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35
Performing with the Keyboard
Performing
■ [H-Bar Manual] button
When this function is used, the harmonic bar settings will change from the
settings of the registration to the positions (settings) of the harmonic bars on
the panel.
fig.04-10b
What Are “Feet?”
Historically, the “feet” (“ ' “ symbol) indications of the harmonic bars
originate in the length of the pipes of a pipe organ. The length of pipe used
to produce the reference pitch (the fundamental) for the keyboard is eight
feet. Reducing the pipe to half its length produces a pitch one octave higher;
conversely, doubling the pipe length creates a pitch one octave lower.
Therefore, a pipe producing a pitch one octave below that of the reference
of 8' (eight feet) would be 16'; for one octave above the reference, the pipe
would be 4', and to take the pitch up yet another octave it would be
shortened to 2'.
On tone wheel organs, the pitch relationship shown in the diagram does not
hold true in a certain region of the keyboard (p. 34). In the high range of the
keyboard, high-pitched feet are “wrapped around” one octave down. High
footages will be “folded back” for high notes, while low footages will be
folded back for low notes. Folding back the high-frequency portion prevents
the high-frequency sounds from being unpleasantly shrill, and folding back
the low-frequency portion prevents the sound from becoming “muddy.” On
the VR-760 faithfully simulates this characteristic.
As you can see from the relation of the pitches, the 5-1/3' pitch is unique in
that it is not arranged in order of pitch. The reason is that the 5-1/3' sound
blends not with the 8' (fundamental), but with the 16' pitch. Acoustic
instruments produce sound consisting of frequencies at integer multiples of
the fundamental frequency; double, triple, and so on. These are called
“integer harmonics.” Relative to the 8' pitch that is the basic pitch of an
organ, the 5-1/3' pitch is not an integer multiple, and does not blend.
However, relative to the 16' pitch (which is one octave lower), 5-1/3' is an
integer multiple and therefore does blend. (Starting at 16', the 5-1/3' pitch is
three times higher.) Because 5-1/3' blends with 16', these two harmonic bars
are colored differently than the other harmonic bars, and are placed
together.