• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Headphone schematic and layout

Just amazing went to China PCB Prototype & PCB Fabrication Manufacturer - JLCPCB followed the very well explained data on how to format the gerbers. Zip them, upload them to the website and all sorts of magic just happens. £5 + £15 shipping for 5x and 6 days later they are here!

Assembled the board - one channel fine one channel distorted. Missed a very short track from the plate of the ECC88 to the transformer connector. Bother - easy to fix. Had done some swapping of the valves when trying out a 90deg rotation and forgot to do the schematic DRC.

Only tried of bench supply but regs are working so will need to check hum with mains transformers.

I would also change a couple of footprints I used the difficult to solder inline TO92 to TO92L. As a test board have learned a lot. Very pleased with KiCad and the China PCB - would suggest giving it a go.
 
20211120_160943.jpg
View attachment headamp.pdf

.. and a big thanks to all who helped.
 
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Some measured results to compare using the RS £15 OPT.
All measurement into 33R load.

20Hz: +/-1.8V OP sinewave
1KHz: +/-3V
20KHz: +/-3V

Distortion 1KHz @ +/-1V
(2nd) -58dB
(3rd) -52dB (.25%)

Frequency response -.5dB 15Hz-30KHz
 
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