Trek IIString Basswith Simultaneous Retentionof Hammond Pedal Tones

This is a nonstandard installation of a Trek II string bass to the Hammond (B3, C3, RT3, or A100). The installation is unique because the standard Hammond 16 ft. and 8 ft. pedal tones are available in addition to the Trek II 16 ft. and 8 ft. string bass tones.

FEATURES

• 4 Drawbars are available for pedal tones; 16 ft and 8 ft Hammond original and 16 ft and 8 ft Trek II string bass. The wires are removed from the brown 16 ft and 5 1/3 ft lower manual drawbars associated with the white “Bb” preset. The 16 ft and 8 ft Trek II string bass outputs are soldered to these drawbars. String bass control via the drawbars is active at all times regardless of which lower manual preset is selected. Pedal tone selection can be: the original Hammond only, Trek II only, or any 4 drawbar combination of the two. If a registration on the lower manual is desired using the 16 ft and 5 1/3 ft drawbars, the black “B” preset should be used. If it is undesirable to use the two “Bb” drawbars, it is very simple to use a SPDT switch to alternate the Pedal drawbars between the stock Hammond and the Trek II.
• The pluck and sustain are adjustable from the console
• The tones are monophonic. This is desirable for faster playing with a relatively long sustain time. A pedal tone does not sound “on top” of the next one. This was a problem with the Krueger string bass since its tones were polyphonic and sustain time was only adjustable from the circuit board. The Krueger provides string bass sustain effect only on the 8 ft pedal tones. The Trek II, with use of 16 ft. and 8 ft pedal tones, produces a much richer string bass with more variation in tone than the Krueger.
• No tone generator wires are removed or cut for the installation
• The bass tones are generated within the Trek II and are triggered from a 1 1/2 octave contact strip previously used on a Krueger string bass. Any normally open set of contacts to a common signal bus (chassis ground) will work.

If the full two octaves of pedal tones is desired from the Trek II, a seven point contact strip can be added to the pedals.

INSTALLATION

A Krueger 18 point contact strip is mounted to the bottom of the pedal support struts. Nineteen wires are required to go between the pedal contact strip and the Trek II board. Eighteen are for each pedal tone of low C to 2nd F at 16 and 8 ft. pitch. and one is the signal common. No. 22 AWG stranded wire is routed via small cable clamps along one of the pedal stationary support struts and then along the front left side of the pedal board. At this point the wires are terminated on a DB25 miniature connector. The mating DB25 connector is wired to the Trek II circuit board trigger inputs for the 18 tones. The wires are routed above the Hammond pedal contact case and up through one of the existing console wire way tubes. The DB 25 connectors provide for easy removal of the pedal board and all wires are out of sight.

The Trek II circuit board can be mounted at any convenient location inside the organ.

The Pluck/Sustain control is usually mounted to the bottom of the organ front wooden rail. Wires from the Pluck/Sustain control plug into the circuit board via a Molex connector.

The power transformer is mounted near the run motor end of the organ to prevent the induction of any hum/noise into the organ signal path.

For photos of the pedal contacts, wiring and Trek II circuit board, go to the organ forum at: http://www.organforum.com/forums/showthread.php?30718-String-Bass-(Trek-II)-with-Simultaneous-Retention-of-Hammond-Pedal-Tones

—JohnMihevic