In Reply to: "cap distortion" in spice. posted by dave slagle on December 4, 2014 at 07:38:25:
"since TK brought up the 'AC signal across a cap'"
The issue I raised was intended to address capacitors used in bypass/decoupling, such as at the cathode or power supply output. I believe there's a threshold involved regarding the amplitude of signal voltage that appears across those caps that's related to whether they're audible. Applying that concept to a coupling cap is more difficult from a measurements perspective, because neither terminal is grounded and both terminals carry signal. That aside, I don't believe all the characteristics that cause caps to color sound can be synthesized in SPICE. We may not even fully understand what those characteristics are, and I was not attempting to open a discussion on that point.
The main issues of interest to me in this regard are (first) agreement that a bypass capacitor with no AC voltage across it cannot contribute its own sound, even if AC signal current is flowing through it. This concept is fundamental to everything that might follow. I also believe it might be possible to (second issue) eventually determine the approximate threshold of audibility mentioned above for capacitors in specific circuit positions, based on the signal voltage across them, signal current through them, and perhaps signal voltage levels present elsewhere in the circuit. This would be a much different discussion than what you've initiated, so I'll wait to start it in its own thread.
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Follow Ups
- RE: "cap distortion" in spice. - Triode_Kingdom 09:01:25 12/04/14 (4)
- "this concept is fundamental" - Jim Dowdy 10:07:06 12/04/14 (3)
- RE: "this concept is fundamental" - Tre' 13:44:53 12/04/14 (1)
- absolutely true...everything else is psychoacoustics-NT- - elblanco 15:59:53 12/04/14 (0)
- RE: "this concept is fundamental" - Triode_Kingdom 12:16:44 12/04/14 (0)