Analog Modular

PugixWelcome to my DIY synthesizer website. The name Pugix (and the graphic toon) belonged to an online gaming character that I used to play and has nothing to do with synthesizers.

My most recent activity:

Large CGS Serge Project

large-serge-panelI am finally getting around to the assembly phase of this project, which I began to design almost a year ago.  Ken Stone has been producing PC boards by agreement with Serge to replicate many of the 1970’s and 80’s era Serge modules.  A couple of years ago I built my CGS Serge panel (see tag cloud) to go along with my BugBrand modular rack.  This new, expanded set of Serge and CGS modules will complement those and live in the same cabinet with them.  The photo above shows five panels, laid side-by-side, with only the panel parts installed.  This is a new panel format for me.  It’s the same form factor as MOTM, and uses the same vertical spacing.  But I laid it out with ten horizontal rows for fitment of banana jacks.  I had originally planned to put this into one gigantic Front Panel Express panel, but then I had an insight to make five separate panels.  The advantages include being able to use the standard MOTM rail system, and also being able to build incrementally, making assembly more manageable.  The downside is that some space was lost and I had to give up one mixer, one waveshaper and one VCA that were originally planned.  So what’s in it?  Going left to right, top to bottom:

  • Two 1973 Classic Serge Positive Slew
  • Classic Serge Smooth and Stepped Generator (SSG)
  • Serge Noise Source (minus sample and hold)
  • Two Original Serge Envelope Generator
  • 1973 Classic Serge Triple Bi-directional Router
  • Four passive attenuator pots
  • Two CGS VCA (Voltage Controlled Amplifier)
  • Two CGS Voltage Processor
  • Serge Resonant Equalizer
  • Classic Serge VC Phaser (with AC Mixers, one on the panel)
  • 1973 Classic Serge R6 Ring Modulator
  • Two Serge Voltage Variable Q VCF (VCFQ)
  • 1973 Classic Serge Triple Wave Shaper (two on the panel)

Color coding for jacks helps during patching:  Signal inputs are yellow, signal outputs are green, gate and trigger inputs are black, pulse outputs are red, control voltage inputs are blue.  The IO inputs on the triple bi-directional switch are gray.  Likewise, yellow knobs are signal attenuators, blue are CV attenuators, and the rest are red.

The next photo shows how many PC boards I have to assemble.  They are:

  • Two CGS 76 Serge Envelope Generator
  • One CGS 83 Serge Dual Positive Slew
  • One CGS 92 Serge SSG
  • One CGS 90 Serge Phaser and Mixers
  • Two CGS 112 Serge VCFQ
  • One CGS 202 Serge Resonant Equalizer
  • One CGS 97 Serge Noise Source
  • One CGS 85 Serge Triple Waveshaper
  • One CGS 88 Serge Triple Switch
  • One CGS 79 Serge Ring Modulator
  • One CGS 81 CGS Dual Voltage Processor
  • Two CGS 64 CGS VCA
  • Six CGS 108 Serge Gain Cell (submodule for the VCFQ)



Ciat-Lonbard Tocante

tocante-topTocante Bistab is my latest instrument acquisition from Ciat-Lonbarde.  Order at SynthMall.  Tocante is yet another masterful creation by Peter Blasser.  It is one of his more pure designs: a wholly self-contained electronic instrument, powered by solar-charged batteries, having a miniature speaker, and which can be played only by touch.

The Tocante line of musical instruments is “about” and “touching” the materials of electronics. Each touchpad represents a pitch according to industry “preferred numbers,” chosen by old wartime engineers for non-musical purposes. Here they form a unique and haunting musical scale, not unlike that of a gamelan or the neutral intervals of Persian music. Beyond these base pitches, three golden sandrodes flank each touchpad; touching these androgynous nodes yields intermodulation, pitch and timbral shifts, and emergent chaotic masses. The instruments come in three flavors: thyris the triangle, bistab the square, and phashi the circle. The oscillators sound like a bowed string, a most powerful clarinet, and a howling serene whistle, respectively. Each responds to touch differently. Solar panels charge the onboard batteries, that power the oscillators and a speaker. They are the perfect self-contained instrument for nightly music at the campground.

Tocante has 24 independent oscillators, each heard by means of a touchpad.  On Bistab, which uses square wave oscillators, the touchpads are square.  On Thyris they are triangular, and on Phashi round.  Touching a pad with a finger creates an electrical continuity through the resistance of the skin, primarily impacting amplitude.  The pads are etched on one side of a printed circuit board, with surface-mount electronic components on the reverse. Moisture increases conductivity. The 24 pitches are fixed, but due to component tolerances are slightly different for each individual instrument, yielding a unique tuning. Pitch bending and crazy cross modulations are done with the ‘sandrodes’, the bars across the middle of the Tocante, each ending in a small pad that’s close enough to bend a finger onto.

Tocante is heard through its own little speaker, and has a mono output jack for processing and amplification.  It also has a power inlet for charging the battery when natural light is scarce.


tocante-bottomI set up a delay processing patch, using both a Blacet Time Machine and the BugBrand PT Delay, to make the following test recordings.  The first is an attempt at playing a rhythm in 3/4 time.

