Independent study final report

Posted on May 1, 2018

As I have mentioned before, the last weeks of the semester have been so busy that I have not been able to post anything. My independent study with Michael Montanaro at the Topological Media Lab has also come to an end, and so I submitted a final report. I formatted the report similar to the NIME publications, as they were also part of the inspiration for my research. Below is the report formatted to fit in blog format. Find the PDF version of my report at the bottom of this post.

The search to build L’Octariphone, a sound sculpture with guitar electronic components

Abstract

Traditional musical instruments rely on a tradition of craftsmanship. Since the 19th century, all sorts of mechanical and electrical instruments have been invented. These more recent instruments have often attempted to synthesize the natural behaviours of the traditional instruments. This report outlines the research and the prototyping that occurred in order to discover how to create a sound sculpture built on top of the lessons learned by the creation of electrical string instruments, mainly the guitar.

Keywords

Sound sculpture, sculpture, Brutalism, string instrument, guitar, electrical guitar, electromagnetism, pickups, amplification, electronics, scenography.

1. Overview

Computers and electronic parts are necessary and inspiring materials with which I work, however they are not what I wish to showcase. I prefer to concentrate on the value of craftsmanship, almost like a modernist reaction to contemporary creative technological fields.

I intended for this independent study to be a research-creation moment where I could investigate the craftsmanship required to build a functional electrical instrument. I am fond of deconstructing and reassembling components of my own life—objects, relationships, finances, etc. As a guitarist myself, I appreciate the visual language and the mechanical and functional parts of instruments—pickups, metal strings, tuning keys, etc.—which I wanted to repurpose to create visual artistic objects, as well as sound art.

Just like musical instruments, I intended for this artwork to be flexible enough to be reused in many contexts.

It is important to underline that due to the time required by the fabrication of the many components and tool prototypes, as well as some other external factors which I will mention further, I was unable to complete the sculpture at this time.

1.1 Electronics

Electric guitars use a simple electrical circuit to convert the electromagnetic field created by the vibration of the steel strings into electrical current. My research intended to discover how this is done, and to reproduce the necessary components that would be custom-made for the sound sculpture.

As I did not wish for the strings on the sculpture to be bowed, plucked, or hammered, I needed to investigate a way to vibrate the strings without touching them. The commercial product EBow does just that, and has been used by guitarists like Robert Fripp and Brian Eno for years.

1.2 Informed by Brutalism

A few years ago, I created a sculpture for the reactive installation The Office of Dr. S. Plant. It was made of square tubes, mounted semi-randomly to evoke the shape of a plant, onto which 16 small loudspeakers were attached, and connected so that they were used as microphones. A few people commented as how it was reminiscent of Brutalism, which was just a coincidence at the time.

For this independent study, I wished to willfully acknowledge the form of Brutalism and its geometrical shapes, so that it would inform the shape my sculpture would take.

Brutalism is an architectural movement popular in the mid-20th century. Its name comes from the French “béton brut,” which literally translates as “raw concrete.” As expected, the buildings constructed with that architecture are made out of concrete. They are often shaped with hard geometrical edges. It has been said that this architecture could feel oppressive to those inhabiting such buildings.

The intent and the results of this architectural movement deserve a paper of their own, which was not the intent of my research. The scale of my sculpture would be much smaller, thus the oppression felt by the size and heaviness of the buildings would be unlikely to be reproduced.

1.3 Sculptural Form

Fig. 1: Initial sketches

The guitar places its strings in an array, each string close to another so that a human hand can actually be placed on all of them at a time, as the musical composition requires. The sound sculpture I wished to create had not such constraint, and since I was investigating how to create my own electromagnetic pickups, I could choose to place them in whichever way was more aesthetically satisfactory for the sculpture.

Fig. 2: Latest design

After sketching many potential iterations—going from a printer-like shape where a head holding the signal generator above the strings to a stick tree-like structure—I settled for an octagonal tube with slanted angles. This is how the name Octariphone was created.

Each of the faces of the sculpture would hold a string and a signal generator would be placed to vibrate the string as it gets powered. At the bottom of the sculpture would be a ¼” jack output, so that each string sound output can be routed independently—as opposed to a guitar, whose electronics mashes all the strings into a single sound output.

1.4 Scenography

The original idea was that the Octariphone would control its own signal generators, creating melodies in a semi-random fashion. In order to do that, there would be a small microcontroller—potentially a Raspberry Pi or an Arduino board—that would run constantly, and turn the signal generators on or off.

From that point, the sculpture could be presented in multiple ways. The first idea would be to place the Octariphone at the centre of a somewhat dark room, with a spotlight on it, from above. Jack cables would run from the sculpture to eight speakers positioned evenly around the room. The sound sculpture would then create an infinite spatialized melody.

