Wiardgroup

Hello Herr Doktor,

Can you clarify something on the first sheet of Woggle mods?  

For mod 2 you've got the cathode of Vactrol VC1 connecting directly 
to +15 V.  Looking at that and the 555 control circuitry in the third 
mod,it looks like Vactrol VC2 is completely left out of the original 
Wogglebug design.  Is that correct?

The way I undersstand it, in the original design, the CV input based 
around Q1 drives both vactrols in tandem, one which controls the 
amount of the LF398s output going to the Smooth PLL, the other 
controls the 555 clock's frequency.  

BTW, thanks for submitting your mods... they look quite useful.

Also, I've wondered what kind of craziness a sync circuit on the 555 
would provide, such as the one on Rene Schmitz' VCO:

http://www.uni-bonn.de/~uzs159/vco3.html

Has anybody tried this?

Romeo

Hi Romeo
    I will do my best to answer your questions 'in line'...

--- In wiardgroup@yahoogroups.com, "vtl5c3 <rfahl@e...>" <rfahl@e...> 
> For mod 2 you've got the cathode of Vactrol VC1 connecting directly 
> to +15 V. 

correct! after this mod, Q1 drains current through ONLY VC1 and thus controls ONLY the 398's output.


> Looking at that and the 555 control circuitry in the third 
> mod,it looks like Vactrol VC2 is completely left out of the original 
> Wogglebug design.  Is that correct?

yes,
I eliminated VC2 from the design. I like the response curve of the more elaborate 555 control circuit and it freed up a Vactrol (a species that is expensive and in dwindling supply) for other evil plots.


> 
> The way I undersstand it, in the original design, the CV input based 
> around Q1 drives both vactrols in tandem, one which controls the 
> amount of the LF398s output going to the Smooth PLL, the other 
> controls the 555 clock's frequency.  
> 

quite right!'
I wanted the ability to control the two parameters you mention separately. As with all of my mods the changes were made to adapt the sound to my personal (and highly idiosyncratic (I'm told) tastes). But prompted by your questions, I should mention that these mods (1-3) DO CHANGE THE FUNCTION OF THE ORIGINAL DESIGN.

> BTW, thanks for submitting your mods... they look quite useful.
> 

and thank YOU for raising this issue as I probably should have addressed these points more explicitly in my notes

Perhaps I'm splitting hairs, but it would be possible to control both the 398-out and 555-rate with the same CV but the response curves would still differ from the original designs tandem vactrol arrangement




> Also, I've wondered what kind of craziness a sync circuit on the 555 
> would provide, such as the one on Rene Schmitz' VCO:
> 
> http://www.uni-bonn.de/~uzs159/vco3.html

precisely the kind of thought that keeps me awake at nights 
thanX!!!!

-doc

Dr Mabuse,

	I understand that Grant chose to sample a noise modulated sawtooth 
wave, rather than the noise modulated sine wave found in the Buchla SOU 
circuit.  Have you done any mods regarding this sampled waveform?

gary chang

--- In wiardgroup@yahoogroups.com, "gcmci <gchang@e...>" <gchang@e...> wrote:
> Dr Mabuse,
> 
> 	I understand that Grant chose to sample a noise modulated sawtooth 
> wave, rather than the noise modulated sine wave found in the Buchla SOU 
> circuit.  Have you done any mods regarding this sampled waveform?
> 
> gary chang

Hi Gary,
    (BTW I thought the painting was VERY beautiful)
;'>
    Yes, I've tried: white & pink noise, random freq & amplitude sines at audio & sub audio ranges, the 'dirty' tri-wave from a homebrew version of a partial SOU circuit, and even radio signals...  but IMHO the effect was fairly pallid, definitely not enough magic to justify an on-board mod (to me anyway). The production Wbug (#6 standard) has a patch point(J22) and a jumper (JP1) that allow the user to send an alternative waveform into the sample/hold, So, there is certainly plenty of opportunity for more experiments. 
    From my view, it was one of those things that LOOKED like it would set the world afire on the schematic. But, in practice, it just didn't bear out the theory.
    I'm only guessing but I'd bet that Grant put a lot of time into experimenting with various schemes to feed interesting stuff into that point on the circuit himself.

