magnetic tape loop

To get  the magnetic tape inside the climate chamber and to use always the same sample, I need a magnetic tape loop. A piece of recorded magnetic tape is cut and spliced end-to-end, creating a loop with the Tesla reel to reel machines.

What does Wikipedia say: Tape loops are loops of prerecorded magnetic tape used to create repetitive, rhythmic musical patterns or dense layers of sound. Contemporary composers such as Steve Reich and Karlheinz Stockhausen used tape loops to create phase patterns and rhythms. In the early 1970s, musicians Brian Eno and Robert Fripp created Frippertronics, a system for creating "tape loops" during a live performance, though these weren't actually loops at all, merely a long tape-delay. In the mid-1980s, digital sampling overtook much tape loop use. In the 1990s and 2000s, digital looping pedals became more affordable. One man bands use looping pedals to record a groove or riff, and then they solo over the riff as it repeats. (Wikipedia: http://en.wikipedia.org/wiki/Tape_loop)

In the installation, the loop comes from the reel ro reel machine and goes straight into the climate chamber. There are two reels, one for each reel to reel machine.

Aktualisiert (Donnerstag, den 11. März 2010 um 14:53 Uhr)

climate chamber

Temperature and humidity are important for the preservation of audio tapes. Usually archivars want to keep these two variables constant in special storage environments. The installation climate chamber simulates extreme temperature and humidity values. Actually this is no simulation, these are real temperature changes between 0-60°C and relative humidity changes from 10-90%.

Climate chambers are quite expensive, from 3000€ - 20.000€. - So expensive for an art project, that I had to find a bricolage strategy. So what is the hack? A contemporary solution for an climate chamber is using peltier elements:

The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely when a voltage is applied to it, it creates a temperature difference (known as the Peltier effect). At atomic scale (specifically, charge carriers), an applied temperature gradient causes charged carriers in the material, whether they are electrons or electron holes, to diffuse from the hot side to the cold side, similar to a classical gas that expands when heated; hence, the thermally-induced current.

This effect can be used to generate electricity, to measure temperature, to cool objects, or to heat them or cook them. Because the direction of heating and cooling is determined by the sign of the applied voltage, thermoelectric devices make very convenient temperature controllers. (Wikipedia: http://en.wikipedia.org/wiki/Peltier_effect#Peltier_effect)

Using the peltier elements allows to change temperature fast from around 0-60°C. These elements are also used in sophisticated cooling boxes, that heat and cool medicaments, food, drinks, ... So I hacked the cooling box by controlling the peltier elements. 

The next step is the control of humidity. The humidity is dependent from the temperature. If I want to influence the relation, I have to bring water in the cooling box. A bit more precise: a humifier. Originally the humifier should be channeled into a terrarium. It should make reptiles happy. Anyway I also control the humifier with an Arduino microcontroller. 

Aktualisiert (Donnerstag, den 11. März 2010 um 14:57 Uhr)

Dust & magnetic interference

Dust and debris do also influence the life span of audio information on magnetic tapes. In the installation I use sandpaper to simulate the real conditions. The other, more rare influence is magnetic disturbance, here simulated by a magnet.

Dust, smoke particles, and tape debris present in the environment can get wound into the tape pack as the tape is played, resulting in dropouts when the tape is subsequently played. The lost signal is generally greater than expected from the size of the particle. The record and read heads must maintain very close contact with the tape. A particle of dust on the tape causes the head to ride up over the particle and lose contact with the tape. For perspective on the size of various debris particles compared to the normal head to tape spacing, see Figure. (from: http://www.clir.org/pubs/reports/pub54/5premature_degrade.html)

Finally the magnet and the sandpaper are mounted on a servo motor.

Aktualisiert (Donnerstag, den 11. März 2010 um 15:07 Uhr)

 

tesla b 100

For information.storage/refesh I want to use real historic reel-to-reel tape recorders. And finally I found a few tesla b100 recorders, produced in the 70s or 80s in the Czech Republic.

Here some basic info about the different recorders from the Czech Republic at the Tonbandmuseum or here at oldradio.

Specifications:

Stereo tape recorder with 4 tracks, speed 9,53 cm/s, frequency characteristic 50-15000Hz. Counter, manual record level control, volume, bass, treble control, wooden cabinet, metal panel. Installed speaker for left channel.

Production: 1973/75

Semiconductors: 4x KC149, 12x KC148, KU605, 4x KU611, GC511K, 4x GA201, 8NZ70, 4x KY702F

Size: 470 x 310 x 145 mm, hmotnost/ weight: 10 kg

Aktualisiert (Donnerstag, den 11. März 2010 um 15:08 Uhr)

 

getting started

It took a long time to get on with this project. Finally it will be realized for the first time in ESC im LABOR , best gallery for experimental arts in Graz (Austria).

Reel-to-reel, open reel tape recording is the form of magnetic tape audio recording in which the recording medium is held on a reel, rather than being securely contained within a cassette. (see Wikipedia)

This first version works with two projection areas, an 8-channel
audio system and a lot of open harware electronics, lets say Arduino.

Software packages are mainly open source Pure data and Processing and Python.

Aktualisiert (Donnerstag, den 11. März 2010 um 15:09 Uhr)