If a room is not available, it could be possible to place the Octariphone on a wall or in a corner, and then stack the speakers vertically, changing the presentation to something more akin to a rock performance, but still coming from a static sound sculpture.

Since each string has its own discrete output, it would also be possible to run each one through its own guitar pedal, or even through a sound board, to change the way the sound output is generated or spatialized.

Since the sculpture houses a microcontroller, an API could even be created to communicate with it, so that it can be reactive to its environments, or to performers.

2. Research

Since I do not have any sort of formal training with electronics, my knowledge is mostly built on top of trial and errors during prototyping. Since functional electronics were necessary before I started to design any part of the sound sculpture, I spent most of the time of my research creation study to prototype and test my custom electronics.

2.1 Brutalist Pickups

Fig. 3: Guitar pickup diagram

As I mentioned in the Overview section, electric guitars use electromagnetic pickups to sense string vibration and convert it to electrical current. In the case of single coil pickups, these pickups are made of six magnet polepieces around which coil wire is wrapped, all of which is enclosed in plastic. In the case of humbucker pickups, two single coil pickups wound with opposite polarity are used conjointly, so as to reduce if not remove hum—noise that comes from the electromagnetic field and the electronics.

There are multiple sources of information available to create guitar pickups. There are even some tools build specifically to wind those pickups. I could not use those tools as they were, since they are designed to function specifically for actual guitar pickups.

Fig. 4: Brutalist pickup design evolution

In my case, I first had to design the enclosure that would house the magnetic polepiece and the coil wire, as well as how this could be connected to an actual electronic circuit afterwards. Initially I only expanded on the circular shape of the magnetic polepiece so that the top and bottom parts were big enough to cover the wire coiled around the polepiece, the screws to hold the pieces together, and the eyelets into which the ends of the coil wire would connect to electronic wires.

After a few design iterations—mainly to lower the eyelets so as to accomodate the position of the wire as it gets spooled around the magnetic polepiece—I chose to redesign the enclosure so its shape would be straight with hard edges, to be reminiscent of Brutalism.

Coiled copper wire can be used as is as a way to pick up ambient sound. Because of the air between the coils, the vibration of the sound will be picked up. In guitar electronics parlance, such a pickup would be called “microphonic.” This is an issue, as a guitar pickup is meant to only sense the electromagnetic vibrations of the strings, and not act as a microphone.

Fig. 5: Potting pickups in wax

In order to resolve this issue, the pickup must be soaked in melted wax, this process is called “potting pickups.” The wax must be a mix of beeswax and paraffin, with a ratio of 20% and 80% respectively. The wax mix will melt at around 60–70º C. Once the mix is liquid, the pickups must be dunked and remain in there for some 30 minutes. During that time, small air bubbles will leave the coils, which the wax will fill. Once that process is complete, the pickups will be ready to sense only electromagnetism.

Fig. 6: Completed Brutalist pickups

2.2 Spooling Machine

Guitar pickup winding machines are not made to work with custom pickups like the design described in the previous section. In order to be able to spool copper wire, I had to design and build a tool myself.

Originally, I built a bit to add onto a drill, thinking that it would have worked properly. Unfortunately, holding the trigger of a drill for a long time makes it hard to precisely control the speed at which the drill is going. Random bursts of speed kept breaking the coil wire.

Inspired by the guitar pickup winding machines, I started designing my own. The design was made using lasercut ⅛” thick plywood, a dowel inspired by toilet paper rolls, old film sprockets, an Arduino board, a stepper motor, as well as some switches and knobs. The lessons learned from the drill bit prototype were used to create a small bit to put on top of the motor, onto which the pickup would be attached while the spooling happens. This machine was a great success, and lead to the fabrication of some eight pickups.

Fig. 7: Spooling machine

2.3 Signal Generator

Fig. 8: Alleged functional homemade EBow circuit

This part was a bit more of a challenge for me. The EBow, the commercial product whose behaviour I wished to emulate, has a proprietary electronic circuit. There are some people on the Internet who published their supposedly successful recreation of the circuit. While it is not a challenge for me to put together an electronic circuit—it is just fabrication on a smaller scale after all—it is however almost impossible for me to judge if a circuit diagram is valid or not. I attempted to build a few versions of the circuit, only to never be able to generate any signal or string vibration.

Fig. 9: Signal generator circuit

However, I did stumble onto something interesting: with a pickup connected at each end of my homemade signal generator circuit, and while moving each pickup close to each other, I obtained the behaviour of a Theremin.

