CV In Max/Min Voltage Inoperative

Polyphonic Analog Synthesizer
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devnull
Posts: 24
Joined: Sat Dec 19, 2020 1:00 pm

CV In Max/Min Voltage Inoperative

Post by devnull » Sat Dec 19, 2020 5:14 pm

Settings>CV Inputs has Max/Min Voltage on CV Inputs. The values appear to do nothing on Exp In 1 and I assume other CVs as well. The manual says that you can set the range , and that making Max < Min would invert the setting value transmitted.

I'm using a Moog EP-3 pedal in EXP 1 input. The EXP In 1 menu shows the voltage sweeping from about 0.070V to about 4.909V with the pedal knob fully clockwise.

When I use EXP1 as a modulation source, it behaves as if 0V would be 0% and 5V would be 100% (i.e. it is unipolar). Changing the values of Max Voltage In and Min Voltage In has no effect on the voltages read on the display or the behavior of the modulated destination.

Setup:
INIT Patch
Modulation Matrix:
Source: Exp1 2.19%, Controller: Mod Wheel-100%, Transform: - Destination: All OSC-Patch LFO 1 AMT

a) Setting the Mod Wheel to full off - C3 note has no wavering.
b) Setting the pedal full off and Mod Wheel full on - the note wavers a little.
c) Setting the pedal full on and Mod Wheel full on - the note wavers intensely.

So the pedal at full off does not result in a 0% source input which is not surprising given the input is not 0V.

I would say the CV IN Min/Max Voltage should work as follows:

Set CV In Min to the minimum voltage your pedal generates or a little higher.
Set CV In Max to the maximum voltage your pedal generates or a little lower.
This should result in you getting full range of the pedal producing the effect of a modulation input change from 0% (pedal full off) to +100% (pedal full on). Reverse Min and Max values should get you a modulation input change from 0% (pedal full off) to -100% (pedal full on).

Specifically the Modulation Source value from a CV input should be calculated as:
Vin = Voltage of CV Input
Vin = Min(Vmax, Vin)
Vin = Max(Vmin, Vin)
Modulation Value(%) = (Vin - Vmin) / (Vmax-Vmin)

This would be a unipolar value in the range of 0 to 100% (Vmax > Vmin) or 0 to -100% (Vmax < Vmin).

As a workaround, I've used:

Exp 1: 8% / Controller: Constant 2% / Transform: Diode (S-C) / Destination: Pitch LFO 1 Mod

But then I need to burn a variable if I need an actually controller or transform.

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