McIntosh MA6400 Owner's Manual page 19

The 120 volt AC current switching capabilities of the MA6400 can be Increased by
adding an optional Mclntosh R612A or PC-2 Power Control Relay.
18. SPEAKERS 1 - SPEAKERS 2
Connect two pairs of loudspeakers to the SPEAKERS 1 and SPEAKERS 2 terminals. Make
sure that the speaker plus and minus. (Hot and Common) terminals are connected to the
corresponding plus (+) and minus (-) amplifier terminals.
The HOT and COMMON ( + and -) terminals of both pairs of speakers must be connected
in an identical manner to the proper amplifier output terminals so the speakers will operate IN
PHASE. This means that the speaker driver surfaces move back and forth the same in each
speaker system. Almost all loudspeaker systems have their hot and common terminals color
coded, with red usually as hot or plus and black as common or minus. The output signals of all
Mclntosh power amplifiers are always IN-PHASE with the input signals.
Use high quality speaker cables since this is an important link in your stereo system.
Selection of the proper size and type of speaker cable is necessary for you to receive the best
possible performance from your amplifier and speaker combination. Consult your Mclntosh
dealer for recommendations on the cables that will best fit the needs of your stereo installation.
19. EXTernal SENSOR
Connect a coaxial cable, (RG6 or RG59U), from the EXTernal SENSOR connector to a WK-2
keypad or an R649 wall mounted IR Sensor. This allows the MA6400 Hand Held Remote
Controller to send control signals to the MA6400 without aiming it at the front panel.
One example of a need for this feature would be if the MA6400 were installed behind a
cabinet door that would block the front panel IR sensor.
Another use for this feature is to place a keypad or sensor in the remote area where a second
pair of loudspeakers is installed. You can select program sources and control volume in the
remote area. (The same program source and volume level will also be present in the main
listening area loudspeakers if they are selected.)
20. PWR CTL (Power Control)
This connector supplies a control signal that will turn ON or OFF the AC power of an
accessory component with a Power Control Input connector.
A Power Control cable uses single conductor shielded wire with 1/8" mini phone plugs
on each end. Connections are to the tip (+) and sleeve (-) of the plug.
(Mclntosh Part No. 170-202.)
THE REAR PANEL
AND HOW
TO MAKE
CONNECTIONS
17