[sdiy] Various colors of noise.

[Michael E Caloroso]

Few people realize that the venerable Minimoog includes red noise.  But
it's a modulation source not audio.  The front panel NOISE switch
alternates between white and pink noise as an audio source, and also
between pink and red noise as a modulation source.  Red noise as a
modulation source sounds like smoothed S&H.

MC

On Tue, Mar 3, 2026 at 6:14 PM Thomas Hudson via Synth-diy <
synth-diy at synth-diy.org> wrote:

> BTW, while researching creating green noise I came across a website for a
> Mac and iOS app:
>
> The original free color noise generator on the Internet. Hear what your
> mind has been missing… <https://simplynoise.com/>
> simplynoise.com
> [image: cropped-web_sn_appicon_512-1-180x180.png]
> <https://simplynoise.com/> <https://simplynoise.com/>
>
>
> In addition to noise colors, t also has beach sounds, fireplaces, babbling
> brooks, etc.
>
> Fun little app.
>
>
> On Mar 3, 2026, at 5:56 PM, Thomas Hudson via Synth-diy <
> synth-diy at synth-diy.org> wrote:
>
> Interesting idea and article.
>
> On Mar 3, 2026, at 4:58 PM, Mike Beauchamp <list at mikebeauchamp.com> wrote:
>
> Hi Thomas,
> Maybe take all of the different noises, and feed them into an
> interpolating scanner circuit (like this one:
> https://till.com/articles/scanner/ ) and from there you could control the
> output noise colour (and anything inbetween) with the wandering CV.
>
> I wonder if the different noise colours all need to be derived from a
> single source for the crossfading to work.
>
> Mike
>
>
> On 2026-03-02 18:20, Thomas Hudson via Synth-diy wrote:
>
> I have an analog module that can generate blue, white, pink, and red
> (brownian) noise. I’m interested in how I might create a random walk using
> perhaps a sample/hold and smoothing function to produce a sort of wandering
> control voltage from each of these noise sources.
> I also was recently introduced to green noise. From Wikipedia:
> * The mid-frequency component of white noise, used in halftone
>   <https://en.wikipedia.org/wiki/Halftone>dithering
>   <https://en.wikipedia.org/wiki/Dithering>^[19]
>   <https://en.wikipedia.org/wiki/Blue_noise#cite_note-19>
> * Bounded Brownian noise
> * Vocal spectrum noise used for testing audio circuits^[20]
>   <https://en.wikipedia.org/wiki/Blue_noise#cite_note-comp.dsp_FAQ-20>
> * Joseph S. Wisniewski writes that "green noise" is marketed by
>   producers of ambient sound effects recordings as "the background
>   noise of the world". It simulates the spectra of natural settings,
>   without human-made noise. It is similar to pink noise, but has more
>   energy in the area of 500 Hz.
> Wondering how I might generate this other than using something like a
> bandpass filter tuned to 500 Hz using pink noise. I want to generate it in
> the analog realm.
> TIA,
> Thomas
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