What are the different parts of a pipe organ?

What’s in an organ? Blag your way in any organ conversation with the aid of our whistle-stop tour of all the stops, pedals and manuals that make up a church or concert organ

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PIPES

The sound of an organ is built up in layers using different lengths of pipes, the most common being 32′, 16′, 8′, 4′ and 2′, each an octave apart. Mixture and mutation stops provide harmonics for drama and spicy solo effects.

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What are the different types of pipe in an organ?

There are three basic styles of pipe in an organ.

Principal: Also known as diapasons, these are traditionally-shaped metal pipes on the outside of an organ case – they provide the basic church organ ‘sound’.

Flute: Wooden pipes with various names, including bourdon, claribel, Rohrflöte and, of course, flute. A soft, mellow, rounded tone.

Reed: From posaunes in the pedals to oboes on the swell organ (see manuals), reed pipes incorporate a vibrating brass tongue, as opposed to flue pipes with no moving parts (see principal and flute).

MANUALS

Organs have anything from one to five manuals (and very occasionally more):

Swell: The swell organ, third one up, is enclosed in a box with shutters on one side that can be opened and closed with a pedal, causing the sound to increase or decrease in volume. Hence ‘swell’. Beloved by many organists are the ‘strings’ – a combination of celeste and salicional, the slightly ‘off’ tuning of the former producing a shimmering effect.

Great: The guts of the organ. The second manual up on UK and US organs, the bottom one on many others. Main stops are here, from the 8′-4′-2′ principal ‘plenum’ suitable for much German Baroque repertoire, to large flutes and mixtures. Usually a trumpet or two, as well.

Choir: Not used to accompany a choir, in fact, but a smaller division derived from the word ‘chair’. The choir organ is sometimes placed at the front of the case, below the player, resembling the seat of a chair. This division contains softer flutes and reeds, plus usually a few sparkling mutation stops. Sometimes called the Positif.

Echo: Only if you have four manuals – you’ll find lovely ethereal sounds on here, the pipes sometimes tucked in a triforium or some nook.

Bombarde: If you have a fifth manual, this one’s right at the top. There you’ll find the heavy weaponry, from piercing trumpets to head-splitting tubas.

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Words by Oliver Condy