Actually the full name of the module is the Cat Girl Synthesizer CGS01 Sub Oscillator / Harmonic Sequencer…. but that is one heck of a long title.

The CGS01 is a tremendously powerful module whose capabilities are often not completely understood.  Truth be told I have yet to fully understand the module’s abilities but I hope to pass on what I do know with this article.

Several CGS01 modules have been built here in the studio.  The build is actually quite easy. That is they are easy up to the point it’s time to connect the flying wires.  Once you get the trick of where everything goes, though, the modules are a snap to build.

For the CGS01 builds the boards were purchased from  At the time of this writing Ken Stone, the board designer and manufacturer is no longer selling the boards through his site but his product line is available from (at very reasonable prices I might add).

Cat Girl modules are among the most unique of the DIY modules out there.  First of all they  provide a wide and assorted array of features which are not otherwise available in modules by other manufacturers.  If the features are available Ken has put interesting spins in his version.  Second, CGS modules are frightening to build.  When I first came upon the CGS site and read Ken’s FAQ and disclaimer I practically ran away screaming in fright.  As a new DIY builder his warnings are very valid.  With some research and the excellent support of users on forums such as Muff Wiggler and Electro-Music I was able to successfully build several of his designs.

My first build was the CGS01 Sub Oscillator / Harmonic Sequencer which had some very intriguing features.  Rather than acting as a single sub oscillator which would play a note one or two octaves below the main oscillator’s note the CGS01 has a variety of divisions of the primary input note.  Further a combination of two inputs could be multiplied and divided then mixed together to produce even more interesting sounds.

In addition to these sound contorting features the CGS01 could alter control voltage inputs such as LFOs.  The output of these mashups could then be fed into an oscillator’s 1V/Oct input to create bizarre sequence effects.  This is a way cool feature!

2 CGS01 Modules Built an Ready for Wiring

The largest number of components on the board are resistors, primarily in the mixer section. A few capacitors and some diodes (and 2 ferrite beads) make up the remainder of the small components.  There are 9 integrated circuits used but none of them are particularly expensive or difficult to obtain.  In short;  building the PCB is a snap.

Wiring the board to the outside world is a bit trickier.  There are a number of variations which can be done depending on how large a panel you wish to use, how many potentiometers you want and how complex you want your options.

Ken’s 14 Potentiometer Design
8 Pot Alternate Layout

To keep things within reason and to reduce the footprint of the module I decided to go with Ken’s alternate layout with replaces some potentiometers and a 5 position rotary switch with some toggle switches and a reduced number of pots.  I utilized a combination of Ken’s panel layout and one done by Kindredlost from Muff Wiggler to create my panel design which I silk screened onto a Q132 Double Blank panel from

My Test CGS01 Panel

The wiring diagrams on the CGS site are a bit confusing when it comes to wiring up this alternate panel layout so I created my own wiring diagrams for reference.

CGS01 - Page 2

CGS01 - Page 1

As suggested in Ken’s documentation I did not tie the flying wires together in my build to prevent cross talk so from the back the module is a bit less tidy than I like but we do what works rather than what is pretty.

The CGS01 Wired Up And Ready To Test


Describing the features of the CGS01 doesn’t do the module justice so please watch the following demonstration video for more information.

So to summarize;  Great module.  Not as scary a build as you might think.  Incredible features with a multitude of possibilities.  Try one out!