Adding another stage to this schematic...

[EETStudent]

Im looking to add another stage to this preamp for more gain. Any advice on how to wire up the triode for optimum performance?

[tubeswell]

Hmmm, I dunno My two cents worth if you're looking for 'overdriven' pre-amp sound try a 470pF - 1nF coupling cap after V1A with a 150k-220k rp and a .47uF ck/1k rk combo, then have a 1nF-2nF coupling cap and a 390k/390k - 470k/470k voltage divider going into the next stage maybe, and make the stage bypassable with an 'OD switch'?

That might likely get a sustainy mid range sound when you flick the switch.???

[EETStudent]

Just so Im clear on your idea, you are saying do all between stage 1 and stage 2? Add the coupling cap feeding the tone stack, and change the plate resistor to 150-220k. If so, I had actually already done that mod with a .022 coupler and 220k Rp. And then youre saying going into the next stage(after the volume control) try another coupling cap with some grid resistance to ground? I think thats what youre saying, and Ill give that a whirl

[EETStudent]

Oh wow i feel retarded. I thought you were suggesting modifying the original circuit. I see what you are saying now by adding that extra stage. My bad

[tubeswell]

Yep sorry - should've said extra stage - my bad ;-)

As an after-thought you'd need to make the 'OD switch' after the new stage before the tone stack and have it so it was a toggling switch that switched the signal path of the new stage to ground after the coupling cap, whilst simultaenously toggling to the V1a signal path. And you probably would need to tweek your supply voltages

[Tubis]

Do you realy want the eq before all those distortion stages?
I would put the eq after the preampstages. You get a much better tone by cutting bas and treble in the distortion stages by fixed filters and thene tuning the eq after. Just my taste.

[tubeswell]

Do you realy want the eq before all those distortion stages?
I would put the eq after the preampstages.

Yep I must admit I had the same thought. Certinly I anticpated the extra stage would go before the EQ

[EETStudent]

I see. Well, at the moment its stage one, stage two, EQ/master volume, stage 3 into phase inverter. You think Ill have better results by putting the eq after the 3rd stage?