Technical Information
Resistance - A property of any material that opposes electrical current when voltage is applied to it.
Resistors- A component with a defined value of resistance.
The BEO is an oscillator which uses graphite pencils to create an audio signal through the process of drawing. It works on the principle that resistors are made from a form of carbon, also present in graphite, which enables drawn lines to conduct an electrical current. The pencils are wired to an oscillator and act as a variable resistor which disrupts the flow of electricity so the drawing becomes an extension of the circuit by reconnecting the current to produce an audio signal.
The act of drawing alters the level of resistance which modulates tone with low resistance producing a high pitch and visa versa. There are four main characteristics, which determine pitch in each drawing; the length, width, density and position of line.
1) Short lines offer little resistance so they will produce high pitches and visa versa
2) Thick lines offer little resistance so they will produce high pitches and visa versa
3) Pencils contain different densities and therefore conduct differently e.g. 2B pencil will contain less carbon than a 9B pencil. 2B pencils thus offer more resistance and can produce a similar range of tones but the range is so condensed that the possibility of variation is severely limited.
4) Position. If pencils A and B are close together they produce a higher pitch and visa versa.
As an extension of the electrical circuit the drawing must inherently adopt one other major characteristic to create an audio signal, it must contain at least one conductive line joined by positive and negative contact.
The tuning of sounds is constantly being redefined throughout the drawing process. In this case the drawing is being used as a unique instrument, in that the instrument, the sounds it produces, and the notation of these sounds are being created simultaneously.
The sound produced by the BEO’s oscillator is a low bandwidth pure tone that is limited in variance to pitch and timing. This audio signal is used as an out of control source sound and processed in realtime using various sound machines.
The BEO is augmented with synthesizers and effects extending its aural capabilities.The sound of the performance is constructed in realtime through action (drawn tone), reaction (processed sound) and interaction (new action) of the performers.
