Mode 7: Single channel freeze spectrum/capture transient vocoder
The vocoder makes it possible to build a spectrum with even more than 30 harmonic frequencies using a proper
input signal to the microphone (i.e. also other than human voices). Mode 7 has been added in order to be able to fix
a desired spectrum using the frequency analysis filter bank of the vocoder. It allows three different operations:
.
1
Freeze spectrum: When turning the mode selector either from Mode 6 or Mode 8 to Mode 7, the instantaneous
spectrum is frozen and can then be played and modified using mostly the same controls as in Mode 6.
.
2
Transient capture: a duration of 1.1 seconds of the input signal can be captured, vocoded, and then played back
using the live vocoder controls, and additionally with variable playback speed.
.
3
Some typical vocal and special effect transients are stored in the non-volatile memory and can be played
readily.
In this mode, the controls and
envelope input
functions are equal to the ones in Mode 6, with three exceptions:
1.
Because we now have stored data, its replay speed can be varied. The replay speed is controlled using
sliders 9 and 10. When
Slider 9
is off (= fully down), raising
Slider 10
will slow down the replay, and
when
Slider 9
is not off, raising
Slider 10
will speed up the replay. As you can hear, because in the
vocoder the sound parameters are isolated, the replay speed does not change either the pitch or the spectral
envelope (as would be the case if the raw original sound sample would be played back).
2. Slider 1
is used for controlling the capture and storage operations. Thereby the automatic/manual noise
control stays only manual in this mode.
3. Envelope input 3
is used for determining if a stored transient is played or a new transient is captured.
The following instructions explain the three use cases:
1. Freeze spectrum
: If you want to freeze a spectrum coming from Mode 6 or 8, then keep Slider 1 at
the middle position. Sing a desired vowel continuously while simultaneously switching the mode
selector from 6 or 8 to 7. Now the spectrum at the switching moment will be frozen and you can
continue playing in the same way as in Mode 6 (except that no microphone is needed any more).
Leave e
nvelope input 3
open or grounded.
2. Transient capture
: Keep the three position toggle switch in the middle position (
gate off
) and leave
e
nvelope input 3
open or grounded. Then move Slider 1 to its lowest position. Now the vocoder
works in the real time mode, as explained in Mode 6, and you can listen to the signal from the output
jack. The transient capture starts when raising Slider 1 upwards. The distance from the “off” position
now determines the capture sensitivity. Sensitivity increases with increased distance, i.e. when the
slider is close to the bottom position, a large amplitude is needed for triggering the capture, and when
close to the middle position, even a very small signal in the microphone will trigger. So try to
synchronize your speech or other signal with the slider movement, or just try with a suitable sensitivity
setting and loud enough voice to automatically start the recording.
A duration of 1.1 seconds is always recorded. If you want the transient to die away when played, then
stay silent at the end of this duration, otherwise the last remaining spectrum is sustained after the
transient when played longer than 1.1seconds. Playing the transient needs to have the toggle switch in
the
gate on
position, so that each keyboard key activation starts the transient. Please check that your
Midi interface has the gate signal connected to the
gate
input. The transient is volatile, so it will not be
stored over power down.
3. Stored vocoder transient playback
: The vocoder has 26 fixed transients stored in the nonvolatile
memory, containing both human voice and musical instrument spectra. These are 1.1s each. Reading
the transients is done in the following way:
Keep the toggle switch in the
gate on
position. Connect e
nvelope input 3
to
D.C. Out
. Now
rotating
adjust 1
CW causes the transients toggle one item forward each time the gate signal rises, i.e.
when any keyboard key is pressed. Correspondingly rotating it CCW toggles them backward. The
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