Ceriatone Chupacabra mods

[SpiderWars]

I was wondering the same thing, but I think he's referring to the .022uf from the tone stack/mv into the pi and the.1uf on the other pi input.
The Friedman Dirty Shirley has a .0022uf on the pi input fwiw....

That's what it seemed to me too but the context was about the output couplers and bias feeds so that's why I was asking. Since the 0.1uF on the 'other' PI grid is to ground and is just putting that grid at AC ground, the input signal to that triode is thru the cathode. And that signal is affected by the input cap for sure but I didn't know there was a 10:1 'rule'.

But I always try to remember that with guitar amps we are; in the eyes of the great Radiotron, trying to make them sound 'bad'.

 

[FourT6and2]

You’re stuck on 0.1uF/110k. I’m only talking about textbook reasons why the in phase differential input decoupling capacitor should be 10x smaller than the out of phase input. Fuck the resistor. I don’t rightfully care what Marshall are ceriatone or anyone for that matter prefers for tonal reasons.

And you keep quoting “messing with” as if I haven’t explained the theoretical reason why already, if you can’t follow and that’s all you get from my comment then you’re looking for a posting pissing contest. If you want more of an explanation then I’ve also quoted free sources - I don’t need or care about going to ampbook.com

You're doing exactly what you're accusing me of doing. And I'm not going to put up with it. You are accusing me of "going off". That's what you're doing. You're accusing me of trying to engage in a "pissing contest". That's exactly what you're doing. OP is asking me for advice/my opinion on tweaking this amp. You popped in to start an argument with me. So what do you want out of this exchange? Time to add each other to ignore lists.

 

[FourT6and2]

I was wondering the same thing, but I think he's referring to the .022uf from the tone stack/mv into the pi and the.1uf on the other pi input.
The Friedman Dirty Shirley has a .0022uf on the pi input fwiw....

Seems the majority of this discussion is about the pi OUTPUT couplers and the bias feed resistors. The size of these components affect "bias excursion" as there is a time constant involved. As mentioned, Aiken has written about this, and there is a calculator an ampbooks for these values.
The gist being you have to watch the size of the caps and adjust the resistors accordingly, or the recovery time will be too slow.
I tend to agree with 46&2 that .022uf and 220k is the way to go, although you could go with 150k and leave open the ability to run 6550's if desired.
I don't hear much difference between 150k and 220k, and I like swapping in 6550s in some Marshall style circuits, especially when diode clipping is being used.

Yes, exactly. You get it.

I don't know why he's hung up on this 10:1 thing. I'm talking about the PI OUTPUT couplers and the gird leak/output resistors. Not the 0.1uF in the PI input. He's being abrasive and talking past me when he knows damn well what I'm saying. And I know what he's saying too, which is why I mentioned looking at the calculator on AmpBooks.com. And yes, we've all read what Aiken has to say on the matter.

That doesn't change the fact that IN THIS AMP, 0.022uF/150K or 220K in the PI is just fine and will sound a million times better than 0.1uF/110K. Who the hell cares about all the theoretical BS. Swap the parts, play the amp, and you'll hear how it sounds. If ya don't like it, try something else. It's not going to hurt the amp.

I've tried every combination of 0.022uF, 0.047uF, 0.1uF, and 82K, 110K, 120K, 150K, 180K, 200K, 220K in the PI output. If someone wants to understand how it actually sounds, screw the theory and bust out the soldering iron.

 

[FourT6and2]

OP, good luck with the amp and I sincerely hope you have fun tweaking it and getting it to scream. If you have more questions, feel free to PM me directly.

 

[glpg80]

I was wondering the same thing, but I think he's referring to the .022uf from the tone stack/mv into the pi and the.1uf on the other pi input.
The Friedman Dirty Shirley has a .0022uf on the pi input fwiw....

Seems the majority of this discussion is about the pi OUTPUT couplers and the bias feed resistors. The size of these components affect "bias excursion" as there is a time constant involved. As mentioned, Aiken has written about this, and there is a calculator an ampbooks for these values.
The gist being you have to watch the size of the caps and adjust the resistors accordingly, or the recovery time will be too slow.
I tend to agree with 46&2 that .022uf and 220k is the way to go, although you could go with 150k and leave open the ability to run 6550's if desired.
I don't hear much difference between 150k and 220k, and I like swapping in 6550s in some Marshall style circuits, especially when diode clipping is being used.

Yes this is correct and the purpose of my original post - just sharing some guidelines for those that desire to tweak.

 

[glpg80]

Yes, exactly. You get it.

I don't know why he's hung up on this 10:1 thing. I'm talking about the PI OUTPUT couplers and the gird leak/output resistors. Not the 0.1uF in the PI input. He's being abrasive and talking past me when he knows damn well what I'm saying. And I know what he's saying too, which is why I mentioned looking at the calculator on AmpBooks.com. And yes, we've all read what Aiken has to say on the matter.

That doesn't change the fact that IN THIS AMP, 0.022uF/150K or 220K in the PI is just fine and will sound a million times better than 0.1uF/110K. Who the hell cares about all the theoretical BS. Swap the parts, play the amp, and you'll hear how it sounds. If ya don't like it, try something else. It's not going to hurt the amp.

I've tried every combination of 0.022uF, 0.047uF, 0.1uF, and 82K, 110K, 120K, 150K, 180K, 200K, 220K in the PI output. If someone wants to understand how it actually sounds, screw the theory and bust out the soldering iron.

I’m being abrasive? Have you read your own posts? I absolutely agree the output decoupling capacitors Marshall got right at 0.02uF and 150k. I wasn’t speaking about changing those, you were. I just mentioned a random fact about the ratios of the input decoupling capacitors. Why am I hung up on this? Because not many know the ratio even exists for a reason.