Still learning about VCV Rack, thus, please bare with me. As I was reviewing several Omri’s videos, and was trying to better understand the modules, something peaked my interest.
Let me explain… I connected an oscilloscope to the output of the VCO-1 to check its harmonics. I understand that these modules are enabled initially set for middle “C” frequency (261.63, scope showing 262.2). Then, I proceeded to connect the MIDI-CV module to a separate VCO-1 to enable my Mac Bluetooth K/B to trigger the C note. While looking at the scope to both VCO-1’s I noticed the 2nd signal was jittery thus proceeded to connect an analyzer and found out that the 2nd signal (1st harmonic) had shifted by 70.3 Hz (now at 332.5 HZ). Thus, my question of Why? I’d like to understand why it shifted. Any insights would be appreciated! Thank you.
It looks like the entire pitch just shifted? If you reduce the fine control do they match? ( I assume they will). Sounds like MIDI-CV is outputting a non zero voltage? Measure its output with a volt-meter plugin?
Correct! All modules had been initialized (a couple of times to be sure). I have to shift the Freq knob to make them match. The “Fine” all the way down was not enough to compensate.
Testing here it looks you expected the computer keyboard “C” key would output the musical note “C”. It doesn’t, the Rack computer keyboard output gives the note “C” from the “Z” key.
OK, it could be some kind of bug in Rack or the bluetooth keyboard driver. (For me the MIDI-CV module outputs 0 volts by default both on Windows and Mac.)
btw, there are several decent “volt meter” modules. I usually use the NYSTHI ones. He also makes a couple of tuners that will tell you pitch directly. Like most of us, I don’t know what a lot of his modules do, but I do know what these ones do. Everyone needs a tuner or a meter every now and then. OH - I see you found a nice meter.
OK, update - I now proceeded to hit the “Z” key (Note C) and it reset the Voltmeter back to Zero (0), yet, the 1st harmonic peaks are still separated by about same amount. See pic…
All the harmonic peaks are shifted, because they are out of tune. While it’s technically correct to talk about how much each harmonic is shifted, to us normal people saying “it’s out of tune” or “the pitch moved” is simpler a conveys and little more meaning. btw, that Bogaudio analyzer is my favorite module, It’s great.
Yes, got it! After Squinky.Labs input I started messing with the Fine knob. Now back to normal, both shapes at same Freq. I guess I may have to make sure when I startup my K/B connection that I indeed have Zero volts.
Thanks to both of you for the comments, much appreciated! Will keep researching and if I find something will post here.
(For me the MIDI-CV module outputs 0 volts by default both on Windows and Mac.)
