Ciat-Lonbarde Tetrazzi Organus Eurorack Modular Synth Module DIY conversion – with added CV control !

This is a photo tutorial on how to “eurofy”a tetrazzi organus. The tetrazzi organus is a touch sensitive synthesizer that generates highly banded sounds using piezo trasducers attached to rigid boards – press barres. In my implementation y shall teach you how to make the press barres CV controllable with + AND – voltages (you cannot believe how freaking good this sounds!). Additionally i suggest how to construct a euro faceplate and how to power the tetrazzi board using your onboard Doepfer style cable and power supply. This is a physical contraption that I deliberately named E.U.R.A.Z.Z.I.

Why did I do this? because the E.U.R.A.Z.Z.I. was instrumental on interpreting my 2003 graphic score composition entitled “Sonnet“. This composition is based on the juxtaposition of, (i) numerological findings and (ii) musicality features, both systematically extracted from the poem “Sonnet” by Federico Garcia Llorca:

I do not wish to distract you from your eager DIY intentions but, if you want a taste of the E.U.R.A.Z.Z.I’s capabilities you can check “Sonnet” track as follows:

Federico Garcia Lorca - Sonnet

   I know that my profile will be serene
in the north of an unreflecting sky.
Mercury of vigil, chaste mirror
to break the pulse of my style.

   For if ivy and the cool of linen
are the norm of the body I leave behind,
my profile in the sand will be the old
unblushing silence of a crocodile.

   And though my tongue of frozen doves
will never taste of flame,
only of empty broom,

   I'll be a free sign of oppressed norms
on the neck of the stiff branch
and in an ache of dahlias without end.

The tetrazzi organus is defined by Professor Blasser as follows:

“Tetrazzi is the newest incarnation of the Organus series, a mandala of analog oscillator circuits that can cross-modulate to form the empire of infinite circuitry known as pure sonic chaos. Electronically, it represents some of the more profound electronic complices that were developed in the 20th century,  such as Buchla Source of Uncertainty,  U.S. Navy Phantastron Radar Circuit, and Piezoelectric Flex Technology. It is a way to make the touch-sensitivity of human organs into touch-sensitivity on the pipe organ, pipe here meaning “squishing electron flow via ceramic transducer”.  You got to love this man!

Step 1: assemble the tetrazzi board as per Senior Blassier instructions

Step 2: I used a Doepfer A-100B42 42 HP / 213 mm blank panel as a guide to cut a wood front panel from a 3.5mm timber sheet.

Step 3: give it a bit of a sand and mark the mounting holes.

Step 4: cut another sheet of the same height but 5-6 cm narrower – this will make your press barres

Step 5: divide the 2nd sheet on 4 equally sized press barres … ca va?

Next … step: i have a jigsaw + I am sloppy so i have to sand them all down to straight sides!

then … your press barres sould look like this 

the next step: get some M3 screws/nuts and place your press barres – the nuts will serve as spacers that will elevate all barres at the same height. it is also a good idea to number all barres 1 to 4 and make sure that:

1. you drill and place the screws so that you clear the mounting rails

2. the screws can conduct electricity – they will be your bend/touch points (4/barre)

take the plunge into the next step! … give your timber tender loving care with a bit of oil or varnish … make it look gorgeous!  

what’s up now? another step: drill and mount

1. x4 momentary switches

2. 4 pots – 100K

3. L-out and R-out (middle left and right jacks)

4. x4 CV in jacks for press barre modulation

… also drill 4 holes for press-barre piezo cables to be solder into the tetrazzi board

LooKing GooD! don’t you think? –

step (n+1) … attach the tetrazzi board to the back-panel … i used PCB stick-on elevators – – you might also use brackets – crews+PCB separators … you decide my friend!

now solder all panel components to where they suppose to be according to ciat-lonbarde’s assembly instructions … i will tell you how to wire your barre-CV-in’s soon – do not despair amigo.

now, how to build and connect you Doepfer-style ribbon connector … the next image will tell you that you would solder all GND pins together and all +12 volts pins together and then just connect +12 and GND to whey belong in the tetrazzi board (the PSU adapter points)

now triple-check your doepfer jack since you now shall epoxy this baby onto the board and against one on the jack triplets. Use clamps to assist epoxy-driven union and let cure according to your epoxy instructions

voila … you have officially EUROfied a tetrazzy – since you have all that epoxy goo mix drying out, hurry and glue the piezos to the barre boards and then attach the barres to your panel – remember – one nut serve to elevate the barre from the panel and a 2nd nut shall secure it to the dorsal/back panel. do not forget to solder the piezos on the board  🙂

ahora … otro paso: give your baby its umbilical cord – she is hungry!

well, the time has come, i’ll let you know: for your barre-CV-in’s, wire GND of each CV jack (the closest jack-pin to the panel) to its corresponding black/GND piezo connection at the board. the connect each CV-jack-tip-pin to a 330K resistor and the other end of the resistor to the red/positive piezo connector at the board. if you have an eagle eye you can see this at the next couple of pics …

happy chappy ? you bet – you have build a tetrazzi organus into your eurorack modular synth. you can CV-modulate it using bipolar voltages and also play-it with your pressure gestures concomitantly

if you build one of these … please let me know and send some pics: that will pay-off the time and effort that I invested into this post. lots of love,



Moby Plexus, custom white H-Pi Tonal Plexus Review

I recently commissioned the H-Pi crew, the making of a microtonal controller for my upcoming research/compositions at QLD Conservatorium.  From their blog:

H-Pi: “Composer Jesus Lopez recently contacted me from Australia with an interesting request: would it be possible for me to make a Tonal Plexus keyboard without colored keys – only black white and grey? And could the controls also be white? And the body, could that also be white?

