Hello, People.
I am making a hybrid headphone amplifier, for 60-600ohm headphones, using subminiature tubes with mu of 25 (planning to use "real" grounded grid amp), followed by solid state output stage (impedance multiplier circuit with LT1206 opamps).
While 600ohm headphones make use of the extra voltage gain, 60ohm ones are reaching high levels already with output from DAP I am using, at 60% of volume.
While I am still waiting for various parts to be delivered, I experimented with the "inverted triode" circuit, which has gain of approx 1/mu. It worked, and I figured out I could use it as "attentuator stage" after grounded grid stage for low impedance loads. (A switch would be used to select "Grounded grid -> IMC" or "Grounded grid -> inverted triode -> IMC".
I would like to use the same heater PSU for both grounded grid and inverted triode, which is elevated to 1/4 of B+.
But does the same principum of cathode - heater voltage apply to inverted triode, or would it now be heater - grid voltage?
Thanks in advance.
I am making a hybrid headphone amplifier, for 60-600ohm headphones, using subminiature tubes with mu of 25 (planning to use "real" grounded grid amp), followed by solid state output stage (impedance multiplier circuit with LT1206 opamps).
While 600ohm headphones make use of the extra voltage gain, 60ohm ones are reaching high levels already with output from DAP I am using, at 60% of volume.
While I am still waiting for various parts to be delivered, I experimented with the "inverted triode" circuit, which has gain of approx 1/mu. It worked, and I figured out I could use it as "attentuator stage" after grounded grid stage for low impedance loads. (A switch would be used to select "Grounded grid -> IMC" or "Grounded grid -> inverted triode -> IMC".
I would like to use the same heater PSU for both grounded grid and inverted triode, which is elevated to 1/4 of B+.
But does the same principum of cathode - heater voltage apply to inverted triode, or would it now be heater - grid voltage?
Thanks in advance.
