Korg MICRO manual Editing a vocoder program, Structure of a vocoder program, Carrier, Modulator

Editing a vocoder program

Overview

A vocoder is a device that analyzes the character (the frequency response of each band) of a "modulator" signal (typically a human voice from a mic), and applies a filter with the analyzed characteristics to the "carrier" signal (typically a waveform produced by an oscillator), imposing a vocal character on that waveform, and making it seem as though the instrument is talking.

The microKORG contains an eight-channel vocoder (sixteen filters in pairs). In addition to simulating the classic vocoder sounds of the past, you can modify the character of the sound, or edit the level of each frequency band to create truly original vocoder sounds.

As shown in figure v0-1, a vocoder program consists of a carrier (the signal that is modified), a modulator (the signal that modulates the carrier), a vocoder section, effects, and arpeggiator.

Carrier

The carrier signal that is processed by the vocoder effect can be the microKORG's internal waveform selected by OSC 1 and NOISE, or a waveform that is input from AUDIO IN 2 (LINE jack). Suitable choices for the carrier waveform are sawtooth waves which contain a rich array of overtones, and the VOX WAVE which has a character similar to human vocal cords.

The volumes of OSC1/NOISE/AUDIO 2 IN are adjusted by the MIXER, and the combined signal is output to the Vocoder section.

Modulator

The signal that is input to the AUDIO IN 1 (CONDENSER jack or DYNAMIC jack) will be the modulator. In general, it is most common for a voice to be input to the modulator, but you can create unique effects by inputting rhythm sounds or other waveforms.

Vocoder section (Vocoder sec.)

This consists of two sets of 16 band-pass filters (ANALYSIS FILTER and SYNTHE- SIS FILTER) and the ENVELOPE FOLLOWER.

The audio signal from the AUDIO IN 1 jack (modulator) is input to sixteen

The structure of a vocoder program

bandpass filters (ANALYSIS FILTER), and the ENVELOPE FOLLOWER detects the volume envelope (time-variant change) of each frequency band.

Then, the signal from the internal tone generator or the AUDIO IN 2 jack (carrier) is input to the other set of 16 band-pass filters (SYNTHESIS FILTER), and processed by the envelopes detected by the ENVELOPE FOLLOWER to modulate the carrier with the features of the voice, producing the impression that the instrument or sound is talking (vocoder effect).

It is also possible to use the "FORMANT SHIFT" or "CUTOFF" parameters to change each frequency of the carrier band-pass filter. This will cause the frequency response curve to be raised or lowered while preserving the character of the modulator, and will dramatically affect the tone.

EFFECTS

The output from the vocoder section is sent to the modulation effect (MOD FX) ➝ delay effect (DELAY) ➝ equalizer (EQ).

For the modulation effect you can choose from three effects such as chorus. For delay, you can choose from three types of delay, including stereo delay. The equalizer is a two-band equalizer.

ARPEGGIATOR

The arpeggiator can be used to play a vocoder program.

This is a step arpeggiator with six arpeggio types.

Figure v0-1

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