HX3 Extension Board Installation

HX3 Extension Board Installation

The extension board for HX3 mk3/mk4 mainboards adds two additional audio outputs, Leslie(R) control and preamplifier for 9- and 11-pin Leslies, headphone jack, USB interface for parameter control to your HX3 mainboard. It also adds a MIDI OUT in case HX3 mk3 board is jumpered for two MIDI inputs.

For additional audio outputs, the extension board has a secondary A/D converter. Outputs may be configured by MenuPanel or HX3 Remote to any HX3 audio source, but we recommend using the two channels for plain audio and bass pedal signal as it is routed to the Leslie connector.

A 16-pin header provides send/return of Leslie and headphone signals to insert potentiometers (and 10k to 47k audio taper pot will do) or effects like 3-band equalizer. If no pots or effects are inserted, pins 1-2, 3-4, 5-6 and 7-8 must be bridged by jumpers. The connector also provides symmetrical 12V power supply for audio preamp circuits (see schematics PDFs).

The extension board connects to HX3 by 26-pin header PL33 and flat ribbon cable. Length of cable must not exceed 15 cm (6") as high-frequency digital signals are transmitted.

PL31 carries complete 11-pin Leslie(R) control signals (power, slow/fast, audio signals organ and bass pedals). It connects to 11-pin Amphenol jack one-on-one. Pins 12 to 14 of PL31 remain open. For connection of 9-pin Leslies, mind the different pinout. 6-pin Leslies (122/147) need an additional interface/relay circuit; please ask an experienced Hammond tech.

USB interfaces to HX3 controller for setup via HX3 Remote or HX3 Flash only. Connect a USB A/B cable to your PC and follow instructions on HX3 Remote or HX3 Flash page. USB jack is no USB MIDI interface!

Connection to 11 pin Leslie
pin 1 (Rotary audio channel)
pin 2 (Stationary audio channel)
pin 4 (Audio ground)
pin 5 (Common ground for control signals)
pin 6 (Power)
pin 7 (Fast)
pin 8 (Slow)