A-129-2

Vocoder Synthesis

Note: Per Doepfer's A-129 Vocoder-Subsystem page, the A-129 series is no longer available.

The signals of A-129-1 are sent through a set of parallel filters with successive envelope followers that create a "signature" of the input signal, based on the frequency content and level of the frequency components. The signal to be processed (e.g. VCO or Noise) is fed into the synthesis input of the vocoder (A-129/2) and sent through an identical set of parallel filters with a separate VCA (voltage controlled amplifier) behind each filter. The envelope follower outputs of the analysis section are used to control the VCAs of the synthesis section. The filter signature created during the analysis of the human voice is used to filter the synthesized sound with a frequency responce similar to the voice. Consequently the output of the vocoder contains the synthesized sound modulated by the filter created by the voice. One hears a synthesized sound that pulses to the tempo of the voice with the tonal characteristics of the voice added to it: the synthesized signal "talks".

http://www.doepfer.de/a129e.htm