3.28 Tuning of the two Twin Transposers
It is the purpose of the transposer to change the pitch of the organ's
master oscillators in discreet steps which correspond to half-tones.
The Galaxy is equipped with a total of 3 tone generators (generator
I, generator II and accompaniment generator).
The twin transposes !affects the pitches of the organ generator) as
well as the auto accompaniment generator. Also refer to Figs. 86
and 87.
The twin transposes II controls the organ generator II only. The
second half of this transposer is not used.
We presume that both organ generators are properly tuned and
that the accompaniment generator is tuned but still set up for tuning
(steady tones of the chords).
1. Preparations:
a) "Master Pitch" control (on AP1G) at centre of rotation.
b) "Orchestra Intonation" control (on right control panel)
at centre of rotation.
c) "Slalom" control (on left control panel) at the right-
hand stop.
d) No vibrato set, n o Wersivoice activated, no reverb
on, no couplers on, no "Ensemble Tuning" buttons
depressed.
e) Select the fixed stop Clarinet 8' in both U /Man and
M/Man respectively.
f) Transposer switch at "C".
2. Depress and hold the A-key of the 3rd octave on the middle
manual. You should hear the "middle A" of exactly 440 H z
(you tuned it earlier). If the pitch is slightly off against your
reference (other instrument, tuning fork, absolute ear, etc.)
adjust the master pitch control (on AP 1 G) to set it correctly.
3. Set the transposes switch to " C # ". Depress and hold the
key G#. Set the trim pot P 12 on the twin transposer l (next
to Key Pop) until the tone is pitched to middle A (= 440 Hz)
again.
4. Set the transposes switch to " D': Depress and hold the key
G. Set the trim pot P 13 on the same twin transposes until
the tone returns to middle A (= 440 Hz).
5. Continue, using the same procedure, until you reach the
transposes position "F ". Then, tune the other half of the
rotation, from B down to F#. This time hold and depress keys
above the middle A key. Consult the Tuning Table below.
Note 1:
There are many ways to tune the transposers. The method
described above has the advantage that you are always tuning
towards the same pitch, namely middle A (= 440 Hz). This is
especially useful if you only own a single tuning fork (and not 12).
Note 2
: if you are using a frequency counter, connect it to the test
point "3 520 Hz- of the generator being tuned (via its transposer)
and consult the Tuning Table for frequencies vs. transposer
positions.
Note 3
: It is possible that, due to the additive effect of parts
tolerances, the range of a trim pot on a transposes does not allow
the tuning to the perfect pitch. In that case, the series resistor
associated with that trim pot has to be changed to a larger or
smaller value. Refer to the schematic diagram in the AM 102 "Twin
Transposes".
6. Set the transposer switch to " C': Depress and hold the
middle A key of the upper manual, in addition to the held A
AM 075 (Part)
29
Summary of Contents for GALAXY
Page 1: ...Master Assembly GALAXY AM 075 AM 075 Part 1 ...
Page 4: ...Figure 1 Layout of the building blocks in the organ top AM 075 Part 4 ...
Page 5: ...Figure 2 Block diagram of the audio distribution and associated DC controls AM 075 Part 5 ...
Page 6: ...AM 075 Part 6 ...
Page 33: ...Figure 4 Schematic layout of the wiring harness GO 4 AM 075 Part 33 ...
