RE: [sdiy] preferred noise source circuits

[rdrake]

the shimmer from the Cynare is more of a pitched noise source, to my ears... still recognizable as an additive collection of tones, rather than a filtered noise.  i built it w/ the variable pots on each schmidt and you can dial in a wide variety of sounds, and that worked well; i'm not sure about the other mods you mention but sounds like it could be fun.

i love Ken's digital noise circuit tho, it's a gem.  pink out as an FM to oscillators is a go-to patch for me.  i put a threeway switch to select larger timing caps on the PLL, down to 2uf i think, which gives you the random pulse thing; VC on the PLL is also a treat.    

bbob
www.fluxmonkey.com
>----- ------- Original Message ------- -----
>From: dixon at interchange.ubc.ca
>To: lists at studionebula.com,
>synth-diy at dropmix.xs4all.nl
>Sent: Fri, 26 Jun 2009 12:50:53
>
>This has been a pretty interesting thread on noise
>so far.  I'm still
>deciding what to do, although I will most likely
>use either an analog source
>(tranny with reverse-biased e-b junction) or
>something digital but
>simplistic using counters.
>
>One thing I came across lastnight which I found
>intriguing was the "shimmer"
>generator on Ken Stone's Cynare drum synthesizer:
>
>http://www.cgs.synth.net/modules/cgs47_cynare.html
>
>This is basically six schmitt trigger oscillators
>at different frequencies
>multiplied through four exclusive OR gates
>(basically, a 40106 and a 4030)
>and averaged at a divider.  I gather that he uses
>it to provide a shimmering
>sound like a cymbal.  I've simulated it and the
>output is pretty "noisy".
>One could replace the feedback resistors in the
>oscillators with pots for
>all sorts of interesting effects.  Also, if the
>oscillators were slowed
>down, this looks like an interesting source for
>random gates and triggers.
>Finally, by taking the output (which is 10Vpp) and
>dropping it 5V through an
>adder, one gets a pulse wave with pseudo-random
>+/-5V positive and negative
>pulses.  Hence, this would make a pretty cool kind
>of LFO, especially if one
>put an integrator on it to generate random
>triangles, and polarity switches
>to rectify the output in either direction (my
>triple LFO has this feature,
>and I have found it to be extremely useful).
>
>Has anyone else played with this shimmer generator?
>
>
>
>
>> From: synth-diy-bounces at dropmix.xs4all.nl
>[mailto:synth-diy-
>> bounces at dropmix.xs4all.nl] On Behalf Of Adam
>Schabtach
>> Sent: Friday, June 26, 2009 12:08 PM
>> To: 'sdiy DIY'
>> Subject: RE: [sdiy] preferred noise source
>circuits
>> 
>> It's also far simpler to generate mathematically
>correct pink noise with a
>> microprocessor (i.e. with software) than with
>analog circuitry. I learned
>> this years ago when I wrote the pink~ object for
>Cycling '74's MSP.
>> Unfortunately I don't have any references handy
>to cite, and I suppose it
>> would be a violation of their copyright for me to
>post the source code
>> here
>> (if I still have it, which I'm not sure that I
>do). Google should help the
>> curious as always, though.
>> 
>> So, I'm in agreement with Tom. You could build a
>dandy white and pink
>> noise
>> source with one microprocessor. OTOH if
>hardware's your thing and software
>> isn't, then you're welcome to use many more parts
>to create an
>> approximation
>> of the same result.
>> 
>> --Adam
>> 
>> > -----Original Message-----
>> > From: synth-diy-bounces at dropmix.xs4all.nl
>> > [mailto:synth-diy-bounces at dropmix.xs4all.nl] On
>Behalf Of Tom
>> > Wiltshire
>> > Sent: Tuesday, June 23, 2009 7:55 AM
>> > To: Amos
>> > Cc: sdiy DIY
>> > Subject: Re: [sdiy] preferred noise source
>circuits
>> >
>> > Well, if we're talking about "white" noise,
>then I mean noise
>> > that is genuinely white - i.e. has an equal
>distribution of
>> > energy across all the frequencies of interest
>(the audio band
>> > in our case). That's not really subjective at
>all. Likewise
>> > if you're generating random pulses or gates,
>then "better
>> > quality" means statistically indistinguishable
>from random.
>> > You don't want any unwanted weighting creeping
>in unless you
>> > put it there.
>> >
>> > Obviously whether white noise is the best kind
>for many
>> > synthesis purposes is a much more subjective
>issue. Perhaps a
>> > 6dB rolloff of the high end makes a better
>audio noise source
>> > since it doesn't sound so harsh. If you've got
>good quality
>> > white noise to start with, then you can choose
>what you do to
>> > it. If it's got it's own flavour already, it's
>much harder to
>> > remove that.
>> >
>> > T.
>> >
>> >
>> >
>> > On 23 Jun 2009, at 12:38, Amos wrote:
>> >
>> > > On Tue, Jun 23, 2009 at 6:09 AM, Tom
>Wiltshire
>> > <tom at electricdruid.net>
>> > > wrote:
>> > > "a digital noise source with a simple 8-pin
>DIP microprocessor that
>> > > will give you much better noise quality than
>most analogue noise
>> > > sources."
>> > >
>> > > see now, I don't mean to stir the pot, but
>"much better
>> > noise quality"
>> > > seems pretty subjective to me.  This is what
>it (ought to,
>> > > IMO) come down to when choosing your noise
>source.  What
>> > qualities do
>> > > you evaluate when determining "goodness" of
>noise?
>> > > This is more an open question for anyone who
>has an opinion on such
>> > > things.
>> > >
>> >
>> >
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