A quote from Tom Danley on another forum in a thread about the need for high power amps:
"For me this happened when I had a chance to be in an official ABX listening test of a number of amplifiers. I brought in my trusty Threshold stasis as my known reference and used speakers I had designed at work and had at home as well.
There was plenty of time and I went through a number of my reference CD’s to find a few passages that brought out the differences best and then went to “without knowledge” listening. At this point one could still hear some differences between them but they generally fell into two groups which I could reliably hear. What I heard were differences in the decay part of the sound which I have no explanation for (I used to build amplifiers too).
A funny and unexpected thing also happened which is why I am writing, in comparing the various pro-amps to my Threshold, I found that one group and it were indistinguishable except the Threshold began to sound “less dynamic” as I increased the level. AS the Thresholds VU led scale showed the peaks were -20dB or so down, I was puzzled. Connecting an oscilloscope to the output revealed the truth.
At a point WAY below one could hear it as a “flaw”, at a point that indicator showed peaks as 1/100th rated power, there was instantaneous voltage clipping.
To be very clear, this WAS NOT audible at all as a flaw or heaven forbid the familiar “clipping” the only clue was that compared to a much larger amplifier, the Threshold was somehow less dynamic above a modest level.
At that point, I switched to a larger pro-sound amplifier at home too. Currently my upper speakers (SH-50’s) are about 100dB 1w1m and I use an 800W/ch power amp on these above 80Hz.
With any commercial recording or movie soundtrack, this is more than enough headroom to never breathe hard but I can still reach instantaneous limiting with the fireworks recording.
Anyway, the big and unrealized advantage of having more power is that the short voltage clipping events reduce the dynamics long before it’s audible as a flaw. This can be seen (when present) by using an oscilloscope to examine the Voltage waveform going to the loudspeaker.
To be clear, just as a subwoofers job is to extend the response and that is not the same as “turning up the bass”, this IS NOT the same as “cranking it up” although a larger amplifier lets you do that too if your speakers are up to it.. This is about reproducing the peaks (in the “good” recordings) which are often clipped off much more often than people realize."
A quote from me: "
I still love my low power tube amps.
"
Lin
