Vibro Champ Clone wants some breakup

[maxkracht]

Makes no sense to me that pin 6 is so high since it's connected at the same supply as pin 1, then both have 100k resistors that measure good.

Modulating the bias of that triode is what makes the tremolo. Even when the trem is turned off with the foot pedal, the intensity pot will change the bias.

[cdemike]

Makes no sense to me that pin 6 is so high since it's connected at the same supply as pin 1, then both have 100k resistors that measure good.

Modulating the bias of that triode is what makes the tremolo. Even when the trem is turned off with the foot pedal, the intensity pot will change the bias.

Agree that this seems to be a likely culprit for that big voltage disparity. Relatedly, experimenting with the value of the second triode's cathode resistor might be a good way for you to alter the amp's headroom. I substituted a Supro 6424 style tremolo for a Vibrochamp style trem in a homebrew amp because at high intensity settings with the footswitch engaged the amp had very little headroom. Unless you're playing with extremely low output pickups, I'd expect you'd be able to get a decent amount of overdrive at high intensity settings with the Vibrochamp tremolo topology.

[ampgaragemc]

Thanks for all the help and suggestions. Before I read these latest comments what I did was swap out the 100k V1B plate resistor for 200k. It dropped the voltage to 246v. It definitely has some breakup now and cleans up sweet when I back off a little. Overall, I think it's not as loud as before but that's good for what I need. And it has a NFB switch if I ever want to open it up. I'm going to try it like this for a while.

Thanks for the comment on the design. I'd read a lot of what Rob Robinette says to connect the last filter to the signal ground instead of the power ground. Also, I wanted the rectifier to see 20uf instead of 40uf so I had to put another cap outside of the can cap. The first time I started it up I thought, crap this thing is dead, and I have no idea how to fix it. Then I turned it up and it was amazing. Absolutely no buzz or hiss or anything. The tone and the breakup are controlled completely by the guitar.

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