Originally Posted by Tom Danley
About 10 years ago, I was part of a ABX blind listening test comparing a number of Pro-sound amplifiers. I was using some early time coherent speakers I had designed for the company and as a sanity check, brought in two hifi amplifiers, one being a Threshold Stasis.
The amplifiers did not all sound the same, after searching recordings I found a couple parts where one could reliably hear differences, not in anything obvious BUT oddly in the decay parts of the sounds.
Anyway at a modest level (peaks about -15 -20dB on the Thresholds fast meter, it began to be different in a different way, it sounded slightly less dynamic.
I was very puzzled (it was my listening amp at home) and grabbed an oscilloscope and examined the outputs. Sure enough around the point it began to sound less dynamic, it had reached instantaneous clipping.
TO BE CLEAR this is nothing like clipping which everyone knows, this was ONLY detectable if one had a without version to compare to (in this case from a much larger amplifer).
By it self, it sounded fine, no problems and that not hearing the problem is exactly why most sound level meters and other volume level indicators do not show the peak requirements.
There is something I don't understand here. Do recordings really have short peaks 30 dB (or whatever number) above the average? If the speakers can take the amplifier's maximum output, and the source has its peaks below clipping (e.g. 1 Volt on analog), then surely a much larger amplifier
won't make a difference. It seems to me that such a dynamic recording with very loud peaks would play very softly overall to leave room on the medium for those peaks without clipping. If I need to crank the volume to 0 dB to hear 80 dB music, I know I should sit tight because a 120 dB peak could occur at any time. I couldn't have higher peaks that that because the source input would have clipped by then.
However, if the sources were momentarily clipped, and amps sounded different when playing back those short clipped parts
, then that is very interesting. This should be investigated further (in spite of being OT for this thread). It could be an explanation of why some people hear differences in amps and others don't.