Excuse me, Tim. I'm going thru a rough patch and get a bit cranky. All you say is correct. How does it apply in a guitar circuit? Where does the any frequency enter or go thru the cap? As I had posted before, I got schooled about this at Whirlwind, after I made some bold claims about how much better pio caps were in my Les Paul.
The two top engineers and designers, one, Tony was from the old original MXR andthen ART before Whirlwind. I lost my bet when we tested every type of cap, precisely measured recorded and frequency plotted the results and there was no audible or measured difference between any of the caps with the same simple old digital meter.
So I end up measuring and matching hundreds of flippin' resistors and caps and handwiring the first couple of hundred Rochester Series FX pedals. I swear by everything holy, I WAS WRONG. I am relying on the real example, shown to me and the explaination given me by very acomplished audio engineers with proven, real world experience and degrees in electrical engineering,to. And like everything I have found true, some seem to look for excessively minute, hair splitting molecular differences hat have no applications to the function at hand.
So yes capacitors are complicated and fascinating components that have real and nuanced effects, in amp circuits.
So please tell me what exactly is the sonic effect in a guitar tone circuit? What exactly can be heard between a .022 pio cap and a butt simple .022 ceramic disc in a guitar tone circuit? Really, I just need to know how our ears and expensive testing equiptment failed. 'Cause I don't have a degree, I barely understand he deep science of this and rely on what my ears tell me and what my eyes see on the frequency analysers and graphs show. I also rely on the knowledge of those more learned than myself to try and get at least a basic understanding. So was I tricked into doing a boring job by smart hucksters? 'Cause I don't see where signal goes through the cap and I could not detect any difference among any of the many different caps of all types with the exact same measured capacitence load.
Al, first I never said there was a difference or that you would be able to hear one. My first post was to just say I can see where there could be given the different constructions. IE, just because two differently built caps have the same discharge time constant (which is how they calculate it's capacitance value), they may not offer the exact same resistance to current flow at higher frequencies due to molecular differences, though I'm sure they would be close.
Then you replied, "only applicable in amps where voltage and current enter." This I disagree with because there is current generated by the pickup passing through the tone cap in the guitar. The tone pot only allows a small amount to pass through it on '10', but as you turn it down and take resistance away, more and more of the pickups signal is passing through the cap. The only current that can't pass through a cap is DC, which the pickup is not making anyway, it's all AC. For the higher frequencies, the cap is much less resistive and essentially you're shorting those high frequencies out across the pickup's terminals and they never make it to the amp and you never hear them. The low frequencies are attenuated as well by the cap but not near as much as the high frequencies are.
The resistance of a cap is 1/(2*pi*f*c) so at higher frequencies or higher capacitance values or both, the cap becomes less resistive.