Connecting an Allen MDS-Expander II voice module (photo) to play through any make or model of MIDI-capable hybrid pipe/electronic or all-electronic organ console is a valuable complement to the instrument's voices.
This is a stand alone unit made to operate through any of the console's bottom three manuals (Swell, Great, Choir/Positiv) and Pedal. Its supplemental voices include classic organ stops, mutations, ancient reeds, theatre organ ranks, percussions, and a variety of orchestral and other keyboard instruments. Up to 4 of its 99 onboard voices may be accessed at any one time, and these 4 may be apportioned to the manuals and pedals in any arrangement desired, whether loaded all on one division or spread around. The module also comes with 60 presets which assign various voices to different divisions which may be altered by the player or restored afterwards to original factory configuration.
Most consoles built these days are provided with a short row of rocker tablets controlling MIDI functions. Any of the Allen voices may be assigned to these divisional rocker tablets which may then be brought on or off with hand-registering or captured and stored on any of the organ's general or divisional combinational pistons to play either singly or with the instrument's stops.
The module may be tuned up or down to sound slightly sharp or flat to the tuning of the host instrument's Great manual up to 100 Cents, or a full chromatic semitone, in either direction. Since the ear will tolerate a little sharpness but not the same degree of flatness, setting the tuning of the module sharp by up to five Cents is advantageous by simulating the random effect of real pipe ranks which are never perfectly in tune with each other. The result of combining the Allen voices with the rest of the instrument is improved realism with the full organ and all the mid-level ensembles involved in its buildup.
When this unit which measures 11 inches deep is placed atop the console within reach of the player, and the right and left stop jambs are the only possibilities for placement, it will need to be elevated a couple of inches to allow room for its rear cable connections. One satisfactory way to do this is to raise it with a square piece of green flora-foam cut to the correct size (For photo, see main menu, Videos, The Viscount Organ subpage, then scroll to bottom). This material is stronger than and will be found superior to conventional styrofoam, plus it also compliments the module's green display screen.