Re: box vs film caps (if that even makes sense)

Posted by induction on Oct 27, 2015; 10:14am
URL: http://guitar-fx-layouts.238.s1.nabble.com/box-vs-film-caps-if-that-even-makes-sense-tp25024p25534.html

Drey wrote

6% Distortion at 10 Hz is a lot. With distortion circuits and fuzz boxes maybe thats not even that bad but with other clean effects like chorus boxes I think there's definitely a difference. Guitars usually don't go down to 10 hz but a low e is about 82 Hz.

What interests me is if you really can hear the difference. I need to build 2 chorus pedals or compressors with different caps and let my ears decide if I hear any major sound degradation

Don't forget that frequency is inherently logarithmic with pitch. 10 Hz is 3 octaves below the low E, and one full octave below the range of human hearing. The same test at 100 Hz (guitar amp outputs range from roughly 100 Hz to 10 kHz) showed only 0.25% harmonic distortion. This will be undetectable to humans in any guitar signal, whether it's fuzzed to death or crystal clean.

Two of the video's conclusions are pretty specious, in my opinion:
1. Capacitor composition definitely affects distortion.
(Fair enough.)
2. The type of distortion is discordant odd-order.
(It's only discordant if you can hear it.)
3. Ceramic capacitors are unsuitable for inter-stage coupling caps.
(Far from demonstrated. In fact, the tests shown in the video demonstrate that in the test circuit, the distortion measured in the audio range is too low in amplitude to hear.)