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Discussion Starter · #1 ·
Do you think you can hear the difference between two amps?

Seriously, any two amps?

I am not joking. If you can hear the difference between two amps, you can make $10,000.00


Here is how it works:


Richard Clark, of Autsound 2000 and other assorted professions will pay you $10,000 if you can hear the differences between two amps, set up identically 24 out of 24 times.


Now, originally this was for car-audio amplifiers, however Richard claims that you cannot hear the difference between the best home amp and the worst car amp.


To read more check out:
Car-sound forum


Here the rules of the challange:
Quote:
THE $10,000 AMPLIFIER CHALLENGE RULES {April 21, 2000}

By Richard Clark

There is no question that all amps are not the same. It is very easy to measure large differences in the performance of amplifiers. This is true in nearly every known specification, including power, noise, distortion, etc. My experience has led me to believe that even though these differences can be easily measured, hearing those differences may not be so easy. Given the relatively small magnitude of performance differences, there is a giant step between amplifier performance and our ability to hear performance differences.

It is claimed by designers, manufacturers and especially salespersons that differences in amplifiers are clearly audible. Reasons include "obvious" advantages of one type of circuit topology over another. For example, it is claimed that certain designs have a smoother midrange response whereas other amplifiers exhibit tighter bass. Tube fanatics claim that tube amplifiers have that "warm" sound we all need in our systems.

Such descriptive terms are certainly subject to personal interpretation. It is not my intention to determine if one particular amplifier is better than another amplifier. Differences in the quality of the discrete components and constructions are more appropriate for settling the issue of "good - better - best." The sole purpose of my amplifier challenge is to determine if the differences in amplifiers are audible.


What differences are Audible?


I believe the perceived differences in amplifiers are all due to various factors that can be explained with basic physics and elementary psyco-acoustics. For instance, if two amplifiers are not carefully matched in volume, and one amp is slightly louder than the other, then it would be a simple matter to detect such a difference. In such an example it is important to understand that it is not the circuit topology, quality of the component, design excellence, or superb marketing and packaging that caused the noticeable difference - it was an error in the test setup! It is my present belief that as long as a modern amplifier is operated within its linear range (below overload), the differences between amps are inaudible to the human ear.


Comparing Amps


The idea here is for a test subject to scientifically demonstrate his/her ability to hear differences in amplifiers. It is our job to carefully match the amps so that we are comparing "apples to apples" instead of "oranges to frogs." This means that we sure wouldn't want to compare one amplifier that had + 12 dB of high frequency boost against another amplifier that was adjusted for + 12 dB of bass boost. Such a test would be easy to pass - even on identical amplifiers with consecutive serial numbers.

For our comparison test, we aren't concerned with which amplifier sounds best to the test subject. We only require that the listener be able to identify each amplifier when it is powering the speakers. Since many folks seem to believe that amplifiers have some kind of distinctive sonic character, this test should be easy to pass. Right? After all, we're talking about comparing those harsh sounding, high distortion, squeaky "widget As" to those warm sounding, smooth, bass hog "widget Bs."

Now pay particular attention to the following sections. Since we're looking for differences in amplifiers, and we already know that those differences are probably going to be very, very small, it is important that the parameters under our control be carefully adjusted so as to be equal as possible. This means that we must be cognizant of differences we might unknowingly introduce between amp A and amp B. They must be adjusted as identical as possible. We already mentioned the importance of volume. The same goes for the L and R balance. It sure would be easy to choose an amplifier that exhibited left side bias over a balanced amp. Right?

Well, in order to keep this amplifier comparison test fair, there are a few other parameters that must be considered. I'll list them all in the following section.



Amplifier Comparison Test Conditions


1. Amplifier gain controls - of both channels - are matched to within +- .05 dB.


2. Speaker wires on both amps are properly wired with respect to polarity. (+ and -)


3. That neither amp has signal phase inversion. If so correction will be made in #2 above.


4. That neither amp is loaded beyond its rated impedance.


5. That all amplifiers with signal processors have those circuits bypassed. This includes bass boost circuits, filters, etc. If frequency tailoring circuits cannot be completely bypassed an equalizer will be inserted in the signal path of one (only one and the listener can decide which) of the amps to compensate for the difference. Compensation will also be made for input and output loading that affects frequency response. Since we are only listening for differences in the sonic signature of circuit topology, the addition of an EQ in one signal path only should make the test even easier.


