Yeah, drone machine was the initial idea. I'll keep going at it when I get some time (which hasn't been much of late, hence the delayed release of this demo)
I do think I'll need to reduce the scope from the original idea. Probably just one LFO and one Envelope per voice. The important thing is to keep the processing as fast as possible. I have done the envelopes already they're just not in this demo.
The tricky bit with the synth engine has been to code the LFOs etc in a way that they can be totally scaled/modified on-the-fly. A simple LFO can be done very quickly but if you need to add scalability then processing gets a little more complex and consequently a little slower. The slower the processing the less intense the FM effect etc. It's an interesting little balancing trick 
One of the odd/cool things is that the synth engine just processes the shit out of as much as it can so you'll get odd artefacts when processing gets shared between two (or more tasks e.g. a LFO and an envelope together won't be able to FM the pitch as fast compared to if you only had the LFO going). Ideally it wouldn't do this but it will add a bit of randomness/unpredictability into the mix which I kind of like.
I'll work towards making a proper demo with all 4 voices. I need to think more about a possible step sequencer so that will have to wait for the time being.
