Originally Posted by A9X-308
The SST brochure gives rated spec as 0.005% at 600W/8R and it goes from this to 1% at 632W/8R a 46dB difference in 0.2dBW (an inaudible difference with programme material) and you don't consider that a 'knee'? I already said in the previous post that clipping is the point where the waveshape changes because of an amp limitation and distortion increases; the 1% number is just a uniform metric so that different amps can be compared on the same level. It could easily be another number, say 0.1%.
Because you haven't seen it described that way, those of us involved in amp design most likely have.
Tube amps get away with a 3% or 5% number because if they didn't use that (sometimes not specified at all) they'd never be able to compete in the marketplace with SS amps as thier power outputs would be much lower in many cases that what manufacturers currently specify. Depending upon topology, especially those with little to no gNFB have a slowly changing spectrum, typically with no obvious 'knee' so you need to pick a number (and parameters) and go with that. An OTTOMH example is the Cary 805
. Contrast with the ARC Ref 150
No, despite the fact that one percent is laughably close, in meaningful output, to the knee, it is NOT the knee. Weirds me out when folks who seem all science like start saying "but look, it's close enough." when I said they were the same, I meant they were effectively the same for purposes of my testimony." Where I dwell, when stuff like that comes up one to three lawyers are just hoping the testimony will get to the end of the day so they can figure out how to rehabilitate their perfectly truthful and scientific witness that the jury has been convinced lied to them. So yeah, forty or 60 or whatever watts above the knee is not relevant in SPL at the listening position at the powers we are looking at, but it's still 40 or 60 watts . . . or whatever
Part of the issue for me is the bizarre discussions that arise around "clipping" and damage to speakers. At the knee, or even at 1%, absent a really weird spectrum for the distortion, we can call it "clipping' but it's meaningless with respect to "excess" power delivered to any driver . . . . But folks act like if you can call it clipping, it is outputting a square wave. It ain't by miles (as is obvious both in the chart you posted, and I'm sure every amp test you ever conducted). I'll reiterate my old saw, apparently guitar players identify amps at ten percent distortion as being "clean." You can't even reasonably estimate power at 10 percent distortion from the graphs in Stereophile, at least usually. ANd you're still quite far from outputting a square wave. . . . but I digress.
It does seem like if there was a supersecret engineers' cabal agreement that everybody will think of the knee as the onset of clipping but dwill ensure that it is never discussed that way in any technical journal or specification, and to make sure that the uninitiated don't find out . . . . I want to know. And somebody would tell..