[sdiy] Mixing several noise generators

[Tom Wiltshire]

Hi all,

Most analogue polysynths that feature a noise generator use one common noise generator which is then fed to all the voices. Presumably when the voices are mixed in the mixer, the noise will add up linearly, since it is simply more copies of the same thing. By which I mean if voice A provides 1V of noise, then voices A+B will provide 2V of noise.

But let's assume we've got a synth that has a separate, independent noise generator per voice. The two noise signals will now cancel about as often as they'll reinforce. At least, that's my gut feeling, and what I'm dead sure of is that they won't reinforce *all* the time like the copies of the same noise source. So I'd expect the noise volume to not increase so much. So perhaps there are other reasons beyond the obvious cost-cutting to use one noise source only.

Does anyone know;
	how much the noise does increase if it is an unrelated source?
	any examples of instruments that use independent noise sources?

Thanks,
Tom