DIY Digital Mixer

[eehobby]

I have an analog mixer with 4 mic inputs, 2 stereo line inputs and outputs for main, monitor, headphone, tape, & effects. It works well for what our little folk group needs - BUT occasionally we need more mics, and often we need more line inputs. Since I am well equipped for electronics construction, and I have done numerous projects with embedded micro controllers, (including an audio distribution system (with ADC->S/PDIF-mux->multiple DACS), I was thinking of making a Digital Mixer. After searching commercial products, and these forums, and chip datasheets, it looks like it should be doable; but, there are some things that I haven't found yet. For inputs and outputs, I could use a PCM3070, or a miniDSP module, but I still don't see what to use to replace the buses in my analog mixer. Conceivably I could find a chip that has multiple I2S inputs and outputs - then (hopefully) program that to do the mixing for main, monitor, effects, etc; but I would need at least 16 in and 8 out, and preferably a design that is extensible. Is there a building block like that?

NB - If this is the wrong forum, please advise which would be a better choice.

Thanks,
Jake

 

[Fio]

As a starting point:
ADAU1442 eval

It is possible to control it with a uC or Pi/BBB/.. and for example a touch LCD.
You can also use GPIOs, but a mixer will need a lot of them.

 

[eehobby]

FYI - Thanks to advice from FIO, I have moved ahead on the design of the input channels and I have a reasonably good plan for the whole thing.
I have a preliminary schematic for the mic/input section, but I would like to simulate one of each input. Does anyone know where to get an LTSPICE model for THAT1583 Audio Preamplifier? I tried their website, and even though it listed a library, the specific device wasn't included.

Thanks,
Jake