<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">There's a similar heavily-filtered noise source ("infra-red" noise) in the Polyfusion synth schematics.<div class=""><br class=""></div><div class="">One problem with this way of generating this type of wandering modulation voltage is that the voltage level is heavily reduced on average, but adding gain to bring it back up is uncertain since the potential maxmium level isn't really decreased at all. E.g. if you add gain, it'll clip - not often, but probably sooner or later.</div><div class=""><br class=""></div><div class="">I've used cosine interpolation between random points to generate a similar waveform digitally. That avoids this issue, and has the advantage that you get some level of control over how fast the waveform changes too.</div><div class=""><br class=""></div><div class="">Tom<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 4 Mar 2026, at 04:19, Michael E Caloroso via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" class="">synth-diy@synth-diy.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">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.<div class=""><br class=""></div><div class="">MC</div></div><br class=""><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Tue, Mar 3, 2026 at 6:14 PM Thomas Hudson via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" class="">synth-diy@synth-diy.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div style="line-break:after-white-space" class="">BTW, while researching creating green noise I came across a website for a Mac and iOS app:<div class=""><br class=""></div><div class=""><div style="display:block" class=""><div style="display:inline-block" role="link" class=""><a style="border-radius:10px;font-family:-apple-system,Helvetica,Arial,sans-serif;display:block;width:300px;overflow:hidden;text-decoration:none" rel="nofollow" href="https://simplynoise.com/" dir="ltr" role="button" width="300" target="_blank" class=""><table style="table-layout:fixed;border-collapse:collapse;width:300px;background-color:rgb(13,43,150);font-family:-apple-system,Helvetica,Arial,sans-serif" cellpadding="0" cellspacing="0" border="0" width="300" class=""><tbody class=""><tr class=""><td class=""><table bgcolor="#0D2B96" cellpadding="0" cellspacing="0" width="300" style="table-layout:fixed;font-family:-apple-system,Helvetica,Arial,sans-serif;background-color:rgb(13,43,150)" class=""><tbody class=""><tr class=""><td style="padding:8px 0px" class=""><div style="max-width:100%;margin:0px 16px;overflow:hidden" class=""><div style="font-weight:500;font-size:12px;overflow:hidden;text-overflow:ellipsis;text-align:left" class=""><a rel="nofollow" href="https://simplynoise.com/" style="text-decoration:none" target="_blank" class=""><font color="#FFFFFF" style="color:rgb(255,255,255)" class="">The original free color noise generator on the Internet. Hear what your mind has been missing…</font></a></div><div style="font-weight:400;font-size:11px;overflow:hidden;text-overflow:ellipsis;text-align:left" class=""><a rel="nofollow" href="https://simplynoise.com/" style="text-decoration:none" target="_blank" class=""><font color="#FFFFFF" style="color:rgba(255,255,255,0.698)" class="">simplynoise.com</font></a></div></div></td><td style="padding:6px 12px 6px 0px" width="30" class=""><a rel="nofollow" href="https://simplynoise.com/" target="_blank" class=""><span id="cid:ii_19cb70f593fbd2bc8d21"><cropped-web_sn_appicon_512-1-180x180.png></span></a></td></tr></tbody></table></td></tr></tbody></table></a></div></div><br id="m_3538729242626118336lineBreakAtBeginningOfMessage" class=""><div class=""><br class=""></div><div class="">In addition to noise colors, t also has beach sounds, fireplaces, babbling brooks, etc.</div><div class=""><br class=""></div><div class="">Fun little app.</div><div class=""><br class=""></div><div class=""><br class=""><blockquote type="cite" class=""><div class="">On Mar 3, 2026, at 5:56 PM, Thomas Hudson via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" target="_blank" class="">synth-diy@synth-diy.org</a>> wrote:</div><br class=""><div class=""><div class="">Interesting idea and article. <br class=""><br class=""><blockquote type="cite" class="">On Mar 3, 2026, at 4:58 PM, Mike Beauchamp <<a href="mailto:list@mikebeauchamp.com" target="_blank" class="">list@mikebeauchamp.com</a>> wrote:<br class=""><br class="">Hi Thomas,<br class="">Maybe take all of the different noises, and feed them into an interpolating scanner circuit (like this one: <a href="https://till.com/articles/scanner/" target="_blank" class="">https://till.com/articles/scanner/</a> ) and from there you could control the output noise colour (and anything inbetween) with the wandering CV.<br class=""><br class="">I wonder if the different noise colours all need to be derived from a single source for the crossfading to work.<br class=""><br class="">Mike<br class=""><br class=""><br class="">On 2026-03-02 18:20, Thomas Hudson via Synth-diy wrote:<br class=""><blockquote type="cite" class="">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.<br class="">I also was recently introduced to green noise. From Wikipedia:<br class=""> * The mid-frequency component of white noise, used in halftone<br class=""> <<a href="https://en.wikipedia.org/wiki/Halftone" target="_blank" class="">https://en.wikipedia.org/wiki/Halftone</a>>dithering<br class=""> <<a href="https://en.wikipedia.org/wiki/Dithering" target="_blank" class="">https://en.wikipedia.org/wiki/Dithering</a>>^[19]<br class=""> <<a href="https://en.wikipedia.org/wiki/Blue_noise#cite_note-19" target="_blank" class="">https://en.wikipedia.org/wiki/Blue_noise#cite_note-19</a>><br class=""> * Bounded Brownian noise<br class=""> * Vocal spectrum noise used for testing audio circuits^[20]<br class=""> <<a href="https://en.wikipedia.org/wiki/Blue_noise#cite_note-comp.dsp_FAQ-20" target="_blank" class="">https://en.wikipedia.org/wiki/Blue_noise#cite_note-comp.dsp_FAQ-20</a>><br class=""> * Joseph S. Wisniewski writes that "green noise" is marketed by<br class=""> producers of ambient sound effects recordings as "the background<br class=""> noise of the world". It simulates the spectra of natural settings,<br class=""> without human-made noise. It is similar to pink noise, but has more<br class=""> energy in the area of 500 Hz.<br class="">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.<br class="">TIA,<br class="">Thomas<br class="">________________________________________________________<br class="">This is the Synth-diy mailing list<br class="">Submit email to: <a href="mailto:Synth-diy@synth-diy.org" target="_blank" class="">Synth-diy@synth-diy.org</a><br class="">View archive at: <a href="https://synth-diy.org/pipermail/synth-diy/" target="_blank" class="">https://synth-diy.org/pipermail/synth-diy/</a><br class="">Check your settings at: <a href="https://synth-diy.org/mailman/listinfo/synth-diy" target="_blank" class="">https://synth-diy.org/mailman/listinfo/synth-diy</a><br class="">Selling or trading? 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