    Screwing around with widely disparate freq ranges on the 2 4046 PLL's yielded a lot more of my kind of fun!
   
alea iacta est,
-doc

Dr.,

Thanks for your insights on this - I have been wondering about whether 
or not this made a difference, or my memory of the SOU was a little bit 
fuzzy.  I remember how broad and smooth that you could make the SOU, 
and I have been trying to recreate this ever since I started to play 
with the 'Bug.

What a quality problem, huh?  Playing around with my Bug....

Gary



--- In wiardgroup@yahoogroups.com, "drmabuce <drmabuce@y...>" <
drmabuce@y...> wrote:

> --- In wiardgroup@yahoogroups.com, "gcmci <gchang@e...>" <gchang@e...> wrote:
> > Dr Mabuse,
> > 
> > 	I understand that Grant chose to sample a noise modulated sawtooth 
> > wave, rather than the noise modulated sine wave found in the Buchla SOU 
> > circuit.  Have you done any mods regarding this sampled waveform?
> > 
> > gary chang
> 
> Hi Gary,
>     (BTW I thought the painting was VERY beautiful)
> ;'>
>     Yes, I've tried: white & pink noise, random freq & amplitude sines at audio & sub audio ranges, the 'dirty' tri-wave from a homebrew version of a partial SOU circuit, and even radio signals...  but IMHO the effect was fairly pallid, definitely not enough magic to justify an on-board mod (to me anyway). The production Wbug (#6 standard) has a patch point(J22) and a jumper (JP1) that allow the user to send an alternative waveform into the sample/hold, So, there is certainly plenty of opportunity for more experiments. 
>     From my view, it was one of those things that LOOKED like it would set the world afire on the schematic. But, in practice, it just didn't bear out the theory.
>     I'm only guessing but I'd bet that Grant put a lot of time into experimenting with various schemes to feed interesting stuff into that point on the circuit himself.
> 
>     Screwing around with widely disparate freq ranges on the 2 4046 PLL's yielded a lot more of my kind of fun!
>    
> alea iacta est,
> -doc

--- In wiardgroup@yahoogroups.com, "gcmci <gchang@e...>" <gchang@e...> wrote:
> Dr.,
> 
> Thanks for your insights on this - I have been wondering about whether 
> or not this made a difference, or my memory of the SOU was a little bit 
> fuzzy.  I remember how broad and smooth that you could make the SOU, 
> and I have been trying to recreate this ever since I started to play 
> with the 'Bug.
> 
> What a quality problem, huh?  Playing around with my Bug....
> 
> Gary
>
Hi Gary,
i, too, have a soft spot in hy heart (head?) for the contours of the SOU. I have a dodecamodule on permanent loan to a local college electronic music lab and i'm familiar with the SOU's loopy, 'graceful' sort of character. 
i believe the SOU was a source of inspiration for the Wbug but the similarity is very abstract when you get down to resistors and capacitors. Under the hood, the Wbug design is very unique (and unusually original by today's standards) and IMHO the comparisons with an SOU are blown a bit out of proportion. My take on it is that the Wbug's smooth CV out  makes the same kind of unexpected leaps that the SOU does but it's glide from voltage to voltage is more abrupt especially on wide intervals. 
If i might suggest something-
try running the smooth CV out through some outboard lag processing. i think that a simple passive RC-type lag circuit might even give better results than an active type despite it's range limitations. The SOU's jumps sound closer to linear than logarithmic (to my battered ears anyway!)
at any rate it's always fun to yammer on about those 'pokey old Buchla gadgets'
;']

best,
-doc

Doc,

	A lag, such as the bidectional slew found on the VCO should do the 
trick.  Thanks for the analysis!  

