Propeller Head Plaza

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

Posted by tomservo on December 27, 2015 at 12:59:43:
A couple thoughts;
Whatever that group of voices or instruments present to a single microphone, is simply the vector sum of all those magnitudes and phases. The concern is what comes out of the loudspeaker if that signal faithfully captured is fed in?
Looking at frequency is useful when one has steady state signals BUT the idea of Frequency doesn't exist until some period of time has passed. For example, take a super low distortion oscillator and a FFT analyzer and examine the oscillator output. It has one frequency component and "no" other harmonics (being very low distortion). Now what happens if one doesn't have a steady signal? Take the oscillator's output and change it's amplitude and you see the signal covers a bandwidth and is no longer a single frequency. Modulate that signal so that it has a 5 cycle "envelope" with a Gaussian shape and you see the low distortion oscillator signal is about 1/3 of an octave wide. The point being that large fast changes in level require more bandwidth than a steady state sine wave view suggests.
Your right to be concerned about dynamics too, many recordings are compressed within an inch of their lives and then on playback very often the signal chain is clipped somewhere and often the amplifier. You can't hear short term clipping as a flaw like it sounds when it lasts longer, but it does sound different , less dynamic than the same signal unclipped. If one has an oscilloscope, examine the amplifier output for flat topping on transients.