[sdiy] preferred noise source circuits

Tom Bugs admin at bugbrand.co.uk
Fri Jun 26 16:34:44 CEST 2009 

A similar project is the Syn-bal -- I did a search and found this thread 
at EM (includes project docs)
http://electro-music.com/forum/post-143488.html
Interestingly this has a 'tune' control which is actually power 
starvation for the 40106 chip (retunes all the oscillators - in a weirdy 
way too)
My Weevils are actually based around this sort of thing... (shows how 
simple they are!)
All best,
Tom / BugBrand

rdrake wrote:
> 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.
>>>>>
>>>>>           
>>>> _______________________________________________
>>>>         
>>>> Synth-diy mailing list
>>>> Synth-diy at dropmix.xs4all.nl
>>>>
>>>>         
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>
>>     
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at dropmix.xs4all.nl
>>>
>>>       
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>     
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com 
> Version: 8.5.375 / Virus Database: 270.12.92/2203 - Release Date: 06/26/09 05:53:00
>
>

More information about the Synth-diy mailing list