Modified Yamaha DX-100 Mini FM Synthesizer

YouTube via rolandsh1000
"The DX-100 is a fun, little, fully-programmable FM synthesizer. It's probably most famous as the synth that Roger Troutman of Zapp used for a lot of his talkboxing (he originally used a minimoog). If you search Youtube, you'll find a lot of videos that demo the talkbox capabilities of the DX-100.

This modification isn't a talkbox, but enables a capability that used to be dedicated to the breath control input. On the big brother of the DX-100, the DX-7, you could route the mod wheel to the EG BIAS of various operators. This would allow you to selectively control the relative amplitude of a modulation operator with the mod wheel. Depending upon the algorithm you had set up and the relative frequencies of the carrier and modulation operators, this could give you filter sweeping effects similar to those found on analog synthesizers by rotating the mod wheel.

On the DX-100, the mod wheel can only apply relative amount of LFO to various operators. Only the breath control input can do EG BIAS!?! I thought that sucked, so I changed it. (I actually play with windcontrollers and I think breath control is amazingly expressive for synthesizers, but sometimes you just want to use your hands.)

So, on this DX-100, I added a switch that can route the voltage on the mod wheel to either the mod wheel analog input of the main microprocessor (stock performance) OR the signal from the breath controller jack of the DX-100. This mod I think is acceptable, because (1) I'll bet 99% of the breath control jacks on the existing DX-100's out there have never been used; (2) most people playing with the DX-100 are probably using their mouth to talkbox anyway.

Ignore my lame playing in this video - it's just a demo of the capability."