	It's funny, at Calarts, there were two SOUs in each system -I used 
both modules on every patch that I made on the Buchla.

	On my Serge, there are 6 Stepped and Smooth Generators.

	I have one, and hopefully, will end up with two Bugs by the time 
that I have finished my Wiard system.  I guess that I am just a random 
kind of guy....


gc

--- In wiardgroup@yahoogroups.com, "drmabuce <drmabuce@y...>" <
drmabuce@y...> wrote:
 Hi Gary,

> i, too, have a soft spot in hy heart (head?) for the contours of the SOU. I have a dodecamodule on permanent loan to a local college electronic music lab and i'm familiar with the SOU's loopy, 'graceful' sort of character. 
> i believe the SOU was a source of inspiration for the Wbug but the similarity is very abstract when you get down to resistors and capacitors. Under the hood, the Wbug design is very unique (and unusually original by today's standards) and IMHO the comparisons with an SOU are blown a bit out of proportion. My take on it is that the Wbug's smooth CV out  makes the same kind of unexpected leaps that the SOU does but it's glide from voltage to voltage is more abrupt especially on wide intervals. 
> If i might suggest something-
> try running the smooth CV out through some outboard lag processing. i think that a simple passive RC-type lag circuit might even give better results than an active type despite it's range limitations. The SOU's jumps sound closer to linear than logarithmic (to my battered ears anyway!)
> at any rate it's always fun to yammer on about those 'pokey old Buchla gadgets'
> ;']
> 
> best,
> -doc

I understand that Grant chose to sample a noise modulated 
sawtooth 
> > wave, rather than the noise modulated sine wave found in 
the Buchla SOU 
> > circuit.  Have you done any mods regarding this sampled 
waveform?
> > 

In the original Source of Uncertainty, a white noise source is 
used to modulate a triangle wave oscillator. A white noise 
source has a Gaussian probability distribution (clustered around 
zero). By using noise to modulate an oscillator, then sample that, 
you produce a uniform probability distribution (any sample value 
is as likely as any other).

It does not matter if you use a triangle wave or a sawtooth wave, 
they both produce uniform probability distributions.

In the case of the Woggle Bug, the sawtooth output of the woggle 
circuit is sampled for it's input. In computing terms, the circuit is 
recursive. Because it is recursive, it has reduced information 
entropy relative to a truely random source (noise source).

The purpose for this is that music in NOT very random. In 
information theory terms, it has low information entropy. 
Because it repeats and exhibits short term self similarity.

Doctor Mabuse and I feel that the SOU is one of the most 
"musical" of the random generators. The use of recursion to 
further reduce the entropy level is an attempt to make it even 
more "musical". In theory, it should generate "random" 
sequences which exhibit short term self similarity and repeating 
features, like music does.

This WILL limit the fluctuation range of the smooth source, so to 
get a full 8 volt range from the smooth CV output, you need to set 
the "Smooth Range", "Woggle Range" and "Woggle Time" 
controls to maximum.

As a rule of thumb, the more time the yellow "Bug Light" LED is 
on, the more random the output functions will be.

i, too, have a soft spot in hy heart (head?) for the contours of the 
SOU. I have a dodecamodule on permanent loan to a local 
college electronic music lab and i'm familiar with the SOU's 
loopy, 'graceful' sort of character. 
> i believe the SOU was a source of inspiration for the Wbug but 
the similarity is very abstract when you get down to resistors and 
capacitors. Under the hood, the Wbug design is very unique (and 
unusually original by today's standards) and IMHO the 
comparisons with an SOU are blown a bit out of proportion.

The Vactrol controlled LFO, sample and hold and linked Vactrol 
smoothing filter are taken verbatem from the smooth source on 
the 266. Any difference in "feel" would boil down to the less 
random nature of the recursive design. However, you control the 
level of randomness with the knob settings, so you have a LOT 
more control of the output character than the original SOU.