OPFXS V-Zero User manual

V-Zero
Monophonic Guitar Synthesizer
www.opfxs.com
User Manual
V-ZERO is a monophonic guitar synth based upon principles of subtractive synthesis. When a note is played the pedal
senses the pitch of the note and drives the on board oscillators. The generated signals can be mixed and processed in
various way by filtering and applying modulations.
Detailed description of every control
Oscillators:
OSC1 Waveform (4P rotary switch): Sine, Saw, Square, Triangle
OSC2 Waveform (4P rotary switch): Sine, Saw, PWM, Triangle
OSC1 Octave (6P rotary switch): 6 octaves range
OSC2 Octave (6P rotary switch): 6 octaves range
OSC 1-2 mix (pot): mixes OSC1 and OSC2
OSC 1 tune (pot): fine tunes OSC1 pitch
Mix and output:
Mix (pot) : mixes dry guitar signal with synthesizer signal
Volume (pot): output level
Output jack: a standard TS jack plug can be used or TRS for splitting the output. TIP of the jack carries synth +
dry guitar signal, RING carries dry signal. TIP signal is affected by MIX and VOLUME controls and can be
bypassed while RING signal is not affected by MIX or VOLUME and can't be bypassed. Split function permits to
drive two different amplifiers or routing the signal to different external devices.
Modulation:
LFO rate (pot): speed of the LFO
LFO depth (pot): depth of the LFO
VCA mod (tactile switch with blinking LED):
oshort press: LFO modulates VCA
olong press: instrument envelope modulates VCA
LPF mod (tactile switch with blinking LED) :
oshort press: LFO modulates LPF
olong press: instrument envelope modulates LPF
opressing CONTROL and LPF MOD together turns on or off “LPF frequency modulation from OSC2”
Pitch mod (tactile switch with blinking LED):
oshort press: LFO modulates pitch of both OSC1 and OSC2 (Control LED = green)
olong press: applies pitch portamento, portamento time can be set with LFO rate pot
opressing CONTROL and PITCH MOD together turns on or off LOW TRACKING FUNCTION
LFO Wave (tactile switch with LED) : when off the LFO wave is a sine wave, when on the LFO wave is a square
wave
opressing CONTROL and LFO Wave together switches between LFO groups (SINE/SQUARE or
SQUARE/SAW)

Footswitch:
Control (footswitch with bicolor LED):
owhen off the sustain is in STANDARD mode.
oa short press of the footswitch indicated by yellow LED turns on NOTE HOLD mode. When NOTE HOLD
mode is on the last note picked will play indefinetely until a new note is played.
oa long press (250 milliseconds) of the footswitch indicated by green LED turns on the LFO.
oa longer press (1 second) indicated by yellow/green LED turns on both NOTE HOLD mode than LFO.
oa very long press (5 seconds) will set and save GATE ON threshold based upon position of LFO rate pot.
opressing CONTROL and PITCH MOD together turns on or off LOW TRACKING FUNCTION
Bypass: standard true-bypass switch
Filter:
LPF (pot): low-pass filter. When full clock-wise the filter is flat. Turning LPF pot anti clock-wise the filter start
cutting high frequencies progressively.
Resonance (pot): controls the amount of resonance (Q parameter) of the filter. When full anti clock-wise
resonance is off.
Other infos:
V-ZERO works with any pick-up position but with some instruments open strings E tracks better with bridge
pick-ups.
V-Zero works with any type of guitar (6 strings, 7 strings etc). Different tunings of the instrument is also
possible.
CONTROL LED
HOLD
MODE
LFO
PITCH mod button
VCA mod button
LPF mod button
short press
long press
short press
long press
short press
long press
off
off
off
off
Portamento ON
(portamento time set
by LFO rate)
off
Envelope
modulation
off
Envelope
modulation
YELLOW (short
press of CONTROL)
ON
off
off
Portamento ON
(portamento time set
by LFO rate)
off
Envelope
modulation
off
Envelope
modulation
GREEN (250ms long
press of CONTROL)
off
ON
LFO
modulation
Portamento ON +
LFO modulation
(portamento time set
by LFO rate)
LFO
modulation
Envelope +
LFO
modulation
LFO
modulation
Envelope +
LFO
modulation
YELLOW/GREEN
(1sec long press of
CONTROL)
ON
ON
LFO
modulation
Portamento ON +
LFO modulation
(portamento time set
by LFO rate)
LFO
modulation
Envelope +
LFO
modulation
LFO
modulation
Envelope +
LFO
modulation
YELLOW/GREEN
blinking (5sec long
press of CONTROL)
LFO Rate sets GATE ON threshold and saves it

LOW TRACKING FUNCTION
When CONTROL and PITCH MOD are pressed at same time the LOW TRACKING FUNCTION is turned on or off. In LOW
TRACKING mode the pedal will only track lowest notes on fretboard leaving highest ones to pass through unaffected.
Pay attention that primary functions of CONTROL and PITCH MOD will be turned ON too, so you may need to press
CONTROL and PITCH MOD again to go back at previous status.
V-Zero memorizes the status of LOW TRACKING FUNCTION and will recall it at next power on. By default it’s turned
off.
LPF frequency modulation from OSC2
When CONTROL and LPF MOD are pressed at same time the Low Pass Filter is frequency modulated by a pitched
down version of OSC2. Basically this replaces LFO modulation (when LPF mod is short pressed). Modulation wave is
fixed as TRIANGLE but the pitch range can be selected with OSC2 Octave rotary switch. Modulation is proportional to
the note played (the lower the note pitch and lower frequency modulation will be).
Pay attention that primary functions of CONTROL and LPF MOD will be turned ON too, so you may need to press
CONTROL and PITCH MOD again to go back at previous status.
V-Zero memorizes the status of LPF frequency modulation and will recall it at next power on. By default it’s turned
off.
LFO groups
When CONTROL and LFO Wave are pressed at same time the LFO selection switches between Sine/Square and
Square/Sawtooth. This simply means that by pushing LFO wave button it will either switch between Sine (LED off) /
Square (LED on) or Square (LED off) / Sawtooth (LED on).
Pay attention that primary functions of CONTROL and LFO WAVE will be turned ON too, so you may need to press
CONTROL and LFO WAVE again to go back at previous status.
V-Zero memorizes the status of LFO groups and will recall it at next power on. By default Sine/Square group is
selected.
HOW to set GATE ON threshold and TRACKING range:
Long press CONTROL footswitch for 5 seconds until CONTROL LED starts blinking. Move LFO RATE pot to set GATE ON
threshold and LFO DEPTH pot to set TRACKING range. Play until you find the best setting to suit your playing. Once
finished press CONTROL once to store the settings and exit.
You can set both GATE and TRACKING at same time or just one of them. Parameters for GATE ON and TRACKING are
only updated when pots are moved, so if you only want to set GATE ON only move LFO RATE pot and leave LFO
DEPTH in position.
GATE ON threshold sets the point where gate turns on and signal from oscillators is output.

TRACKING range is used to set the response of V-ZERO all over the fretboard. Low settings improve tracking on low
frequency notes, high settings improve tracking on high notes. Just play with the control until you find the sweet spot
and balance between low and high notes tracking.
TIPS
Avoid playing close to the amplifier with pickups facing the speakers, this can make tracking of V-Zero less effective,
always play with pickups off-axis with respect to speakers or 180° from them.
Tech Specs:
The pedal works with standard 9V DC PSU negative center.
Current consumption min: 260 mA (all LEDs OFF)
Current consumption max: 290mA (all LEDs ON)
Input Impedance: 1M ohm
Output Impedance: 100 ohm