2OPFM

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. 

Power Requirements:

+12V: 45mA

-12V: -5mA 

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 :) 

Notes:

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.