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Building a tone capacitor switch

10/3/2002 2:37 PM
Fuzzboxfive Building a tone capacitor switch
Have any of you ever made a tone capacitor  
switch ? what values and how did you construct  
this switch? I'm new at fx building and i  
would like to vary the tone in front of a  
ts-9 or fuzzface to tweak the high's  
also put one inside a home made fuzzface.  
thanks for you help..... Rick.
10/4/2002 2:45 PM
Mark Hammer
What you do depends on what the circuit affords the opportunity to do.  
For Fuzzfaces, you should look closely at Joe Gagan's various FF-derived pedals like the Brontoboost, Dinofuzz, Sky-Ripper, and the most recent Tarpit. He has a nifty way of adjusting the tonal balance of the input signal using a pot that pans between two input paths. Kind of like the Big Muff Pi tone control, only at the front end.  
Other simple ways involve using toggle switches to add capacitors in parallel with the existing input cap. Note that you should probably replace the existing cap with a smaller value so that you can produce more, normal, and less bass cutoff as you add in caps.  
Simple parallel cap switching has a problem, and that is popping noise. When one end of the cap is lifted from circuit, there is nowhere for the charge to drain through, so when you reconnect that leg of the cap, it discharges quickly and you hear this as a pop. One nice solution for avoiding this is to use SERIES cap which retain connections for both leads of the cap at all times (although Joe's pot solution is probably more elegant). When caps are in parallel, their values are added, but when in series you compute their value the same way you would for parallel resistors capacitance = 1/Ca+1/Cb). So, if you have a .01uf input capa back to back with another one in series, their combined series capacitance would be .005uf. However, if you use a toggle to shunt/bypass one of those caps, the effective capacitance becomes .01uf, with no switch-popping.
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