--tchless tone stacks

[drewl]

What is it with the oddball tone shaping networks of these things?
I've built a few and sometimes they work right sometimes not quite.
I just finished a clubman today and the bass only works with the last 1/4 of the pots range, and the treble only the first 1/3 of it's range.

think I'll just scrap it and put in a fender stack!

[MattT]

I'm only familiar with the Chieftain which also had a weird stack...I know the mid control is called a T-filter in that one...and the treble control was just a treble bleed (LPF).

But IIRC, the bass control in that amp uses a reverse-audio tapered pot. Could that be it? I assume you're using a log-tapered treble pot too...right?

[drewl]

yeah, I knew about the reverse pot.. don't have one so I tried a linear, hooking it up backwards yields better control, but it's freakin backwards!
Is the treble linear? I can't remember.

[MattT]

My Chieftain schemo says 250K-A for the treble...the treble control is just a treble bleed and is in parallel with the volume control and is separated from the mid and bass controls by a triode gain stage (it goes: input gain stage - mid/bass controls - gain stage - treble/volume controls - PI).

Didn't Fenders use a 2M reverse-audio pot for something? I think that's what I used (it was some 2M-RA pot I had lying around) with another resistor in parallel for my bass control...but that amp never sounded any good so I gutted it for something else.

[drewl]

this circuit is actually a clubman35, but i used 6V6's with Marshall 15w/18w iron so it's putting out around 25w.
It only uses a bass and treble in what looks like a baxandall tone stack and has the volume after the second tube stage.
it also uses a crossline master.

I built a Cheiftain out of a traynor reverb master, and a chieftain without reverb from a mojo jtm45 kit.

[Mouthurst]

thanks

[rocket]

yeah, I knew about the reverse pot.. don't have one so I tried a linear, hooking it up backwards yields better control, but it's freakin backwards!
Is the treble linear? I can't remember.

How can a linear pot backwards give better control, it should be symmetric!

[drewl]

What I meant was I tried a linear, it didn't work very well, then I tried the log hooked up backwards which yielded more working range, but in reverse.
I found a fender 3meg reverse log I might try if I get around to it.