Parenthesis

by Antony Chazapis

My take on an Internet classic. The DIY Audio Projects hybrid headphone amplifier. Read more info on the design here, and many interesting implementations at the forum page. I have had great success with another project from the same site many years ago – my first tube amplifier. This was built as a gift for a good friend.

Headphone amplifier decomposed

The amplifier uses very few parts. I already had a 12AT7/ECC81 tube from some hamfest. The output MOSFETs and LM317 regulators where mounted on a CPU heatsink, using an M3 tap. The enclosure was spray-painted red. Most components were soldered directly on the tube socket and the output jack. To power the amplifier from a 13.8V power supply, I placed two diodes in series with the power input. Thus I got about 12.6V at the tube filament.

I don’t have the experience to accurately comment on the sound, so don’t expect a thorough critique. I can just say I like it.

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