mayhem

iTrader: (1)

how do you guys feel about amps effecting sound quality? some say that regardless of an ampifiers internal components, it does not effect, or change the sq, hence, all amps sound the same? in some other forums this is a real "hot issue". what do you guys think?

iLLlegal

iTrader: (1)

well. imo amps do effect the sound quality. like SPL amps designed for high output but you lose that extra sq. so I believe no not all amps sound the same. considering the earthquake PH-D2 which has distortion over 4%. but high efficiency about 80%. yup so basically different amps can effect soundquality. some more than others. thats not all my 2 cents but for now ill keep it at that.

mayhem

iTrader: (1)

i tend to agree, but there is an individual named richard clark that begs to differ, anybody heard of him?

WD21

if they didnt have anything too do with SQ, why the hell would someone buy a complete F#1 statis system when they could get a jensen, pyrimid, pile system that would put out the "same" amount of power?>

AMPS DO EFFECT SQ IMO!

mayhem

iTrader: (1)

again i agree, but if you get a chance read about richard clarks amp challenge. i`ll try to find a copy of it.

iLLlegal

iTrader: (1)

please do sounds interesting. but yup us pathfinder owners think alike haha

mayhem

iTrader: (1)

i`d post the link, but i`m computer inept, so its cut and paste.

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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.

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.

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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 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

WD21

there exspensive? hum, never knew that