Plaits: Tuning does not match physical module

[cschol]

The tuning of the Macro Oscillator 2 module is about 4 semitones sharp from the physical Plaits module when the Frequency knob is set to exactly 12:00.

Here is the current implementation:

Playing around with the values, here is an updated implementation with the following line (Plaits.cpp, l.145):

// Original: patch.note = 60.f + pitch * 12.f;
patch.note = 56.25f + pitch * 12.f;

I haven't looked at the code enough to understand the math, but with 56.25 the tunings match and there is almost zero drift between the two oscillators.

Now, it may as well be the physical module that is out of tune, but I figured I'd mention it.

Update:

Here is a test with the physical module at max. frequency and Macro Oscillator 2 at the original 60.0f value:

That looks correct at the high end. With 56.25f the high end is actually 4 semitones flat compared to the physical module. I think it is just a matter of linearity across the pot range that is different in the physical Plaits.

Let me know if you want me to look into this further.

[AndrewBelt]

What's the approximate angle difference between knobs? Matching knob angles exactly isn't necessary.

[cschol]

This is a picture of the physical Plaits at 12:00 and the Macro Oscillator 2 matching the frequency. You can see the approximate angle difference from noon position in the picture:

[AndrewBelt]

If I recall, it was done this way so that the default 12 o'clock pitch follows the pitch standard at https://vcvrack.com/manual/VoltageStandards.html.

[cschol]

Sounds good. Thanks.