OPFXS V-Zero User manual

V-Zero
Monophonic Guitar Synthesizer
www.opfxs.com
User Manual
V-ZERO is a monophonic guitar synthesizer that operates on the principles of subtractive synthesis. Upon playing a
note, the pedal detects the pitch and activates the on-board oscillators. The resulting signals can be mixed and
processed in various ways through filtering and the application of 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: utilize a standard TS jack plug or TRS for output splitting. The TIP of the jack transmits both the
synthesizer and dry guitar signals, while the RING carries only the dry signal. The TIP signal is influenced by the
MIX and VOLUME controls and can be bypassed, whereas the RING signal remains unaffected by MIX or
VOLUME and cannot be bypassed. The split function enables the option to drive two distinct amplifiers or
route the signal to various external devices.
Modulation:
LFO rate: speed of the LFO
LFO depth: depth of the LFO
VCA mod:
oshort press: LFO modulates VCA
olong press: instrument envelope modulates VCA
LPF mod:
oshort press: LFO modulates LPF
olong press: instrument envelope modulates LPF
oPressing CONTROL and LPF MOD together toggles "LPF frequency modulation from OSC2."
Pitch mod:
oshort press: LFO modulates pitch of both OSC1 and OSC2
olong press: applies pitch portamento, portamento time can be set with the LFO rate pot
opressing CONTROL and PITCH MOD together toggles the LOW TRACKING FUNCTION
LFO Wave: when off the LFO wave is a sine wave, when on the LFO wave is a square wave
oshort press: toggles between Sine and Square waves
olong press: turns on Sawtooth wave

Footswitch:
Control footswitch with bicolor LED:
oOff: Sustain is in STANDARD mode.
oShort Press (Green LED): Turns on NOTE HOLD mode, sustaining the last note until a new one is
played.
oLong Press (250 milliseconds, Red LED): Turns on the LFO.
oLonger Press (1 second, Orange LED): Activates both NOTE HOLD mode and LFO.
oVery Long Press (5 seconds, Orange blinking): Enters Gate and Tracking select mode.
opressing CONTROL and PITCH MOD together turns on or off LOW TRACKING FUNCTION
Bypass: standard true-bypass switch
Filter:
LPF: low-pass filter. Fully clockwise the filter is off; counterclockwise progressively cuts high frequencies.
Resonance: Controls the amount of resonance (Q parameter) of the filter at cut-off frequency point.
Counterclockwise turns off resonance.
Other infos:
V-ZERO is compatible with any pickup position, but open strings E tracks better with bridge pickups.
V-ZERO works with any type of guitar (6 strings, 7 strings, etc.), and different instrument tunings are 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
GREEN (short press
of CONTROL)
ON
off
off
Portamento ON
(portamento time set
by LFO rate)
off
Envelope
modulation
off
Envelope
modulation
RED (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
ORANGE (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
ORANGE blinking
(5sec long press of
CONTROL)
Gate and Tracking adjust mode

LOW TRACKING FUNCTION
When you simultaneously press CONTROL and PITCH MOD, the LOW TRACKING FUNCTION is activated or
deactivated. In LOW TRACKING mode, the pedal exclusively tracks the lowest notes on the fretboard, allowing the
highest ones to pass through unaffected.
Please note that the primary functions of CONTROL and PITCH MOD are also activated in LOW TRACKING mode. To
return to the previous status, press CONTROL and PITCH MOD separately (not simultaneously).
V-Zero saves the status of the LOW TRACKING FUNCTION and will recall it upon the next power-on. By default, it is
turned off.
LPF frequency modulation from OSC 2
When CONTROL and LPF MOD are simultaneously pressed, the Low Pass Filter undergoes frequency modulation
through a pitched-down version of OSC 2. Essentially, this replaces LFO modulation (activated with a short press of
LPF MOD). The modulation wave is fixed as a TRIANGLE, but the pitch range can be chosen using the OSC2 Octave
rotary switch. The modulation is proportional to the note played, meaning the lower the note pitch, the lower the
frequency modulation.
Please be aware that the primary functions of CONTROL and LPF MOD are also activated in this mode. To revert to the
previous status, press CONTROL and PITCH MOD again separately.
V-Zero retains the status of LPF frequency modulation and will recall it upon the next power-on. By default, this
feature is turned off. off.
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.
EXPRESSION PEDAL ASSIGN FUNCTION
You can assign almost every knob and rotary switch (with exception of Dry/synth Mix, Level and Wave rotary
selectors) to an expression pedal.
Connect an expression pedal to EXP jack with a TRS jack cable:

