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Another (free) option: If you are doing things that only require audio bandwidth, you can construct any arbitrary function generator in VCVrack and send it thro

Another (free) option: If you are doing things that only require audio bandwidth, you can construct any arbitrary function generator in VCVrack and send it through the audio output. You can trivially do fm modulation, wavetable synthesis, frequency domain and phase shift synthesis, etc. A push/pull follower made from 2 transistors, an opamp, and a pot for adjustable gain would probably be a good addition. You can also use standard midi (see rs232) messages and audio inputs to control modulation etc. Edit: also wanted to mention the python-rtmidi library, which can construct virtual midi interfaces. It synergizes nicely when used as a control interface.

Tade0 7y ago
One issue with your standard phone or laptop audio output is that its clock is not overly precise. I learned this when I tried to combine the output of multiple sources generating a sawtooth wave from the same file - any two sources would sweep at around 1-2Hz. It's still usable, just not in scenarios where you have many of them.
- yummypaint 7y ago
  That's interesting. Were these two hardware outputs from the same audio device, or two different computers? It's true built in audio on most mobos is notoriously bad, and most musicians and podcasters use an external audio interface. I would imagine those don't suffer the same problems (plus they usually support higher bandwidth), though at that point the cost becomes non-negligible.
  - Tade0 7y ago
    Two different devices - phones, laptops. I didn't think of using an audio interface, since mine was, ahem, "consumer grade". Also I didn't have a second one to confirm that both have a good, steady sample rate.
    - yummypaint 7y ago
      Some amount of relative drift in inevitable when the sources are independent, but yeah this suggests that the precision is only on the order of 1/48k. I cant imagine the hardware oscillator being that imprecise; crystals and mems are both better than 1/1M. I wonder if it's somehow software related. Ive seen some mysterious stuff with built in audio like variable input latency. if the output latency fluctuated similarly it might effectively introduce a low frequency modulation.

Tade0 7y ago

One issue with your standard phone or laptop audio output is that its clock is not overly precise. I learned this when I tried to combine the output of multiple sources generating a sawtooth wave from the same file - any two sources would sweep at around 1-2Hz. It's still usable, just not in scenarios where you have many of them.

yummypaint 7y ago
That's interesting. Were these two hardware outputs from the same audio device, or two different computers? It's true built in audio on most mobos is notoriously bad, and most musicians and podcasters use an external audio interface. I would imagine those don't suffer the same problems (plus they usually support higher bandwidth), though at that point the cost becomes non-negligible.
- Tade0 7y ago
  Two different devices - phones, laptops. I didn't think of using an audio interface, since mine was, ahem, "consumer grade". Also I didn't have a second one to confirm that both have a good, steady sample rate.
  - yummypaint 7y ago
    Some amount of relative drift in inevitable when the sources are independent, but yeah this suggests that the precision is only on the order of 1/48k. I cant imagine the hardware oscillator being that imprecise; crystals and mems are both better than 1/1M. I wonder if it's somehow software related. Ive seen some mysterious stuff with built in audio like variable input latency. if the output latency fluctuated similarly it might effectively introduce a low frequency modulation.