Trautonium

The trautonium is a monophonic electronic musical instrument invented about 1929 by Friedrich Trautwein in Berlin at the Musikhochschule's music and radio lab, the Rundfunkversuchstelle. Soon Oskar Sala joined him, continuing development until Sala's death in 2002.

Description

Instead of a keyboard, its manual is made of a resistor wire over a metal plate, which is pressed to create a sound. Expressive playing was possible with this wire by gliding on it, creating vibrato with small movements. Volume was controlled by the pressure of the finger on the wire and board. The first Trautoniums were marketed by Telefunken from 1933-35 (200 were made).

The sounds were at first produced by neon-tube relaxation oscillators (later, thyratrons, then transistors), which produced sawtooth-like waveforms. The pitch was determined by the amount of resistive wire chosen by the performer (allowing vibrato, quarter-tones, and portamento). The oscillator output was fed into two parallel resonant filter circuits. A footpedal controlled the volume ratio of the output of the two filters, which was sent to an amplifier.