xLPG VariPass Gate Effect

Any LPG – is a Low pass gate effect, which can be used to produce various tuned percussion sounds such as a congas, bongos, steel drums, marimba, plucks, etc. LPG processes the original signal using the control trigger signal (which opens the gate). This is a legendary effect known in the modular world as the “Buchla Bongo” sound effect and was a very popular sound-design tool used by the pioneers of electronic music. The effect continues to be used today by modern electronic musicians using Eurorack/Buchla modules. LPG also enables the creation of natural-sounding decays.
xLPG is not just a simple LowPass Gate, it is a VariPass Gate effect which can be used as a Multimode Gate with various filter modes (LowPass Gate, BandPass Gate, HighPass Gate, State-Variable Gate and also Comb Gate effect). This provides an impressive selection of alternatives to classic LPG.

Vactrols (optocouplers) lie at the heart of the LPG and help to create natural sounding decay. xLPG includes 9 internal types of Vactrols, each with their own individual characters.
xLPG can be used as both a simple VCA (amplifier) or as a multimode filter (VCF). Its main use however is as a very unique Vactrol based VariPass effect with 9 custom Vactrol modes.
The envelope section includes additional controls for adjusting Attack, Hold and Release parameters. These can be used to further increase flexibility in forming the processed signal. 

This however is not all, the device includes four Gate modes:

- VPG (VariPass Gate). When the OFFSET knob is set to 0% the gate is fully open. When set to 100% the gate is fully closed. In this mode, as the OFFSET knob is dialed from 0-100%, the filter opens and at the same time the VCA increases the Vactrol processed signal to 0dB.
- MDF (Mid Feedback Gate). This mode works in the same way as the VPG mode, but adds decay feedback when the OFFSET knob is set near to 50%.
- FOG (Full Open Gate). In this mode the device works in an inverse fashion to VPG mode. When the OFFSET knob is set to 0% the gate is fully closed. When set to 100% the gate is fully open. Dialing the OFFSET knob from 0-100% results in a linear increase of the main signal coupled with a corresponding reduction of the Vactrol-processed signal.
- VPGQ (VariPass EQ). This mode adds only EQ charatcers of the Vactrols (not creating decay).
xLPG is a modern effect processor which can be used to create natural sounding rhythmic percussive sounds. Experimenting is highly encouraged.
LPG processes signals only when it recieves an active control signal. This can be done in three ways: Using CV Trigger input (like a real modular), by Sidechain audio input or by the TRIGGER button. The main parameter of the device is the OFFSET knob which controls the Filter, VCA or LPG level. When in BOTH mode both filter and VCA operate at the same time. This is what is usually referred to as a LowPass Gate.
xLPG, however, is more than just a simple LowPass Gate. It is a Varimode Gate effect which includes 9 vactrol models.
This Modern Vari Pass Gate effect is unique and will be a magical and powerful addition to your Reason Rack.

MODE SECTION

BOTH: The default setting for xLPG. This setting engages both the VCA (amplifier) and VCF (filter) modes at the same time. The VCA controls the main signal level. The control signal can be generated by CV Trigger input, Sidechain audio input, or by the Trigger button. The filter works by default in LowPass 12dB mode (emulating LPG). Other filter types are also selectable. These can create variative functionality of xLPG as a Vari Pass Gate effect.
OFFSET controls the filter Cutoff and amplifier level at the same time
FILTER (VCF): In this mode the VCA (amplifier) is disabled and the device functions as a Multi-mode Filter.
VCA: In this mode the device functions as a traditional amplifier with a range from silence (infinity) to 0dB. The control signal (CV Trigger input, Sidechain input or Trigger button) sets the main signal level affected by the Vactrol decay and Envelope curve.

ENVELOPE CONTROL

The envelope section includes additional controls for adjusting Attack, Hold and Release parameters. These can be used to further increase flexibility in forming the processed signal

VACTROLS

A Vactrol is a resisitive opto-isolator, or photoresistive opto-isolator.
The simplest form of Vactrol is an analogue optoisolator (Optocoupler). Optocouplers are made up of a light dependent sensor (LDR) and a light source (LED), housed within a light-isolated casing. Increasing the LED brightness causes a decrease in the LDR resistance.
No two Vactrols will sound exactly the same due to variations in distancing between the LED and LDR, different LED brightness etc. xPLG includes 9 types of custom vacrols / optocouplers

Vactrols / Optocouplers work in the following 3 modes: VariPass Gate, Filter and VCA.
In Filter Mode the Vactrol emulates a Vactrol-based VCF.
In VCA mode the Vactrol emulates a vactrol-based VCA.

FILTER

When the device is running in either BOTH or FILTER modes the incoming sound is affected by the filter. In VCA mode the filter is disabled.
The filter is set by default to LowPass 12dB/oct, which emulates an LPG. xLPG offers 9 internal filter types which add new possibilities for creating not only LowPass Gate effects, but also modes such as BandPass Gate, Comb Gate, etc.

CONTROL SIGNAL SOURCE

Control signals work in pairs with the main signal going through the Vactrol which creates the natural sounding decay. xLPG can recieve Control signals from any one of the following:

SIDECHAIN INPUT and CV TRIGGER: The CV TRIGGER Input can be used to initialise the control signal.
The Sidechain audio inputs can also convert incoming audio signal to the control signal. Sidechain inputs and CV Trigger input can be found on the rear panel of the device. Beside the Sidechain Inputs is a Sidechain Intensity knob (this is used to control the level of the sidechain input).

TRIGGER BUTTON and CV TRIGGER: The CV TRIGGER Input can be used to initialise the control signal.
Using this mode disables the Sidechain Input. The TRIGGER button can also be used to initialise the control signal.

DISABLED: This disables the control signal at all inputs (Sidechain Input, Trigger button and CV Trigger input) and preserves only the main signal. The VCA mode controls the level of the main signal. The Filter mode operates as normal.
In BOTH mode the selected filter operates in combination with the VCA. That is to say, they work together as a Vactrol-based filter with VCA level control (without the need for control signal triggering)

GATE MODE

GATE MODE select the principial scheme of the Gate opening.

VPG (Vari Pass Gate): Default mode. When the OFFSET knob is set to 0% the gate is fully open. When set to 100% the gate is fully closed.
In this mode, as the OFFSET knob is dialed from 0-100%, the filter opens and at the same time the VCA increases the Vactrol processed signal to 0dB.
The trigger works regardless of whether the gate is open or closed

MFD (Mid Feedback): This mode works in the same way as the VPG mode, but adds decay feedback when the OFFSET knob is set near to 50%.

FOG (Full open gate): In this mode the device works in an inverse fashion to VPG mode.
When the OFFSET knob is set to 0% the gate is fully closed.
When set to 100% the gate is fully open.
In this mode, dialing the OFFSET knob from 0-100% results in a linear increase of the main signal coupled with a corresponding reduction of the Vactrol-processed signal.

VPGQ (Vari Pass Equalisation): This mode adds only equalisation characteristics of the Vactrols (and not creating decay).