The Hammond Organ EXP-20 is an expression pedal, a foot-operated control that changes a parameter of the instrument it is plugged into as you play. In this case the parameter is volume: Hammond designed it to control the volume of the XK-1 and XK-3c organs and the Legacy Sk keyboards1. For an organ player, that is the familiar swell shoe job done with a floor pedal, letting you fade a chord in and out while both hands stay on the manuals.
What it does and how it connects
The EXP-20 is a passive expression pedal: it sends position information down the cable rather than processing any audio. Hammond's product page describes it plainly as "designed to control the volume of the XK-1 and XK-3c Organs and the Legacy Sk Keyboards"1.
Connection is direct. The 1/4-inch jack provided on the pedal plugs straight into the expression pedal connector on the XK-1, XK-3c and Legacy Sk instruments, with no interface box in between1.
Using it with other gear
Hammond also states that the EXP-20 may be used with any other instrument using a 1/4-inch TRS jack1. TRS stands for tip-ring-sleeve, the three-conductor plug format most keyboards and multi-effects units use for their expression pedal input. That means the pedal is not locked to Hammond's own instruments: if your keyboard or effects unit has a TRS expression input, the EXP-20 can sit alongside it on the floor.
Expression pedal wiring is not universal between makers. Hammond specifies TRS compatibility for the EXP-201, but how a given instrument reads the pedal's movement can differ, so behavior with non-Hammond gear depends on that instrument's expression input.
Where it sits in Hammond's range
Hammond Organ makes other expression pedals besides the EXP-20, including the Hammond EXP-100f and the Hammond EXP-50J. If you are comparing options for an XK or Legacy Sk setup, those pages cover the rest of the range. For a broader look at how pedals of this kind work and what else is available, see Expression Pedals.
Questions
What instruments does the Hammond EXP-20 work with?
Hammond designed the EXP-20 to control the volume of the XK-1 and XK-3c organs and the Legacy Sk keyboards. The 1/4-inch jack on the pedal plugs straight into the expression pedal connector on those instruments. Hammond also states that the EXP-20 may be used with any other instrument that uses a 1/4-inch TRS jack for expression, which covers most keyboards and effects units that accept an expression pedal.
How does the EXP-20 connect to an organ or keyboard?
It connects with a 1/4-inch jack that plugs directly into the expression pedal connector on the XK-1, XK-3c and Legacy Sk instruments. No separate power supply is involved: the instrument reads the pedal's position over the TRS connection. For other gear, the same 1/4-inch TRS plug goes into whatever expression pedal input the instrument provides.
Sources (1)
- EXP20 - Hammond Organ, Hammond Organ
