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The ConVertor general input and output map
Hello and thank you for purchasing a ConVertor synthesizer!
The ConVertor is a semi-modular, audio controlled, analog synthesizer. This
means
,
that it’s fully equipped to play a pal
e
t
t
e of sounds using a mono
audio signal alone, while still being able to communicate with modular synths
via CV signals. It generates its sound using a proprietary custom analog chip
called the Audio Controlled Oscillator (ACO100). The ACO chip has an analog
audio input at line level and is able to identify the fundamental frequency
(pitch) of a monophonic input audio. It then plays a square wave and a
sawtooth wave simultaneously at the pitch of the input audio (or optionally
at one of several discrete harmony intervals offset from the input audio) while
generating Con-trol Voltages (CV) representing pitch and gate. The gate’s
threshold is fixed at -48 dBu (post preamp). That means that as long as the
audio input is louder
than -48dBu the gate will remain “open” (+9V) and let
the synthesized sound through to the output. When the input audio drops
below -48dBu the gate
will be “closed” (0V) and the ACO’s output will be
silent. The pitch CV output of the ConVertor synth varies between 0V and 8V
at 1V per octave like other Eurorack compatible synths. The ACO is only one
part of this ACS (Audio Controlled Synth) and the following manual will
describe the rest of the parts and how they work with each other to create
musical sounds.
In the ConVertor all the audio inputs are accom
m
odated via mono
instrument jacks (TS) at the back panel and all the CV inputs and output
s
are
accom
m
odated via mono mini
jacks on the front panel. The only stereo
mini
jack is the gate/trigger output which share
s
a stereo mini
jack. Plug a
mono mini
jack to have the gate output, or use a stereo Y cable to split the
Gate CV from the L channel and the trigger CV ou
t
put from the R channel.
Pitch tracking / The ACS
The ACO chip is powered from 4.5V and its inputs and outputs are scaled
to 9V (to achieve 1V/oct pitch CV) inside the ACS.
Using the ACO, the
ConVertor completes the full blood stream of all modular synth essentials:
Pitch, ENV, gate and trigger CVs. The ACO can detect frequencies between
25Hz and 6kHz and will lock to the fundamental frequency as long as it’s
the strongest frequency in the audio. Some recommendations for better
pitch tracking include:
1.
Switch
ing
to the neck pickup, as the bridge pickup generally contains
much more treble (more energy in higher harmonics).
2.
Turn
ing
down the treble tone knob, if you have one.
3.
P
icking with your fingers instead of a pick if you can.
4.
P
lay
ing
as “cleanly” as possible - muting adjacent strings etc. The
ACO sometimes does some interesting things with polyphonic input but
make sure that
'
s what you are going for.
2 examples of Audio Controlled Synths usage