6. That neither amp exhibits excessive noise (including RFI).


7. That each amp can be properly driven by the test setup. Not normally a problem but it is theoretically a problem.


8. That the L and R channels are not reversed in one amp.


9. That neither amp has excessive physical noise or other indicators that can be observed by the listener.


10. That neither amp has DC OFFSET that causes audible pops when its output is switched.


11. That the channel separation of all amps in the test is at least 30 dB from 20Hz to 20kHz.


Page 1 of 2



In addition to these requirements the test will be conducted according to the following rules.


Amplifier Test Comparison Rules


1. To make things easy we would prefer to use high quality home type loudspeakers for the test. If our speakers are not acceptable, the listener can provide any commercially available speaker system as long as it uses dynamic drivers. The actual measured impedance cannot exceed the rated load impedance of the amplifiers tested. If, however, the tester would like to perform the test in a car, we will use a car, however, it will have to be provided by the test subject. For practicality we will have to limit the number of amplifier channels to four or less.


2. Amplifiers will be powered from the same power supply at a nominal 14 volts DC. (any voltage is OK as long as it is the same for both amps)


3. The test can be conducted at any volume desired; however, the amps will not be allowed to clip. In other words, listening volume can not exceed the power capacity of the smallest amp of the pair being tested. (power capacity will be defined as clipping or 2%THD 20Hz to 10kHz, whichever is less)


4. No test signals can be used - only commercially available music.


5. The listener can compare two amps at a time for as long as desired. For practical reasons we would like to keep this at least no more than a few hours. A test session will consist of 12 A/B sequences. Passing the test will require a positive identification of each amp for all 12 sequences. Remember, guessing will get you about 6 out of 12. If the differences are so great, and a subject can really hear the difference, then he/she should be able to do so for all 12 sequences.


6. To win the $10,000.00, the listener must pass two complete sessions of 12 comparisons. Passing the test means 24 correct responses.* The amp of choice can be compared to the same or a different amp in each session - challengers choice. We have many amplifiers in our demo inventory such as, but not limited to, Alpine, Rockford, Kicker, Phoenix Gold, Precision Power, MTX, Adcom, Kenwood, Pioneer, Sony, etc. You can pick any of them or bring your own.


7. All amps must be brand name, standard production, linear voltage amplifiers. This does not exclude high current amps. Amps can not be modified and must meet factory specs. They must be "car audio amplifiers designed to be powered from a car's electrical system."


8. Failure of an amp (this includes thermal shutdown) during the test will require that the test be repeated after repair or replacement or cooling of the amp. This means that the entire test session will have to be repeated.


9. The amps will not be overloaded during the session from either a voltage or current requirement.


10. To save time the listener will have to pass a quick 8 trial session to qualify for the extended 2 session test for the money prize. Any 2 amps can be used for this test. Passing this qualifying test will require at least 6 out of 8 correct answers.


11. The amplifier power up and/or power down sequence will not be acceptable for comparison. (The turn on/off noises of some amplifiers would give it away.)


12. Although anyone is welcome to take the test, only subjects employed in the car audio industry or Car Sound subscribers are eligible for the $10,000.00 prize.


13. Cost to take the test is $100.00. $300.00 for people representing companies. Payable in advance, scheduled appointments only. Done correctly the test takes several hours and I don't have the time if you aren't serious.


* Twelve correct responses in a row is certainly a lot of correct listening but $10,000 is also a lot of money for a few hours of easy listening. The way people describe the differences is that they are like night and day. I would certainly not have any trouble choosing between an apple and an orange 12 times in a row. When compared fairly I believe the differences in amps are much too small to audibly detect and certainly too small to pay large sums of extra money for. If I am wrong someone should be able to carefully take this test and win my money. Even if I am right, if enough people take the test eventually someone will take my money due to random chance. This is the reason for the large sample requirement. If you feel that you can easily pass this test but 12 sequences will give you "listening fatigue" I am willing to modify the requirements. Since the way it is being offered is a challenge and only my money is at risk I am willing to let a confident challenger "put his money where his ears are". If we are willing to make this a bet instead of a challenge, I am willing to drop 1 sequence for every thousand dollars put up by the challenger against my money. This would mean:



____My___________ _ _Your________Trails Required to win__

$10,000 to $0 = 12 Tries

$9,000 to $1,000 = 11 Tries

$8,000 to $2,000 = 10 Tries

$7,000 to $3,000 = 9 Tries

$6,000 to $4,000 = 8 Tries

$5,000 to $5,000 = 7 Tries

$4,000 to $6,000 = 6 Tries


I will not do the test with less than 6 trails. It would be statistically meaningless and reduce the challenge to mere gambling.


Page 2 of 2
Think you can hear a difference? Take the challange, no one has yet to win.