To make the assignment:
1) press ASSIGN button (left side RED LED will turn ON)
2) move the desired control you want to assign (left side RED LED will turn OFF)
To clear assignment long press ASSIGN button for more than 2 seconds, left side RED LED will blink fast to confirm
that assignment has been cleared.
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.
LEFT SIDE bi-color LED
This LED is used both to check the EXPRESSION assignment/erase process and check when MIDI message is received.
When a MIDI message is being received the GREEN LED will turn ON.
MIDI
Note ON and note OFF messages
V-Zero detects note ON and note OFF messages, you can play V-Zero with an external MIDI keyboard.
Control Change –CC
With control change messages you can modify every V-Zero parameters and turn on some hidden functions.
Some V-Zero parameters have to be assigned to MIDI before being able to control them via MIDI.
For example, take the LFO Speed, to be able to control it via MIDI you need to set CC number “1”(LFO Speed to MIDI)
to “1”. Once the LFO SPEED to MIDI is set to “1” the LFO Speed control knob on V-Zero will stop working cause it’s
now handled by MIDI and you can now send to CC number “0” the data from 0 to 127 to change LFO Speed.
Example for LFO Speed:
1) Send to CC number “1” the CC data “1”. LFO Speed now is assigned to MIDI
2) Send to CC number “0” the CC data from 0 to 127 to change LFO Speed
3) To clear the MIDI assignment send to CC number “1” the CC data “0”. Now LFO Speed is set by V-Zero
LFO Speed knob.
Example for LFO Depth:
1) Send to CC number “3” the CC data “1”. LFO Depth now is assigned to MIDI
2) Send to CC number “2” the CC data from 0 to 127 to change LFO Depth
3) To clear the MIDI assignment send to CC number “3” the CC data “0”. Now LFO Speed is set by V-Zero
LFO Depth knob.
Basically all the parameters with “to MIDI” mean that sending a “1” will turn on MIDI assignment and sending a “0”
will turn off MIDI assignment for that specific parameter.

MIDI messages table
CC number
CC data
Description
Info
0
0-127
LFO Speed
1
0-1
LFO Speed to MIDI
2
0-127
LFO Depth
3
0-1
LFO Depth to MIDI
4
0-4
LFO Wave Select
0: Sine 1: Square 2: Saw 3: Triangle 4: PWM
5
0-1
LFO Wave Select to MIDI
6
0-1
LFO SAW wave Invert
Invert the direction of the LFO sawtooth wave
7
0-127
LFO PWM duty cycle
8
0-1
OSC 1&2 Mix to MIDI
9
0-127
OSC 1&2 Mix
10
0-127
Instrument Input Level
11
0-1
OSC 1 Wave Select to MIDI
12
0-3
OSC 1 Wave Select
0: Sine 1: Saw 2: PWM 3: Triangle
13
0-1
OSC 2 Wave Select to MIDI
14
0-3
OSC 2 Wave Select
0: Sine 1: Saw 2: PWM 3: Triangle
15
0-1
OSC 1 Octave Select to MIDI
16
0-5
OSC 1 Octave Select
17
0-1
OSC 2 Octave Select to MIDI
18
0-5
OSC 2 Octave Select
19
0-127
OSC 1 PWM duty cycle
20
0-127
OSC 2 PWM duty cycle
21
0-1
OSC 1 Tune to MIDI
22
0-127
OSC 1 Tune
23
0-11
OSC 1 Tune Notes
24
0-11
OSC 2 Tune Notes
25
0-1
LPF to MIDI
26
0-127
LPF
27
0-1
LPF Resonance to MIDI
28
0-127
LPF Resonance
29
0-1
LPF Modulation switch to MIDI
30
0-2
LPF Modulation switch
31
0-1
LFO -> VCA to MIDI
32
0-1
Envelope to MIDI
33
0-1
LFO -> VCA toggle
34
0-1
Envelope source select
35
0-1
LFO -> VCO to MIDI
36
0-1
LFO -> VCO toggle
37
0-1
Portamento to MIDI
38
0-1
Portamento Toggle
39
40
41
0-1
Master Tune to MIDI
42
0-127
Master Tune
43
0-1
OSC 1 to Voice 2
44
0-1
OSC 2 to Voice 2
45
0-1
HOLD Voice 2
46
0-127
Synth Level
47
0-1
Control Footswitch HOLD to MIDI
48
0-1
Control Footswitch HOLD
49
0-1
Control Footswitch LFO to MIDI

50
0-1
Control Footswitch LFO
51
0-127
Portamento
52
0-20
EG Attack Time
Attack time of envelope generator from 1ms to 2001ms in steps of
100ms
53
0-19
EG Release Time
Release time of envelope generator from 201ms to 4001ms in steps of
200ms
54
55
56
57
58
0-1
LFC -> EG
Low frequency clock triggers the envelope generator
59
0-127
LFC Rate
Frequency of low frequency clock
60
0-127
LFC duty
Sets duty cycle of the clock from 1% to 99%
127
0-16
Set MIDI input channel
1-16 for the channel, 0 for listening to all channels (default mode). This
parameter is saved in V-Zero memory and loads at power up.
PURE DATA MIDI PATCH
If you have a USB MIDI Controller you can download our Pure Data patch to start playing with V-Zero via MIDI from
your computer. To run the V-Zero Pure Data patch you need to install Pure Data, go here to download Pure Data.
MIDI LED
This LED flashes in GREEN when a MIDI message is received.
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