The Arp 2600 synthesizer has a preamp that takes an unbalanced signal and amplifies it 10x, 100x, and 1000x. This project is a workalike for the classic design from the 70's. it uses 2x SOIC 2-circuit op amps and includes a switch to add input impedence if needed.

It also has both AC (capacitor coupled) and DC inputs and an output that servers as a unity gain buffer as well as amplification.

The circuit is 8HP in Euro format and draws 10mA of current per rail.

Low noise gain was a design goal.

The project includes 2 gerbers--the main board, and if you are building Eurorack gear, the front panel. If you build the front panel please consider using a black soldermask with white front silks.Check the box that for an extra $1.50 leaves the project number off the PCB.

more information at the blog post here:

https://audiodiwhy.blogspot.com/2023/08/arp2600-style-preamp-understanding-and.html