Cap valve on 1st stage plate resistor question

[dude]

A Fender 6G3 has two 220k plate R’s to first stage of each channel, bright and normal. The cap across the normal channel’s plate R is .003 in parallel or l believe 3,000p. That value takes out too much treble or too dark, what way should l go, lower or higher valve? And any suggestion what value to try? Without that cap the channel is too bright, .003 too dark.

[PRR]

If zero is bright, and 3000 is dark, pick a number in the middle. Like 1000.

[2deaf]

The power supply node for that plate resistor looks like ground for audio signals, so a capacitor across a plate resistor like that is about the same as a capacitor from the plate to ground.  The larger a capacitor is from the plate to ground, the more high frequencies are cut.  The same is true for capacitors across the plate resistor.

[dude]

For some reason l keep thinking the opposite for cap values, so if l have a 100p (the same as .0001uf, correct?), going smaller would be going to 500p and going larger would be 47p? Or do I have this backwards? To transpose “uf to p”, move the decimal to the right 6 digits, is this correct? I should know this stuff by now. 


Anyway, thanks for the quick answers.

[shooter]

this might help, not the one I have, but then, I can't find it 

http://www.uf-nf-pf.com/uFnFpF-Chart.pdf

[2deaf]

For some reason l keep thinking the opposite for cap values, so if l have a 100p (the same as .0001uf, correct?), going smaller would be going to 500p and going larger would be 47p? Or do I have this backwards? To transpose “uf to p”, move the decimal to the right 6 digits, is this correct? I should know this stuff by now. 

If you have the same letter ("p" for instance), a larger number means a larger capacitance.  500p has a larger capacitance than a 47p.  If you have different letters ("p" and "u" for instance), convert them so they both have the same letter.  Then you should be able to see which one is larger.

[PRR]

500 is more than 47. Both in raw numbers, and (often) in physical size. And in effect on the circuit.