Analyze this tone stack

[Lynxtrap]

As usual, I have a hard time wrapping my head around tone stacks.
I'm trying to understand the one in this schematic, and what makes it different from a two knob Fender stack. Might want to mod one channel, but I'm not sure what to do for instance if I want more mids.

[martin manning]

I think I would just convert to a Fender stack, ala Deluxe Reverb. That should reduce the mid scoop.

[Lynxtrap]

I think I would just convert to a Fender stack, ala Deluxe Reverb. That should reduce the mid scoop.

Do you see this one as even more scooped than a Fender?

[martin manning]

Yes, and it has the bass pot going to ground at one extreme, which is generally not a good idea.

[Lynxtrap]

Yes, and it has the bass pot going to ground at one extreme, which is generally not a good idea.

Ok, thanks. The bass pot to ground made me think that getting more mids out of it wouldn't be as simple as raising the 10K resistor to ground.
I have to say I find this tone stack pretty ok for clean sound. But I'm looking at getting some overdrive out of one channel, so more mids might be nice.
I will probably place the tone stack after the second gain stage in that channel.

[tubeswell]

It helps to picture the tone stack as just resistors and caps. (i.e. Draw different versions of it with the pots fully rotated one way, then the other, then in the middle, but draw the pots as resistors). Then do bode plots of each part of the filter with straight asymptotes. Then sum the plots.

[shane]

It's basically a bandmaster tone stack. So it should sound like a fender!

[martin manning]

Which Bandmaster? I don't see the similarity.

[sluckey]

Looks like 6G7, 6G4, and 6G5. I have never heard any of those.

[martin manning]

Ah yes, the earliest ones. But that is not a typical Fender stack. I would try something like the mark-up below to make it more like a Deluxe Reverb. You could also try replacing the 100k with a 150k or 220k.

[Lynxtrap]

Thanks!
That's interesting. I didn't realize this would be found in old "Brownface" amps, you don't see those every day...
I'll have to see what works. I guess a James wouldn't be out of the question either.

[martin manning]

And it disappeared right away, note it’s in the 6G7, but not in the 6G7-A.

[Lynxtrap]

Yes, lots of things came and went with the Brownface line.
I must say I'm not a big fan of the BF/SF tone stack, although this might be even worse. Both work fine for fendery clean sound, but not so much for overdrive or when better control of the frequency bands is needed IMO.

But being able to tune the mids by swapping resistors is a step ahead.

[shane]

I've tried this in a couple of amps and it sounds quite good.
Not blackface really. It has some similarities to the vox tone stack.
It worked quite well in a medium gain (jcm800 type of gain) amp I did

[Lynxtrap]

I've tried this in a couple of amps and it sounds quite good.
Not blackface really. It has some similarities to the vox tone stack.
It worked quite well in a medium gain (jcm800 type of gain) amp I did

Really? I'm trying something similar with this one, but I get way too much lows. It's almost too much with the bass pot at zero.