Beavis Ultrasound PnP ISA Sound Card Replica
The Beavis Ultrasound PnP is an open source replica of the Gravis Ultrasound Pnp. Unlike other clones, this design includes the entire schematic as well as the reverse-engineered source code of the GAL.
If you want to build this board, first make sure you have an AMD InterWave chip, the AM78C201. The design of the card is quite simple since essentially all sound card functionality is built into the AMD chip.
Note: I have not generated the fab package since I have not actually fabricated the board and tested it for functionality. Build this board at your own risk.
The board is 8.2 x 4.2 inches (208 x 107mm) and 4 layers. Feel free to go with ENIG plating for the edge fingers; although hard gold is technically better, it is ludicrously expensive.
The dual op amps may be substituted. The BOM calls out the LM833 but the JRC5532 will also work. Basically, any ~10MHz low noise op amp that can handle a +/-8V input power supply will suffice. If you want to get fancy, install sockets and experiment.
The ferrite beads were missing from the card I started with so their values are unknown but you can replace them with a 0 ohm resistor or a piece of wire. It's a little odd using ferrite beads to filter the voltage regulators when they are really only effective at frequencies far higher than the audio range.