I built this 2 watt Class A smp several months ago and thought I would share it with you all, its a really great first time into DIY building and works very well with low to high impedance headphones. Details of mine and several others build is locatated at : https://www.diyaudio.com/forums/headphone-systems/343616-noir-transistor-headphone-amp-class-single-150ma-bias.html
Basically here are the design criteria:
- Solid state, all discrete: no ICs, no vacuum tubes
- Single ended, Class A circuit operating at 150 mA bias current (exceptionally high for a headphone amp)
- No mains voltage inside the DIY chassis. Power is supplied by a commercial, safety rated, wall wart @ 24V DC
- All thru-hole parts, mounted on a single PCB with generous spacing between components
- Very easy to stuff and solder; suitable for first time DIYers. Component IDs and component values printed on PCB silkscreen.
- Headphone output on front panel, linestage preamp output (RCA jacks) on rear panel
- Pre-made front and rear panels, drilled and silkscreened, for DIYers who prefer not to do metalwork themselves. These are black PCBs, 2.0mm thick, cut to match the diyAudio Store “1U Galaxy” chassis front & rear panels.
- Detailed, 37 page .pdf file named “Noir Build Instructions” walks you through the assembly process with plenty of photos. It’s 4.7 megabytes long, over the size limit for attachments here on the Forum, but is available for download on the sales page of the Store.
Here are some of my pix:
Pix after the T2 name was changed to NOIR to avoid conflict with existing gear: