MOTM

I was thinking about this idea a bit over the past couple of days (in between 
reading speed typist Hendry's several different perfect solutions to his 
Magic Bus concept!) and I thought how I might like a module to behave in a 
similar regard to what motivated my previous question (below).

I'd like to see a VCO that also had a chaotic input. What I mean is with 0V 
at the CHAOS input it would track like a good VCO, but as the voltage 
increased at that same input, the output would be increasingly indeterminate 
(either chaotic or nonlinear in some other way).

I use a similar approach to my guitar playing when playing rather loud to 
produce two very different types of feedback. One kind is the more common 
controlled style (a harmonic style developed by Buddy Guy, Townshend, 
Hendrix, etc.) which involves inducing the string (or strings) to resonate 
via the speaker's output. The other type involves holding the guitar pickups 
about 12" from the speaker (again at very high SPL) which causes the pickup 
itself to resonate (I think most PUs have a resonant frequency of around 
8KHz), producing a squealing sound -- BTW, I've come to believe this is 
destructive to the guitar's PUs (not to mention ears), so do this at your own 
risk. 

It is easy to use modules to mimic either type of behavior (harmonic or 
chaotic) but it requires a number of modules which are usually better suited 
for other purposes. So yesterday I tried a bit of an experiment to induce 
chaotic behavior with a small number of MOTM modules. 

About 18 months ago someone posted to the DIY list that he'd done some work 
on chaotic (Chua) oscillators, and mentioned that chaotic behavior could be 
coaxed from a standard VCO by plugging an output into an FM input of the same 
oscillator, though it may need to be amplified first. So I took an output 
from a MOTM 300 and routed it through a MOTM 110 VCA and then back into the 
300 FM input. I used the pressure output from my Serge Touch Keyboard to 
control the gain of the VCA (the GAIN knob on the 110 was at full). 

While I found this patch did a little of what I'd expected, I needed to add 
another 300 as a basic VCO (for tracking the keyboard), and have the chaos 
VCO sync to the second VCO, since it didn't seem to track very well. I also 
thought that the effect might be more pronounced if my CV source went from 
0-10V (the Serge only goes to 5V). If the effect had been more pronounced, I 
had intended to try using a VCF in the feedback loop, but that would be 
premature at this time. I'm wondering if anyone has any experience with 
patches like this, or if anyone else is interested in this type of behavior 
from what would otherwise be a standard module? 

John (Ziegfried) Barlow

In a message dated 11/5/99 9:24:59 PM, synth1@... writes:

>No. My feeling was you do not "play" the chaos module. Rather, you
>place limits on the probability of the possible output.

>>From: JWBarlow@...

>>In a message dated 11/5/99 4:54:44 PM, synth1@... writes:

>>>That is what I said: each PIC has a CV input. The CV input determines
>>>just how chaotic it behaves,

>>Stupid question: would this have something like a 1v/oct input? The reason
>I
>>ask is if one is indexing through a number of "standard" musical phrases
>(or
>>referents -- very postmodern!), and they are all in one key (say C), and
>the
>>only means of transposing is to increase the voltage at the chaos input,
>then
>>it seems that one would almost never perceive these phrases since they
>would
>>often not be in the same key.

>>And this comes from a (never in tune) guitar payer!
>>JB