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Fusion Preamp Interface

(1 customer review)


Connect and control rotary speakers.

The Fusion Preamp Interface is a versatile interface tool for connecting – and controlling – rotary speakers.

SKU: FPI Categories: , ,


The Fusion Preamp Interface is a robust, flexible interface designed for safely connecting and controlling Leslie® speaker cabinets. Not limited to just organs, the FPI expands Leslie® connectivity to any ¼” audio source with unprecedented ease.

The built-in preamp provides 26dB of clean gain with a simple ¼” audio input. It also features tone controls, hi-gain switch, low cut switch, and effects loop.

The ¼” TRS speed control input is compatible with any CU-1 half-moon style switch or dual footswitch. A COT (Chorale/Off/Tremolo) screw terminal allows optional hardwiring of speed control.

Some Leslie® amplifiers have been modified with an EIS Trek II or other solid-state relay to add a Stop mode. The FPI is compatible with both 3-speed and 2-speed Leslie® amps. Two Y/N (Yes/No) switches select either Fast/Stop/Slow mode (Y position) or Fast/Slow mode (N position) for the 122 and 147 outputs individually.

All models come with all features included in the base model FPI-D-EFX, listed under “Features” section below. Other standard models have expanded connectivity options, including 11-pin input or output, and 6-pin input.


  • Allows simultaneous Leslie® 122/147 usage.
  • Safe, low-voltage DC speed switching for 122 and 147 Leslie® operation.
  • Capability to mount inside or outside of Leslie® cabinet or organ enclosure.
  • Plug any ¼” audio source into your Leslie®.
  • Low-cut switch eliminates muddiness for guitars or other higher-register instruments.
  • Hi-gain switch means Lo-Z instruments (electric guitar or bass, for example) can be plugged in directly.


  • 122 and 147 Outputs: Standard on all models, can be used simultaneously.
  • Other Input/Output Options: Other models include 11-pin or 6-pin input and 11-pin output.
  • Audio Input: Standard on all models, ¼” jack.
  • Speed Control: 1/4″ TRS Input – compatible with any CU-1 half-moon style switch or dual footswitch.
  • Y/N Switches: Allows for 3-speed (Slow/Stop/Fast) or 2-speed (Slow/Fast) operation, for 122 and 147 individually.
  • COT Terminal: Allows hardwiring of CU-1 hand switch or dual footswitch to unit for speed control.
  • Preamp: Volume and tone control, hi/lo gain and low-cut switches, effects loop.
  • Mounting Kit: Comes with a mounting kit for mounting onto Leslie cabinet or organ enclosure.

Standard Models Include:

  • FPI-D-EFX: 122/147 6-Pin Output
  • FPI-D11-EFX: 11-Pin Input, 122/147 6-Pin Output
  • FPI-D11-11-EFX: 11-Pin Input, 11-Pin Output, 122/147 6-Pin Output
  • FPI-D6-EFX: 6-Pin Input, 122/147 6-Pin Output
  • FPI-D6-11-EFX: 6-Pin Input, 11-Pin Output, 122/147 6-Pin Output

The FPI is fully configurable with a wide variety of input and output options. Contact us for additional modifications or customizations.


Leslie® is a registered trademark of Hammond Suzuki Corporation.

Additional information

Weight 50 oz
Dimensions 8.75 × 5.5 × 3 in


1 review for Fusion Preamp Interface

  1. Johnny B

    This Fusion Preamp Interface is absolutely amazing! It’s just what I needed to hook my new Crumar Mojo Classic up to my 147 Leslie with Trek II EIS solid state relay. Works flawlessly and the build quality is exceptional. Nothing cheap about it. I love having the ability to use a 3-way half-moon switch (slow, stop, fast). Stop mode gives me a unique sound reminiscent of a Hammond PR-40 in good shape. The only thing I had to do was change the wiring of the Crumar half-moon switch – Crumar configures their switch differently than the Hammond CU-1. No big deal. Oh, having low voltage DC switching is brilliant. Thanks for offering such a great line of products to help keep that Hammond sound alive!

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