Low Impedance Bus Board (LIBB)

Technical Details

LIBB’s +12V and -12V power rails have entire planes of 2 ounce copper dedicated to their distribution. Other bus boards use “fat traces” of copper (usually 100-200 mils = 0.1-0.2 inch wide) which cannot compete with the power distribution of a complete power plane. The LIBB power plane is essentially a 1.9 inch wide trace, one for each +12V and -12V power rail.

Most low cost passive bus boards use simple 1 ounce thick copper and 2 PCB layers and are not much better than ribbon cable for power distribution. LIBB uses six layers of 2 ounce thick copper. The dedicated layers guarantee more power distribution capability, and are superior to 2 layer boards with 3 or 4 ounce copper due to the more effective use of copper.

Ground is provided through three heavy 2 ounce copper ground planes, plus a partial fourth ground plane with generous ground stitching vias to avoid dead return current flow areas of the board. The net effective copper is 7 ounces.

The +12V and -12V power planes are each closely coupled to ground planes on each side, creating a distributed capacitance across the board for additional high frequency noise filtering.

The CV and Gate signals are separated by the +5V power bus to avoid coupling of fast Gate signal edges to the sensitive Control Voltage signals.

The +5V power bus is a 200 mil wide trace of 2 ounce copper, and is lower impedance than most other bus board’s +12V and -12V power rails.

State of the Art Power Distribution

Power distribution is through a centrally mounted barrier strip, providing the shortest distance for power input to power output. The heaviest gauge wire possible is recommended for installations to the power supply, 12 AWG stranded or solid wire for lowest distribution impedance. Note that Genus Modu Low Impedance Bus Board PCB nearly matches the impedance per inch of 12 AWG wire. Two barrier strip connections are provided for ground to better match the combined +/12V power returns and for lowest ground impedance.

The low impedance for ground and power creates the equivalent of an electrical star power distribution, which is the desired topology for lowest noise coupling. The board provides significant module noise coupling reduction without replacing standard 10 or 16 wire euro power connectors. This is because power noise coupling occurs through the shared impedance of the bus board and common power wires, not through the individual ribbon cables to each module.

The Low Impedance Bus Board is suitable for new installations or retrofits. LIBB is designed to give the confidance of a trouble free installation and power distribution that just works. No one wants to be troubelshooting noise issues when you should be making music. Stop wasting time with cheaper solutions, get the assurance you need for critical music performances or recordings, using a professional bus board engineered for the 21st century.

Further Information

Features for maximum flexibility

• Compact size fits in any 3U 84hp or 104 hp skiff or case, with space left over for smaller power supplies.
• The board mounts on ½ inch (12.7 mm) tall standoffs, included with the board. The combined height of SMT component, PCB board and standoff is 0.683 inches (17.3 mm), making it a good fit or retrofit for any low profile skiff or case.
• Standard Euro power 16 pin shrouded right angle headers are mounted underneath the board for the lowest profile connections. Euro power cable connectors will not add to the height. Sixteen headers provide enough connections for most 3U and many 6U applications.
• A right angle barrier strip mounts underneath the board, with top access to the terminals. Barrier strips allow wiring with just the use of a wire cutter, wire stripper and screwdriver. No special connectors or crimping tools are required. Two wires can be mounted per location, allowing daisy chaining to additional bus boards directly through the wire connections, not the PCB traces. The barrier strip uses M3 screws and has 3 walls of isolation to prevent wiring shorts.
• Three low profile surface mount LEDs are on the top for all three power rails, green for +12V, red for -12V and amber for +5V.
• There are nine mounting hole locations for secure mounting. 4-40 screws and standoffs are provided with the bus board. M3 size screws and standoffs can also be used. Plastic PCB standoffs that glue-mount to your system are not recommend as they can come loose over time and result in power shorts or physical damage to your system.
• Bulk capacitors of 3x220 uF for each 12V power rail, 1x220 uF for each 5V power rail. DIP switches to enable/disable 2nd and 3rd 12V capacitors to optimize power supply start up.
• Clear labeling of red stripe location and power pins.