Comments on: BEHRINGER A500 AMPLIFIER TEST PART 1

By: lakshmiwynter

lakshmiwynter — Sun, 18 Jul 2010 00:05:04 +0000

i can hear the distortion as u turn it down, has anyone done the same test with tone only and no test gear??

By: olsmokey

olsmokey — Sat, 17 Jul 2010 23:08:02 +0000

the distorted waveform on the CRO is not visible in this video. Can we have a clear closeup of the distorted part of the waveform?

By: ebaystars

ebaystars — Sat, 17 Jul 2010 22:37:35 +0000

really sorry yes i know its there but diffo to see i'll try again but the amps are going back so may not have time, if u listen you can hear the distortion on the video, i ran a few watts just to test from my yamaha desk and as i turned the amp gain i heard the distortion so i took out the test gear, behringer offered a refund but no explanation, alesis amps need testing as they look identical to behringer!?

By: folkdr

folkdr — Sat, 17 Jul 2010 22:36:30 +0000

It appears that the distortion is only present while adjusting the volume - an amplitude modulation. Basic fourier analysis says that the amplitude modulated signal is a wave packet that would certainly not be a pure sine wave. I would reckon that you would see the same results on any amplifier.

By: lakshmiwynter

lakshmiwynter — Sat, 17 Jul 2010 21:56:28 +0000

Not so clever Mr FFT, but thanks for the academic viewpoint - I won't re-run the tests as it was the same on a steady state signal!!, how's your job at Behringer, the modulation rate (AM) of the sine tone was too slow to affect the spectra of the test model within the useable bandwidth of the system (10hz to 20 Khz), use your ears instead of your head.

By: folkdr

folkdr — Sat, 17 Jul 2010 21:01:46 +0000

First off, I'm concerned that you called me a wanker. That's suppose to be a closely guarded family secret and I'd like to know where you got your information. It wasn't an academic point of view but a knee jerk reaction to what I thought was mad science. But, I re-watched the video and at about
4:50 the distortion does revert to .02 quickly upon reaching full power. Also at around 5:31 the distortion was about .56 while the power was steady at 42%. I stand corrected.

By: folkdr

folkdr — Sat, 17 Jul 2010 20:27:26 +0000

It would be fascinating to see the same test on whatever you replaced the A500s with or on something like the Alesis RA300 which is comparable in price/performance. I just bought an A500 from Musician's Friend. It had problems but it didn't cost me a cent to get it replaced and the new one is working fine.
Even with the problems it's a fantastic bang for my measly bucks.

By: folkdr

folkdr — Sat, 17 Jul 2010 19:30:25 +0000

I was considering the Alesis RA300. I went with the A500 because it had half the THD. But your measurements for the A500's THD appeared to be twice what they should have been even at full power. But all manufacturers make thier measurements look as excellent as possible. Hence my interest.

By: ebaystars

ebaystars — Sat, 17 Jul 2010 19:24:03 +0000

we take all that rudeness back, it was drug induced. The distortion was noticeable by human ear! - when simply setting up, then we carted out the ancient DFM kit to see it for real. My main monitors at home are nostalgic tannoy 15s in lockwood cabs and quad valve amps, i notice 3rd H distortion of an unpleasant nature and design RF equipment at work .. I may well do the yamahas (and on a steady tone) I thought you were a disgruntled Dr Behringer, trying to rubbish me, sorry

By: wae5

wae5 — Sat, 17 Jul 2010 18:47:57 +0000

So this amp doesnt meet specs when its volume controls are NOT turned all the way up. So what? If you have a separate amp, its volume is controlled by a preamplifier. The Behringer controls are not meant to be used like normal volume controls because they will wear out if used too much. The proper way to use this amp is to turn its volume controls all the way up and use an active or passive pre amp to control its volume. Used this way, it sounds fine and is an brilliant bargain.