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View Full Version : Swiss Army Synth Audio Board?



drjohn
06-08-2016, 06:52 PM
The stand alone audio board and the prop shield are great, but...I'd love it if there was a board that had support infrastructure for all manner of audio projects, whether they be CV based, stomp box, or stand-alone instruments. Basically spots for the buffers, optoisolators, and DACs that accrue.

Ideally it'd have pads to support (*=eurorack version concessions):


MIDI in and out, with optoisolator
Buffered audio in (ideally stereo)
Stereo audio out, with and without amplification
Connections for teensy ADC pins
Buffered inputs for ADC *that can handle CV voltage range
Buffered inputs for logic *that can handle typical gate voltages (up to 12V)
Connections for DAC pin
Dual outboard DAC *with op-amp for modular CV scaling (+/-5V or 0-10V)
micro SD slot
onboard memory
barrel and *eurorack power connectors


One could argue that I should just switch over to the Axoloti (www.axoloti.com), which has most of the I/O covered and a fairly slick GUI-to-finished-program process. OTOH: It's expensive in a per-board level and I like the control that the Teensy audio set-up offers.

I have poked around for teensy based projects with PCBs, and the closest I found is a partial (http://tomashg.com/?p=1126) match that isn't available anymore. Anyone have pointers for a better match, a PCB they've tested, or interest in designing something along these lines, with or without the eurorack safety/compatibility considerations? I'll get around to designing something eventually, but 1) probably not before the next version of teensy comes out, and 2) not without a lot of painful iterating on my part (I'm a doctor, not an PCB designer). Bonus: If there was a standard board that people were working with, it would decrease noob mistakes and enforce best practices, just as the other audio boards have.

mxxx
06-09-2016, 09:41 AM
I have poked around for teensy based projects with PCBs, and the closest I found is a partial (http://tomashg.com/?p=1126) match that isn't available anymore. Anyone have pointers for a better match, a PCB they've tested, or interest in designing something along these lines, with or without the eurorack safety/compatibility considerations? I'll get around to designing something eventually, but 1) probably not before the next version of teensy comes out, and 2) not without a lot of painful iterating on my part (I'm a doctor, not an PCB designer). Bonus: If there was a standard board that people were working with, it would decrease noob mistakes and enforce best practices, just as the other audio boards have.

fwiw, Paul seems to have had a vague plan (https://forum.pjrc.com/threads/33466-Teensy-3-2-DAC-gt-full-AC-signal-generator-LFO-for-audio?p=99909&viewfull=1#post99909) along these lines.

as for available PCBs, there's quite a few teensy-based eurorack modules, of course; ie if that's what you're after, but none that would cover every item on your list, AFAIK. for example (though i won't work on this until the next teensy comes around) i once made a small 6HP version of the audio adapter (+/- some details): https://github.com/mxmxmx/minitrash ; or https://github.com/mxmxmx/eurotrash_mkII (with display, but lacking audio inputs); useful up to a point, but in lots of cases dedicated hardware ( = designed for some specific purpose) ix the more desirable thing to have, imho.