Reverse-engineering the analog audio connector (DB44 HD) on an ESI Maya1010 pro soundcard I got without the original breakout panel. These cards were made in mid 2000s but you can still get drivers for the modern OSes, and now, thanks to Pipewire, they're mighty awesome in Linux! That's 8 channel input and 8 channel output goodness for ya :). Planning to switch over to ESI fully and disable the built-in soundcard.

First (and done a long time ago) was tracing the ground pins. They're evenly spaced, 4 pins between them. I found GND at 4, 9, 14, 17, 22, 27, 35, 40.

The reverse-engineering process differs slightly for input and output tracing. I traced the outputs by generating a 400Hz tone (command: ffplay -f lavfi -i "sine=frequency=400" -nodisp) and patching it to output channels on the Maya1010, one by one, and looking for them with an amp acting as a signal tracer. That's how I created an output channel map:

OUT 1 - 23 OUT 2 - 37 OUT 3 - 36 OUT 4 - 6 OUT 5 - 5 OUT 6 - 19 OUT 7 - 18 OUT 8 - 32

Then I traced the input channels, also one by one. The setup in qpwgraph was more complicated and involved running several instances of pavumeter (software level indicator) patched to individual channels, feeding into the audio output for monitoring. Then it was just feeding the output of a CD player into DB44 pins and watching the signal appear, mapping pins to channels. It's worth noting that while the outputs are unbalanced, the inputs are balanced, so every channel has its hot and cold wire that goes through the input amplifier and ADC to the software. I managed to map the input channels #3...8, as the first and second must be set up in some additional software to work either on line or mic level, with an optional 12VDC phantom power feature. I haven't checked the phase on the input channels (ie hot or cold), it's still WIP.

Intput channel map, polarity not tested: IN 1 or 2 - 15, 30 IN 2 or 1 - 29, 44 IN 3 - 28, 43 IN 4 - 13, 42 IN 5 - 12, 41 IN 6 - 11, 26 IN 7 - 10, 25 IN 8 - 24, 39

Two additional pins on the connector (1, 31) measure 5VDC on the meter and are routed through resistors. 1 measures 15.5k positive and 8.5k negative to ground, some semiconductor is involved. 31 measures 1k5 to ground both ways. One of them may be the power to the breakout panel and the other one may be a pulled-up control line. It's all speculation as I don't have the breakout panel itself.

The other pins may be for jack state detection (on or off), but again, it's just speculation.

Sorry for the hum on my mike... I shouldn't have moved my mike stand to the desk where it picks up vibration and stuff. Nah.

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