Expression pedal

Separate expression pedals can often be added to a guitar amplifier or effects unit and used to control many different aspects of the tone.

Moreover, the tone will remain constant in pitch, volume, and timbre until the key or pedal is lifted, at which point the sound stops.

The expression pedal gives the organist control over the external source of power, and thus the volume, of the instrument, while leaving the user's hands free.

In addition, this location for most expression pedals, above the center of the pedalboard, is much more convenient for use by both feet if necessary (although it is usually operated with the right foot).

Correspondence to The Musical Times in 1916 debates the merits of both the ratchet lever and balanced pedal systems of expression.

One organist most open to the change suggests that real crescendos and diminuendos are not possible with a ratchet swell lever, as the notches provided are always either just under or just above the required dynamic level.

Furthermore, he states that the balanced expression pedal affords the ease of use of either foot, whereas the previous correspondent desired two ratchet levers, one at either side of the pedalboard.

Reed organs and harmoniums of the late nineteenth and early twentieth centuries featured a pair of bellows pedals at the base of the instrument.

This capability made the harmonium widely available to homes and small churches, though the dynamic range tended to be limited (not to mention that the organist would eventually tire from pumping).

A single shutter in the top of the box, inside the organ case, allowed the volume to be controlled.

The lever operated horizontally, and the player pushed their knee towards the side of the instrument to open the shutter.

This tendency increased with the arrival of spinet organs and modern synthesizers, which offset the expression pedal and reduced the size of the pedalboard.

Some guitar expression pedals include integrated toe switches similar to those for some electric organs.

[5] Expression has been taking a detour from pedals with advances in technology making smaller and remote devices possible.

Expression pedals are typically used to control a range of synthesizer functions and effects parameters in real time.