[sdiy] converting white noise to pink noise

harrybissell at wowway.com harrybissell at wowway.com
Tue Mar 4 18:02:38 CET 2008


inline...


On Tue, 4 Mar 2008 11:00:56 -0500, Robert Lorentz wrote
> Interesting that you used the 4001 and 2x4006 to do it.

I copied the circuit from some Popular Electronics circuit
of about 1970 vintage (I could tell for sure if interested...)

even MORE interesting if Roland liberated the same circuit, eh ???

> 
> 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 :)

I tried to make a very small analog noise source that could retrofit the
MM5837 but if I amplified to et the signal levels I needed, the noise
was clipped and the spectrum was awful (sounding).  So I went to the
digital source.


> 
> 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
> > > > > -- phLUTe - FPGA Based Monophonic Physical Model MIDI Synthesizer
> > > > > -- FatMan: home1.gte.net/res0658s/fatman/
> > > > > -- NonFatMan: home1.gte.net/res0658s/electronics/
> > > > > -- When the going gets tough, the tough use the command line.
> > > > >
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> > > > Harry Bissell & Nora Abdullah 4eva
> > > >
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> >
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> > Harry Bissell & Nora Abdullah 4eva
> >
> >


Harry Bissell & Nora Abdullah 4eva




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