6FQ7/6SN7 + MOS. FET Hybrid power amplifier

( add some more gain to the Baby 300B )

I built this 100W tube sound alike amplifier with the 6SN7 or 6FQ7 for driver and the MOS. FET for power output. I have built a total of 5 of these, one for myself and other four for my friends. This hybrid amplifier had beaten down a few expensive amplifiers on market during in A/B test.

  1. You may use 6FQ7 or 6SN7 on this project.
  2. All are 1W resistors in 1 % accurate expect the bias setting resistors.
  3. Set until you get 0 volt DC on output with the 2K adjustable resistor for DC balance.
  4. The resistors with *** are use for setting bias, starting with 87K and reduce the value to get the correct bias. Use 2W resistors.
  5. After replace the 6FQ7 with new tubes, the used tubes can use on the tube regulator, they work fine there.
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