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Making Of Le Refuge des Cordes

Hardware     Software     Tuning     Training, Rehearsing and Performing

Tuning

The tuning of the six strings is based around 50hz which is the utility frequency of the electric current in Finland and many other parts of the world. The fundamental frequency of the string depends on three factors: the length of the string, its diameter and the weight of the rock used. Initial calculations were made using Arto’s string calculator. Since I wasn’t able to adjust the tension of the string (chipping away at a rock wasn’t an option), I had to adjust the pitch by changing the length of the strings.


When using A=450hz as a tuning reference 50hz is G2. 6 notes are derived from the frequency of 25hz (G1) using simple harmonic ratios. This tuning creates a pentatonic C scale in just intonation. Plucking a string triggers sine waves tuned to those same ratios but using the string’s frequency as a fundamental. This fractal-like structure creates a mode consisting of 12 ratios using 50hz as a base note.

1/1, 9/8, 147/128, 81/64, 21/16, 189/128, 3/2, 49/32, 27/16, 441/256, 7/4, 63/32, 2/1.

Software

There is three light presets that are programmed in the Feather M0 microcontroller. The first one is a preset where all the LEDs are at full brightness. The second one is a random light pattern that is triggered when the rope moves. The last preset happens when a string is plucked while the rope is moving. It allows only the light above a string that resonates to light up proportionally to the amplitude of the string resonance. The microcontroller FioV3, to which the IMU sensor is connected, is sending three values (pitch, yaw and roll) to Max/MSP. Matti Niimaki from Aalto University help me a lot in working with microcontrollers. The rest of the computation happens inside Max/MSP which sends data via OSC to the Feather M0 microcontroller. Max/MSP also receives data from the IMU Sensor via OSC to detect if the rope moves. There is a different patch used for the installation and the performance. This is to limit the possibility of a bugs or CPU overload during the performance.


Installation

  • In p StringAmp simple effects (compression, EQ and reverb) are applied to the signal of the 6 electric monochords. Each signal is output to one of the 6 speakers and to the subwoofer.

  • The p synthspectral and p tuning are sinewaves which are triggers when a string is plucked.

  • The p AmbientOuput and p SamplesOutput control the levels of the samples.

  • In p DataToFeatherM0_NeoPixels data is sent to the microcontroller for controlling the lights.

  • In p DataFromFioV3_IMU data is receive from the IMU sensor

  • In p control, the different lights and sound presets are chosen depending on the data received from the IMu sensor and form the amplitude level of the strings.

  • In p lights, the abstraction audiotolights uses the amplitude of the strings to control the level of the lights.

  • In p controlsamples, the abstraction attackdetection uses the object bonk~ to detect attacks and trigger sound files and sinewaves 

  • In p mc.samples, the abstraction mc.sampetrigger triggers different sound files depending on the amplitude of the attack detected. The channels of each soundbank are routed differently to outputs using mcs.matrix.

  • Soundbanks are made in p playlist.


Performance

  • p StringAmp, p synthspectral, p tuning, p DataToFeatherM0_NeoPixels, p controlsamples have the same roles as in the installation patch

  • The p voiceVbap module is the main difference. During the performance, the performer is singing through an autotune system which uses the tuning explain earlier. The p voice subpatch uses the object retune~. When a string is pluck only 6 notes are available for the performer to sing which correspond to the pentatonic scale in just intonation of the fundamental of the plucked strings.


Pure data

I actually coded most of the work in Pure Data but I changed my mind a month before the opening realizing that I needed a higher level object to achieve simple sound processing effects (compressor, reverb and equalizer). I also wanted to use an autotune for the performance which is done easily in Max 8.

Premiered at the gallery Forum Box, Helsinki (FI) during *Immortal’s Birthday*, an exhibition created in collaboration with artist and researcher Maija Tammi (17.6–12.7. 2020).

Hardware

In the year 2019, I started designing the different physical parts constituting the sculpture. I had in mind to use all the elements of an electric guitar but to explode them in space. This guided me in the choice of using wood chips underneath the sculpture as if the body of an electric guitar had been shredded in pieces. Also, because the standard electric guitar has six strings, I chose to have six electric monochords suspended from a hexagonal metal frame. One of the main challenges for the design was to make something that is both massive, transportable and safe. For those reasons, I chose to work with metal as the main material. My father in law, Markku Tammi has a metal workshop where I built most of the hardware.


Electric Monochords

The monochords consist of two main parts: the “body” and “head”. The “body” part consists of an electric pickup, a jack input, as well as a bridge. These elements are mounted on a small metal plate (4 cm x 12 cm). The plate is bent to allow the pickup to be right under the string. Five holes are drilled into the metal plate. One is for hooking the instrument, the second one is for the jack input, the third is for the string and 4th and 5th is to secure the pickup in place.


The “head” is where the other end of the string is attached to. Because this instrument has no neck, the tension necessary for the string to vibrate at the proper frequency is determined by the weight attached to this “head”. The mass at the bottom of each string is between 5 and 10 kg. The device that connects the string to the weight has to exert strong pressures to maintain the string in place. At the same time, I had to come up with a system that allows changing the length of the strings to tune it precisely. This simple system uses a shackle, a screw with a hole drilled in the middle and 3 bolts. The third bolt is used to hold the screw in place. The 2 middle bolts are used to secure the piano wire going through the hole. The shackle is used to attach the weight.


