bjosephs
Well-known member
The monitor controller I built recently lacks headphone amp. I'd always planned to make little standalone box that would take in a balanced line level signal and drive phones. Something small I could velcro under my desk with just enough access for a volume knob. The OPA1688 app notes are simple enough but I wondering how to give it a small, quiet bipolar supply. I think an internal transformer and mains voltage is a bit overkill for one active device device so I've settled on a wall wart of some kind. The choices are:
- An AC wall wart that I can half wave rectify for positive and negative rail, regulate and filter. I'm worried about proximity and hum.
- A DC/DC converter that takes in ~9-12v and makes +/-12. CUI has a PDQ2 series with a 100kHz switching frequency.
- I guess I could also try to get a DC wall wart with a rather high output (like 24-36VDC) regulate that down and use virtual earth. Can headphones float at 1/2V or would I need to AC couple the outputs?