AGO Organ Maintenance & Tuning Basics 3 — Questions and Answers
Question 1: What is a 'wind chest' in an organ?
- The outer cabinet housing the blower motor
- The pressurized chamber that distributes wind to the pipes on each manual (Correct answer)
- The bellows used in older mechanical organs before electric blowers
- The swell box that controls dynamic expression
Correct answer: The pressurized chamber that distributes wind to the pipes on each manual
The wind chest is a sealed pressurized box that holds the organ's pipes and contains the valve mechanisms (pallets or sliders) that control wind flow to each pipe.
Question 2: When tuning reed pipes, adjustments are made by:
- Rolling the top of the resonator open or closed
- Moving the tuning wire up or down to alter the effective vibrating length of the tongue (Correct answer)
- Bending the languid to change cutup
- Adjusting the toe hole diameter with a drill
Correct answer: Moving the tuning wire up or down to alter the effective vibrating length of the tongue
Reed pipe pitch is controlled by a tuning wire (wire spring) that limits how much of the brass tongue vibrates — raising it sharpens, lowering it flattens.
Question 3: Which type of pipe is most sensitive to temperature changes in terms of pitch stability?
- Stopped wood flue pipes
- Open metal flue pipes (Correct answer)
- Reed pipes with metal resonators
- Bourdon pipes with conical resonators
Correct answer: Open metal flue pipes
Open metal flue pipes are very sensitive to temperature because pitch is proportional to the speed of sound, which rises with temperature, causing metal pipes to go sharp when warm.
Question 4: What does 'cutup' refer to in pipe voicing?
- The process of cutting down overlong pipes during installation
- The height of the mouth opening (the gap between the lower lip and the languid) (Correct answer)
- The removal of excess metal from the pipe foot
- Shortening the tuning slide of a stopped pipe
Correct answer: The height of the mouth opening (the gap between the lower lip and the languid)
Cutup is the height of the pipe mouth — the gap between the lower lip and the upper edge of the languid — which critically affects tone color and speech.
Question 5: A 'stopped' pipe (Gedackt) produces a pitch equivalent to an open pipe of:
- The same length
- Twice its length (Correct answer)
- Half its length
- One-third its length
Correct answer: Twice its length
A stopped pipe behaves acoustically like an open pipe twice its length, sounding an octave lower than an open pipe of the same physical length.
Question 6: What is a 'blower' in organ terminology?
- A pipe rank designed to produce a wind-noise effect
- The electric motor-driven fan that supplies pressurized wind to the organ (Correct answer)
- The device that controls wind pressure regulation
- A type of swell shoe that controls volume
Correct answer: The electric motor-driven fan that supplies pressurized wind to the organ
The blower is an electrically powered centrifugal fan that generates the pressurized wind supply required for all organ pipes to speak.
Question 7: When checking organ wind pressure, the standard measurement unit used in the US is:
- Pounds per square inch (PSI)
- Inches of water column (WC) (Correct answer)
- Millibars (mb)
- Pascals (Pa)
Correct answer: Inches of water column (WC)
Organ wind pressure is traditionally measured in inches of water column (WC), using a water manometer or digital gauge calibrated to this unit.
AGO Organ Maintenance & Tuning Basics 3
What is a 'wind chest' in an organ?