[sdiy] Modulation question

[Ian Fritz]

At 08:09 AM 11/9/2007, Tom Wiltshire wrote:
>Hi All,
>
>I've been thinking about modulation sources on synths. Basically you
>get envelope generators of some sort, and LFOs.
>
>One of these generates aperiodic changes, and the other produces
>periodic changes. I had thought that that pretty much covers it,
>since every kind of change is either periodic or aperiodic.
>
>However, there is something else which I'd been missing which is that
>some changes are predictable and some are not. Envelope generators
>are a source of predicable aperiodic changes, and LFOs are obviously
>predictable, since they're periodic.
>
>Consequently, I'm currently working on an unpredictable aperiodic
>modulation source, done digitally. The basis is a 64-bit LFSR noise
>source. The source (I'm calling it a random modulation generator,
>RMG) can either interpolate linearly between noise values to produce
>random slopes, or interpolate quadratically to produce random curves.
>I've been having an absolute bitch getting sufficient accuracy out of
>16-bits to allow really slow modulation waves.
>
>That's the background, but what I'd like to know is whether there are
>other important types of modulation that I'm still missing.

Yes, you are missing modulation from chaos generators.  Chaotic signals are 
deterministic but irregular.  The amount of irregularity can be varied by 
changing the parameters of the system.  I've been working on this for a 
couple of years, and I have more information on my website.

Ian

http://home.comcast.net/~ijfritz/ch_over.htm
http://home.comcast.net/~ijfritz/ch_close.htm
http://home.comcast.net/~ijfritz/ch_circ.htm