[sdiy] LFSR digital noise source

ColinMuirDorward colindorward at gmail.com
Mon Nov 11 00:31:42 CET 2019

Wow, and I thought noise was just to make hihats!
Only kidding, but what a depth of answers, I'm glad I asked. Lots of
applications I never thought of before.

On Sun, Nov 10, 2019 at 7:47 PM <rsdio at audiobanshee.com> wrote:

> One advantage of a CPU-based noise source is that it can be combined with
> a DAC for CV modulation.
> Digital noise chips typically use the single-bit output for audio. Thus,
> it’s like a square wave with random period but basically constant
> amplitude. The conversion to analog can vary the amplitude if there is a
> PWM effect (via capacitance).
> With a CPU and a long enough register, it’s possible to gather 8 or more
> bits into a word to feed a DAC. Just be sure to shift in 8 new bits for
> each 8-bit conversion, otherwise the values aren’t entirely independent of
> each other. You can easily extend this to 16-bit or even a 24-bit DAC,
> although using a 24-bit DAC for CV is quite dubious. LFSR hardware should
> be able to run at 8x, 16x, or 24x the sample rate with no problems.
> Of course, with counter logic and a stand-alone DAC chip, it’s possible to
> do this in pure hardware. So, I guess the CPU doesn’t really have a unique
> advantage here.
> Brian
> On Nov 10, 2019, at 4:32 PM, bbob <fluxmonk at gmail.com> wrote:
> > sometimes for the sound directly (crunchy/brittle), but more often
> slowing the clock and then using it as a modulation source
> >
> > On Sun, Nov 10, 2019 at 7:11 PM ColinMuirDorward <colindorward at gmail.com>
> wrote:
> >> Hope this isn't too off topic, but I've often wondered when/why you'd
> choose a digital noise source over an analog one. It is simply for the
> acoustic flavour?
> >
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