2OPFM is a digital 2-operator FM voice in 6HP.
It features 2 sine wave oscillators and a decay envelope to control their amplitudes. Perfect for growling percussion and plucky melodies.
: The length of the internal decay envelope. The associated jack is an offset to the slider.
FM: The amount of FM modulation of the carrier. The associated CV input is an offset to the slider.
KHz: The base frequency of the carrier oscillator. The associated CV input is an offset to the pot.
RATIO: The ratio of modulator frequency to carrier frequency.
OP1: The main output.
TRIG: A rising edge triggers the built in decay envelope. This envelope modulates the amplitude of the carrier, as well as the modulator (at a slightly faster rate) Incoming triggers are ignored when the envelope is active, thus allowing for frequency division based on the decay slider.
While the look of 2OPFM has changed, this demo video from version 1 modules still is a great intro to its features. The main addition here is voltage control of the internal envelope :)
1: -12V is unmarked on the power header on some runs (who would do such a thing?!) The red stripe on your power cable should go DOWN. -12V is DOWN.
2: The KHz input does not have a 1V/oct response, but more like a 0.5V/oct response. This is on purpose, to allow for the big tasty range of timbres that makes 2OPFM a very flexible tonal source. If you want it to play in tune, you can feed a 1V/oct signal through an attenuator, set to approximately 50%, and tune it up.