Pardon my ignorance, but can somebody explain to me exactly what processes "Sync" and "Pulse Wave Modulation" describe--and what general effect they have on the experience of the sound, i.e. how/why you use them? Thanks for your help on this--I feel like I really should know by now...

Hi Paul,

what ignorance? When you sync two oscillators the master osci restarts the phase of the slave osci when the masters phase is zero. This means that even when the phase of the slave osci is not at zero yet it is forced to restart at phase zero. You get the typical sync sounds when you drastically change the pitch of the master osci e.g. with a pitch envelope. I like Square waves with sync a lot.
Pulse width modulation is something that is not too far away from sync. A square wave is half of it's cycle at full negative value and the other half on full positive value of it's amplitude.
So a square wave has a pulse width of 50%. When you change that ratio between the lenghts of the positive part and the negative part you're changing the pulse width of this pulse (square) wave. A square wave that has not a 50/50 pulse ratio is called (wopp!) pulse wave. Modulating this pulse ratio is called PWM. Try to do it with an LFO which gives some kind of an illusion of more than one osci.

I suggest that you might record such sounds and have a look at both cases in a waveform view of a sample editor or in the audio editor of your audio sequencer and you can see these things very clearely. Hope that helped.

PWM is one of my favorite way to make cool sounds, mostly because I got an analog sysnth at home that only has one oscilator a lfo that you can use for PWM and filters ect. its simple put sounds so fat.

One of the standard ways to get a nice blurry string sound in something like a Pro52 is to detune the two oscillators and to apply PWM to both. This really fattens the sound and gets it away from a static organ type sound.