I believe self-oscillation is where the resonance is set so high that it excites itself (almost by feedback) and creates a new tone.
Easily done. Use a low-pass filter, lower the cutoff frequency to about half, press a key on the keyboard and then slowly turn up the resonance until it distorts and creates a new tone several octaves higher. That is self-oscillation (in the digital world).
I think the difference between self-oscillation in digital and analogue is that in analogue you don't have to hold down a key. I think the reason this is is because the VCA stage doesn't fully gate out the oscillator signal OR that background residual noise is apparent, and it leaks through to the filter stage. Even though you cannot usually hear the noise or signal because they're so low, if you ramped up the resonance to full this very low signal entering the filter is amplified exponentially and creates the tone. You wont get this in digital as the VCA gating stage fully shuts off the oscillator signal away from the filter, so no signal is getting to the filter (unless you hold down a key).
In both analogue and digital self-oscillation you can then use the filter cutoff knob to pitch up/down the new tone.
A tip for self-oscillating filters is to therefore modulate the filter cutoff using key-follow. This way you can change the tone of the self-oscillation depending on what key you press. Effectively giving you a third oscillator (albeit a sine wave).
PS > And another thing! Will the Ti|3 have user customisable/importable wavetables?
A ribbon-controller or XY-Pad might be nice, too, please! Thanks!