Organ Watch


Protecting your church's investment

Canada is considered by organ builders throughout the world as having a radical climate with extreme changes in temperature and humidity throughout the year. Central heating systems are used to provide comfort in winter months but these systems, along with Canada's love affair with carpet, rob the air of precious moisture needed to maintain a constant specific gravity of air. Most churches in this country do not have any means of humidifying the heated air and the humidity ranges between 10% in the winter and 80% in the summer. To properly protect the organ during the heating season the humidity should not be allowed to fall below 30% in the church. Heat and moisture should never be applied directly but indirectly by natural convection. Forced air heating systems can easily be fit with a humidifier. Hot water heating systems require a vaporizing system to inject moisture into the air.

In this country most churches have the pipe organ tuned twice each year, in the spring and fall, to align the tuning. Climate changes affect the different materials used in pipe making in varying degrees. Sound waves travel with less resistance in lower density air and this is why the pitch of the pipe organ sharpens with rising temperatures and flattens with lower temperatures. Some of our customers ask us to tune the organ to the piano. This is like the MTO requesting drivers keep two chevrons between moving vehicles on Highway 400.

The pitch of a pipe organ is determined by the pipe makers and voicers when the pipes are made. International Concert Pitch, A440, is the choice of most instrument makers today and the pipe voicers set the pitch to A440 at 21 degrees Celsius and 40% to 60% humidity. The tuner looks for these conditions to obtain best results from tuning but realistically this rarely happens and the tuner must learn how to compensate for differences when each church environment offers its own challenges.

In tuning a pipe organ the tuner will use multiple references throughout the organ from which to align all stops. Equal temperament is best for the greatest variety of repertoire. Full compass interval tuning is more important in a pipe organ than any other keyboard instrument as tuning discrepancies are much more obvious to the listener. Mixtures and reeds are the most revealing. Reed tongues need to be clean and well curved to hold their tune. The tuning devices on the pipes also need to be secure. Rotten leather in stopper gaskets of wood flutes on older organs for example, will reduce fundamental tone and tuning stability.

Wind pressure is another very important consideration in maintaining good tonal regulation and tuning. Waterless digital wind meters are very accurate in reporting the pressure and if there is a discrepancy from the original setting the organ technician should look for a broken spring, faulty bellows table height regulator, seized pressure regulator ball joints, etc. Each division should be tested for pressure drop at "full organ" to ensure the pressure holds within two millimeters and returns to normal when the chord is released.

The blower is often neglected and it is important to learn the maintenance requirement of your specific organ blower. For example, what is the frequency and type of lubrication required for the fan shaft and motor bearings.

Keeping an instrument clean is always a challenge especially when construction projects near the instrument can cause serious damage from construction dust. Every effort should be made to protect the organ from dusting to avoid the high cost of a detailed cleaning. Under normal conditions the organ will need a thorough cleaning every thirty years or so depending on the enclosure. Unenclosed divisions will be effected by dust cover earlier. The cleaning of the organ should never be attempted by inexperienced personelle.

Releathering of pipe valve actions and pressure regulating bellows will be necessary in the long term. The rate of leather deterioration is dependent upon air pollutants and tanning procedures. Perforations will determine the timing of refabrication.

In older organs the preset combination and switching systems can become unreliable. It is common these days to retrofit these systems with solid state components which offer the player greater variety and flexibility.

An "Organ Service Record Book" can be a useful tool for communication between the player and the organ technician, providing an on going record of repairs. We find this to be helpful in keeping on top of minor problems that occur from time to time in each instrument. We all remain better friends if a reasonable list can be dealt with during the course of a tuning visit.

Copyright Dodington & Dodington Pipe Organ Services Inc. 1998


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