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LIGHT PEDAL IS THE WORLD’S FIRST ANALOG OPTICAL SPRING
REVERB SYSTEM THAT USES INFRA-RED OPTICAL SENSORS TO
HARVEST THE FULL TIMBRAL AND HARMONIC RANGE OF A
SPRING REVERB TANK
GCA was founded with a single mission in mind - to help spark a new
wave of originality and innovation in the field of music technology
and audio electronics. We are constantly searching for new ways to
create and manipulate sound, and we work hard to produce audio
tools of the highest quality.
The LIGHT Pedal combines all the best features of a classic spring
reverb with an innovative optical sensor system and a powerful effects section that opens up countless new types of reverb textures
and sounds never heard before.
HOW IT WORKS
The LIGHT Pedal’s central component and main source of sound is
a traditional spring reverb tank, consisting of three major elements:
INPUT TRANSDUCER
(spring exciter)
Much like a speaker driver,
the Input Transducer converts audio
signal into mechanical impulses,
thus creating vibrations along the springs.
The reverb tank’s sound depends largely
SPRINGS
on the springs’ length and their tension.
The Output Transducer completes
the circuit by converting the mechanical
impulses from the vibrating springs
back into audio signal.
OUTPUT TRANSDUCER
(pickup)
There can be a lot of complexity in the movement patterns that
occur in the spring during the reverberation process, especially near
the input transducer.
However, due to the spring elasticity, by the time vibrations travel to
the output transducer we are mostly hearing the spring’s own resonant frequencies, which is why all spring reverbs have such a particular jangly, metallic sound.
The LIGHT Pedal’s spring output (spring knob) offers a classic high
quality spring reverb sound with the option to adjust the spring “drip”
(drive knob) and the output signal’s tone (tone knob).
OPTICAL SENSORS
To capture the full range of the spring’s
movements, the LIGHT Pedal uses multiple
sets of special Infra-Red optical sensors that
act as photoelectric pickups. Each set of IR
sensors is directed at a different point on the
moving spring’s surface, thus giving access
to a whole range of additional reverb textures
and tones.
The optical sensors are also able to detect
much finer movements than the output transducer which makes longer decays possible,
as well as a much wider frequency response,
including subharmonics and overtones.
Additionally, some amazing modulation and
tremolo effects can be achieved by scrolling
through the optical sensors or by switching
them on and off (optical effects).
CONTROLS
MIXING DRY SIGNAL WITH REVERB
The LIGHT Pedal offers three separate volume
levels for your dry signal, for the traditional
spring signal (produced by the spring tank’s
output transducer) and the optical signal.
The Tone control will affect both the spring
and the optical signals while leaving the dry
signal as is.
When using sweep or trem optical modes, you can either use the
optical signal on its own, or combine it with the spring tank’s output
for a multi-layered effect.
For example: fast optical sweep + constant spring tank reverb.
DRIVE
Determines the amount of signal being sent
into the spring tank in all playing modes.
When turned all the way down there will
be no reverb at all.
Placing it at 12 o’clock is the safe bet.
When maxed out, the spring tank will start
gently breaking into distortion, as well as
affecting the textures of all optical signals.
GATE
Gate is also a global parameter that affects both reverb outputs
and all effect modes. When the Gate knob is at 12 o’clock it is
neutral and does not affect the LIGHT Pedal’s sound.
To the left, all reverb is
gated - the louder you
play, the more reverb. As
soon as the instrument’s
signal stops, the reverb
To the right, all reverb
sounds are ducked reverb levels are reduced in proportion to
your playing dynamics.
cuts out.
EFFECT MODES + CTRL KNOB
The 6-way selector knob gives you
access to different effect modes.
The first three (optics, sweep, trem) are
optical effects, whereas the reflect,
feedback and harmonic effects occur
within the spring tank itself.
1 OPTICS
Lets you choose a specific
combination of optical sensors.
Use the CTRL knob to select
different optical sensor pairs
(opt. calib).
Each sensor combination will have a slightly different texture and
timbral quality, as well as a different resonant frequency. As a
general rule, moving towards the middle of the spring will pro-
duce warmer and richer reverb textures.
2 SWEEP
CTRL knob adjusts the rate of
the sweeping motion.
Sweep is a modulation mode
that rhythmically scrolls back
and forth through the different
optical sensor pairs.
Use the CTRL knob while
holding down the pedal’s
Footswitch to adjust the
sweep modulation curves.
3 TREM
CTRL knob adjusts the tremolo
This is an optical tremolo
mode, that turns the optical
sensors on and off rhythmically.
The tremolo effect can also
apply to the spring tank output
if the spring output (1) level is
set equal to or higher than the
optical output (2) level.
4 REFLECT
This mode is a lo-fi delay that
rate.
CTRL + Footswitch calibrates
the optical sensor pairs.
1
2
Spring
trem
Opt
trem
CTRL knob adjusts the delay
rate.
Both
will send the instruments
signal back into the reverb
tank several times.
