ZEN Amplifier Mini with IRF610 as Headphone Amplifier for 32 Ohm

The initial PCB was a small victory, although I need to fix the footprints for the jack and pot, the channel layout works well and the performance was pretty much the same as perfboard build.

I'll test the timer circuit next and populate the second channel before giving it a listen but still having far more fun with this than you would think to get from so few parts.

It pulls 210mA @ 24V. PCB is 100mm x 100mm. Schematic is from post #24. Active parts are BC559B, BD140-16 and IRF520. Measurements are taken with a 150R load resistor on the output.

Cheers,
Stephen

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I have tweaked the circuit further. Lots of changes.
This version is for 32 Ohm, but I think it will work alright with other impedances.
Bias is increased to 300mA, and the output is at 12.2V.
Input capacitor is now film 1uF.
Relay capacitor is 100uF. Gives delay 5 seconds.
There is no new parts, so I think it will work with same PCB.

ZEN Mini Headphone Amp_19.jpg
 
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This is the result of Fourier simulation.
As can be seen there is H2 dominant.
And H3 is 35dB down and the rest very low.
This is typical for Nelson Pass ZEN amplifiers.
It is the way he likes it. Makes amplifier 'sing'.

ZEN Mini Headphone_20 Fourier.jpg