opaqueice;172039 Wrote: > Actually you're wrong - that's precisely the case in which my > extrapolation is correct. > > Suppose the measured amplifier signal is A = A0 + N, where A0 is the > ideal (non-distorted) signal, and N is some componenent which doesn't > scale with A0. What's plotted is the log of the ratio of the > distortion component to the ideal: log((A-A0)/A0) = log(N/A0) = log(N) > - log(A0). So the distortion is linear in log(A0), which is indeed > what the graph shows, and is exactly what I assumed above. > > Now that I think about it, you stated before that this was evidence of > crossover distortion - actually, it's simply evidence that there's a > component to the THD+N which is independent of the power. That is > always the case - even with the amp switched off you'll measure some > voltage across the outputs due to random noise. On the other hand the > FT shows most of the noise is from harmonics, so I suppose that > indicates it's related to the signal. I don't know enough about the > spectrum of crossover noise to say whether it looks consistent with > that or not.
OK, I misread your earlier post. Then we both agree that Fig 4 at http://theaudiocritic.com/blog/index.php?op=ViewArticle&articleId=20&blogId=1 actually indicated a constant level signal related distortion mechanism? I.e a fixed size discontinuity in the transfer curve. Yet, this is ignored, and the FFT is presented at maximum power, showing "the distortion is almost completely dominated by the second harmonic, which is basically harmless".. This is a bit silly, as no-one will listen at max power much of the time. It does make sense, however, if one assumes good behaviour for small signals, around the crossover point. Hence my earlier remarks about reviwers not expecting 1970's style distortion. I believe the Behringer will sound very good in damped large rooms with relatively inefficient speakers (a typical home theater setting in other words). In a small less damped room with efficient speakers, however, I suspect small signal distortion will be too high to be pleasant. -- P Floding ------------------------------------------------------------------------ P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=31843 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
