The resulting sound is like a coronet and is frequently used as a solo stop. It is not as bold as a reed stop but it has similar characteristics. There are many more types of registration but there is not room to list all of them. Organists in graduate programs are expected to know registration so well that they cannot pass their oral exams without demonstrating knowledge of specific registrations. Tuning Tuning a flue pipe is achieved through altering the length of the pipe.
Open pipes have a collar on the top that can be raised or lowered for tuning.
Stopped pipes are tuned by raising or lowering the stopper. The felt around the stopper ensures a tight seal but also allows the stopper to be moved. Reed pipes are tuned by raising or lowering the tuning wire. As the wire moves, the length of the tongue allowed to vibrate changes and the pitch is affected. Pipe organs can go out of tune with weather changes.