Buchla Card 10

Card 10 contains the Preamplifier and LPG-1. Vactrols VT1 and VT2 needs to be matched. In electro-music forum I found an other matching method where vactrols are connected in series and LDRs form a voltage divider between +V and -V. In theory the more similar vactrols are the closer to 0V the output will be. Pulse LFO worked the best and I managed to match to pairs of vactrols for Card 10 and 11. I cross-checked this to the first matching method with Card 5 and these give similar results.

Vactrol matching.