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  1. #1

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    Question Amp "differences"

    The $10,000 amp challenge got me interested in the "differences", and I stumbled across this post at ecoustics and thought I would share:

    Do different transistor amps sound the same or is there some magic sound associated with a certain manufacturer?? Why do I pose so many questions???

    You'll remember that last time we discussed why transistor amplifiers sound inherently different from their tube counterparts. Now we'll listen to some transistor amps to see if they sound different from each other.

    A few months ago the Wayside Inn was kind enough to let us use their back room for an evening of fun and frolic. What I did was get samples of amplifiers from Crown, Carver, and Marantz. The Crown amps were from their PowerBass line, a fairly standard "heavy" amp with good specs. The Carver amps were lightweight units with their proprietary "Magnetic Field Modules". And the Marantz amps were from my own collection, a pair of mono class "A" audiophile amps with a great reputation for accurate sound. I also talked Ken Carpenter from Carpenters World of Music into loaning me his big 3-way Community sound system. With all the hardware in place it was time to define the test.

    THE QUESTIONS

    My main questions were:

    (1) In a rock-n-roll situation, is there any discernable difference in the sound of transistor amplifiers?

    (2) Is there any sonic penalty for using "smart" amplifiers like the Carver's... And do they stand up to the abuse we often see (and contribute to) in concert and club usage?

    Here's a list of the amps tested with their specs:

    Crown PowerBass 1 200 watts per channel @ 8 ohms - 300 watts @ 4 ohms Weight 30 lbs
    Crown PowerBass 2 320 watts per channel @ 8 ohms - 400 watts @ 4 ohms Weight 32 lbs
    Carver PM1200 450 watts per channel @ 8 ohms - 600 watts @ 4 ohms Weight 21 lbs
    Carver PM1800 675 watts per channel @ 8 ohms - 900 watts @ 4 ohms Weight 48 lbs
    Marantz PA-5 150 watts Mono @ 8 ohms - 250 watts @ 4 ohms Weight 32 lbs each
    My trusty sidekick Darwin helped build a switchbox that allowed us to hot switch between two different amplifiers. After a little gain matching, we were ready to begin. We also tried to keep the main signal matched so that no amplifier exceeded it's rated power output. (No clipping, please)

    The tests were interesting, to say the least. First off, I'm a skeptic as to most of the claims of so called audiophiles over the sound of a particular amp. Certainly, all microphones sound different, even the same models can have a distinct sonic signature. Also, all speaker cabinets introduce a lot of coloration and distortion. I have tested and been amazed at the different sound of various phono cartridges (geeze alert, geeze alert).

    But amplifiers??? Give me a break..... If there's one thing a sound reinforcement amplifier's supposed to do, it's to sound transparent and not introduce any sound of its own. (Guitar amplifiers are a different breed, please reread last month's column if I appear to be off my rocker)

    THE ANSWERS

    Here's the bottom line. Everyone present agreed there was no appreciable difference between the sound of any of the amps at any reasonable level (and those big Communitys were LOUD). Once the levels were matched, we could switch back and forth any pair of amps, and there was no difference. I also added a 100 ft 16 gauge extension cord on the Carver amps to see if the old wives tale of deficient bass on a spongy power source was true, and there was no audible change. Maybe a whole rack of them would pull enough peak load from the line to make a difference, but one of them was no problem at all.

    Even my Marantz amplifiers (at $3,000 a pair) sounded no different than the Carvers or Crowns (at 1/3 the price). What's going on here??? Is amplifier sound a big gimmick devised by the industry giants to bilk us of our hard earned bucks?. Were our tests flawed in some way so as to disguise the magic sound?? Did Jim Morrison really die from a heart attack or are he and Elvis having a big laugh???........

    (A) Yes

    (B) Yes

    C) Maybe.

