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WIGGLING 'LITE' IN GUEST MODE

Serge Divide By N COM in MU
MUFF WIGGLER Forum Index -> 5U Format Modules  
Author Serge Divide By N COM in MU
Flareless
I just completed the first version of Random Source's Serge Divide By N COM module in MU format.

This is a really cool that, like many Serge modules, is difficult to wrap your head around. I did an earlier video demonstrating some of its capabilities and since then I have had a chance to do a couple of things;

FIrst, to the best of my testing it seems that the module runs fine un-modified on +/-15 volts. I was able to calibrate it without a problem plus the module passes all the defined calibration tests in the documentation I was able to find.

Random Source did a good job with the module and it's not a difficult build for you DIYers out there. They do use some whacked out part values. The parts are not hard to find, just a pain in the ass if you keep larger inventory of more standard parts.

The second thing I did was to get a panel screened for the module. I tried to keep the design similar to the original while working in the input attenuator added in the Random Source version.



This week the studio is being painted and moved around. Once that's complete I plan to record a more comprehensive video demo of the module.

Here's the original video...
Huba-Swift
Serge has got some really appealing modules. It's cool to see you build lots of the Serge format stuff into MU. Your right when you say that Serge modules are tough to wrap your head around. I'm building a standalone Serge unit right now and I don't know what half of the stuff I'm building does. Guess I'll find out once it's all finished.
So, what does this module do? Does it turn normal waveforms into stepped variants? Seems interesting.
JohnLRice
The MOTM-730 seems like a greatly expended version of the upper half of this module? hmmm..... I don't know if it was inspired or not by the Serge circuit but possibly studying the docs for the MOTM-730 might lead to a better understanding of the Serge Divide By N?
http://synthtech.com/motm/730/
Flareless
Ok, here's what it does....

<< from the Random Source manual >>

The ÷N COMPARATOR consists of two sections - a comparator (right side) and a voltage-controlled pulse divider (left side). The ÷N output of the pulse divider sends out a pulse on every N-th comparator pulse where N is a number from 1 to 31. N can be (pre-)set with the divider’s control knob (1 ÷N) and can by changed with a control voltage. The VC knob (attenuator) on the bottom of the left side determines how much effect the control voltage has on “N”. In addition, the divider generates a staircase waveform with N steps. This can be used to produce whole-tone steps when run into the 1V/Oct input of a VCO or as a stepped control voltage to change for instance the cutoff of a filter.

The comparator provides a number of useful “housekeeping functions”: Logical decisions (if the +input is greater than the -input, the output will be high, otherwise low), Level detection (whenever a variable waveform crosses the theshold, a pulse is generated ), Pulse width modulation or Rectifying a waveform (e.g. a sine or triangle wave). More uses are explained in the original 1983 Serge catalog:

For audio frequencies the divider can be set to output sub-divided frequencies with digital precision: Output frequency depends on “N”. If “N”= 2, 3, 4, etc. the output frequencies will be an octave, an octave and a fifth, or two octaves below the input, respectively. Because ‘’N’’ is voltage controllable, arpeggios and various melodies can easily be programmed. The nature of this type of divislon (Integer division) results in frequencies that fall along the sub-harmonic series, a series that has great tonal charm.

For sub-audio frequencies. the divider acts like a counter. Outputting a pulse only after ‘’N’’ number of input pulses. Input pulses can be fairly random or reqular. This capability is especially powerful for determining tempos and rhythmic patterns when using several sequencers (especlally if the “N” VC input is taken from one of a sequencer’s rows of controls ). ln a more random situation, using a microphone preamp / detector as input, the divider might be set to count how many times a sound of a certain lloudness will have occurred and be set to trigger an event upon reaching the count. Since the count can be made variable (from 1 to 31), fairly complex and subtle interactions can be generated.


My version has the Comparator section on the bottom rather than the right side and my Pulse Divider on top but otherwise things make more sense. There are actually 2 Random Source build docs for this module; one with this very useful description and one without.

I'm going to post the complete version here for anyone looking for it.
kdjupdal
This is an interesting module. It is basically a voltage controlled clock divider, if I understand it correctly.
MindMachine
kdjupdal wrote:
This is an interesting module. It is basically a voltage controlled clock divider, if I understand it correctly.


With a comparator and a staircase generator. You can also generate PWM from a sine wave (maybe all Comparators do that?). It is a super handy module for audio as much as control voltages or gates/triggers.
kdjupdal
I am not clear on what the staircase generator actually does. Can someone explain? Is it like a stepped sawtooth wave?
JohnLRice
kdjupdal wrote:
I am not clear on what the staircase generator actually do. Can someone explain? Is it like a stepped sawtooth wave?
It's like a saw or ramp wave that is stepped instead of smooth on the gradual rise or fall. I found this image on the interwebs:


If you were to patch a low frequency stepped wave into the CV input of a VCO it would sound like a step sequencer.
Huba-Swift
Thanks for the explanation of the module Flareless! I wonder if at audio rates you could get a cv controlled sub oscillator.
MindMachine
Huba-Swift wrote:
I wonder if at audio rates you could get a cv controlled sub oscillator.


Yes it is/does. Put VCO into the + Comparator input. Put your CV source into the - (negative) Comparator input. Take the Divided By output for your audio. The 1 thru 31 Divisor knob controls the sub root note pitch.

It is an amazing module.
Flareless
Thanks for all the great feedback guys! thumbs up

My studio is still under construction so I can't try out any of this cool new knowledge on the module but I will report back when I get a chance to.
PrimateSynthesis
JohnLRice wrote:
The MOTM-730 seems like a greatly expended version of the upper half of this module? hmmm..... I don't know if it was inspired or not by the Serge circuit but possibly studying the docs for the MOTM-730 might lead to a better understanding of the Serge Divide By N?


I doubt it. Having a divide by N was likely inspired by the Serge module. But the digital circuit in the 730 is completely different.

Juergen Haible figured out how the Serge module might have worked:



Notice that generating a staircase is inherent to the /N function.
wackelpeter
just having build this Haible VC Divider… i think i'll take use of the staircase function too… very minimal effort to build this module both on parts Count as on difficulty Task... i like it and well with the staircase function it would be a good competitor to my CGS VC divider…

with two VCS, DUSG or equally modules a VC divider and the use of it's staircase ouput you can make cool effects that resemble a ping pong ball dropping down on the floor...
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