v/oct tracking precision?

[XORadmin]

Preface: All outputs I’m about to describe are within a millivolt or two at their 0V and 10V extents.

I should clarify that most of the outputs where I’ve noticed larger issues can be off by up to a half semitone at some point(s) in their range. These could be off by a semitone once processed downstream by certain modules, due to their quantization of the values, and hence my mention of semitone in my previous reply.

I do have at least one CV16 output where 5V is being output as 4.985 which, as you might imagine, makes that output unusable for pitch whether quantized downstream or not.

(Switching outputs to bipolar definitely throws some off more than others and recalibration is clearly necessary after throwing any switch. Most of my bipolar measurements don’t account for that yet so I’ll have to redo them at some point. As such, this message only covers unipolar output issues.)

I could work up a more detailed spreadsheet in relation to some or all of these outputs but, with two NerdSEQs and three CV16 modules, that would be quite a job all at once. What I’ll perhaps do instead is set up that spreadsheet today but just test and fill in values as I go to use each output. The timing is relatively good as I’m currently building up a big new patch heading into the new year.

As for more detailed calibration possibilities, I would hope that even just a few more calibration points per output would be sufficient but one per volt might help balance detail against calibration simplicity. That said, perhaps this could be both more accurate and simpler still...

I imagine something roughly like the following: Manually calibrate a single output at much greater detail, at least volts, perhaps even tenths of volts. Then use that output to perform a very detailed automatic calibration of the four CV inputs. Then use those CV inputs for automatic loopback calibration of the other outputs, each at rather great detail. (Optimally with the ability to dive down and manually tweak each value in the calibration results if needed for some reason.)

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On a related thought: Is there enough horsepower in NerdSEQ and/or CV16 to turn this into a (reasonably low-order) polynomial curve-fitting problem? It’d produce a better result, and likely with far fewer values to adjust, but I would totally understand if there’s only enough horsepower for linear interpolation rather than calculation from polynomials.

I don't really think it is necessary to have any extra adjustment points as again the response of the DAC is linear by specifications. If it is not the case with you then you got most likely a hardware problem and should contact me directly. Any additional adjustment points would be a workaround only I think (thinking twice about it)

As for the bipolar vs. unipolar. The calibration is being done with the unipolar settings as these are the only ones that matter for music notes. Bipolar setup is for modulations.