that-------what idiots..............RC

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CT-----i read your thread over at SD------no suprises-----exactly what i have heard for over ten years----by now its almost funny-----the part that really amuses me is just how twisted the facts become-----it was claimed that i said the test was to fool listeners-------here is the fact of how it originated------about 15 years ago a company of mine (Concept Design) embarked on an engineering project to design a high speed digital recorder/playback device for professional use-----this was long before i had any interest in car audio-------i had a real good team of engineers working on the project and it was going right on schedule--------as it was i was the only person in the group that had any "audiophile" interest-----i was a long time subscriber to mags like "the "absolute sound" and the "stereophile"-----i read them religously and at the time i truly believed that wires, tubes, exotic caps, fets, etc, etc all had sonic signatures------i believed i too could hear them and had no reason to doubt it----the evidence seemed way too solid----after all how could an entire industry be wrong??????----the best proof that i bleieved it was my personal expenditures on high end audio gear------as part of our design project i felt it would make sense to take the time to research the audibility of the components we were using in the new digital recorder------i also wanted to investigate the audibility of certain audio specifications in order to determine the design requirements of the device---------this was a multimillion dollar project and the unit price was nearly a quarter million dollars each so there was a budget to do the research-------after a very short time i began to realize that just about everything i had taken for granted was not true------sort of like the first time you got the feeling that there might not be a santa claus---------i soon learned the facts and it certainly had a great effect on how i looked at audio from then on--------later when i got into car audio i took what i had learned from the research and applied the rules to car amps------at first the early tests were easy to pass--------each time i had a successful test i examined the setup to determine if the listener had indeed heard sonic differences or if it was something else-------every time it always wa something like a turn on/off noise, bass boost on one amp only etc.-------eventually i boiled it down to the rules as they are today and i believe i have it covered-------and to anyone that has a moderate level of intellegence and grasp of scientific procedure the clear fact is that up to now no one has ever been able to demonstrate that there are audible differences in audio amplifiers--------someone even went so far as to say that somehow the mag was responsible for my beliefs----believe me when i say that this is a REALLY SORE SPOT with the mag------their job would be a whole lot easier if we did what the other mags do and fill the reviews with the BS about amp sound quality--------the amp reviews done by A2000 will always be objective only until just ONE PERSON can show me that the differences can be heard.....................RC

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----as far as i am concerned you can do anything that isn't clearly spelled out on my list-----any speaker in the world-----any two amps----- I'm sure you can find some pair here that don't like each other and pull it off and win the 10k... tube amps and ESLs perhaps?

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Ahhh... The amp challenge is resurfacing yet again. Another generation of car audio fanatics to enlighten!

Seriously guys and gals, no one has ever (that's EVER!!!) proven that they can hear the difference between amplifiers under the criteria in which the test is administered. I've been through it many times, and even thought I heard a significant difference once. That was until I took it again and proved myself wrong.

The test parameters are totally on the up and up, and there is no hidden capability to slant the results. Every part of the test set up is plainly visible. Last time I saw it, even the circuit boards were visible. The entire test is designed to determine if there are audible differences between two amplifier designs under normal, undistorted listening conditions.

How many people have taken it now, Richard? Several thousand?

Come on everybody. Somebody needs to take RCs money! He's been winning this challenge for way too long now.

C-ya!
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Mark Eldridge

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napee-------sorry to see it but you are wasting your time arguing science with infidels------a profit factor?------i am so far from a profit in the amp challenge that is is pathetic--------a couple hundred dollars for a days work when i have more important things to do------numerous times I have done this for large groups of folks for only one charge------if the charge really offends them tell them i am willing to wave it for anyone that feels it is my motivation-------it will not matter----heck-----if its that much of a hinderance tell them to find a golden eared representative they trust and i will pay him to come take the test-----see how that grabs them-------they will just come up with another excuse-----it is truly amazing just how many people do not understand the scientific principle of testing and how ignorant they appear when attempting to discredit it-------it is best to just let them continue to pay their good money for "intangible" things that they cannot detect, identify or prove------idiots and suckers------the world needs them so the con artists have someone to prey on..........RC

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joe---can you get your hands on one of those $20K amps and bring it to autosound for a listening test????--------better yet do what i did once to a manufacturer that was selling a $15K 50 watt mono tube amp-----i told him that if he could demonstrate to me that he could hear the difference between his $30K stereo pair of amps and a ordinary 500 dollar amp that i would buy several pairs of them for my studios------it was a fun afternoon full of great excuses...........RC

