[sdiy] Buchla 266 fluctuating voltages

[harrybissell]

Of course the 5837  (the only known chip to SUCK MORE than a bbd...) is the
perfect example of a too-short shift register with a too-low clock rate.

For its intended purpose, an audio noise source for room equalizing instruments...
the
warts will really not matter, its 'good enough' for 1/3 octave, yes ???

As a synthesizer noise source, it, well... sucks :^P

H^) harry

Scott Gravenhorst wrote:

> James Patchell <patchell at cox.net> wrote:
> >At 01:38 AM 5/30/2004 -0700, Scott Stites wrote:
> >
> >         The 5837 is not at all subtle, if you listen directly to its
> >output, you can plainly hear it repeat about every one or two seconds.  And
> >I have a tin ear, I guess you could say, because, in general, I can not
> >tell if audio is being processed in an brand x or y module....they pretty
> >much all sound the same to be...more of less.
> >
> >         Another alternative, if you need to have pseudo random noise, is
> >to make your own from some HC164 shift registers and a quad xor gate.  32
> >bit long sequences sound pretty white....and the repeat rate is hours....
>
> This is very true.  Someone here, maybe Magnus, pointed out that the spectrum
> of LFSR generated noise is a series of lumps and that the more bits you use
> (with maximal length taps) the more lumps you get and the faster you clock the
> shift register, the closer together they are.  So as you increase the number
> of bits and increase the clock, you simulate a continuous spectrum more closely.
>
> Whoever posted this, please do correct me if I'm inaccurate about this.
>
> I have a chart at http://home1.gte.net/res0658s/electronics/LFSRtaps.html that
> shows maximal tap arrangements for up to and including 168 bits.  I have found
> no data source that goes higher than this.
>
> What I would find interesting is at what number of bits can people no longer
> tell the difference between the noise quality of one LFSR and x bits more.
> Eg. is it possible to tell the difference between a 32 bit and a 64 bit LFSR
> clocked at the same rate?  Can we safely say that 64 is ridiculous?  I've
> built these up to 24 bits and even that sounds very white to my ears (not sure
> what metal my ears are made of...).
>
> >
> >
> >>I didn't use the 5837 - it was a tad too unobtainium for me, and I was
> >>a-feared it would come out sounding cyclical.  I've been dying to find out -
> >>can you discern a 'heartbeat' using the chip?
> >>
> >>Cheers,
> >>Scott
> >
> >         -Jim
> >***************************************************************
> >http://www.oldcrows.net/~patchell
> >
> >***************************************************************
> >
> >
>
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