This project was created with the intent to solve a problem with my folk’s home theatre setup. They had multiple surround sources going into a single stereo system, but wanted to have the ability to play multiple sources at once (i.e. be able to hear a response from an Amazon echo while watching TV without needing a separate stereo system).
I also had a large collection of surface-mount operational amplifiers salvaged from several dead speaker PCBs. I also was looking to test the capbilities of my home PCB etching process, so a fairly complex two-sided SMT design would be a good benchmark. It became clear that my process is still far from perfect, as I had to make several bodges in order to get things to work.
The enclosure was made from a pre-fab aluminum project box, with all of the cutouts machined on my DIY CNC router. The potentiometers were salvaged from a dead audio mixer, and the knobs were printed in a silver TPU filament. The power supply was an old linear +/- 15v supply that my dad had laying around.