I used piano wire since the string had to be longer than the usual guitar string. I’m using two different gauges (0.8 mm and 1 mm) to get lower sound with lighter weight. I’m using two ferrules at each end of the piano wire to create a “knot” so that the wire doesn’t slip out. 


After trying many different objects, I decided to use rocks as the weight. I like the contrast it created with the wood chips and the feeling of lightness that it suggests. Rocks are also the raw material from which metal is made. Drilling hooks in the rocks was a very straightforward and elegant solution.

Lights

I used those LED rings because they fit nicely around the string. They looked like small halos. The Neopixel rings are also very easy to program in with a microcontroller. I used Adafruit NeoPXL8 FeatherWing for Feather M0 system which made the wiring much easier since I was able to have seven independent data cables going to each ring instead of having a single data cable going through all the LEDs.

Wiring

Since I wanted to have a clean look where the rocks are suspended above wood without any other electronic in between,  I had to design the sculpture so that all the cables are attached to the instrument and lights from up instead of down. 


Because magnetic pick-up creates so easily humming sounds, I had to balance their signal as soon as possible through two direct boxes. I didn’t want to use a humbucker (which would have a lower noise signal ratio) because they wouldn’t fit the design of the monochords. Even though the di-boxes helped lower the humming noise, it still was very noticeable. Instead of fighting against it, I decided that the hum would be a feature of the work and not a bug. I decided to build the whole tuning of the instrument around 50hz which is the frequency of ground loop noise in most parts of the world. The sound coming from the magnetic pick-up goes into a di-box attached to the hexagonal metal frame. The signal from the di-boxes then goes down through a snake to the sound card which is on the floor.


Each Neopixel ring has to have its power wire. seven ground and live wire are connected to the rings and join in the power divider and the 5v 3amp power supply. An extension cord then links the metal frame to the ground. The data cables used to send data to the ring are two 15m CAT6 ethernet cable which divides into 8 different data wires each (4 data and 4 ground). The ethernet cable is directly connected to the Adafruit NeoPXL8 FeatherWing.

Rigging

The hexagonal metal frame is made with six steel pipes bent at a 120 degrees angle. Deciding the length of those pipes was a crucial decision. I wanted something difficult enough to reach from the center but not impossible. I settle on a diameter of 2.30 meters. To be able to adjust the system and make the installation easier, two pulleys are used to lift the metal frame at different heights during the installation process. 


Rope

During the initial work on Corde à Vide, I was using a rope ladder system which made it very easy. I was able to sit and relax easily. During the process of Refuge, I wanted to challenge myself and try to see if I could do it with a single rope. I was inspired by the traditional circus discipline of corde lisse. At the same time, I also wanted moments in the performance where my hands and feet could be free and where I could concentrate on making music. I chose to use a harness for those reasons. 


IMU Sensor

An inertial measurement unit (IMU) is connected to a FioV3 microcontroller which sends data wirelessly using an Xbee system to the computer. The IMU sensor detects 3-dimensional movements in space. It is attached to the rope and detects when the rope moves.  I experimented a lot with this sensor. My first idea was to have it at the bottom of the rope and be able to control a synthesizer in Max/MSP using the 3-dimensional movement of the rope. Although that system worked well, I didn’t end up using it because it added a layer of complexity which I felt wasn’t necessary.

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Training, Rehearsing and Performing

Creating the performance was something I wasn’t able to do beforehand because the setup was so different in the space. Even though it is simpler then Corde à vide, the setup still needs to need the suspension of a human which limits the number of places available.


Barn

The first space I use was a barn in Aura where my parents in law live and have a farm. It was easy to set-up there since a barn has high roofs and solid wood beams on which I can rig. We used my father in law tractors to rig the whole work. I build and tested the hardware there.

 

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Dome

I use the new MuteLabs space on Bulevardi to test the software and experiment with the sounds of the strings. I used the dome structure to suspend my hexagonal frame three meters in the air.

Gallery Forum Box

Arriving in the final performance space was a blessing. I hired Jukka from Helsinki Rigging Company to help me with creating a strong anchor point in the ceiling where I would hang myself as well as a 100kg of metal and stones. Once the installation was done I still needed to create the performance. Being in the space changed my plans totally and I had only two days before the first performance. Performing in the space with the sculpture in its proper form was so different from all the other spaces that the work has been so far. I used the firsts performances as a work in progress. On the 17th of June, the work lasted only ten minutes.  On the 29th of june, it lasted 35 minutes.

Circus Helsinki

I use the  space Circus Helsinki to train with the rope with aerialist Verna Laine. For a few months, I went there twice a week experimenting with the rope and gradually being overwhelmed by the difficulties and pains of that discipline. Rope training is very challenging. I had some background doing climbing but it was completely different. The muscular part was okay but the hardest part was the pain and the burning sensation on legs and feet when holding different positions.