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 Forum index » Wanted, For Sale, Opportunities and Requests » Equipment/Software Wanted and For Sale
Doepfer Vocoder Rack
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Joined: Jun 11, 2009
Posts: 14
Location: san francisco

PostPosted: Mon Jan 07, 2013 12:33 am    Post subject: Doepfer Vocoder Rack
Subject description: Modular Vocoder Rack
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Hi everyone Happy New Years. This is a Dopefer Vocoder Rack Module bought new by myself many years ago. It is a 220 Volt power supply rack but its easy to use a converter with. It consist of the A-129/1 Voc-A, A-129/2 Voc-S, 3x A-129/3, A-114 Ring Modulator as a Xtra goodie. Last tested everything worked perfect and I will power up again before shipping as I always do and make sure its "Talk'n". Its history as I said before, one time owner "me" always used in studio, properly stored, non-smoking enviroment, no dings or dents. Technically this is a great Vocoder because it is Modular! You can patch all kinds of stuff in and out from other sources such as parametric Eq's, dual slope generators, and all kinds of frequency attenuations, with each frequency CV controllable. A wide and varied scope of sonic effects can be attained well beyond the classic Vocoder, thats why this unit is special. Below you will find more information provided by the Doepfer web site on Vocoding. If your not familiar with Modular synthesis I would not recommend this unit for you. Any questions , please ask. Handling cost goes towards packing materials, bubble wrap, new box etc. Funds left over from packing cost will be refunded to buyer.

Working principle of a the Vocoder----Courtesy of Doepfer

The term vocoder is derived from the words voice and coder. A vocoder is an audio processor that captures the characteristic elements of an an audio signal - normally a human voice - and then uses this characteristic signal to affect another audio signal (e.g. a synthesized sound like VCO or Noise). The technology behind the vocoder effect was initially used in attempts to synthesize speech. The effect called vocoding can be recognized on records as a "talking synthesizer", made popular by artists such as KRAFTWERK. Pioneers of electronic music took this concept and turned the vocoder into what it is now - a tool for creative sound design. The vocoder works like this: The sonic character of the analysis signal - i.e. normally human voice - is extracted and transforms the signal at the vocoder's synthesis input. For this, a set of filters, envelope followers and voltage controlled amplifiers are needed, making good analogue vocoders very expensive.
More detailed the vocoder works like this: The voice signal is fed into the vocoder's analysis input (A-129/1). This signal is 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".

For most of the standard vocoders the control voltages generated by the analysis section (envelope follower outputs) are connected to the VCA control inputs of the synthesis section. For the modular vocoder A-129 the control voltage outputs of the analysis section A-129/1 and the control voltage inputs of the synthesis section are available as jack sockets. This enables the user to process the control voltages with other modules (e.g. the slew limiter/attenuator/offset generator (see A-129/3 and A-129/4) to obtain functions not possible with a non-modular vocoders. Another advantage of the modular concept is the possibility to exchange or shift frequency bands. And the modular vocoder could be "abused" in many ways, e.g. by controlling, modifying or creating the control voltages with other A-100 modules. LFOs, S&H, Random CV, Shepard voltages) or even to record the "vocoding" with CV-to-MIDI and MIDI-to-CV interfaces (e.g. A-192 and A-191).

The A-129 series of modules forms a modular vocoder. The basic components are an analysis section (A-129 /1) and a synthesis section (A-129 /2). As mentioned above the vocoder needs two input signals: a voice element which serves as the raw material for the tonal shaping, and is patched into the analysis section; and a carrier signal, which is patched via the instrument input into the synthesis section.
The speech signal is chopped up and analysed in the A-129/1 module, and then combined with the carrier signal in the A-129/2 synthesis section. As a result of this procedure, the carrier signal assumes the tonal character of the speech signal, but with its own pitch maintained.
Since the A-129 is a modular vocoder, and the connections between the analysis and synthesis section are external, using patch-leads, you can use this interface to patch in your choice of modules (eg. attenuator, slew limiter, CV-to-MIDI / MIDI-to-CV interfaces,, inverter, etc.). There's also the possibility of connecting the frequency bands of the analysis and synthesis sections arbitrarily, so that, for instance, a low frequency band in the speech signal can control a high frequency band in the carrier signal.
The A-129/2 synthesis section can also be used as a stand-alone voltage-controlled filter bank - or in combination with a MIDI-to-CV interface as a MIDI-controlled filter bank.

The A-129/1+2 both use 15 high quality narrow filters: 13 band pass filters, 1 low pass and 1 high pass filter:

Front shot of rack. Very clean unit. 220 Volt
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