Chris Meyer (Learning Modular) shared this video look at active vs. passive multiple in modular synthesis.
There is a lot of debate and confusion among modular synth users about whether or not you need an active, buffered multiple to control multiple VCOs accurately in a modular system.
The answer is “it depends” – on the buffering and output impedance of the module sending the control voltage, and the input impedance of the modules being controlled. Some combinations work fine with a passive multiple. Some most certainly do not, going out of tune within +/- 1 octave.
This video – excerpted from a longer one in my “Learning Modular Synthesis: Moog Mother-32” course – demonstrates a case where passive multiples do not work. As a result, just to be safe, I keep a few good buffered multiples – like the Intellijel BM or Malekko Performance Mult – in my system, just to be safe. (I also have the Xaoc Dvices Warna II and AJH Synth V-Scale arriving soon.)