PROC

Triple Voltage Processor

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Proc front panel

Overview

Proc is a triple voltage processor and summing amplifier, providing continuous control over attenuation, inversion, and bias of each of the three channels. It's an essential tool in any modular video system, enabling a long list of creative effects. These include, but are not limited to:

Duplicate (buffered multiple)
Generate static voltages
Pick colors in RGB or YIQ component spaces
Attenuate or amplify values
- amplitude, gain, contrast, white point
Raise or lower values
- bias, offset, brightness, black level, pedestal
Add
Subtract
Mix
Invert
Convert between unipolar and bipolar
Convert RGB to luminance
Colorize luminance or RGB

Legacy

Proc is the third generation of this module concept. It was preceded by the Visionary series Triple Voltage Processor and the Expedition series Passage modules.

Key Specifications

Parameter	Value
Mounting Width	8 HP
Power Consumption	12V @ 110 mA
Power Connectors	16 pin EuroRack ribbon, 2.1mm DC barrel
Video Sync	None
Included	DC barrel power cable, EuroRack power cable

System Integration Advice

Proc is a fundamental component of any LZX-compatible modular system. It's impossible to overstate the importance of Proc as a general purpose processing tool. Almost every patch uses Proc in some way. It's the "Swiss Army knife" of modular video, performing a wide array of creative and utilitarian functions.

The nature of Proc is so foundational, and its functions so essential, that any system except the very smallest will ultimately need more than one Proc. In modular audio, it's often said that "you can never have enough VCAs". In modular video, you can never have enough Procs. A reasonable rule of thumb is that a system will need one Proc per approximately 100 HP of space.

:::tip Proc pairs particularly well with modules capable of handling bipolar signals, such as Swatch. The I and Q color components range between -0.5 and +0.5 volts. Proc can bias the color components up or down, to or from the unipolar range of 0 to +1 volts. This allows I and Q to be processed by modules that can only handle unipolar signals. :::

Controls & Connectors

Proc consists of three identical channels. The inputs to each channel are arranged in rows 1, 2, and 3. Rows are color-coded red, green, and blue, respectively, but this is only for convenience. Any video or control signal can be patched into any input.

Each channel has two input jacks, in columns A and B.

Each channel has two potentiometer knobs, Gain and Bias.

Proc controls and connectors

The inputs are internally self-normalled to cascade from top to bottom. A signal patched into a top row input flows to the other inputs in that column.

Proc internal normalling

Operation

Each channel sums the A and B inputs, plus an internally generated static voltage C. Input A is added without alteration, so it's also known as the Thru input. Input B is multiplied by its corresponding Gain knob before being added. It's also known as the In input.

Proc block diagram Function block per channel

The output can be expressed the sum of jack A, plus the product of jack B and potentiometer B, plus potentiometer C.

$$ jA + (jB \cdot pB) + pC $$

Proc formula

Gain

Each Gain potentiometer, labeled B, can attenuate or invert the value of the signal at the channel's B input. At the 12 o'clock position, the signal is multiplied by zero, so none of the B input signal is added to the output. Turning the knob clockwise to the right of 12 o'clock increases the amplitude up to the full value of the input signal. Turning the knob counterclockwise to the left of 12 o'clock inverts the signal, sending it into the negative voltage range.

Bias

Each Bias potentiometer, labeled C, adds a static voltage to the output. At the 12 o'clock position, the voltage is zero, so no offset is added to the output. Clockwise rotation to the right of 12 o'clock adds a voltage, biasing the output up. Counterclockwise rotation to the left of 12 o'clock subtracts a voltage, biasing the output down.

Proc gain and bias

Voltage range

Proc can handle input signals that add up to a value range from -2 to +2 volts without distortion. Note that the internally generated bias voltage C is also an input signal, even though there's no C input jack.

Proc can also output signals in that same range, -2 to +2 volts. This allows for bidirectional conversion between unipolar signals that are only positive, and bipolar signals that can be positive or negative.

:::note As the animation above illustrates, negative voltages are outside the visible range of LZX video. Some modules can handle bipolar signals with negative voltages, but an encoder such as ESG3 can only accept values in the range from 0 to +1 volts. Any value below zero will simply be ignored by the encoder. :::

Self-patching

By sending the output of one channel to the input of another, we can create more complex effects by combining more than two signals. For example, if we patch output 1 to input A2, and output 2 to to input A3, we can combine up to four signals with the remaining inputs of A1, B1, B2, and B3.

Video Tutorials

3 Patches for Proc
presented by Johnny Woods

LZX Proc: Video Synth Tools & Techniques
presented by Aaron F. Ross

Example Patches

Buffered multiple

Proc buffered multiple

Static voltage

Proc static voltage generator

RGB color picker

Proc RGB color picker

{/* RGB color picker Proc RGB color picker */}

Bias / brightness

Proc bias

Add

Proc addition

Amplify / increase contrast

Proc contrast

Subtract

Proc subtraction

Invert

Proc invert

Mixer: three variations

Proc modulation mixer

Priority layering

Proc + DSG3 priority layering

Installation

Proc installation

Requirements

EuroRack enclosure
12V DC or EuroRack power supply
2.1mm DC barrel power cable or a EuroRack power cable (both options included)
Four M2.5 x 6mm mounting screws, or screws provided or specified by the enclosure manufacturer
#1 Phillips head screwdriver, or hand tool provided or specified by the enclosure manufacturer

Procedure

Power off and disconnect the EuroRack enclosure's power supply and any attached DC adapters.
Connect either the EuroRack Power Cable or the DC Barrel Power Cable to the module. Do not connect both Eurorack and DC Barrel power.
Ensure that no mounting screws are in any holes in the area where you wish to mount the module.
Carefully test fit the module with its attached power cable in the open space in the EuroRack enclosure. If it is obstructed by the enclosure or any internal assemblies, abort this procedure.
Connect the disconnected end of the power cable to the power supply.
Mount the module to the EuroRack rails using all mounting holes.
Store the unused cable along with the product box in a safe location.
Power on the EuroRack enclosure and start patching.

Full Specifications

Connectors

Controls

Proc: labeled front panel controls

Jack	Function
J1	A1 in (thru)
J2	B1 in
J3	Channel 1 out
J4	A2 in (thru)
J5	B2 in
J6	Channel 2 out
J7	A3 in (thru)
J8	B3 in
J9	Channel 3 out

Potentiometer	Function
P1	Channel 1 B gain
P2	Channel 1 C bias
P3	Channel 2 B gain
P4	Channel 2 C bias
P5	Channel 3 B gain
P6	Channel 3 C bias

Technical Data

Parameter	Value
Manufacturer Part Number	950048
Mounting Width	8 HP
Mounting Depth	32 mm
Mounting Hole Count	4
Power Consumption	12V @ 110 mA
Power Connectors	16 pin EuroRack ribbon, 2.1mm DC barrel
Input Impedance	1M ohms
Output Impedance	75 ohms
Input Protection Range	+/-20V
Input Clipping Range	+/-2.5V
Output Range	+/-2.5V
Included	DC barrel power cable, EuroRack power cable
EuroRack Power Cable Type	16-pin
EuroRack Power Cable Length	25 cm
DC Barrel Power Cable Length	25 cm
RoHS Compliance	Manufactured with lead-free processes
Video Sync	None

Maintenance

Keep the module free of dust and debris by performing periodic cleaning. Spots may be cleaned from the front panel with a microfiber cloth and isopropyl alcohol or other electronics cleaner.

Hardware Revisions

The hardware revision code is printed on the circuit board visible from the rear of the module.

PROC: Triple Voltage Processor