HX3 KeyB Duo Installation

This page shows installation of an HX3 mainboard (FPGA based) as a replacement for KeyB Duo sound generator (DSP based). Board is completely remoted by MIDI from KeyB controller. All knob/button/drawbar functions are retained.

Installation is quite simple, but requires soldering skills and crimping flat ribbon cables. Click pictures to enlarge.

Replacing the KeyB key scan is optional. Installing a FatarScan2 board for direct connection to HX3 yields much lower key latency.

Remove KeyB DSP board and install HX3 board with plastic spacers, using M3 screws. Some holes must be drilled in base plate. Route 10-wire ribbon cable from PL17 PREAMP CTRL to KeyB controller board.

Remove old connectors from cables and install new connectors as shown. Audio cables both connect to HX3 stereo output. Ribbon cable to PL14 is required when using FatarScan2 board for key scanning instead of MIDI input. Note position of 220R resistor.

To prevent KeyB to send MIDI data before HX3 is ready to accept, the KeyB Duo controller RESET must be delayed. This is done by using a signal on wire 8 of HX3 PL17. Solder wire 8 from ribbon cable to R10 on KeyB controller board as shown. Cut off all other wires.