Marshall Tonestack question.....

[frequencycentral]

Hi everyone,

Yesterday I built a Marshall tonestack:



It's for a pedal I'm building (Tube Town Pepper Shredder - I'm using 6111's instead of 12u7's - with a boost on the front end, probably an LPB-1)

I fired my Valvecaster (9v battery powered) into the tonestack and was pleased with the middle and bass controls, but the treble just seemed to lower the volume. So after a bit of dabbling with different values I parrallelled a 0.0022uf cap with with 470p - which achieved a nice tinny sound with the treble full up.

My question is - did I choose the extra cap out of pesonal preferance or is the Marshall tonestack just not good at accentuating treble - or is it an impedance issue or something similar?

Does that make sense?

I basically just fiddle with different parts until I get a sound I like - can anyone cast some light on what I did?

[drewl]

well you actually increased the capacitance of the 470pf by adding the second cap.
Remember tonestacks like this only cut frequencies, they can't boost.

To simplify your experiments try downloading Duncan's tone stack calculator....you cant plug in different values and see on a graph the change in freq. response.

[anchovie]

you cant plug in different values and see on a graph the change in freq. response.

Yes you can 

[drewl]

That's what happens to my typing after a few %^&*tails.
You CAN plug in different values and SEE the change.

Fender uses a 250pf instead of the 470 for example.