HPA-1 Class A Headphone Amplifier

This class A headphone amplifier from 2014 is based on the design I used in my ‘Symphony’ preamp. It will drive a pair of 32 Ohm headphones to 6V pk-pk and remain in class A with < 330 parts per billion distortion at 20 kHz. At 16 V pk-pk output into 32 Ohms, the distortion is about 2 parts per million. Note that an average pair of 32 Ohm headphones will be producing > 115 dB SPL at 6V pk-pk.

I am working with a US based diyAudio member (as of August 2020) who is designing a set of PCB’s including PSU. Stay tuned for further updates.