When a pipe organ is built a decision is made as to the pitch. The organ would be set at the standard pitch of the time. This is why today many organs have different pitch’s, and an orchestra can struggle to tune up or down to meet them. In order to overcome the problems of incompatibility, the organs pitch needs to be reset. Sometimes this can be very straightforward. If the pitch is not too far away, a full re-tune can be performed having set Middle C to 523.3. In other cases achieving the desired pitch can be a problem. Every flue pipe in an organ such as a Principal or Salicional, has a means of tuning that will either lengthen or shorten the pipe. Whether this is a tin slide at the top of the pipe that can be tapped up or down, a stopper in the top of a pipe that can be moved up or down or a flexible lead cap that can be opened or closed, they all create the same effect. A reed pipe, such as a Cornopean or Oboe has wire that can be moved up and down the reed to lengthen and shorten it’s speaking length. These tuning methods can only move so far. If a pipe is not long enough to achieve the pitch, the slide will simply fall off. If a reed pipe needs to move too far in either direction, the note can become soft or not speak, or the quality of the note will be lost as the speaking length of the reed tongue is too long. These problems can be overcome in the following ways.

Raising the pitch.

In order to raise the pitch of an organ every pipe will need to be shortened. If during the change you find slides are going down to meet the tops of the pipes, you can trim a small amount off the top of each pipe to gain the correct note. However if the pitch is a long way out, to keep the quality and tone of the organ you will need to physically move every pipe, on every rank, down one note. In effect Middle C becomes Tenor B, Tenor B becomes A#, A# becomes A and so on. New pipes will then be required for the top notes on every rank, and you will be left with a lot of redundant Bottom C pipes. Reed pipes could also require moving up a note. While they can handle greater fluctuations in pitch, if you go too far the note will become strangled, making it soft and slow to speak.

Lowering the pitch.

In lowering the pitch you will be lengthening every pipe. In some cases slides will be long enough to be raised and lengthen the pipes to achieve the desired note. Stoppered pipes will not react the same way. Pull the stopper up too high and it falls out. In these cases the pipes need to be moved up a note, and a new Bottom C pipe fitted. This would need to be done on all stoppered ranks to achieve the length in the pipe. Reed pipes again will need to be moved up a note. As mentioned before they can tolerate movement, but again if the speaking length of the tongue is too long the note can growl and lose quality.

Every pitch change on every organ is different in one way or another. Some change easily and others don’t, but the end result is an organ that can be used with an orchestra for recitals and concerts.