Valve Headphone Amp

[simon]

I've got a Spice model working for a ECX10N20 MOFO. It might even be something like accurate. Or not. Set up at 20V Vdd and 4A through the ECX10N20 and choke.
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Zen2 20V 4A MOFO circuit.png (98.71 KiB) Viewed 1868 times

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AC analysis. Interestingly it looks like gain of the buffer is x0.9, a bit lower than I might have expected.

Zen2 20V 4A MOFO AC.png (123.53 KiB) Viewed 1868 times

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Transient analysis with an input voltage of 10V. I reckon by 12V it's clipping at the top of the wave. Purple is the input signal, green the output.

Zen2 20V 4A MOFO transient.png (117.75 KiB) Viewed 1868 times

[Nick]

AC analysis. Interestingly it looks like gain of the buffer is x0.9, a bit lower than I might have expected.

Seems about right into a 8 ohm load. Current gain of course is much higher than 1

[simon]

Yep. If I get chance tonight I've have a look at the OP to see what happens if I "reduce" it to accommodate the relatively low swing of the potential input.