WurliTzer 3/10 — How Pipe Plays

Warragul Theatre Organ Society Inc. (WTOS)



How an organ pipe plays —  a simplified explanation

For more information about the organ parts
click on a number
at right  > > > or scroll down


Diagram applicable to the Warragul Wurlitzer installation


    KEY on Keyboard    

The organist plays a note (presses a key) on the keyboard, which closes electrical contacts.  This closing registers with the CONSOLE  ELECTRONICS.  

There are 3 manuals (keyboards) named Accompaniment (Accomp.), Great and Solo.

Accomp. is the bottom manual (nearest to the organist), Great the middle and Solo the top manual.

      TAB on Stop Rail      


Before a Key is playable, one or more TABS must be selected for the manual (keyboard) that is being played.

In this example, the organist is pressing down the 16 TIBIA CLAUSA Tab for the Great Manual (at centre of photo).

This selects the Tibia Clausa rank at 16 foot pitch (which in this case) will be played from the Great Manual.

A number of Tabs are assigned to each manual.

White numbered buttons below the keys, allow the organist to quickly choose a pre-selected group of Tabs.




The tremulants allow the pipes to 'speak' with the characteristic vibrato sound of theatre pipe organs.


On this organ console, there are five Tremulant Tabs.  Each of these Tabs allows the organist to turn on or off one of the Tremulants in the Chamber.  (The Tibia/Vox tab controls two trems.)  Three of the tremulants are connected to two ranks. 


With all the trems. turned off, the sound is typical of a Concert (classical) Pipe Organ.


A Multi-core cable links the Console Electronics to the Chamber Electronics.

The cable conveys electronic data from console to chamber. 

Inside rear of console, hinged 'flap' lowered




Two systems - which allows organisation of preset combinations.





Rear of the Console (photo below).  Installation—working on the cable connections.  Every key, tab, switch and pedal is connected to the circuit boards within the console.


Rank drivers (photo below) are housed in a cupboard within the Chamber.  The rank drivers receive electronic data from the Console Electronics.  

For every rank of pipes there is a rank driver — which individually controls each of the electromagnets in the Pipe Chest.  Commonly, there are 61 pipes on the chest with extensions onto off-note chests.  

Rank extension is a feature of theatre organs.


Most pipe chests are built to accomodate 61 pipes.  When there are more than 61 pipes in a rank, the additional pipes may be placed in an off-note (or off-set) chest located elswhere in the organ chamber.

This organ has 10 ranks, with a total of 742 pipes.

The String Celeste rank is shown in both photos to the right (other pipe ranks behind)


The Pipe Chest physically supports the pipes and controls the air to each pipe


Simplified Cross-section Diagram of Pipe Chest (not to scale)

Red Arrows indicate direction of parts travel

Blue Arrows show Exhaust Air direction

The words Air and Wind may be used interchangeably

How it works:-  

In this diagram, all moving parts are in the rest position

(1) Wind supply from Blower (via Regulator) fills Pipe Chest, channels and bellows of Pneumatic Motors with positive pressure air.

Organist pressing Key on keyboard, (via electronics) turns on
(2) Electromagnet which  attracts (3) Armature (small metal disc), holding disc up.
The positive pressure air to
(4) Primary Channel is now shut off.
Air exhausts from Primary Channel, via hole in
(5) Tube Screw to outside.

The positive pressure air against (6) Primary Motor bellows, causes bellows to collapse, raising attached (7) Valve Wire with two Valve Discs.

The positive pressure air to (8) Secondary Channel is now shut off.

The Secondary Channel exhausts its air to outside.

The positive pressure air against (9) Secondary Motor bellows, causes bellows to collapse.  The attached (10) Striker, moves (11) Spoon which pulls (12) Pallet open, against the Spring pressure.

Wind is admitted into the Organ Pipe—and sound is heard!

The sequence (2) to (12) is FAST; capable of 20 repetitions per second!  



Primary and Secondary Motors—Leather (white) used is Kangaroo skin—thin, strong and very pliable 

Primary held open Primary held closed Secondary Motor held open Secondary closed


When the organist selects a Tremulant Tab, the Console Electronics signals the Chamber Electronics which operates the Tremulant.  


There are six tremulants (trems) in this organ.


For a detailed description, see 
'How Does It Work'
on the 
Tech Specs  page.


Each box (with vent holes in the top) houses a tremulant action.


1. The regulator in this photo is 'at rest' - the springs are 'closed' (the organ is turned off).

There are seven regulators in this organ.  They maintain a constant wind pressure to the organ chest in each rank, no matter if one pipe or many pipes are being played.

2. The regulators in this photo are in use.  Wind pressure has expanded the bellows against the tension of the springs.



Wind from Blower—

  1,300 cubic feet per minute

  Pressure 15 inches


The restored Blower (without motor) prior to dispatch for Warragul

The Blower is a powerful fan-unit driven by an electric motor.  It provides all the wind supply for the organ.

Wind makes the pipes sound, and also operates the tremulants, pneumatic motors on swell shutters,  hammers and other devices on percussion instruments. 

During Blower installation at Warragul