[sdiy] converting white noise to pink noise

Robert Lorentz robert.lorentz at gmail.com
Tue Mar 4 17:00:56 CET 2008


Interesting that you used the 4001 and 2x4006 to do it.

I saw that when building a TR-909 circuit:
http://www.colinfraser.com/tr909/909noise.gif

I didn't actually build that circuit though because I was hoping for
something more "modern".  I was doing a lot of comparing between those
original schematics and the "modernized" 9090 ones, unfortunately the
latter have (accidentally I think) not published their noise
schematics so I couldn't tell if this original way was good or bad

I ended up using the noise generator that Jorg Schultz had
http://www.analog-synth.de/synths/tr909/bassdrum.jpg but it would have
been much better to reduce that down


Did I mention that my circuit never ended up working?  But I learned
the critical lesson that any time I build a circuit with oscillators I
will either fab a PCB, or plan a physical layout very carefully,
instead of running long noisy jumper wires all over the place :)


Thanks for everyone's thoughts on these noise IC's and am interested
to hear more..


Robert


On 3/4/08, harrybissell at wowway.com <harrybissell at wowway.com> wrote:
> The MM5837 is really just misapplied in synth applications.
> The repeatability is a boon in apps like room equalization and
> other audio measurements.
>
> Compared to most semiconductor junction noise sources, its really
> good.
>
> Just sucks for synthesizers...
>
> I don't know od another single-chip noise source, although some
> have suggested that a small PIC micro might be prorammed to perform
> this function.
>
> Magnus Danielson has a list (somewhere) of optimum LFSR
> noise sources.
>
> I have one made with three chips (4001, 2x 4006) that does not
> noticibly repeat...
>
> H^) harry
>
>
> On Tue, 4 Mar 2008 10:38:43 -0500, Robert Lorentz wrote
> > My question is, since the MM5837 is garbage white noise on a chip,
> > what is a better (preferably not obsolete) noise IC to use for this
> > and other applications?
> >
> > Robert
> >
> > On 3/4/08, harrybissell at wowway.com <harrybissell at wowway.com> wrote:
> > > LOL
> > >
> > > Make some ocean or wind sounds, listen to the little train
> > > go chu-chug-chug in the background
> > >
> > > H^) harry
> > >
> > >
> > > On Tue, 04 Mar 2008 06:19:18 -0700, Scott Gravenhorst wrote
> > > > Yes, thanks Dave.
> > > >
> > > > I like this little bit:
> > > >
> > > > "The MM5837 provides a uniform noise quality..."
> > > >
> > > > shhh-tick-shhh-tick-shhh-tick-shhh-tick-shhh-tick-shhh-tick
> > > >
> > > > I guess "uniform" also includes the precise replication of the
> > > > repeat pattern...
> > > >
> > > > John Mahoney <jmahoney at gate.net> wrote:
> > > > >At 01:47 AM 3/4/2008, Dave Manley wrote:
> > > > >
> > > > >>I put a scan of the pink noise generator from the 1976 Audio Handbook
> here:
> > > > >>
> > > > >>http://www.sonic.net/~dlmanley/PinkNatSemiAudioHandbook1976.jpg
> > > > >>
> > > > >>The -3dB/octave response is claimed to be +/- 1/4dB from 10Hz to 40kHz.
> > > > >>
> > > > >>-Dave
> > > > >
> > > > >
> > > > >Aaaargh, it's the dreaded MM5837, again! Ah, well, it's fine for
> > > > >testing purposes, it's just no good for making music.
> > > > >
> > > > >Thankfully, the pink noise filter is a separate circuit -- and it's
> > > > >totally passive, to boot. Thank you, Dave.
> > > > >
> > > > >John
> > > > >
> > > > >
> > > > >--
> > > > >No virus found in this outgoing message.
> > > > >Checked by AVG Free Edition.
> > > > >Version: 7.5.516 / Virus Database: 269.21.4/1310 - Release Date: 3/4/2008
> > > 8:35 AM
> > > > >
> > > > >
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> > > >
> > > > -- ScottG
> > > >
> > > > -----------------------------------------------------------------
> > > >
> > > > -- Scott Gravenhorst
> > > > -- GateMan-III - FPGA Based Monophonic MIDI Synthesizer with SVF
> > > > -- PolyDaWG/8 - FPGA Based 8 Voice Polyphonic MIDI Synthesizer
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> > > >
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> > > Harry Bissell & Nora Abdullah 4eva
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>
> Harry Bissell & Nora Abdullah 4eva
>
>



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