Tuning
All notes of the pedal solo unit are simultaneously tuned by adjusting two tuning
knobs located on the pedal solo generator. These change the frequency of the master
oscillator by shunting small additional capacitors across the main tuning condenser.
To tune the pedal solo unit to the organ, proceed as follows:
(a) Press only the 4, MUTE, and PEDAL SOLO ON tablets and hold down the middle D#
pedal. The pedal drawbars must be pushed in, and the vibrato should be off.
(b) Pull out only the first white drawbar for either manual and press the
corresponding preset key. Hold down the D# key above the middle C, with the
drawbar and the volume control knob set to give approximately equal volume.
(c) Set the fine tuning knob on the pedal solo generator to its center position
and adjust the rough tuning knob to the point which brings the two notes most
nearly in tune (slowest beat between them). Then adjust the fine tuning knob
to make the beat as slow as possible. While it is generally not possible to
tune exactly to zero beat, the accuracy of tuning provided will be found to be
sufficient.
(d) The organist may prefer to have the pedal solo generator tuned slightly sharp
to increase the chorus effect between it and the main tone generator. To tune
it sharp, turn the fine tuning switch counterclockwise one step.
Note: Never tune on the lower pitch registers (especially the 32-foot range) where
the pitch acuity of the ear is insufficient for accurate tuning. If the 4-foot stop
is tuned as directed above, all other registers will be in tune because they are
locked by the frequency dividers to exact octave intervals.
Wiring of Pedal Switch
The nine contacts of each pedal key make contact with nine busbars extending the
length of the pedal switch assembly. One set of contacts and the corresponding
busbar, used for tuning the pedal solo unit, are wired to a terminal panel on top of
the pedal switch, where the tuning coil cable connects. The other eight sets of
contacts are wired to the main tone generator as indicated in the pedal wiring chart
in the section on manuals and pedals, although only seven sets are actually used to
carry tones from the main generator to the pedal drawbars.
The contacts of one set (the one marked 12th harmonic in the wiring chart) are used
as control contacts for keying the pedal solo unit. The fact that they are connected
to ground through the pedal switch wiring and the tone generator wiring does not
affect their use for this purpose, since the keying circuit impedance is high by
comparison. The busbar for these contacts is wired to a terminal on top of the pedal
switch to which the white keying wire from the pedal solo control panel connects.
These contacts are wired to the main tone generator in the usual way in order that
they may supply the 12th harmonic in case special circumstances make it desirable
to omit the pedal solo unit. In this case a green wire from the pedal resistor panel
on the manual assembly (it will be found wrapped around the pedal switch cable, is
connected to the busbar terminal on top of the pedal switch (see appropriate figure
in the section of wiring diagrams). The pedal tones will then be identical to those
on the B and C series organs.
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