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482 Chapter 26 EVB3
Note: 2 2/3' is the fifth over 4'. 1 3/5', is the major third over 2'. 1 1/3' is the fifth over 2'.
In the bass range, this can lead to inharmonic tones, especially when playing bass lines
in a minor key. This is because mixing 2', 1 3/5' and 1 1/3' results in a major chord.
Residual Effect
The residual effect is a psychoacoustic phenomenon. Human beings can perceive the
pitch of a note, even when the fundamental is completely missing. If we didn’t “hear”
this way, it would make listening to music with a kitchen radio impossible. Its speaker
will never play back the fundamental of the bass line, as this frequency is far below the
range that the speaker can transmit. If you pull out all registers of the drawbar organ,
except for the fundamental—16', you’ll still perceive the same pitch. The sound
becomes thinner, with less bass and less warmth, but the pitch remains the same.
Setting drawbar registrations often involves this psychoacoustic phenomenon. In the
lower octaves, mixing the 8' and 5 1/3' sine drawbars creates the illusion of a 16' sound,
although the frequency is missing. Old pipe organs also make use of the residual effect,
by combining two smaller pipes, eliminating the need for long, heavy, air-hungry, and
expensive giant pipes. This tradition is continued in modern organs, and is the reason
for arranging the 5 1/3' under 8: The 5 1/3' tends to create the illusion of a pitch that is
one octave lower than 8'.
A Short Hammond Organ Story
Three inventions inspired Laurens Hammond (1895–1973), a manufacturer of electric
clocks, to construct and market a compact electro-mechanical organ with tone wheel
sound generation. The Telharmonium by Thaddeus Cahill was the musical inspiration,
Henry Ford’s mass production methods, and the domestic synchron clock motor were
the other factors.
The Telharmonium was the first musical instrument that made use of
electromechanical sound generation techniques. In the year 1900, its man-sized tone
wheel generators filled a two-storey building in New York. For a short period around
this time, subscribers could order Telharmonium music over the New York telephone
network (the streaming audio system of the time). The only amplification tool was the
telephone’s mechanical diaphragm, as a proper tube amplifer and acceptable speakers
had not yet been invented. The Telharmonium was a commercial flop but its historical
status as the predecessor of modern electronic musical instruments is undeniable. The
Telharmonium also introduced the principles of electronic additive synthesis (see
“Additive Synthesis With Drawbars” on page 481).
Laurens Hammond began producing organs in 1935, in Chicago, Illinois, making use of
the same sound generation method. The differences were; much smaller tone
generators, and fewer registers. The patent for his model A organ dates from 1934.