Need only 1 CV out to modulate a Moog MF-101, possible?

#1

Hi, this is my first post and I'm from Argentina, so excuse me for my bad grammar.
I'm loving my Axoloty, it's so much more than I expected and having some experience with electronics the patchbay is really interesting to me.
My first project using outside components would be to integrate a Moogerfooger MF-101 Low Pass Filter to any patch.
My intention is to start with a patch like this: Midi IN -> VCO -> Mixer -> Audio Out L module to MF-101 INPUT -> MF-101 Output to Audio In L module -> VCA -> Audio Out R module.
One ADSR module will be controlling the VCA gain and another ADSR module would have to drive the MF-101 Cutoff CV Input so I can modulate the external VCF just like any module of the Axoloti.

So the question is: where should I patch the ADSR out to and which port of the axoloti PCB should be the CV out driving the VCF cutoff mod input?

Thank you all for your time and patience, I will document and post every step of the process when it's working.
Augusto

#2

You can use GPIO PA4 or PA5 for that. Note that this will output a voltage between 0 and 3.3V. Don't know if this will be enough to modulate the Moog filter. You may need an extra circuit to do voltage conversion.

#3

WOW! Thank you very much janvantomme!!! The MF-101 is 0-5V, but I'm never going to use the complete range of modulation with an envelope generator, so I think this will work fine.
Thanks again for the screen capture, you make it very easy for me. I appreciate your effort :smiley:

#4

@janvantomme in that scenario I am assuming the value out equates to 0-64? Any way to do this so simply with a LFO and get the full -64 to +64?

#5

Value out will always be in the 0-64 range mapped to 0-3.3V, as the Axoloti can't output negative voltages.

Most LFO objects also output 0-64, the only one who does -64 to +64 is the sinewave LFO. But you can easily use the conv/bipolar2unipolar object to convert something from -64 to +64 to a range of 0-64.

#6

Great information, thank you!