Tremulant

Tremulant ( from Lat tremulus " trembling ") is a device that varies for certain works airflow (wind) periodically at the organ. This alters the strength of the tone and the pitch, the sound vibrates or shakes, similar to a vibrato. Used the tremulant especially to single out a single voice, the cantus firmus against the accompanying voices. Related to the rotary effects are used in the electronic organ (see Leslie ).

It does however not about a beat: With a beat register a similar effect by two slightly detuned pipes is achieved. By frequency superposition leads to periodic changes in the volume.

Designs

A possible design is Kanaltremulant in which a built-in spring in the wind tunnel, wood or leather flap enabling the air to vibrate. Dom Bedos calls this variant tremblant doux.

The Wippfedertremulant works by a mounted on the wind tunnel Bälgchen, which also comes with the momentum of a spring to vibrate. When the wind is stabilized by an Schwimmer, can serve as a tremulant Stoßbalg which is periodically provided with air shocks and these pulses then transmits the float plate. Such tremulant can usually be regulated by the game of table in speed.

The now most commonly built tremulant works with a Tremulantenrelais. After power ( electrical or pneumatic) to lift three successive plug valves; the previous open in each case the wind supply for the next; the last valve to open the wind supply to a small Tremulantenbalg which sets the primary or Windladenbalg via a rigid connection to vibrate.

In historic organs, there are occasionally two tremulants in various fixed speeds.