Propeller Head Plaza

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RE: Phase Distortion, dv/dt, and Slew Rate

Posted by Lee of Omaha on December 17, 2015 at 09:55:23:
I think you're missing the point about summing sliding sine waves. If two (or two dozen) sines waves are "vibratoing" then occasionally some or (pathological case) all of them could be momentarily in phase, resulting in horrendous amplitude peaks and resulting dv/dt.

Perhaps another way of modelling it would be as noise in frequency domain. Picture the noise (vibrato) components adding randomly, analogous to the way noise voltage adds in time domain. As in time domain, occasionally the peaks are large.

I do know that I have heard few good choral recordings. Most are accompanied by an amplitude-related ripping sound that I think is intermodulation distortion or TIM or slew-induced distortion. It sounds awful and unmusical. Since it is related to amplitude of complex wave forms (many human voices) I think it's related to the cause I described. And if even a single component in the recording or reproduction chain can't keep up, you get that "wonderful" distortion.