[sdiy] Buchla 266 fluctuating voltages

[Magnus Danielson]

From: harrybissell <harrybissell at prodigy.net>
Subject: Re: [sdiy] Buchla 266 fluctuating voltages
Date: Mon, 07 Jun 2004 18:32:14 -0400
Message-ID: <40C4ECEE.46820223 at prodigy.net>

Hi Harry,

> In a low to medium end synth (monopoly) you might understand this... but
> early run Prophet V rev 3.2 used this chip as well...
> 
> hel LOOO.... what were you thinking ???

Oh, neat way to solve that ugly noise problem with trimming and all that in a
simple chip and fix components... which is a good idea but a hell of a mistake
since these chips where a little too short in cycle. An MM5437 is better, with
23 taps instead of 17 the noise cycle-time is 8388607 clock-cycles which is
much better. Then again, with a pair of 4006 and a 4070 you have a much much
better noise source on your hands, and you do like that, don't you?

But then, they didn't have the Synth-DIY email list to check these things on
back then, did they? No, where are standing on other people's shoulders here.
They made the original misstakes we are still learning from. If you want the
MM5837 noise problems, you don't have to haunt the world for the chip but can
do it with a 4006, a spare XOR gate and a spare D-flip-flop.

Cheers,
Magnus - contributing to the noise

> H^) harry
> 
> john mahoney wrote:
> 
> > Hiya, kids! I was on vacation for a week, in Toronto with the Missus. So,
> > there goes the neighborhood again. ;-)
> >
> > Here is a web page with 2 audio samples of the MM5837:
> > http://www.ciphersbyritter.com/NOISE/NOISRC.HTM
> > Listen to the long sample and the looping should be obvious.
> >
> > This is a textbook case of something that measures well but sounds like
> > crap! Look at the graph -- it shows a beautifully balanced frequency
> > spectrum. As Harry wrote, the chip is useful for some things but it's lousy
> > as a noise source for a synth.
> >
> > The Korg Mono/Poly originally used the MM5837, but later models had analog
> > noise sources.
> > --
> > john
> >
> > ----- Original Message -----
> > From: "harrybissell" <harrybissell at prodigy.net>
> > To: <music.maker at gte.net>
> > Cc: <synth-diy at dropmix.xs4all.nl>
> > Sent: Sunday, May 30, 2004 5:40 PM
> > Subject: Re: [sdiy] Buchla 266 fluctuating voltages
> >
> > > 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
> > >
>