Motion Sound MS-1771 - Manual (Page 2)

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Default Internal Adjustments (On PC Board)
Default External Adjustments (On Amplifier Chassis Rear)
Amplifier tone control adjustments
The amplifier chassis on the lower rear of the MS-1771 has external controls for Volume, Bass, and Treble. They are
adjusted with a small blade type screwdriver. The MS-1771 is initially set up for typical installations. There are also internal
EQ adjustments for acoustic and personal taste refinement. Have the Organist/Music director present when making EQ
adjustments. (Internal adjustments are on the PC board, remove lower wood panel for access)
1. The volume trim control (external) should be set with the Organ played at full registration and full volume. Do not turn the
volume control past any sign of distortion.
2. The horn balance: (internal) Adjusts the horn volume in relation to the 15” speaker providing overall cabinet tone and mid-
range balance. Use full registrations when making this adjustment. Some installations will require higher horn levels than
others.
3. Treble Control: (external) Adjusts the very highest (>3 KHz) response of the cabinet and effects key click and brilliance.
4. Bass: (<150 Hz) (external) the lower pedal notes are effected. Play the Organ with full registration and low pedal notes
while listening in several locations in the room.
5. High Cut: (internal) Some Organs may have to much shrill brilliance, the high cut, in conjuction with the treble control, can
help tame an overly bright sound. Set the treble control first then experiment with the high cut. You may have to go back
and forth a few times to finalize the sound.
Rotary Speed Control Adjustments (On PC Board)
All rotor and horn dynamics (internal) have been carefully set at the time of manufacture and should not need adjustment
unless belt tension is changed or a belt is replaced. Of course, speeds can be changed to personal preference. Record trim
control settings in case you want to return to default. There are two sets of trim controls (4 each), one set for the horn, the
other set for the low rotor; Fast speed, Slow speed, Acceleration time, and Deceleration time.
Horn diaphragm replacement .
The horn rotates on sealed ball bearings, no oil or maintenance is required.
Warning! Use a Motion Sound MS-1.2 or certified 8-ohm replacement only .
1. Remove the top rear cabinet cover screws and cover to gain access to the rotary assembly.
2. Remove the top axle shaft top support screws (See image below).
3. Remove the four screws holding the horn driver rotary assembly to the cabinet.
4. Carefully slide the assembly out the rear of the cabinet then remove the speaker wires (note polarity) from diaphragm.
5. Undo the three phillips screws to remove the diaphragm, follow the replacement’s instruction sheet, then reassemble.