Program structure
3
Vocoder program
A vocoder applies the spectral character of the “modulator”
(e.g., a signal received from the AUDIO INPUT 2 jack) to the
“carrier” (e.g., a signal received from the AUDIO INPUT 1
jack).
The most popular way to use this is to input your voice from
a mic connected to the AUDIO INPUT 2 jack, creating the
impression that an instrumental sound is “talking.”
Vocoder section (VOCODER)
The vocoder divides the audio spectrum into “bands”. In the
RADIAS program, 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 Modulator), 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 envelope
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, producing the
impression that the carrier sound is “talking” (the typical
vocoder effect).
You can use the
Formant Shift
and
Frequency
Offset
parameters to shift the frequencies of the carrier bandpass
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 Source1 and In
Source 2).
As the In Source1 you can use the mono-mixed signal from
the output of the amp section (the signal before it is sent to
the insert effects). In Program mode, the synth sound of the
program is fixed as In Source 1.
As the In Source 2 you can use an external input (e.g.,
AUDIO INPUT 1 jack) or the AUX bus (insert effect output).
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 (AUDIO INPUT 2 jack) or AUX bus
(an external input processed by an insert effect, or a
program sound such as rhythm) 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.
Pan
Band Level
Analysis
Filter
Envelope
Follower
Synthesis
Filter
Resonance
Frequency Offset
Formant Shift
Env. Follower sens
Band1
Band16
In Source2
In Source1 (Synth)
LEVEL Modulator
Carrier
LEVEL
Modulator
Direct Mix
Modulator
High Mix
HPF
Modulator
Select
Audio Source
AUX Bus
Formant
Motion data
To EQ
Vocoder
Vocoder on
Vocoder program
Vocoder
Carrier
Modulator
Audio In 1
Audio In 2
To Mixer/Effect
EQ
Synth
Input Source
Formant Motion Data
Analog Input 1/2
S/P DIF L/R
FireWire L/R (option)
AUX Bus
AUX 1/2
AUX 3/4