The Amp Garage

So I found the biggest problem, and it was just a shorted switchcraft jack. I replaced it and now the gain channel is "mostly" working. The resistor on the gain pot wiper seems to be intended to "tame" a bit the gain before the second gain stage. I tried 470k, 470k+220k, and 1M. The later produced ...

I think I've gotten out of this thread as much as I can hope to get. Any more dialogue I fear will just become pointless bickering so if it's all the same, I've requested this thread be locked.

Appreciate all of your help, @Sluckey @B Ingram

The resistor is always connected, that is, the switch doesn't physically snip off the leads and connect them back into the circuit. Think about where the current wants to go when the switch is engaged (in parallel across the resistor). There is about ~0 ohms through the switch, and 10k in the resis...

The resistor is the component that is in circuit at all times Not so. The resistor is shorted out when the cap is switched in. Though there was a concern raised by @Stevem about there being oscillation issue running all the way across the amp to the push-pull pot. That's possible. Only you can know...

Right on :lol: I suppose it's the best of the options thus far, I can live with a little bit of a gain reduction if that's the price to pay of making it all work silently. The resistor is the component that is in circuit at all times - the cap still gets switched or paralleled in, which I thought is...

sluckey wrote: ↑Sat Feb 22, 2025 7:13 pm

GlideOn wrote: ↑Sat Feb 22, 2025 7:04 pm I see now what he was eluding to, but doesn't a resistor in series with a cap limit the effectiveness of said cap? That's not necessarily something I'm looking for...

Duh Huh!

Okay. Thanks for the diagram btw. I see now what he was eluding to, but doesn't a resistor in series with a cap limit the effectiveness of said cap? That's not necessarily something I'm looking for. I've done the 10k + .1uf trick for Marshall Cold Clipper stage in a SIR36 mod to limit the gain and s...

sluckey wrote: ↑Sat Feb 22, 2025 5:11 pm

GlideOn wrote: ↑Sat Feb 22, 2025 4:04 pm Edit: I drew up a switching scheme as @B Ingram suggested

That drawing does not represent what B Ingram said. All your circuit does is switch the 10K in parallel with the original cathode resistor. The cap never gets switched.

Fixed! Forgot the jumper wire.

Edit: I drew up a switching scheme as @B Ingram suggested, went with minimal 10k (all changes highlighted in Pink). However, the added resistor is in parallel with the 200r and lowers the overall resistance to 196r-ish. Not a huge deal but it could make the bias a tad hot or over the 90% dissipation...

Has anyone done or compared bypassed vs unbypassed power tube cathode? This is such a simple thing to do. In the time it takes to read this reply you can just do it. Then you'll have your own opinion rather than trying to decipher someone else's opinion. It may be a simple thing to try, but it's no...

... are you saying the 'anti-pop' resistor is at the positive (+) side of the cathode cap, the "not grounded side?" ... Resistor is on the negative side of the bypass cap. Between the cap & Ground. ... what will be the side effects of going from a fully bypassed cathode (cap) to an unbypassed (resi...

You do not want to run output stage signal all the way back up into the preamp section to access the use of that pot switch because you will likely have a oscillating mess of a amp on your hands from that mod. Get a rotary switch of the type that's makes before breaks as they are called to change o...

I have a push/pull bass pot in my amp and I currently have it utilized to parallel in the tonestack a .068 cap in with the existing .022, but it's not a very dramatic effect as I'd like. While reading up on fixed vs cathode bias switching in the power amp, I read that having no cap can increase NFB ...

I think this solution has a few issues. If you simply bypass a stage using this stereo jack then you'll have a long wire run coming out of the amp to your pedalboard and with a high gain lead stage that could pick up a lot of noise. Especially since it will be hanging like an antenna when not in us...

How about just the first 1/4 of the amp then? The rest I'm sure is fine as it's more or less unchanged.

Edit: Here's the rest of the amp removed with just the first stage: