Thunderchief treble question

[jimmy54]

Hi fellas,

When using the Thunderchief with my Strat in the bridge position I have to roll the tone knob more or less all the way down otherwise it is far too trebly.  I've tried ading a 100uf electrolytic in parallel with the 680nf cap, it's a little better but not much.  What would be the best way to reduce the treble in this circuit?

Cheers,

Jimmy

[MartyMart]

Try increasing the two 2n2's at the back of the circuit to 3n3's, if that's too much, then just the
first of the 2n2's .

MM.

[Mark Hammer]

I just fired up a tonestack-equipped Thunderchief coupled to an LM380-based 2W amp and I have to say I find it a little too harsh and strident too.

I increased the 1k source resistor in the second FET to 1k8 to tame the gain a bit, and while that helped, it is still a little too aggressive for my tastes.  I think I may reduce the value of the 470pf cap that goes in parallel with the 1M resistor after the gain pot, as well as the 470pf cap in the tonestack.  The 2-pole filter at the output seems fine but the top end consists of a little too much upper midrange, I think.  Of course, this is also very much an issue of the particular 8" speaker I'm using it with.

[Skreddy]

Could you not add a negative feedback cap to one or more gain stages ala Big Muff?

And maybe eliminate the 470p parallel with the 470k resistor altogether (perhaps changing the 470k to maybe 100k too)?

And maybe change the 1k/.68 on the drain of the 2nd fet to a 1k trimpot with the .68 to ground from the wiper (ala FuzzFace)?

[jimmy54]

Thanks for the suggestions fellas, I'll give them a spin at the weekend.

Jimmy

[jimmy54]

Replacing the first 2n2 cap with a 3n3 did the trick.   If I had a second 3n3 cap I'd do the other one as well but I'm happy for now.

One other thing.  With the volume control at ten the effect is pretty quiet hum-wise (and this is with the effect un-boxed).  However, reducing the volume to 8 increases the hum to a really noticable level.  Continuing down to ~ 5/6 on the vol removes the hum again.  What's the score here?

Jimmy