In theatre organ terminology what is the meaning of Ranks and what it the meaning of divisionals?

Answer 1

"Ranks" in pipe organ terminology, whether theatre/cinema organs or concert/church organs, are individual sets or rows of pipes operated by a single control known as a STOP.

A rank can be anything from a few pipes to more than 100. Organs may have only 1 rank of pipes - a practice instrument in a house, perhaps. A large cathedral or concert organ might have more than a hundred ranks of pipes. The largest pipe organ in the world has so many ranks nobody has been able to get an exact count of them!

Each pipe rank is made to sound, or SPEAK, by a switch or knob (called a STOP) at the keyboards (called the CONSOLE). This opens a valve which allows WIND into the WINDCHEST underneath the rank of pipes. But the pipes won't sound until the organist presses a key on the keyboard which opens another valve under the correct pipe. This makes it easy for the organist to vary the sound without a break in the musical performance.

An organ might be described as a WurliTzer 3/8, to give an example. The first number tells you how many KEYBOARDS (for the hands) the instrument has - 3 in this case: the second number is the number of PIPE RANKS in it. This instrument has 8 ranks

The foundation sound in a theatre organ comes from a set of pipes called the TIBIA rank. This sound is often made to shake or vibrate by causing a variation in the wind supply. This effect can be switched on or off by using the TREMULANT switch at the keyboards or CONSOLE.

The foundation sound of the classical/church organ is made by ranks of DIAPASON pipes.

If all ranks of pipes were made the same length (just shortening them to make the notes rise up in pitch) the sound would quickly become boring. So ranks of pipes are made in varying lengths.

A theatre organ would have a rank of TIBIA pipes. When the TIBIA 8' stop is turned on, this would sound at the same pitch as a piano. The measurement of a pipe is that of the longest pipe in the rank, which is played by the lowest "C" on the keyboard. The control (stop) for this would be labelled TIBIA 8'.

But on its own this is a dull sound.

To brighten it the organist might add a pipes from the same TIBIA pipes one octave higher, which would have the name on its stop, TIBIA 4'. These pipes would play 8 notes - or an OCTAVE - higher than the 8' rank. However, a theatre organ just adds 12 pipes to the end of the rank to add an extra octave, versus a classical organ which typically has a rank of pipes per stop There might even be a stop labeled 2' which would make for a very bright sound. The control for this would be labeled TIBIA 2' and the pipes would sound 2 octaves (16 notes) above the 8' rank.

Therefore, if the organist switches on the TIBIA 8' and TIBIA 4' and TIBIA 2' stops and plays the bottom note "C" on the keyboard you would hear THREE pipes sounding together and making a bright sound. Every key he pressed would also make 3 pipes sound at the same time.

Ranks of pipes in an organ are also made in different shapes to create different kinds of sounds. Just as a Trumpet makes a different sound from a Trombone which has a different sound to a tuba. An organist can get many varieties of tone color by combining different ranks of pipes and varying the combination as he plays.