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v6----i wrote those rules myself over a period of several years-----i tested listeners and everytime they were able to "hear a difference" i carefully examined the setup to determine if i could find a logical reason for their ability to "hear" a difference-----at first the differences were simple like different gain or bass boost on only one amp---eventually i was able to quantify what i believe is every reason for the audible differences----and none of them turned out to be "tube magic"----it was always wiring differences,level differences or simple frequency response differences etc-----it never turned out to be because the tubes were doing something special-----once i zeroed in on all the things that were responsible i found that no one could EVER tell the difference-----once i was confident i issued a challenge---and to date over a couple thousand people have tried and failed-----the reason for the number of "chances" is simply math----eventually someone wins the lottery------and its not because they are math experts-----now if you would be willing to put up YOUR $10K against MY $10K how about a 6 out of 6 outright bet?????----i am confident enough to make that challenge-----have i got any takers?????----if so pack up the amps and head to A2000 with a certified check made out to me........RC

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peter----it is true that at least a couple thousand folks have taken the test--------in the early years it was widely believed that the differences were so obvious that it could be done in a room full of people with a home system----and we did many tests like this------at A2000 seminars and private manufacturer seminars where we were paid to do them for selected installers------and even once at the MES show in Atlanta-------of course it quickly became obvious (or at least that became the popular excuse) that any differences that might exist were not so easy to pick out-----doing tests like this really racked up the numbers------the last time we did a large test was about 1995/96 or so-----eventually we started only doing one or two people at a time and even then it still supported the same results---------there are even people that have driven their own cars here so they can do the test "in an environment that they are intimately familiar with"--------notice that in the amp challenge i allow the use of a car as long as the car is provided-------i merely place a table alongside the car and place the extra amps nearby----------wiring is then run to connect the switcher so the amps in the car and the external amps can be selected by the listener in the car-----------as for those that believe that "harmonics" above 50K are necessary or audible for an audio system?????????----if that isn't obvious BS marketing I have never seen a better example-------my definition for SACD-------Stupid Audio Compact Disc----------personally i do not believe it will become a succesful format-------i don't believe there are enough suckers with money to support it---------- but only time will tell...............RC

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iyam-----there are several issues here-----first----22 out of 24 would be statistically significant-----in fact it would PROVE that the results were audible----in fact any AVERAGE score more than 65% would do so------but no one has even done that------its just that for me to shell over 10K I want to see somebody ace this------and by the way guys talk about their amps it should be a cake walk---------comparing speakers???? i have never heard any two speakers that sounded the same------i have heard many that were similar but not so identical that they could not be identified in a A/B test-------even with equalization---------as for the measured differences in amps????????------the differences are enormous on the test bench------no two are alike and if there were ten different brand amps on one side of a wall with only the input/output wires available to me as long as i have access to my Audio Precision System Two i could identify each one of them forever---- 100% of the time with no uncertainty at all----heck as long as we are talking about measuring I could probably do the same with a simple set of bathroom scales-------but just because i can easily measure weight differences of a few ounces or distortion and wattage differences of triple digits, that does not mean that any human can hear those same differences.........RC

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edouble----and i'll take bets on one thing for sure-----there were slight level or crossover differences in those amps when you A/B'd them----it doesn't take much of a level difference for most anyone to hear a "sonic" difference-----when the volume difference is very small it is not peceived as louder, just better or different or punchier----------in the early days of A/B'ing i used to take a simple fluke and match levels to a few tenths of a dB------i soon learned that for critical listeners the difference had to be much less than 0.1 dB or it would be percieved as a sonic difference----the question for me was purely scientific----were they actually hearing differences or was it just level differences?????-----when someone comes to take the test i still use the fluke to level match for the qualifying test---its quick and easy-----good experienced listeners usually pass the 6 out of 8 requirement------this test quickly weeds out the "goobers"--------i have found several individuals over the years that can easily ace a test where there are level differences of only tenths of a dB----interesting enough when asked they do not feel that it is level differences that they hear----they usually say they feel one amp sounds different than the other--------then for the actual test i use the Audio precision and match levels to less than 0.01 dB-----all of a sudden the audible differences just seem to go away----now perhaps someday someone is going to be sensitive to level differences less than 0.01 db or actually be able to hear amp differences----if so they will get my money and it will raise new questions-------could they actually hear differences in amps or was it just extremely minute differences in level they were sensitive to????----at this point i will still feel that it is not answered till i re-challenge the winner to retake the test with level matching at 0.001 dB
believe me if you ever experience one of my tests you will see things with a different perspective-----i am very serious about this and take great pains to do it in a scientific manner according to accepted scientific testing methods----- i am only searching for the facts buried in the folklore------i too had read all the conflicting gobbleygook in the press and even believed i could hear the warmth of tubes and the smoothness of exotic products--------i did not set out to "prove" that there were no differences in amps---as an engineer that designs and manufactures very expensive professional audio equimment my quest started to determine what was really important and what was not to make a good sounding amp/preamp----the more I investigated it the more the evidence showed that amps were already beyond the point where their "sound" was an issue and that simply undistorted power was the dominant factor............RC Remember some people have aced the first part of the test where there's a difference of about 0.1 dB

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