Hybrid tube/MOSFET headphone amp


I was messing around in SPICE and think I solved the PSRR problem with a white cathode follower using depletion-mode MOSFETs. I appear to have given it a 26dB improvement.

Is it elegant or another lame-o dud?

The top jfet gets the current sense relative to the supply and send it to the bottom one that inverts and adjusts for matching swings.

Here's a slightly different one that can bring a 25 ohm Denon AH-D2000 to its full 1.8 watts.

I changed the VAS p-device to a Supertex VP0550 which allows the I-to-V resistor to be larger as the D-MOS turn-on is much higher. This gives much more open-loop gain. Each output device dissipates just 900mW at full load or 1.3W at idle.


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