Dolby
®
Model CP650 Installation Manual
B-Chain Alignment
4-2
•
Ensure that there is good air movement through power amplifiers.
Air-Conditioning
If air-conditioning noise is audible in the theatre, arrange for lubrication of the motor
and fan bearings, adjustment of belts and drives, and cleaning of filters to reduce the
ambient noise to a minimum.
4.2 Microphone
Placement
Position a microphone multiplexer in the center of the listening area. Place each
microphone in the auditorium so that each is substantially in the reverberant field
rather than in an area that receives the most direct energy from the speakers. In
addition, avoid perfect symmetry. Arrange the microphones so that they are not
arranged in a perfect square or rectangle parallel to the sides of the room. Take care
not to place any of the microphones (except mic number 1) on the central axis of the
room. Standing waves and nodes at these positions can cause measurement errors.
Microphone number 1 should be placed two-thirds of the distance from the front
speakers to the rear, at the exact side-to-side center of the room, approximately five
feet above the floor level, and rotated 45 degrees upward towards the screen.
Placement of this microphone is important for output level adjustments.
Figure 4–1
EQ Microphone Placement
If a single microphone is used (NOT advised), the recommended position would be
two-thirds of the way from the front speakers to the rear, off the axis of the center
speaker, five feet above the floor level, and rotated 45 degrees upward towards the
screen.
Route the output cable to the CP650 and connect it to the microphone connector on
the rear panel or front setup panel (XLR on the rear panel or nine-pin D-connector
“MIC MUX” input on front setup panel). The mic input connectors are wired in
parallel. Phantom power is optionally provided to both mic connectors by moving
DIP switch 3 to the up position.
1.5 meters
(5 feet)
