Need to do a reduction and some editing of prior posts too. Exceeds my screen resolution of 1280X1024... and takes time to load with slow speed AT&T DSL. Just sayin..!Yeah, they are a little big, aren't they? Okay, pictures will be smaller from now on, currently they are 1600x1200.
I don't think the duration wouldn't effect the voltage where the outputs flat-top and clip unless the power supply sags under load, but yes of course the harder driven into clipping the higher the percentage of distortion. That's like a wall that's limited by the output transistors and power supply. Rated output at the specified distortion is normally just below that clipping point. 3 dB would be double the rated power which ain't a lot of headroom. More real would be a 250 WPC amp that may put out close to 300 Watts before it clips, But that's less than one dB over rated power. I recall I could run an amplifier into clipping easily visible on an oscilloscope before you really start hearing it. That was into a BPI load box that attenuated the monitor speakers by 20-30 dB so you could hear what the amp was doing at a reasonable sound level without killing your ears! Clipping happens well before some realize it.Why, there can be peaks well above the maximum rated output thgat can be in line with rated distortion. I do it all the time. I now have a digital storage scope to go with my Audio Precision ATS-1, maybe I can plot this...
Ed, I think it's the duration of those peaks that would determine the amount of distortion or clip.
Keep an eye out for C13 on the meter board. The parts layout diagram shows it in the incorrect orientation in the service manual.