urlwolf wrote:The 'why do we need more than one osc' is also an interesting question.
I guess a single one, but capable of producing a shitload of waveforms, is easier to learn than the complex interactions between 2, or 3, or 4 oscs... even if the waveforms are simpler?
It might be easier to learn, but that's not sufficient to only utilise single oscillators, IMO. As DocAtlas says, there are synthesis methods that rely on interactions between different oscillators, eg FM, sync, ring modulation, plus you have the ability to stack multiple sources at different frequency intervals. The results of these are not necessarily reproducible in a single oscillator; they can introduce enharmonics and dynamic timbral changes that can, at best, only be approximated with a single oscillator, and at worst, cant be done at all.
If you had two oscillators, and the second was totally limited so that it could only ever be set such that its base frequency was an integer multiple of the first oscillator, and its output amplitude also only had a specific number of possible options, then that could
be replaced by a single oscillator with more waveshapes. Except to do just that, you'd need to provide many more waveshapes.
In fact if you had X waveforms in oscillator 1, you'd have to provide
X * (number of waveforms of oscillator 2) * (number of frequency options for oscillator 2) * (number of amplitude options for oscillator 2)
However if oscillator 2 has full control over its frequency and/or amplitude, then you lose any possibility of replicating that exactly from one oscillator.
Now, its entirely likely that not every oscillator combination sounds different enough from others to necessitate a unique option in your single oscillator. But even so, the number of possibilities is vast. Vaster than makes a single oscillator the 'easier' option.
And that's all before
you think about oscillator-level interactions like FM etc.