5 FEEDBACK
Feedback mode sets the
spring tank into self-oscillation, which lets you create
various drones and
“wall-of-sound”-type distorted
reverb pads. Lots of potential
uses when paired with an expression pedal, or when in
CTRL + Footswitch calibrates the
optical sensor pairs.
Use the CTRL knob to adjust the
feedback frequency.
CTRL + Footswitch calibrates
the optical sensor pairs.
Momentary mode.
6 HARMONIC
In harmonic mode the spring
tank is driven by a special circuit
designed to produce a lot of
overtones and harmonics. Think
of it as a shimmer reverb effect,
but only produced naturally
within the spring tank.
Use the CTRL knob to adjust
the shimmer effect’s central frequency.
CTRL + Footswitch calibrates
the optical sensor pairs.
GATE + EFFECT CTRL
In any one of the 6 effect modes, you can make the CTRL value react
to the instrument’s input signal. This is achieved by turning the Gate
knob while pressing & holding the pedal’s Footswitch .
For example:
1
2
3
Set the pedal into trem mode
Set the CTRL knob to around 12 o’clock
Press and hold the footswitch. While holding the
footswitch turn the Gate knob all the way down.
Now the tremolo rate will slow down as soon as input signal is
detected.
Alternatively - you can make the tremolo rate speed up with each
strum by pressing & holding the footswitch and turning the
Gate knob up.
This principle applies to all effect types, including Optical mode,
where footswitch + Gate knob can make the optical sensor pairs
move forward or backwards based on the incoming audio signal.
Note - if the CTRL value for an effect is already maxed out (or at a
minimum value), the footswitch + Gate knob will only be useful in
the opposite direction.
EFFECT COMBINATIONS
As mentioned earlier, the first three effect modes (optics, sweep,
trem) are so called optical effects, whereas reflect, feedback and
harmonic effects are created directly in the spring tank.
The LIGHT Pedal allows you to combine any one optical effect with
either one of the remaining three spring tank effects. For example,
let’s combine sweep and reflect modes:
1
Set the pedal to sweep mode and adjust the modulation
rate with the CTRL knob.
You can also set up a dynamic rate value using gate knob &
footswitch (see above).
2
3
Press & hold the footswitch and set the effect knob to Reflect.
Now sweep and reflect modes are combined. The CTRL
knob will apply to the currently active effect mode (reflect),
and you can set up a different gate + footswitch parameter
for the reflect mode.
Similarly, you can combine tremolo and harmonic modes, optical
and feedback modes and explore other interesting combinations.
To exit the multi-effect mode, simply adjust the effects selector
knob to a different effect mode. All saved parameters, such as
CTRL and footswitch + gate (dynamic effect) values will be lost.
TAILS LATCH
With TAILS switched ON,
you will be able to smoothly
turn the LIGHT Pedal off,
while preserving the re-
When LATCH is ON the
LIGHT Pedal’s footswitch will
act as a standard latching
on/off footswitch.
verb’s natural decay trails.
When switched OFF, the
reverb trails will be cut as
soon as the LIGHT Pedal is
switched off.
When LATCH is OFF the
LIGHT Pedal’s footswitch will
act as a momentary effect
switch.
For example - set your LIGHT Pedal to feedback mode, turn the
CTRL knob all the way up, and use the momentary footswitch to add
occasional bursts of feedback into your solos.
in
shock sensor
off soft hard
9V DC
exp
out
500mA
SHOCK SENSOR
As we all know, spring reverb units can be sensitive to shaking stages,
heavy stomping and earthquakes.
That is why the LIGHT Pedal features a special shock-sensor mode!
Powered by an accelerometer chip, the LIGHT Pedal can detect sudden
physical impact (measured as G force) and instantly shut off the wet
signal output, as soon as a blow or a shaking motion is detected!
The sensor offers three levels of shock protection: Off, Soft and Hard.
INPUTS & OUTPUTS
The LIGHT Pedal is a MONO pedal with a ¼’ jack INPUT and OUTPUT.
The LIGHT Pedal also features an expression input for ¼’ TS and TRS
jacks, and is compatible with all expression pedal types, as well as CV
signal (active range to +3.3 V).
0
By defaultthe expression input is assigned to the CTRL knob.
You can assign the expression control to any one of the following knobs
- spring, optical, drive or gate. For example, to assign the expression
pedal to the drive knob, unplug the LIGHT Pedal’s power supply, press &
hold the LIGHT Pedal’s footswitch and plug the power back in. A flashing
light will indicate that the Pedal is in exp. assign mode. Now simply turn
the desired knob (drive) and it will be assigned to the expression pedal.
TECHNICAL SPECIFICATIONS
Product Dimensions
Product Weight
Spring Tank
Input Impedance
Max Input Level
Output Impedance
Max Output Level
Peak Power Consumption
WLH 105 x 190 x 40 mm (4.1 x 7.5 x 1.6 in)
1060 g (2.3 lbs)
3 Springs Type, 100 mm
1 MΩ
+6.8 dBu
100 Ω
+6.8 dBu
4 W
Mean Power Consumption
Power Requirements
0.9 W
500 mA min
9 V DC
center negative 2.1 x 5.5 mm plug
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