Note: I have edited this to quote the entire amp challange information, and to remove a link to a deleted AVS thread.

JR
 

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Discussion Starter · #5 ·
ANY amp against ANY amp.


Richard Clarks email is:
[email protected]


And I belive he is in Burlington, NC USA.


And I didn't make the challange, I would however love to see someone take the $10,000.00


Please note, the challange was first for car-audio, but has been revisited to include home audio, and anyone can take the challange.


NO ONE HAS WON YET.
 

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This should be easy money.

Though it's funny how all of us who swear that we can hear differences beween cables, cords, amps, dacs, etc ... never take these people up on their offer !


As far as level matching goes ...

When I am component or cable evaluating, when I think I really like one in particulary, I purposefully set the volume noticabaly lower and verify that it still sounds better to me than the others at a higher volume.


I think people who are hyper about level matching are comparing gear that is too similar to each other, and argue about minutia. Instead, they should seek a component/upgrade that is noticably better to make the spending upgrade worthwhile. -> my 2 cents


- Andy
 

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can i use a 20x4 jensen car amp vs. a b&k reference amp? Driving some maggies?
 

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Discussion Starter · #10 ·
Ok I will say this one last time.
ANY AMP VS. ANY AMP


I believe that Richard supplies the speakers.


And also note, the amps will be driven identically.


No eq's, no x-overs, at the exact same volume, the exact same sounds and you can take as long as you want for the 12 tries.


I have provided his email address. He will take you up on the offer (or so he says), so if youare interested, send him an email.


Think you can do it?

Then take the cash!
 

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"I believe that Richard supplies the speakers. "


Smart man....


$10 says the speakers he uses have a very smooth, benign impedance. That would reduce the interaction between speaker/amplifier and *would* make it much harder to differentiate between amps.


Substitute a speaker with a widly varying impedance curve and he would most likely loose his bet pretty easily.


10-15 years ago E. Brad Meyer did an article about this in Audio Magazine. On one set of speakers the listeners where able to ID the amps used (one tube one SS) in a level matched double blind ABX test. Switching to impedance compensated speakers and the listeners couldn't tell the amps apart.


Shawn
 

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Discussion Starter · #12 ·
Amplifier Test Comparison Rules


1. To make things easy we would prefer to use high quality home type loudspeakers for the test. If our speakers are not acceptable, the listener can provide any commercially available speaker system as long as it uses dynamic drivers. The actual measured impedance cannot exceed the rated load impedance of the amplifiers tested. If, however, the tester would like to perform the test in a car, we will use a car, however, it will have to be provided by the test subject. For practicality we will have to limit the number of amplifier channels to four or less.


2. Amplifiers will be powered from the same power supply at a nominal 14 volts DC. (any voltage is OK as long as it is the same for both amps)


3. The test can be conducted at any volume desired; however, the amps will not be allowed to clip. In other words, listening volume can not exceed the power capacity of the smallest amp of the pair being tested. (power capacity will be defined as clipping or 2%THD 20Hz to 10kHz, whichever is less)


4. No test signals can be used - only commercially available music.


5. The listener can compare two amps at a time for as long as desired. For practical reasons we would like to keep this at least no more than a few hours. A test session will consist of 12 A/B sequences. Passing the test will require a positive identification of each amp for all 12 sequences. Remember, guessing will get you about 6 out of 12. If the differences are so great, and a subject can really hear the difference, then he/she should be able to do so for all 12 sequences.


6. To win the $10,000.00, the listener must pass two complete sessions of 12 comparisons. Passing the test means 24 correct responses.* The amp of choice can be compared to the same or a different amp in each session - challengers choice. We have many amplifiers in our demo inventory such as, but not limited to, Alpine, Rockford, Kicker, Phoenix Gold, Precision Power, MTX, Adcom, Kenwood, Pioneer, Sony, etc. You can pick any of them or bring your own.


7. All amps must be brand name, standard production, linear voltage amplifiers. This does not exclude high current amps. Amps can not be modified and must meet factory specs. They must be "car audio amplifiers designed to be powered from a car's electrical system."


8. Failure of an amp (this includes thermal shutdown) during the test will require that the test be repeated after repair or replacement or cooling of the amp. This means that the entire test session will have to be repeated.


9. The amps will not be overloaded during the session from either a voltage or current requirement.


10. To save time the listener will have to pass a quick 8 trial session to qualify for the extended 2 session test for the money prize. Any 2 amps can be used for this test. Passing this qualifying test will require at least 6 out of 8 correct answers.


