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roglok
Joined: Aug 28, 2010 Posts: 202 Location: uptown
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Posted: Mon Jan 02, 2012 10:59 am Post subject:
Filter White Noise to get Pink Noise |
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Hi all,
After lurking around for years I finally got around to writing my first post - and of course it's a question
Although I'm no electronics expert, I have started to build a +/-12V modular synth and already finished a few modules. I am planning to build Ken Stone's Real Ring Modulator and want to add a really simple noise source to fill up the remaining panel space.
Ray Wilson's simple transistor based circuit caught my eye, but I would like to add an additional noise colour (preferably pink). How complex is it to derive pink from white noise? I have considered a simple RC low pass filter to create brown noise, too...
Here's the original schematic:
Any suggestions and, if possible, schematics are appreciated! |
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roglok
Joined: Aug 28, 2010 Posts: 202 Location: uptown
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Posted: Mon Jan 02, 2012 1:22 pm Post subject:
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I found something. According to this article, pink noise is produced by applying a -3dB filter to a white noise source:
http://www.decodesystems.com/pink-noise.html
Would it work to tap pin 7 of the op-amp in Ray's schematics and simply add this circuit?
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
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Posted: Mon Jan 02, 2012 1:57 pm Post subject:
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roglok wrote: | Would it work to tap pin 7 of the op-amp in Ray's schematics and simply add this circuit? |
It should, yes. _________________ Jan
also .. could someone please turn down the thermostat a bit.
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Captain Biscuits
Joined: Jun 11, 2010 Posts: 116 Location: Northampton, UK
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Posted: Mon Jan 02, 2012 2:51 pm Post subject:
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The schematic for Ray's Noise Cornucopia is probably worth a look. It uses pretty much the same noise source and then uses that noise (the output of pin 7 as you say) to create several different noises. He describes his Low Pass White Noise as "pinkish" so it might depend on just how pink you want your noise to be |
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roglok
Joined: Aug 28, 2010 Posts: 202 Location: uptown
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Posted: Mon Jan 02, 2012 3:04 pm Post subject:
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Thanks guys!
Quote: | it might depend on just how pink you want your noise to be |
Pinkish sounds alright to me Although it requires another IC, I'll probably go for the Noise Cornucopia filter since it throws in some extra high pass noise.. |
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fluxmonkey
Joined: Jun 24, 2005 Posts: 708 Location: cleve
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Posted: Tue Jan 03, 2012 2:41 pm Post subject:
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noise cornucopia is my fave analog noise source, well worth the build. but if you want simpler, there's an even older MFOS design buried in The Cave:
i've built it, i like it. home-etchable PCB layout is there, too _________________ www.fluxmonkey.com |
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roglok
Joined: Aug 28, 2010 Posts: 202 Location: uptown
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Posted: Tue Jan 03, 2012 4:33 pm Post subject:
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ah, now i see... the filter network should be in the feedback path of the amp.
anyway, i have already created a stripboard design for the first part of noise cornucopia (white, lp + hp noise), so i'll probably stick with that. the analog noise is planned as an addition to the cgs digital noise generator, which already features random gates, so the only thing a full build of noise cornucopia would add is grainy noise. |
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