For those still reading, I got the project running without electrocuting myself or setting fire to the house.
I routed the 100pF capacitors directly between the gate and cathode, and thus probably sacrificed quite a bit of the top end, as is apparent in listening to some music. Zero negative feedback means the sound is a little inaccurate, but tolerable. Sounds like a cheap old radio. I guess that sort of tone would work well for guitar.
Also, due to a major mistake on my end the transformer cannot be used in UL mode, because the tap is in the wrong place on one winding
So I have stayed in pentode mode for now, with the FET regulator only for the screen regulation and the input stages, and the transformer connected to the supply just before the regulator.
My main issue is the low gain of the first stage. It was predicted to have a gain of 35dB, which may or may not be enough. The second stage works fine but in the absence of drive from the first stage it just sounds weak and scratchy. I am probably going to try increasing the anode resistor, but would be keen to know if there are other methods of getting more drive out of the first stage.
I routed the 100pF capacitors directly between the gate and cathode, and thus probably sacrificed quite a bit of the top end, as is apparent in listening to some music. Zero negative feedback means the sound is a little inaccurate, but tolerable. Sounds like a cheap old radio. I guess that sort of tone would work well for guitar.
Also, due to a major mistake on my end the transformer cannot be used in UL mode, because the tap is in the wrong place on one winding
So I have stayed in pentode mode for now, with the FET regulator only for the screen regulation and the input stages, and the transformer connected to the supply just before the regulator.My main issue is the low gain of the first stage. It was predicted to have a gain of 35dB, which may or may not be enough. The second stage works fine but in the absence of drive from the first stage it just sounds weak and scratchy. I am probably going to try increasing the anode resistor, but would be keen to know if there are other methods of getting more drive out of the first stage.