A white Tonal Plexus. It would certainly be striking! Of course; yes, I said; I can do that. Since I make every keyboard by hand, I have no problems with these kinds of requests. And there was a good reason to make such a keyboard. You see, Jesus Lopez is color blind.

Most color blind people are known as dichromats, having what is called Red-Green blindness, the ablility to see colors well only in the yellow and blue parts of the spectrum. This is in fact the reason that the default color of the edge keys for Tonal Plexus keyboards was originally blue. Dr. Lopez has wide spectrum color blindness, which is much more rare. I supplied him with some keyboard images, which he used to experiment in Photoshop to find a layout which looked correct to him. The results are quite unique.

The keys themselves protrude through completely white top panels. There are no graphical boxes around key regions, nothing but the key caps themselves to delineate the structure.

The control panel has custom white knobs, with slider knobs of the ‘grab’ style, contrasting the standard ‘push’ style slider knobs used on standard TPX keyboards”

I am going to use the Tonal Plexus to optimally generate microtonal themes and compositional functional blocks for my PhD thesis. Some info in my thesis is as follows:

Preliminary ideas on discovering mental-state biased compositional paradigms for microtonal electro acoustic instruments:

The idea is to explore the mathematics /mental-state/music-perception continuum by using artificial intelligence (AI) techniques applied to music composition. This shall not be a scientific endeavor but rather the generation of a compositional framework that will guide my compositional outcomes during the last stages of my research time at the Conservatorium. Not only musical pieces will be composed, but also, specific electro-acoustic instruments will be designed for these. Therefore, this proposal pretends to be a project on electro-acoustic music composition. Finally, despite this proposal is based on a rigorous and highly systematic approach, the final outcomes will be exceedingly modulated by compositional creativity, previous compositional experience, my cultural background and ultimately my vision of the world.

Artificial Intelligence for the generation of a compositional framework:

AI or machine learning approaches can be either supervised or unsupervised. As I shall potentially apply them to composition,
supervised methodologies attempt to generate compositional paradigms by learning from previous experiences sampled from human or previous compositions’ input. Unsupervised techniques use well-known mathematics/biology inspired algorithms, which are universal, or live within their own realm, and attempt to loosely classify a compositional space of themes.

Whether we considering supervised or unsupervised approaches, the target – or motivation – would be the listener mental state as induced by short musical passages (or themes). All themes would have to be as de-correlated as possible to western traditional musical forms to rule out trivial compositional/cultural biases, i.e. minor vs major triads, simple vs odd signatures, or traditional jazz forms. Ultimately, a large number of microtonal systems will be considered.

Themes will also have to be parameterized in terms of their dynamics, timbers, tempo, and other second order mathematical measures of music, i.e. density of microtonal system, melodic range, counterpoint descriptives, and second order measures like the Laplacian on frequency time series, etc.

Also, a rigorous notation system should be adopted to facilitate discussing themes from an aesthetic perspective and to allow interpreters to generate the themes in a way that is minimizes ambiguity. Nonetheless, such notation system should be open-ended to allow for modern interpretation but also with little dichotomies so it could be easily translated into natural language to be interpreted by the AI algorithms. I would preliminary use an adaptation of Schenker diagrams and perhaps lilypond package as a computational framework.

Given, such archive of the themes (many issues to solve here – see challenges below), listeners will contribute their mental state by choosing from a set of images while listening to the music. This will annotate set of themes, hopefully, with, at least, pseudo-universal states of mind. If universality of theme and mental-states pairs is not achieved, this should not pose any constrain since the objective of this project is to generate a “guiding” compositional paradigm rather than proving that persons are universally biased in the same way by the same musical forms.

After the themes are classified and an annotated archive is generated, a neural network (a supervised AI method) will be used to learn compositional paradigms that are meant to induce mental states – again hopefully with certain level of universality. These neural networks could also be potentially used to augment the themes-set by generating new themes in a generative basis. Concomitantly, Knohonen maps (an unsupervised AI approach) will be generated to discover clusters of compositional parameters – clues – that might also correlate with mental sates and subsequently enrich my compositional framework.

If all goes well [nervousness pause] we should end up with an intelligent artificial framework that will allow composers to guide their creative process based on (1) themes annotate by metal states they induce; (2) Neural networks that will generate themes that will potentially generate predetermined mental sates; (3) Kohonen clusters of compositional and improvisational clues that should either induce mental state sequences in the listener or perhaps augment/inform the performance experience of a given his/her current mental-state.

With this intelligent framework at certain level of maturity, I intend to achieve the following objectives:

(1) Generate a series of compositions based on predetermined mental state sequences. Ideally, the compositions will include a great deal of improvisation guidelines also based on the discovered compositional paradigms that shall be adopted by the interpreter/improviser at he/she leisure as informed by they current mental state.

(2) Since the paradigms departed from highly open-ended themes (i.e., micro tonality, and variations of the real-time variations electronics) instruments will be specially designed and constructed for these pieces. These instruments will be based on traditional musical instruments with altered tunings, spatial arrangements, and electro-acoustic modifications.

Some challenges to this PhD are:

1. Adopting a usable notation system – preliminary I am thinking on
2. Generating a large enough sample of themes and recruiting candidates.
3. Not finding themes that are universally correlated to mental states.
4. Eliminating cultural music form biases.
5. Cost and time associated with constructing/modifying specialized instruments.
6. Finding sound ways for parametrizing themes in a mathematical that it is still translatable to music notation or improvisation guidelines for interpreters.