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.
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)
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) 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.