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PAB

Programmable Active Buffers pab_front_panel

Overview

PAB is a utility for distributing and delaying signals. Duplicate a clean copy of a signal, or delay it in increments of 16 nanoseconds.

With delay times in the range of tens of nanoseconds, the result is an image shifted slightly to the right. Different modules delay signals by different amounts. In complex patches, this can be a problem. When signals are combined, they may be out of horizontal registration. PAB addresses this by inserting strategic delays to make everything line up.


Key Specifications

Mounting Width4 HP
Power Consumption12V @ 50mA
Power Connectors10 pin EuroRack ribbon, 2.1mm DC barrel
Video SyncNone
IncludedDC barrel power cable, EuroRack power cable, red panel, green panel, blue panel

Front Panel Options

PAB ships with a black front panel installed. Red, green and blue panels are also included. All front panels are printed on both sides, allowing a choice of top-to-bottom or bottom-to-top signal flow.

pab_all_front_panels

System Integration Advice

PAB is most helpful in larger systems with many modules, or if you're concerned about horizontal shift. Even relatively simple patches may have registration issues with color components or compositing layers. This is most evident in high definition formats. For example, in standard definition, FKG3 performs an ideal self-key, where the foreground is the key source. But in high definition, the FKG3 self-key is out of registration by a couple of pixels. PAB is the fix for that: send the source RGB channels through PAB before FKG3, and the source luminance directly to FKG3's external key input.


Controls, Connectors & Indicators

pab_controls_connectors_indicators

Understanding Cascading Input Jacks​

PAB uses switched, or normalled, connections between its input jacks. With no cable inserted, a signal flows down from one input jack to another. This connection is overridden when a cable is inserted. Normalled inputs are indicated on the front panel with arrows.

pab_understanding_cascading_input_jacks

Installation

pab_mounting_power_sync

Requirements

  • EuroRack enclosure
  • 12V DC or EuroRack power supply
  • 2.1 mm DC barrel power cable or EuroRack power cable (both options included)
  • Eurorack power for PAB requires a 16-pin to 10-pin ribbon cable
  • Two 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

Pronunciationpab
Mounting Width4 HP
Mounting Hole Count2
Power Consumption12V @ 50 mA
Power Connectors10-pin EuroRack ribbon, 2.1mm DC barrel
Input Impedance1M ohms
Output Impedance75 ohms
Input Protection Range+/-20V
Input Clipping Range+/-2.5V
Output Range+/-2.5V
Propagation Delay16ns
Module Width20.32 mm
Module Height128.5 mm
Product Box Width4 in / 101.6 mm
Product Box Height2 in / 50.8 mm
Product Box Depth6 in / 152.4 mm
IncludedDC barrel power cable, EuroRack power cable, red panel, green panel, blue panel
EuroRack Power Cable Type10-pin to 16-pin
EuroRack Power Cable Length25 cm
DC Barrel Power Cable Length25 cm
RoHS ComplianceManufactured with lead-free processes
Video SyncNone

Maintenance

Keep your module free of dust and debris by performing periodic cleaning. Spots may be cleaned from the frontpanel 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.

PAB-RevA

Initial prototype, January 2025

PAB-RevB

Initial production version, February 2025

Download PAB-REVB Schematic Diagram (PDF)

Download PAB-REVB Interactive Bill of Materials (ZIP)

DIY

PAB is available as a DIY kit that includes a PCB assembly with pre-assembled SMT components and 4 frontpanel options. The user must source the through-hole components such as headers and jacks, as well as a suitable power cable for the module.

In the Hardware Revisions section, you will find downloads for the complete schematic and an interactive HTML BOM.

Bill of Materials

In addition to the PCBs and components included with your DIY kit from LZX, you will need to source the following components from electronics parts vendors.

ManufacturerManufacturer Part NumberDescriptionQuantityReference Designators
Wenzhou QingPu Electronics Co., LtdWQP-WQP518MA3.5mm Jack Mono Switched13J1, J2, J3, J4, J5, J6, J8, J9, J14, J15, J16, J17, J18
Pin Header Pitch 0.1in 2X5 Male Shrouded1J12
Wurth Elektronik694106402002DC Jack Vertical 2.1mm Barrel1J13
Recom TechnologiesR-78K3.3-0.5DC/DC Converter Submodule 3.3V1U6

Assembly Instructions

This assembly job is recommended for intermediate level DIYers who are comfortable soldering thru hole joints in close proximity to surface mounted parts.

  1. Mount and solder rear facing through hole parts first, in this order: pin header, DC/DC converter, DC barrel jack.
  2. Mount and solder front facing jacks next.
  3. Attach the front panel and secure it with mounting nuts for the jacks.