11. The amplifier power up and/or power down sequence will not be acceptable for comparison. (The turn on/off noises of some amplifiers would give it away.)


12. Although anyone is welcome to take the test, only subjects employed in the car audio industry or Car Sound subscribers are eligible for the $10,000.00 prize.


***Note # 12 has been changed, to allow anyone to take the cash. This was the only one set of rules I had availible to me at the time***
 

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Discussion Starter · #13 ·
Also please note, this was originally designed for car-audio (hense the power supply part) - yet changes can and will be made (or so Richard has stated).


Any more questions about the challange please email Riachard.


I am not affiliated with him, or autosound 2000.

There is allot of people that claim they could take the money...so take it allready.
 

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"$10 says the speakers he uses have a very smooth, benign impedance. "


Since I can't get to NC to take him up on this 10000 I think I'll have to settle for your $10 shawn ;)


It does seem fishy that noone can do this though.
 

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Quote:
Substitute a speaker with a widly varying impedance curve and he would most likely loose his bet pretty easily.
Maybe yes, maybe no. He reserves the right to EQ one of the amps so they both have the same frequency response. Hey all you golden ears, here's some easy money. $10K for a day's work ain't bad. Go get it and prove all the objectivists wrong. :D
 

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If you study the test parameters carefully, there are two glaring problems with the methodology. The first one is as follows, and is common in double-blind tests conducted by people who want to disprove the audibility of amps: "Compensation will also be made for input and output loading that affects frequency response. Since we are only listening for differences in the sonic signature of circuit topology, the addition of an EQ in one signal path only should make the test even easier."


Guess what, by putting in this arbitrary compensation network, you've eliminated the "sonic signature." One of the major factors that determine the "sound" of an amp is how it is able to drive a complex load (all loudspeakers). In controlled tests, differences in frequency responses of as little as 0.1dB have been shown to be detectable. Amps will have different frequency responses depending on the load. This is one of the advantages of high current output stages, the amp is less affected by reactive output loads. Richard Clark has eliminated these effects, not to mention that we now have to deal with any distortion introduced by the added network. Here's the other one: "To win the $10,000.00, the listener must pass two complete sessions of 12 comparisons. Passing the test means 24 correct responses." This is an absurd requirement. It is so far beyond statistical significance as to be ridiculous. Any statisticians out there care to run the numbers? I know that to get 12 out of 12 would get you a p number of 0.000244, and any number below 0.05 is significant. He's asking for 24 out of 24! These two issues alone make this offer not worth considering. Other questions to ask would be the quality of the associated equipment, and more importantly, the quality of the switch gear. The only commercial switch gear that is generally considered transparent enough to perform valid double-blind tests is the ABX comparator. Your average car stereo dealer switcher is not up to those standards. There have been several double-blind tests conducted, this isn't one of them.


How about this: Let's get the results of all the "failed" tests, and see if they're statistically significant? That'd be the first step, forget about the $10,000 reward...


Seth
 

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As mentioned prior, all of these tests can be fooled if the parameters of the test prevent it from failing. Speakers that offer complex loads that would throw the test paramters out of whack are not exactly a speaker that the car dealer would probably have on hand... most of it is probably mid-fi or the low-end of the high-end where speakers are still relatively easy to drive and keeps their test from failing. Furthermore, the listening room and setup must be up to par and I doubt that is going to happen at a car audio store.


Remember the old Memorex test where they said people wouldn't be able to hear the difference between cassette and CD??? They had the same problem with their test as the one mentioned here... you couldn't consistently prove the difference because the music selection (no dynamics, compressed, little information in the treble and bass region) prevented 99% of listeners from winning. The test instantly failed when the parameters were changed (in this case, the music selection).
 

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10. To save time the listener will have to pass a quick 8 trial session to qualify for the extended 2 session test for the money prize. Any 2 amps can be used for this test. Passing this qualifying test will require at least 6 out of 8 correct answers.




And, if you count in this little tidbit he throws in you have to get 30 out of 32!!! This guys a ripoff, no one will be able to pass this test as he has it set up!!
 

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Quote:
Originally posted by WXdude
10. To save time the listener will have to pass a quick 8 trial session to qualify for the extended 2 session test for the money prize. Any 2 amps can be used for this test. Passing this qualifying test will require at least 6 out of 8 correct answers.




And, if you count in this little tidbit he throws in you have to get 30 out of 32!!! This guys a ripoff, no one will be able to pass this test as he has it set up!!
Using that methodology, could you pass the test if it were Bose speakers vs. Klipsch speakers instead of amplifiers? So could I.
 
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