Motivation

I want one. I wanted one since i have heard Kraftwerk and seen the DIY Elektor Vocoder. But i didn't have the means. Now i have. Jürgen Haible's Living Vocoder was a great inspiration for me. I have had his really big PCB from the Living Vocoder in my hands. What an impressive work! But i wanted something more flexible and modular. The first thought was to make it like the Elektor Vocoder, one complete channel per frequency band. But then, if you want to change the frequency or filter architecture, you have to replace the whole channel. So i decided to make the filters replaceable. It is possible now to alter the characteristic of the Vocoder by changing just the filters. I studied Jürgens Living Vocoder, the Elektor Vocoder, the ELRAD Vocoder, ETSI Vocoder, EMS Vocoder, Sennheiser Vocoder and some more. And picked up what i think might be useful for my approach. My design holds up to 24 filters in steps of eight. So you can start small. All control voltages are brought out, so you can patch the channels to you liking. This makes for some really weird effects. All components are available (2017) and through hole with one exception. Some 0805 SMD capacitors are used in the bandpass filter. But they are big enough to be soldered by hand without problems. One optional module, the display unit, shows the control voltage per channel. It is attached to the Vocoder Analyzer part. You have a optical control over the incoming spectrum. Never seen this before with a vocoder.

Sitelist

Current state:

Pictuer NGF Vocoder current state

NGF Vocoder Modules

NGF Vocoder Analyzer

NGF Vocoder Analyzer

NGF Vocoder Analyzer

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Current state: Published

The NGF Vocoder Analyzer divides (analyzes) the incoming signal in frequency bands and derives a control voltage according to amplitude of frequency. It consists of up to 24 filters. Eight filters per backplane.

NGF Vocoder Display

NGF Vocoder Display

NGF Vocoder Display

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Current state: Published.

The NGF Vocoder Display visualizes the amplitude of certain frequencies in the incoming signal.

NGF Vocoder Synthesizer

NGF Vocoder Synthesizer

NGF Vocoder Synthesizer

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Current state: Published

The NGF Vocoder Synthesizer modulates the incoming exciter signal with means of the control voltages derived from the incoming speech signal of the NGF Vocoder Analyzer. It is quite interesting to us other control voltage sources as well. Experiment!

NGF Vocoder speech input

NGF Vocoder Speech input

NGF Vocoder Speech input

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Current state: Version 0.9.5 published

The speech input consist of a microphone preamp, a line input and a tone control. It is the front end to the NGF Vocoder Analyzer.

NGF Vocoder pink and white noise source

NGF Vocoder white and pink noise

NGF Vocoder pink and white noise

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Current state: V. 1.1.0 published

Here is the noise module for my Vocoder project. This noise generator is not only useful for the vocoder but also for various other audio and acoustic measurements. The output can be switched between white and pink noise. The pseudo random noise is produced with the aid of a 31 bit shift register. Zero inhibit technique is used. This design follows closely the original from the Elektor magazine.

NGF Vocoder voiced / unvoiced detection

NGF Vocoder voiced - unvoiced detection

NGF Vocoder Voiced - unvoiced detection

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Current state: V 2.0.1 published

The voiced / unvoiced module detects if the incoming speech signal consists of more higher or lower frequencies. It switches the exciter signal between noise and carier signal.

NGF Vocoder slew / sample and hold / freeze

Links and Picture

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Current state: Planned

The slew rate of the control voltages coming from the NGF Vocoder Analyzer can be slowed down or/and "frozen". This stops the output signal of the NGF Vocoder Synthesizer following the input signal from the speech input and holds the last stage.

NGF Vocoder PSU

NGF Vocoder PSU

NGF Vocoder PSU

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Current state: Published

Provides the needed voltages and current. Linear stabilized.

Sitelist

2017 October

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