Folks,
I've now built and tested the V2 prototype and it works and the Teensy Audio driver is in a solid beta state.
- 8 in, 8 out, USB in and out
- 0.002% input distortion with a 10-bit arb function generator. Probably better when I get around to testing with proper audio gear.
- Balanced or single ended inputs. Up to 60dB (PGA) gain on the inputs - so microphone or line compatible.
- Able to drive 600 ohm balanced lines directly by using the headphone outputs.
The downside is that the TLV320 chips are a real pain for humans to solder, being QFN (no pins) packages.
After putting the board through the SMD oven cycle, I spent nearly a day getting all the connections to work - with a needle point soldering iron!
I'm going to price PCBA in the next week to see if its economic to do shortish runs (10 or 20 boards). I have a feeling that the international postage will cost more than a board!
The current PCB is moderately large, 75 x 130. Close to 75 dimension is required if a T4.1 is used (e.g., for network audio).
It might be possible to shave a bit off the length by turning the chips 45 degrees.
Are folks more interested in the smallest possible form factor, or getting their hands on some boards ASAP?
I will open source the design and PCB(s) - this PCB is bare Teensy + CODECs, so I have designed a set of 'wing' boards that can accommodate TRS or XLR connectors. I think that's all explained in an earlier post.
Next up, commissioning a second board and trying out 16 x 16 operation!