Favorite one tube tremolo

[luthierwnc]

Hi Guys;

I'm drafting the winter project and wanted to know if anyone had a favorite bias-modulation trem circuit. I can use up to three triodes but a single tube might work better. Right now I am leaning towards a tweed tremolux but if someone has something interesting, please share.

Thanks, Skip

[tubeswell]

Well I got to vote for a 5G9

[luthierwnc]

Bump

[6267]

I once was reworking an organ amp into something usable for other instruments. The thing had an oscillator for tremolo, but the signal was mixed off-chassis, which was no good to me. I am not sure if this is the "right" thing to do, but I just tapped the oscillator signal, voltage divider'd it down to about .5v (depends on where you're going to put it) and sent it to the unbypassed cathode of one of the preamp stages. I installed a switch to connect or disconnect this wire and a pot to adjust the reduced oscillator signal, and I installed a 1M linear pot in the oscillator's loop to control the rate. To prevent speaker pumping, you will need to have a multiple stage filter to cut sub 60hz or so. I left mine unfiltered, and at max depth the speaker didn't seem to happy.

The good news is that this circuit uses on 1/2 12ax7, and sounds good to my ears. You will have to tweak the voltage divider so that the preamp tube isn't trying to run in class A2 and that it's not trying to run in class C either. in other words, you may have to slightly increase the cathode resistor, and make sure the oscillator is small enough that it does not result in Vk being way too high or low at full signal.