    (A) Sure there's a little hocus pocus from the manufacturers, it's called advertising and competition. You have it in everything from laundry detergent (whiter, brighter) to beer (tastes great, less filling). You've just got to recognize the hype from the facts. Here's some facts:

    If you buy from a major name brand, they'll be very careful not to misrepresent any information such as S/N ration, power output, impedance rating, etc... they have a reputation to protect and could be sued for misrepresentation.
    Professional products are built to withstand the rigors of the road. For example, they have rack mounts, XLR and 1/4" inputs, binding post and 1/4" outputs, huge heat sinks for continuous operation in hostile environments and ruggedized construction. The Marantz amplifiers would never survive on the road. So don't substitute a hi-fi amp for a pro amp, it'll probably let you down.
    (B) There were some flaws in our test. To be really accurate we need to have a double blind test where neither the reviewer, nor the audience knows which amp is in the circuit. This prevents any brand loyalty from coloring our results. Also, we were in a noisy bar with LOUD speakers, any differences would probably only be detectable in a very quiet listening environment with super accurate speakers.

    (C) I'll ask Elvis how Jim's doing next time he's in the studio for a little recording.

    THE BOTTOM LINE

    Does that invalidate our results for the average rock-n-roll band? Heck no, since we all play through big speakers in noisy bars , there's just no real difference in the sound of high quality power amps to the average listener.

    From a user standpoint, you need to pick an amplifier that has enough power and features for your situation. I'd like to have a rack of the PM1200's for myself. They're lightweight, have good metering, and lots 'o juice. You may pick something with more weight, but I've had my share of lugging around heavy racks. (Oh yes, I tried to get Peavey corporation to send me one of their new lightweight "digital " amps for comparison, but they declined... hummmmmmmmm.....) Just make sure you get enough power if you're upgrading. There's no audible difference in volume between a 200 watt and a 250 watt amplifier (less than .5 db). The rule of thumb is to double up when upgrading.

    Stay tuned next month when we start on digital vs. analogue recording (sounds great, less filling)..... See you then.

  2. #2

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    Default Hmmm..

    Very interesting. Thanks for posting it.
    Sunfire TGP III PrePro, Sunfire Cinema Grand Signature 405wpc 5 ch. Amp, Rotel RCD-1072 CDP, Onkyo TA2600 Tape Deck, Pioneer Elite 47-A DVD, Sony 32" XBR TV, Polk RTA-8T Main Speakers, Boston VR-920 Center Channel, Boston PV-600 Subwoofer, Polk DSW 400 Subwoofer, Polk FXi-3 Surround Speakers

  3. #3
    Stronzo
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    Default

    If you cannot hear a difference in amps, consider yourself lucky.. be blessed and buy whatever...

  4. #4

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    Nice post
    When listining to live music ( which i think it is all about now ) :) .
    I dont really care what is powering up the band . All i care about is how good the band is . I take for granted they use good products , but if they want to sound good they better use good products , powering up there gear .
    I do , however hear a difference in sound between amp and pres .
    I used have a NAD set up and went to a Bryston and carver pre , there is a difference in sound , i myself dont like the NAD sound , with my Polks . NAD sounds ok with a klipsh speaker .

  5. #5

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    Default

    There are many differences in sound when dealing with Hi-Fi amp's. When dealing with Pro-Amps the differeneces will be less for sure. The switch box you were using would alter the sound to the point of hiding sonic differences.

    The "amp's make no difference" theory was first started from a writer within Sound and Vision. That magazine to me has as much crediblity as Consumer Reports. He'd have you believe you should spend 60-70% on speakers, amps have no sonic differences and the majority of CDP's all sound the same.

    In a word. Insanity.

    S&V is a Best Buy's and Circuit City's wet dream.

    ps. I honestly believe you didn't hear any differences in the sound, but I also believe that the tests were flawed and that the gear used wouldn't have created the sonic differences found in more traditional consumer grade Hi-Fi.

  6. #6

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    Default

    I agree. Have anyone seen a bad review on S&V? If all amps are the same I guess they'll tell you to buy a $500 amp because it will sound as good as 1k+ amps.

    Maurice
    CD Player: Original CD-A8T
    Pre: Antique Sound Lab Passive T1-X DT
    Amp: NAD C270
    Speakers: B&W DM6
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**

  7. #7

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    Organ
    Sweet
    I see you have that NAD / Klipsh set up . Nice :)
    I guess Hi Fi doesn't change that much over the years , that was a good set up even 20 years ago .
    Ive been out of the loop for about 8 years :) .
    Last edited by wire; 05-06-2004 at 02:15 AM.

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