When pure tones (sine waves) are sounded together, they combine to produce two additional tones whose frequencies are the sum and difference of the two original tones. For example, if the original frequencies are 32hz and 48hz, the resultant frequencies will be 80hz and 16 hz. While this effect occurs at all frequencies, it is most effective to the human ear at low frequencies. (This same acoustical principle is used by celestes to produce a different effect.) This effect was discovered by Tartini around 1714 and by Sorge in 1740.

These stops use this acoustical effect to produce tones in the 32' and 64' octaves, using smaller (and thus less costly) pipes than would normally be necessary. One of these stops, labeled as 32' or 64' pitch, is comprised of two ranks which sound the 1st and 2nd harmonics of the desired pitch (that is, an octave and a twelfth above the desired pitch). For a 32' stop, the two ranks are 16' and 10-2/3'; for a 64' stop, the two ranks are 32' and 21-1/3'. This effect was first used in the organ by Abt Vogler (1749-1814). The first 64' resultant stops were probably introduced in the late 19th century. Some builders have experimented with using resultant tones in the 16' octave, but it is not an effective replacement for a true 16' stop.

The best results are obtained from a dull-toned independent quint-sounding rank placed close to the octave-sounding rank, with the quint voiced somewhat softer than the octave. The resultant effect should only be used in the lowest octave, as true unison-sounding pipes will, by definition, be available above that. The quint can be (and often is) borrowed from an existing unison- or octave-sounding rank; while not quite in tune with the desired harmonic, it will tend to draw in tune, especially if it is close to the other rank. Taking both pitches from the same rank generally produces the least satisfactory results. Additional ranks can be used to support additional harmonics; see Grand Bourdon for details.

The name Tonitru was used by Hope-Jones for a 64' resultant; the name means "rumbling sound" or "thunder". The name Gravissima is typically only used for a 64' stop.

Strony reports that not many American theatre organs had resultant stops, but many English ones did.

N.B. There are exactly two true 64' stops in existence. One is the Diaphone Profundo at Atlantic City; the other is a Contra Trombone at the Sydney Town Hall.

Variants

Examples

Osiris contains 68 examples of Resultant at 32', eleven examples of Acoustic Bass at 32' and one at 64', eleven examples of Resultant Bass at 32' and three at 64', eleven examples of Gravissima at 64', six examples of Harmonic Bass at 32', four examples of Basse Acoustique at 32' and one at 64'. No examples are known of Gravitone, Tonitru or Vox Gravissima.

Julian Rhodes keeps a compilation by David Willey that lists about 40 examples of 64' stops (see Bibliography below). A few examples are listed here.

Gravissima 64'; Woolsey Hall, Yale University, New Haven CT; Hutchings-Votey Organ Company.

Gravissima 64'; Worcester Cathedral, Worcester, England; Hope-Jones.

Gravissima 64'; Liverpool Cathedral, Liverpool England; Willis.

Gravissima 64'; Bremen Cathedral, Bremen, Germany (destroyed?); J. F. Schulze.

Acoustic Bass 32', Pedal; Thomas Coats Memorial Church, Paisley, England; Hill 1890.

Basse acoustique 32', Pédale; St. Fran&ccedi;ois de Sales, Lyon, Rhône, France; Cavaillé-Coll 1880.

Harmonic Bass 32', Pedal; Tewkesbury Abbey, Gloucestershire, England; Michell & Thynne 1885.

Resultant 32', Pedal; Congregational Church, Great Barrington, Massachusetts, USA; Roosevelt 1883.

Megalophone 32', Pedal; Coliseum, Boston, Massachusetts, USA; Wilcox. This is the only known example of this name.

Quintalophon 32', Pedal; Notre Dame Cathedral, Montreal, Quebec, Canada; Casavant. This is the only known example of this name.

Sound Clips

See the Sound Files appendix for general information.

Bibliography