Moog Music Forum

After 23 + years this mod makes that useless FM switch taking up valuable front panel real state useful. The stock Voyager (yours) FM switch brings a new type of FM.; Linear? Exponential? No... it's Bilevel FM - on or off. And it sounds like CRAP! No control over the VCO3 modulator which is half the FM equation. WTF? Of course you can achieve FM through one or both of the mod buses which sounds great, but why should you have to?

This mod duplicates either mod bus driver circuit with a few modifications of its own. It uses the VCO3 level knob/pot to control the amount of modulation. And unlike the original, pot mapping can be used to bring in FM via after touch, velocity etc. After several failed attempts using less parts it's simple, and no drilling into your precious trophy synth front panel.

Happy to share this circuit since it's really Moog's circuit duplicated and repurposed:
No caveats or warning from me. Btw if you break you synth I charge a minimum of $5000 to repair. But seriously, happy to answer any questions. If there's interest I'll put together a short video demo.

I already do this using the pedal mod buss. Variable mod depth, variable shaper, shaper source all do the same as your mod. What's the difference?

The Voyager is no Yamaha FM synth - very rudimentary FM algorithm, and the mod depth drifts with temperature and isn't calibrated or compensated. Mod depth is crucial for chromatic FM timbres..