...no subject...

[scgravenhor at amerhonda.com]

On Tue, 16 Sep 1997 08:43:55 -0700, you wrote:

>The circuit in question ( ETI 4600 page 20 ) couple be expanded without
>too much problem.  The only question is that you would then be having to
>deal with as many as ten ICs with their power and real-estate
>requirements as well as the resistors and capacitors needed for the
>clock generator.  A traditional noise source just requires a few
>resistors, capacitors, a noisy transistor and one op-amp.
>
>You don't double the circuit or cross-couple it, ( there is only one
>input and it is just a fixed frequency clock signal ) you would have to
>extend the length of the PSR-SG and add more taps to the feedback
>circuit.  Easy enough to do and, if it was made long enough, it wouldn't
>suffer from periodicity problems.
>
>Still, the traditional noise sources are quick, easy, simple and
>small...
>

My approach was to use a 32 bit design (for virtually NO repeats) and
I drive it from a VCO.  The effect of this is similar somewhat to filtering,
 
but it does sound different.  I used a standard VCO circuit and added
a CMOS buffer to it's square wave output.  The VCO can then either be
set at some particular frequency (as in the fixed oscillator above) or 
can run around following a pitch CV or any other CV.  You can play noise
melodies and other special effects.  This adds a dynamic unobtainable
from the back biased transistor method.  Besides, the VCO can be used
as, well, a VCO!  I needed an extra one anyway...


-- chordman at flash.net <Synthaholic>