SJS Aoide headphone amplifier
The first prototype SJS Aoide headphone amplifier is assembled and undergoing final testing.
https://dl.dropboxusercontent.com/u/...hone_amp_7.jpg
It is effectively a mW level integrated SET amplifier using triode strapped E55L valves, with custom designed and made HiB Double C core output transformers. These have secondaries which enable switching for low impedance (30 to 100 ohms) or high impedance (120 to 600 ohms) headphones, and either balanced or unbalanced connection. The PSU is valve rectified with choke input filter and second stage LC filters per channel. There are 3 line level inputs, input selector and volume control.
It came about as a result of a commission from a long time Model 1 preamp owner who has switched over to using Audeze headphones. It was designed to be an integrated amp, but a "power amp" version could be made for use with an existing preamp.
It's a prototype at the moment, and I need to sort out the switching arrangement and possibly get different wooden frames, but otherwise it's up and running quite nicely.
Almost forgot, it can also be built as a line stage pre-amplifier by changing the output transformers. I have this version built in another box which greengoblin heard recently when he visited.
The design was developed to match the phono stages built a few years ago
https://dl.dropboxusercontent.com/u/...-overcase1.jpg
Any AoS members in South Manchester who are big headphone users and interested in hearing the prototype, please contact me