It has been suggested to me that my pickups may not have a high enough impedence—they are roughly at 8–12Ω currently—to work properly in the context for which I want to use them. A guitar pickup is likely to be in the hundreds. This could be due to the fact that in order to be able to spool my pickups without the wire breaking all the time, I went from a 42 gauge to a 32 gauge. A potential solution to this issue would be to investigate an op amp circuit.

Out of desperation, I actually wrote to EBow themselves, detailing my research-creation project, and asking them if they would be willing to sell bare components that I could use, instead of me trying to make my own without actually knowing what I am doing. It took them a full month to reply, but the idea did not seem totally out of the question for them:

We do sometimes help out artists by selling just the bottom part of the EBow. That would be the whole foot with potted electronics. The price would depend on exactly what you need. If you can use units with just the normal or just the harmonic setting working, those would be cheaper. Also if you don’t need the light to work, those would be similarly cheaper. Let us know what you think you might need.

I replied and provided a more detailed description of the electronic circuit I wish to build, but they have not followed up on this yet.

3. Known issues

3.1 Brutalist Pickups

As mentioned in the previous section, the pickups’ impedance seems to be very low. It would be ideal to spool new pickups with a thinner wire—which means more coils around the magnetic polepiece—so that they end up with a higher impedance.

Also, I raised the dowel on the spooling machine of a centimetre or two, so that there would be less tension on the wire as the pickup is spooled. This redesign could also help the process a bit.

3.2 Electronics and Signal Generator

My lack of knowledge of electronics led me to quickly believe the different people that said how simple guitar electronics were. It might have been ideal for me to have additionally taken a structured class or training, so that I would not be baffled by the non-functional circuits I have built.

On the other hand, the guts it took for me to ask for help or sponsorship from a company that does know my work may actually lead to a fruitful relationship in the future.

3.3 Lack of Finished Sculpture

The original intent of this research-creation independent study was to have a physical sound sculpture so as to learn different ways to showcase it in a gallery—in other words, design its scenography.

The research and the prototyping—as well as exterior factors—consumed much of the time that was meant for creation and fabrication.

4. Future undertakings

4.1 Spool New Pickups

I raised the dowel on the spooling machine of a centimetre or two, so that there would be less tension on the wire. With this small modification, I will attempt at spooling new pickups with the 42 gauge wire.

4.2 Op Amp Circuit

I will investigate the use of an op amp circuit to amplify the signal obtained from my pickups, and potentially also onto the signal generator circuit.

4.3 Follow Up with EBow

Whenever EBow replies, and if they wish to help me in my creation, it could greatly help.

4.4 Alternative String Vibration Methods

In the event that there is no way to use either EBows or signal generator circuits, I will have to investigate alternative ways to trigger the vibration of the string. A wheel rubbing on the string, like that of a hurdy-gurdy, could be an interesting solution. Maybe mid 19th century mechanical instruments could also provide inspiration

5. Thanks and Acknowledgments

Michael Montanaro for providing guidance during this independent research, as well as giving me the sprockets used in the spooling machine.

Garnet Willis and Martin Peach for sharing their knowledge of electronics when I would get stumped.

Tatev Yesayan for her design advice and a 3D rendering of a potential iteration of the Octariphone.

Concordia’s labs (Digifab Lab, wood shop, metal shop, and maquette shop) and the technicians for answering my many questions during the design and fabrication process.

6. References

alex12349, “Make an E-Bow variant,” Instructables (blog), http://www.stewmac.com/How-To/Online_Resources/Learn_About_Guitar_Pickups_and_Electronics_and_Wiring/Wax_potting_pickups.html.

Christopher Beanland, Concrete Concept: Brutalist Buildings Around the World. London: Lincoln, Frances Limited, 2016.

Céleste Boursier-Mougenot, états seconds. Arles: Analogues, maison d’édition pour l’art contemporain, 2015.

Céleste Boursier-Mougenot, perturbations. Arles: Analogues, maison d’édition pour l’art contemporain, 2015.

Peter Chadwick, This Brutal World. London: Phaidon, 2016.

Lindy Fralin, “Wax potting pickups,” StewMac, http://www.stewmac.com/How-To/Online_Resources/Learn_About_Guitar_Pickups_and_Electronics_and_Wiring/Wax_potting_pickups.html.

Kartja Kwastek, Aesthetics of Interaction in Digital Art. Cambridge: The MIT Press, 2013.

“DIY your own eBow effect for guitar,” YouTube video, 1:06, posted by “pandomovnik,” April 11, 2012, https://youtu.be/1iccGqmEC-M.

“How to Wax Pot Guitar Pickups,” YouTube video, 8:54, posted by “junkmale2000,” April 30, 2013, https://youtu.be/sAB9Psv7jX8.

7. Report in PDF Format