this whole cap thing just blows my mind! i built two fuzzes (FF, silicon), every component was similar except for the output cap (0.01uF) - the first one used boxed metal film, the other a ceramic disc i popped off a junk cassette player. there was a very BIG difference - FF1 (boxed metal film cap) was boomy, plenty of bass; FF2 (with ceramic cap taken from junk radio) was way clearer, less bass, way better in my opinion, that between the two, FF2 will cut more in a live band situation.
i had spare ceramic caps taken from the same junk radio so i instinctively desoldered the metal film cap from FF1. so FF1 and FF2 now sounds very very similar.
now for the interesting part.
last Wednesday (Friday today here), i bought new ceramic caps (103 - 0.01uF) and replaced the old ceramic cap installed on FF1. holy cow! what happened? apparently the bass content came back (well not as much as when i used metal film cap). same cap type, same value, but different sound?
why? could it be because of age? the junk radio has been unused for about 10 years already, and found it in our stack of old junk.