Types of Mechanisms
Types Of Mechanism
Our firm builds both mechanical (tracker) and electric (electro-mechanical, all-electric) action organs. Some other firms specialize in one or another of the types of action.
It is our opinion that success with building mechanical action depends on:
- thorough study of both historic and modern organs,
- having the training and point of view of an organist so as to be able to evaluate the "feel" and responsiveness of the action,
- having the freedom to choose electric action when mechanical action is inappropriate.
By building both types of action, a builder can be objective about the merits of each.
Advantages and Disadvantages
The advantage of mechanical action is that the keys are connected directly to the valves in the chests that let wind to the pipes. This means that the organist physically opens the valves instead of making an electrical contact that energizes an electrical or pneumatic device that opens the valves. Mechanical action provides a kind of tactile feedback which gives the organist better rhythmic control. Also, the organist has some control over the onset of the speech of the pipes. This control is very subtle, seldom recognizable by the average layperson.
The benefit of increased control is lost if the keys are detached (separated) from the console.
Mechanical action requires that the keys be close to the pipes. It is therefore not practical to separate the organ into 2 parts or to set the console to the side so that the organist can face the conductor, the choir, and the organ pipes simultaneously. The keys are often harder to press down than with electric action, especially in older organs, and stop controls are a bit more cumbersome with mechanical action. It is seldom practical to play one pipe from more than one key as is called for with borrowing or duplexing. This means that a mechanical action organ may have less tonal flexibility and color than one with electric action.
In a small to medium size organ, a well-built mechanical action is faster and more immediate in response than electro-pneumatic action. That is, the valves admitting wind to the pipes open and close without delay, closely mirroring the movement of the organist’s fingers. But mechanical action is not faster than a well-built modern electro-mechanical action.
The advantage of all-electric actioni (electro-mechanical) is that it is simple, long-lasting, and fast-responding. A pipe played by a valve which is opened directly by an electromagnet responds the same as if played by tracker action with the key struck sharply.
The advantage of electro-pneumatic action—the system by which a key sends an electrical signal to an electromagnet which sends a pneumatic pulse to a small bellows-like motor which opens the valve to let wind to the pipe—is that it can control large valves and also valves in chests which are operating on high wind pressure. We often use electro-pneumatic action for the largest pipes and electro-mechanical action for the smaller pipes.
The disadvantages of electro-pneumatic action are that it is complex, somewhat slow in response time, and bulky for small pipes. Also, it requires the use of thin leather that has a limited life expectancy.
It is sometimes said that tracker action is longer-lasting than other types of action. Historic European organs from as early as the 1400’s are cited as examples of tracker’s longevity. Long life expectancy is compromised, however, when plastic, leather, and electronic components are utilized in mechanical action organs and when the organ is in a room which is heated.
We expect that modern electric action will last as long as most modern tracker actions given modern materials, modern environments, and modern patterns of church usage.
We recommend that churches analyze their musical needs and the location of the organ before choosing the type of action, addressing such questions as whether the keyboards can be at the pipes or must be detached, the relationship of the organ to the choir, the stoplist desired, etc.
We think that a good organ can be built using any type of action.
We think it important for a church to choose an organbuilder who has a record of building organs which the church likes and thinks will meet its needs, then to work with the organbuilder on choosing the type of action.
The term "Direct Electric" is copyrighted by The Wicks Organ Co.