Supply voltage for transistor / OA preamp from cathode SE power amp

[dobrota]

Is it possible ? - of course after additional RC filtering etc. There's about 16-18V DC on cathode SE power amp with EL34 or 6L6. The idea is use it for supply JFET before 12AX7 preamp tube or OA based reverb circuit.

[dobrota]

I tried it and it works ! I added another RC filtering (R=100 Ohm, C=470u, and I'm thinking also about zenner diode), simple circuit with one dual TL072 OA for spring reverb.

[Steve Conner]

OK, but be sure to check that it still works when you're overdriving the power tube heavily!

Heavy overdrive can decrease the cathode voltage because of blocking distortion, so the system could go unstable and start motorboating.

[dobrota]

OK, but be sure to check that it still works when you're overdriving the power tube heavily!

Heavy overdrive can decrease the cathode voltage because of blocking distortion, so the system could go unstable and start motorboating.

There's only one 12AX7 tube in preamp so only crunch sounds, no heavy distortion. I'll try it (and measure voltage changes) also with solidstate overdrive pedal on input.