M3 Headphone Amplifier - Take Two
This is a work in progress, this article is by no means complete yet!
BackgroundSome time ago, a fellow head-fi'er put up a not-quite-finished M3 for sale and his add caught my attention. I had spoken with him in the past and seemed to remember that the M3 was a dream of his. It seemed he had done all the soldering, but that the casework had effectively stopped his project from being finalized. I contacted him and suggested that instead of selling the project (I already have an M3) we should build a proper case for it so that he would be able to enjoy music the way he intended to. He quickly accepted and we started talking design.
This is what I got, along with a box of stuff for the build. The build featured:
- M3 Amplifier from AMB Laboratories.
- Sigma11 Power Supply fromAMB Laboratories.
- Epsilon24 Power switch Driver Circuit from AMB Laboratories.
- Sigma24 Transformer Board from AMB Laboratories.
- Sigma25 Regulated Power Supply from AMB Laboratories.
- Epsilon12 Headphone Amp Muting delay & DC offset protection circuit from AMB Laboratories.
that the protection relay behaves quite erratic in the standard configuration and often triggers when I play PC games, so we abandoned that also. My own M3 does not have the protection relay either and I have never had a problem with it.
The Sigma11 was chosen as power supply as it complements the M3 design nicely.