A simple headphones amp from yusynth.net

To test the output of my synth, I've built and tested the headphone amp found on yusynth.net:

https://yusynth.net/Modular/EN/MIXOUT/index.html

I had no BC327 transistors, so I replaced both the BC337 and BC327 with 2N3904 and 2N3906. Also, as I was unsure of the ratings of my resistors, I used two 330Ohm in place of the 150Ohm 1/2W, and two 220Ohm in place of the 82Ohm 1/2W. The output seems to have unity gain, way too high for my headphones, so I placed a resistor voltage divider plus an op amp buffer in front of the volume pot. I used 100k and 10k resistors for an attenuation from +/-5V to +/-0.45V. The max volume is still very high but at least more controllable.

Oh, and I forgot the electrolytic caps before the volume pots, I will add those and try again.