Tube amp people Q input cap value C2C Wrecking ball

[jwin615]

I'm wanting to add a tight switch to the C2C wrecking ball, which seems to mostly mirror the mesa triple rec input.
It seems the input stage is wide open 22n and 2M2 form a HPF at ~3Hz. Am I missing something? Would it be wrong to have one of the three positions at ~600-800pF for a 90-120 Hz corner HPF? Any adverse effects there?

Ideally I would like to set this up for something like 90, 60, 20 Hz...

 

[stinkfeet]

For Soldanos, people like using 4.7n for a much less bassy lead sound, and 2.2n for a tighter sound. They also use 1n in the new production Soldanos. Going below 1nf for coupling caps can be weird sometimes, but since this is such a fat circuit, I don't think it would be that bad. You could also change the treble speaker situation of C6 and R11 to the other option in the rectifier of 680k/2.2n, the SLO value of 470k/2.2n, or the later Omega Granophyre value of 470k/1n for a little more tightness.

 

[jwin615]

For Soldanos, people like using 4.7n for a much less bassy lead sound, and 2.2n for a tighter sound. They also use 1n in the new Soldanos. Going below 1nf can be weird sometimes, but since this is such a fat circuit, I don't think it would be that bad. You could also change the treble speaker situation of C6 and R11 to the other option in the rectifier of 680k/2.2n, the SLO value of 470k/2.2n, or the later Omega Granophyre value of 470k/1n for a little more tightness.

Thanks for the reply. I think the kicker is the 3M3 being so large, causing the need for such a small cap. Even a 2n2, you corner frequency is only 22Hz.
What concerns me is getting to the point that the reactance of the cap is limiting the frequency.
Actually, now thinking about it, I think that is all that is occuring here... So I'm trying to make an RC filter where one never really existed.
When you say C6/R11, are you referencing the mesa chem or C2C schem?

 

[stinkfeet]

Thanks for the reply. I think the kicker is the 3M3 being so large, causing the need for such a small cap. Even a 2n2, you corner frequency is only 22Hz.
What concerns me is getting to the point that the reactance of the cap is limiting the frequency.
Actually, now thinking about it, I think that is all that is occuring here... So I'm trying to make an RC filter where one never really existed.
When you say C6/R11, are you referencing the mesa chem or C2C schem?

I was referencing the C2C scheme for C6/R11. Those 2M2s really limit what C1 can do. I've never looked into it for a rectifier before, and I see what you mean now after testing it in SPICE. I'd start by lowering r11 and go from there. You can also lower C9 to 680n or 470n, but it will change the character quite a bit.

 

[stinkfeet]

Something I forgot, cutting signal after the first stage will help tighten it a lot and not really change how much gain it has, putting a resistor between pin 1&3 or wiper to ground on the gain pot would work great, I’d try a value somewhere in between 680k and 220k. The granophyre has a 680k between 1&3. You could also make c3 smaller too, but the first coupling cap will be more important.