If there is a fifth manual it may be called the "Echo" because it has very quiet stops that echo. Alternatively, especially on American organs, it might be a "Bombarde". The Bombarde usually contains loud, bold reed stops, including stops called 'Bombarde'. For instance: a State Trumpet or Pontifical Trumpet might be placed on this manual which can be heard above all the other stops playing. The Bombarde is borrowed from French Organs where it is a standard stop on nearly all the manuals and pedals. Having a Bombarde Manual is something of a luxury for an organist. It can be found, for example, on the organ of Westminster Abbey.
It is extremely unusual to have more than five manuals, but in America there are a few very large organs. The Wanamaker organ at Macy's store in Philadelphia has six manuals. The world’s largest organ is in the Atlantic City Convention Hall. It has seven manuals and over 33,000 pipes. However, the largest organ in the world does not work since it would be too expensive to run it.
Having two or three manuals makes it possible to have quick changes of sound during a piece. The player can also play on two manuals at once: one with the left hand and one with the right. This is particularly useful to make a tune louder than the accompaniment (on a piano this can be done by pressing harder). The manuals can also be coupled together, for example, pulling out the “Swell to Great” stop will make all the sounds from the Swell come out on the Great as well. On an organ with mechanical action the keys of the Swell will be seen “playing by themselves” like a pianola, but on some older organs it can be hard work for the organist’s fingers when the manuals are coupled as it makes the action very heavy.
The notes on the pedals are arranged like the notes on a keyboard, but are obviously much bigger. The player needs to learn to play by 'feel', otherwise he will have to spend all his time looking at his feet. He plays each note, either with the toe or the heel and either on the inside of the foot or the outside. The American and British Standard organ contains 30 notes giving a range of nearly 2 ½ octaves (C to F, or sometimes C to G: 32 notes). They are not quite in a straight line but fan out a little to make it easier to play (it is called a ", pedalboard"). In German and French organs and organs built before 1920, the pedalboard will be straight without any fan curvature to it. Many organists find that this makes it more difficult to play. Organists need a good pair of shoes: ones which have good narrow heels and preferably pointed toes. The soles need to be fairly slippery, but not too much, so that the player can slide the foot from one pedal to another. Organists usually like to keep a pair of shoes which are worn only for playing the organ so that the soles do not have grit or dirt from the street.
The stops on an organ console give different sounds, like the instruments of an orchestra, and have names which tell the organist what kind of sound they will produce. The stops are usually to the left and right of the organist and they are pulled out (“drawstops” or “pulls” because they are “drawn” i.e. pulled). Some organs have “tab stops” or “rocker stops” which are in front of the player and can be rocked forwards and backwards for on/off.
The stops of an organ can be divided into families.
The "chorus" stops are the foundation stops, the basic ones which are good for building up the big, solid sound. A "diapason" or "principal" is a chorus stop.
The "flute" stops sound like flutes in an orchestra. They are gentler than the diapasons and sound good for very quick and light music.
The "reeds" are stops like the "oboe", "clarinet", "trumpet", "fagotto", "trombone". Each pipe has a reed inside. Their sound is very strong and nasal (like speaking through the nose).
The "strings" are quiet stops which sound like string instruments. These are stops like the "violone" and "gamba".
There is another way of grouping the stops. Each stop will have a number underneath the name. The number may be 16, 8, 4, 2, 1 or even 2 2/3 or 1 3/5. If the number is 8 this is called an “eight foot stop”. This is the normal pitch: the note will sound as it is written, e.g. when playing Middle C the sound will be Middle C. A 4 foot stop will sound an octave higher than written, a 2 foot stop will be two octaves higher. A 16 foot stop will sound an octave lower than an 8 foot stop. 8 foot is therefore the normal pitch, and the others are added to it to make a larger, brighter sound. 16 foot stops are normal in pedal parts.
Mutation stops are stops in which a note does not sound a whole number of octaves above the normal pitch. Examples are the Tierce 1 3/5 (which sounds 2 octaves and a third above) and the Nazard or Twelfth 2 2/3 (one octave and a fifth).
An organist needs to learn which combinations of stops sound good together and how to balance them well. Each organ is different and has its own character.
The combination of stops that an organist chooses for a particular piece of music is called the “registration”. The list of all the stops that a particular organ has is called the “specification”. The specification of an organ shows the names of the stops for each of the manuals and for the pedals, as well as the list of couplers.
Organs also have buttons called “pistons” which help to change the registration in the middle of a piece. There are “toe pistons” operated by the feet, and “thumb pistons” which are placed just below each manual so that they can be pushed by the thumb while the fingers keep playing. Large organs often have “general pistons” which change any combination of stops across the organ. These are often be computerised so that players can set them up differently depending on the music they are going to play. If several players regularly use the instrument they can each have their own personal settings for the pistons which they can lock so that no one else can change them.
Each stop controls a row of pipes, called a “rank”. Each rank makes a different sound (one row for the “diapason” sound, another row for the “flute”, another for the “trumpet” and so on). The stops control the air flow through the ranks. Some stops may control more than one rank. For instance, a Mixture stop of three ranks will have 182 pipes (3 ranks of 61 pipes each) and in some organs the Celeste is a 2 rank stop. The celeste pipes are tuned slightly sharper than the rest of the organ so that, when played together with another quiet stop such as the Salicional, there will be a pleasant throbbing beat because two pipes are slightly out of tune with one another. Organ Pipes are normally made of metal or wood. High quality metal organ pipes usually contain 75 percent tin or more, and the rest is lead. The Pipes are placed on windchests inside an "organ case" in a special room called an Organ chamber. A windchest is a box-like device which contains pallets that are opened and closed to admit air to a pipe so that it sounds. The pallets are operated by pull wires and rollers in the case of a tracker instrument but may also be operated by pneumatics or direct electric action using magnets.
There is always air being pumped into the windchest when the organ is switched on. In the days before electricity someone (an organ blower) had to pump the air into the windchest using bellows. This was hard work. Large organs would have needed more than one organ blower to do this job.