DIY Digital Synth

[Tim Ressel]

I also have concidered a digital synth-on-a-chip a la DSP. It is feasable to a
point. There are limitations such as having limited processor cycles per sample,
having to handle patching, and of course EVERYTHING will sound DIGITAL.

I've come up with solutions to some of these. CSound has certainly shown how to
handle control vs signal. These days DSPs are really fast AND bussable for
parallel processing. 

For those who have a ADSP-2181 EZ-Kit Lite, these folks have done some
interesting work:

http://www.gweep.net/~shifty/ezkit/

I plan on adding this to my project list; it is project #3287765/9-P   :0)


Tim Ressel--Compliance Engineer
Hewlett-Packard
Verifone Division
3755 Atherton Rd.
Rocklin, Cal
916-630-2541  
timothy_ressel at hp.com



-----Original Message-----
From: jbv [mailto:jbv.silences at wanadoo.fr]
Sent: Tuesday, September 19, 2000 12:12 PM
To: synth-diy at node12b53.a2000.nl
Subject: Re: DIY Digital Synth


>
>
>     Anything is posible.  Actually the best modular digital I know of is
> the
> Nord Modular.  Although, it is only modular because of "software".  A
> digital
> "hardware" synth would be much more of a challenge.  Patch cords would
> be a
> bitch :^)



What about fiber optic patch cords ?    ;-)

More seriously, I've been wondering a couple of times if a modular
"hardware" digital synth would be feasable... A modular in which
every module would be built around a DSP, or a uC of some kind...

And it appears that the main problem would be sampling frequency :
let's say everything's running at 48 KHz; should every module have
its own clock, with i/o signals fed through ADCs & DACs to make
connections between modules analog (for possible connection with
a "real" analog modular), or should the whole system be driven by
a single clock (and in that case, how should the clock signal be
distributed among modules) ?
Furthermore, I'm afraid that sampling frequency would introduce
audible delays in the signal in case of complex patches in which
a large number of modules are involved...

Last but not least, I tried to figure out what kind of modules would
benefit of being 100% digital... Apart from DVCO (currently
discussed), there's of course various forms of reverbs, delays,
waveshapers & pitch-shifters...
But I was also thinking of some typical & unique type of module
that could not be done the analog way, and I was thinking of
some statistical distribution generators (sorry, can't find any
better description), stuff that would output, when triggered,
clouds of events (ADSR, frequencies, MIDI notes, whatever)
following certain probabilistic / mathematic rules that the user
could modify / program either by tweaking pots on the front panel
or by voltage control... IRCAM MAX and PatchWork software
feature such fonctions; the idea is just to reshape them as
hardware modules...

And there's also that Cellular Automata & Genetic Algorithm
stuff I mentioned in previous posts, but I must confess that
my brainstorming on those topics didn't go very far...

jbv