Korg MMT RADIAS Owner's Manual page 14

Introduction
Vocoder (VOCODER)
A vocoder is available in every program The RADIAS' vocoder contains 16 stereo bands.
A vocoder applies the spectral character of the "modulator" (e.g., a signal received from the INPUT 2 jack)
to the "carrier" (e.g., the sound of a timbre or a signal received from the INPUT 1 jack).
The most popular way to use this is to input your voice from a mic connected to the INPUT 2 jack, creating
the impression that an instrumental sound is "talking."
Vocoder
Audio In 2
IntBus
Carrier InSrc1
Carrier InSrc2
Vocoder section (VOCODER)
The vocoder divides the audio spectrum into "bands". In the RADIAS, the vocoder uses 16 bands. There are
actually two sets of 16 bands; the first is used to analyze the tonal characteristics of one sound (the Modula-
tor), and the second set is used to apply the same characteristics to another sound (the Carrier). Each analysis
band contains a bandpass filter and an envelope follower. Each synthesis band contains a band pass filter
whose output is controlled by the matching envelope follower in the analysis band.
The modulator's audio signal is sent through the sixteen bandpass filters (the analysis filters), and the enve-
lope follower detects the volume envelope (change over time) for each of these frequency bands.
The carrier's audio signal is sent through the other set of sixteen bandpass filters (the synthesis filters), and
the envelope detected from each analysis filter is applied to each synthesis filter to modulate the sound, pro-
ducing the impression that the carrier sound is "talking" (the typical vocoder effect).
You can use the "FORMANT SHIFT" and "CUTOFF" parameters to shift the frequencies of the carrier band-
pass filters. This will raise or lower the frequency response while preserving the character of the modulator,
creating major changes in the sound.
Carrier (CARRIER)
A sawtooth wave (SAW) or other waveform rich in overtones is the best choice for the carrier. As the carrier,
you can use a combination of two sources (IN SOURCE 1 and IN SOURCE 2). One of the timbres can be se-
lected as IN SOURCE 1, and either an external input (the INPUT 1 jack) or an internally bussed sound (pro-
gram output) can be selected as IN SOURCE 2.
Modulator (MODULATOR)
Most commonly, you will input your voice as the modulator, but interesting results can also be obtained by
inputting a rhythm sound as the modulator waveform. You can use either an external input (INPUT 2 jack)
or an internal bus (program output) as the modulator.
There is also a Formant Motion function that lets you record Formant Motion Data to capture the moving
characteristics of a voice or other sound, and use this data to drive the vocoder.
8
Band16
Band1
ANALYSIS
FILTER
LEVEL
RESONANCE
SYNTHESIS
FILTER
LEVEL
CUTOFF (FC MOD)
FORMANT SHIFT
DIRECT
LEVEL
HPF
E.F. SENSE
LEVEL
ENVELOPE
FOLLOWER
FORMANT
MOTION DATA
MODULATOR
SELECT
Band. LEVEL PAN
HPF
To Carrier InSrc1 Timbre EQ