Currently exploring possibilities using the Befaco AC/DC module to generate CV and audio in Cycling '74’s Max. Works beautifully so far, but with one quirk: to generate control voltage, I need to bias the output (which I would expect to go 0.0 to 1.0) to approximately -0.3 to +0.7.
For example, I am using Output 1 of the AC/DC to control the Pitch Input of the 4ms Ensemble (which displays IV/Oct at the input jack). After comparing the Ensemble’s output to a reference tone generated in Max (using the saw~ object), I came up with this formula to go from MIDI notes (0-127) to CV (where ‘nn’ means note number):
(nn*0.0085) - 0.207
This formula works pretty well across MIDI note numbers 36 up to 96 (resulting in CV values from 0.099 to 0.609), but I came up with the formula by trial and error and tuning by ear. In other words, I have no idea really where this 0.207 offset comes from or if 0.0085 is as precise as it could be.
Note also that I’m not using the full range that I described above (-0.3 to +0.7). This is at least partly due to the fact that once I get beyond a certain range in either direction, it’s difficult to tune by ear.
If someone with more knowledge on this topic could clarify what’s happening here, I would be super appreciative. For anyone else using AC/DC to interface Max with modular, I hope some of the info above in useful.