Calibrating pitch CV using DC Coupled interfaces
  • I am hoping in this thread we can compare and consolidate methodology regarding incoming and outgoing cv with interfaces like the ES-8. I would like to figure out how to use audulus for buffered cv distribution currently and am finding some difficulty in figuring out how to properly calibrate the outputs.
  • I made a diagnostic patch where I just run the same cv in and out of Audulus. Not sure how to translate the differential I observed though.
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  • Not sure what you're doing here, but it seems like you'd be getting interference from the noise floor that would be amplified as they are chained together?
  • I'm just trying to figure out a constant that I can use to fix the scaling to the rest of the system. The ratio and difference between the incoming cv and what pops out the other side seems to increase as the voltage increases.
  • I'm sweeping an LFO across an 8 volt range and then bringing it back into audulus and measuring the voltage lost.
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    You can see the difference is greater the more voltage is comes in. The ratio varies as well.
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  • OK, so I went over to a friends house to get some accurate measurements. I needed to multiply incoming VPO signals by 1.05 to get correct octave scaling compared to the original. I am curious if anyone else has used external quantized sequencers or controllers for controlling the pitch of oscillators in audulus.
  • Ahhh I just posted about this in a different thread. Thanks for starting this thread. I'm eagerly awaiting solutions from folks smarter than myself!


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  • @midilifestyle I made a patch that should help you out.
    callibrating VPO with the ES-8.audulus
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  • I'll try to look at this later, I haven't had much time to play recently, but I got my ES-8 + ES-3 + ES-6 setup working, and I'm eager to nail down any translation that needs to be done as well. I did VPO out from the ES-8 and was very impressed by the evenness across channels.
  • @midilifestyle Can you post more about any problems you're having?
  • I made a stab at a calibration method. It doesn't technically require any other equipment, but a multimeter wouldn't hurt.

    I've expanded my ES-8 with an ES-3 and an ES-6, so the test includes them, but it shouldn't matter if you don't have them, those inputs and outputs will just be inactive.

    Test instructions are written in the patch. By the end I realized maybe I should have started with calibrating the outputs, but I think if anybody uses this patch they'll know enough to be able to improve their technique as needed by the end.
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  • @RobertSyrett

    Just checked out your patch, that tune oscillator by ear trick is a nice one, very expedient! I wouldn't have thought to suggest that, but it's actually a great idea.
  • I can already see that I left off the instruction to iterate over all the inputs. If that patch turns out to be useful for anybody, feel free to adjust it as needed, increment the version number, and add your name as a contributor.

    Once you tune a patch like this for your hardware, it should remain essentially the same for all time until you switch out your hardware. So you can make unique ADC and DAC objects for your system and hopefully forget about calibration after that.
  • >unique ADC and DAC objects for your system and hopefully forget about calibration after that.

    That is also a really good idea. I was fortunate enough to have a precise voltage come out from a calibrated cv sequencer, but I should buy a volt meter, that would obviously be super handy.
  • @biminiroad was this the thread you were thinking of?
  • @RobertSyrett - yes thank you! I couldn't find it for the life of me