AGO Organ Registration & Tonal Design 2

Question 1

Which stop family produces tone by causing a metal reed to vibrate against a shallot?

Accepted Answer

Reed pipes

Answer

Reed pipes use a vibrating brass tongue (reed) beating against a shallot to produce their characteristic sound.

Question 2

A 'Quint' stop sounds at which interval above the written pitch?

Accepted Answer

A fifth

Answer

A Quint (or Nazard at 2 2/3') sounds a fifth above the unison pitch, reinforcing the third partial of the harmonic series.

Question 3

When building a full registration from scratch, what is the standard foundational order?

Accepted Answer

Principals → Flutes → Mutations → Mixtures → Reeds

Answer

The classic approach adds principal chorus stops first, then flutes, then mutations and mixtures, with reeds last to crown the ensemble.

Question 4

The term 'Céleste' in a stop name (e.g., Voix Céleste) indicates what acoustic phenomenon?

Accepted Answer

Two ranks slightly mistuned to produce a wavering beat

Answer

A Céleste consists of two ranks — one at normal pitch and one slightly sharp — whose interference beats create a gentle, undulating effect.

Question 5

Which characteristic best distinguishes a Gemshorn from a Gedeckt?

Accepted Answer

Gemshorn has a tapered (conical) body; Gedeckt has a stopped cylindrical body

Answer

The Gemshorn is an open, conically tapered flue stop, while the Gedeckt is a stopped cylindrical pipe, giving each a distinct tonal quality.

(AGO) American Guild of Organists Certification Practice Test