• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Circuit choices for sub output - stay with original intent, or….?

What circuit would you use for the mono sub out?

  • Passive only, resistive mixer

    Votes: 1 50.0%
  • 6/12SN7 triode buffer, then passive mix

    Votes: 1 50.0%
  • 6/12SL7 triode buffer with degeneration, then passive mix

    Votes: 0 0.0%
  • Active mix with 6/12SL7 (plate to grid feedback, 2 inputs)

    Votes: 0 0.0%
  • As above, make Sallen-key low pass filter with the other triode

    Votes: 0 0.0%

  • Total voters
    2
I have this cute little 14 watt per channel no feedback amp thats finding its home as a computer speaker amp. Originally intended as fully class A push pull at 10 watts according to the load lines, but I’ve found it runs a bit into AB with a bit more power. No feedback at all, save the concertina phase splitter. Bass/treble is a passive stack. Im considering adding a mono sub out post tone/volume of course, and having trouble deciding how to implement it. I’m not afraid of feedback at all, just wanted to keep this one feedback free. Have already committed sin with the concertina (and no longer matters)? Would it be sacrilegious to consider using op amp techniques or local degeneration to kill unwanted gain? Just wanted to take the pulse of what others might do. It will mean adding another tube, unless option 1 is chosen.

I have it wired for 12 volt versions of preamp tubes at the moment. I have plenty. Power stage is 10EM7, and I’m making octal/novar adapters to use 10GF7 which I’ve gotten a larger quantity of.