The second is made only by breathing on Tocante. It’s a little horrifying in places, so I called it Horror Breath.

Rollz-5 Quad Drone

This drone uses four identical patches within Rollz-5.  The square wave oscillator is patched through a Gong, used as a filter, and then through AVDog, used as a VCA.  AVDogs are triggering themselves.  The Rollz LFOs weren’t used at all.  The Gong outputs also pass through Ultrasounds.  All 12 outputs are mixed in.  The performance consists of gradual adjustments to the filters.


Here’s a Cocoquantus piece.  It is a single sample from the Sidrax, made to circulate, with the coco time delays being controlled from the Quantussy.  I intervened a few times to touch the nacel to change the lights (the internal interactions).  The noise is part of the piece.

Rollz-5 Experiments

First a dark drone that uses AVDogs and Ultrasounds

Next a rhythmic section created by Gongs with an external digital echo.

Next a combination of external processing with E560 and E580, plus Cocoquantus.

Rollz-5 Completed

Here’s the assembled Rollz-5 project!
rollz-5-patched-runningThe whole assembly can operate outside of its box.  Here it is being tested.  To the right you can see the power inlet, ground jack, and left and right quarter-inch outputs.  Below those, suspended beneath the clear panel, is the hand-wired board containing the voltage regulator (Recom R-78C9.0-1.0) and output mixer.  The single green jack goes to an LED driver and LED on that board for test monitoring.

I described the panel layout in more detail on this previous post.   On the left are the eight Rollz LFO square wave oscillators, each with a separate fixed frequency.  From top (red) to bottom (green) they go from fastest to slowest at non-harmonic intervals.  Next to the right are the four AVDogs with their associated square wave audio oscillator.  The oscillator output is directly available on the panel.  Next come the Ultrasound modules, and finally the four Gongs.  The six gray output mixer knobs are on the right.

Frequency Ranges

The measured frequency range of the manual square wave oscillators is 50 Hz to 2.1 KHz.  The Ultrasound oscillators are 750 Hz to 30 Khz.  And (a bonus from adding inputs and outputs to the Gong) when the Gong output is patched to its own input, it becomes an oscillator with a range of 95 Hz up to 2.1 Khz.  The upper frequency of the Gong is limited by a series resistor installed on the PC board, which I made different values from 47K to 470K.  I will be changing the 470K to a smaller value, since it limits the upper frequency on that Gong to 220 Hz.


The added inputs and panel outputs have really enhanced the patch flexibility of this board.  By accident I discovered that patching the output of an AVDog to the Gong aux input and the Gong out to the AVDog aux input makes an interesting gated oscillator.  The Gong begins oscillating as the AVDog VCA opens up and then stops as it closes.  Since the AVDog can have a very long envelope (several seconds long) that repeats, it results in a repeatedly rising and falling drone.  And you can patch four of them all at different frequencies.  All the pitches are manually tuned, so it can sound melodious if desired.

The AVDog, Ultrasound, and Gong can be patched in series in any combination with the Oscillator inserted at whatever starting point you like.  For example I can route an Oscillator through a Gong then through AVDog.  The switch on the AVDog input selects between the Oscillator and whatever is patch to the violet aux input jack.  Being able to switch this input is useful during a performance without re-patching.  A 10K ohm series resistor on each output allows for stacking outputs together to one input.  I found when using the Gong aux input that if the Gong is also being triggered via the green jack, the aux input tends to overwhelm the ringing, but I can patch in one of my in-line attenuators to remedy this, if needed.  I think I’ll probably use a Gong in either the ringing bongo mode or the filter mode.

The two brown Node jacks on the Rollz LFO allow ample opportunity to link it to other LFOs.  The brown jacks generate short, negative-going (below zero volts) pulses that can be used to trigger AVDog and Gong and also jog Ultrasound.  The orange output is a positive-going square wave, like the Rollz on Plumbutter. Using it as a trigger has subtly different effects on the AVDog and Gong.

Needless to say, I have plenty of experimenting to do with all this patching variety.

More Photos

A closeup of the CGS LED driver board.  These were perfect to use here.  Notice the notch, cut with a Dremel tool, to straddle the solder lug on a banana jack.  I used water-clear high efficiency LEDs, the same ones as used on the Quantisise, because of their low power consumption.  I matched the current resistor with each color to get a more or less uniform brightness across the four colors.


Here are some photos of the assembly, prior to folding it together.  This first one is just after wiring up the Rollz circuits.


This one shows all the wiring.  I estimate there is more than 200 feet of wire.  It took several days of work to wire it all up.  I made one wiring mistake, reversing the connections to the frequency and Q pots on two of the Gongs, because I didn’t pay close enough attention to the asymmetric layout on the board.  But this took only swapping six wires to correct.  This pic shows the incorrect wiring!


And here is how it looks secured into the travel case, a standard tool/gun case.  It pops in and out of the case with just four large screws.  There is room left to store cables and the wall wart power supply for carrying.  It’s waterproof, too!


Naturally I will be posting some recordings.  I also plan to get a video camera soon, so I can make some demonstration videos of this and other projects.