Please help me with this simple tone stack!

[leadfootdriver]

I changed all' the tantalum capacitors to mylars, and micas. It warmed up the sound quite a bit to the point where I need to add some highend back into the sound.

I had a few ceramic disc caps laying around, so I changed C9 to about 382pf by wiring a few in parallel. It sounds like it could go to about 500pf, or a little higher. I'll have to grab some micas and experiment. But the tone sweep is a little limited now, and acts more like a highend roll off.

How should I approach C10, and C11, or anywhere else in the tone stack to get more range? Basically it has plenty of treble potential, so I'd like to add some shredding mids to compliment the sound.

[loudthud]

That circuit is pretty unusual. You'll have to use a modeling progam to plot the frequency response if you really want to know what's going on. By increasing C9, you have probably run up against an inherent interaction in the circuit. The circuit looks like a variation of the Bridged T which kind of acts like a treble and bass booster because it sucks out the midrange. The pot is in position to bring the midrange back but the left side of the pot kills all the treble as you boost the mids. (That's just a guess!)

I would try reducing C12 since it bleeds off the highs when the control is CW, or perhaps a capacitor in parallel with R6. You may have to boost highs somewhere else in the amp.

[leadfootdriver]

Thanks for the reply. I guess it's not as simple as I thought, because you're not the only one who said it was unusual.

I put in 540pf on C9 and got more highs. I also put a .022uf in C12 which does seem to bleed less highs. With C12 open, the high are screechingly hot! From what I can tell, the pot full right notches out the upper mids a bit, and full left rounds off the highs. But the mids are all there.

I might add more pf the C9 so the tone is a little to bright with the pot in the middle. Then I can pot to the left to get the right high mix.