9
HDMI
The MX123 has seven HDMI Inputs, one of which
is capable of 8K video. To take advantage of this
new capability, the use of certified “Ultra High
Speed HDMI” cables according to the 2.1 HDMI
specification is recommended. This would include
support for 8K@60Hz, HDR, Ethernet, and ARC.
Though, HDMI is backward compatible, older
cables may have issues with the higher bandwidth.
Use HDMI OUT MONITOR 1 when connecting to
an ARC (Audio Return Channel) enabled television.
ARC can provide two-way communication between
units allowing for volume control and lip-syncing
functions to ensure audio and video are perfectly
matched. This allows for more intelligent operation
between components as well as less cable clutter.
Make sure the ARC is enabled in your TV’s setup
menu.
USB
There are two type-A ports on the rear of the
MX123. The port labeled POWER SUPPLY is used
to supply power (5 volts / 1.5 amps) via a USB
cable. The second port, labeled USB, is for USB
memory devices. Use this second port for accessing
music from USB storage devices. Plug the USB
memory device directly into the port. USB hubs will
not work. Because of the vast array of USB memory
devices available from countless manufacturers,
McIntosh does not guarantee that all USB memory
devices will operate or receive power.
Microphone
The microphone Input is for connecting the supplied
MX123 Microphone using the microphone’s
attached cable and an 1/8 inch connector. The
microphone is used in the Audyssey
®
calibration for
tuning the system to your room. For instructions see
“Audyssey
®
” on page 28.
RS232
The RS232 jack is used to connect the MX123
to automation controller devices with RS232
connectors. To utilize this feature, you will need an
appropriate RS232 Data Cable. The RS232 Data
Cable should be an 1/8 inch (3.5mm) stereo mini
phone plug to a subminiature DB9 connector.
Figure 04– Mini plug for RS232 connection
Data In
(DB9-pin2)
Ground
(DB9-pin5)
Data Out
(DB9-pin3)
Figure 05– DB9 connector pin layout
RS232 DB9 Connector Pin Layout
1. N/C (no connection)
6. N/C
2. Data In (RXD)
7. N/C
3. Data Out (TXD)
8. N/C
4. N/C
9. N/C
5. Gnd
Typical RS232 settings are:
• 8 data bits, no parity and one stop bit
•
Baud rate fixed at 115,200 bits per second
Wired IR Inputs
The IR Input allows an external IR receiver to be
attached to the MX123. The Input is labeled IR IN.
By attaching an IR receiver using a 3.5mm cable
(See Figure 06), the MX123’s Remote Control can
be used in another location without a line-of-sight to
the MX123’s front IR sensor. In this way, if ZONE
2 is another room, a Remote Control can be used to
adjust the MX123.
Figure 06–
IR Data
Control
Ground
N/C
IR 3.5mm connector
If using an external IR receiver for the MAIN
ZONE in the same room as the MX123, you may
wish to
disable the front IR sensor
, which also
controls the MAIN ZONE. This will avoid potential
timing issues of receiving the Remote Control’s
commands from two different Inputs. The front IR
can be turned on/off by doing the following:
• Put the MX123 in STANDBY mode
• While pressing and holding the front panel
ENTER and RETURN buttons, press the
STANDBY button (a 3-button push)
• Use the Down Arrow on the Front Panel or
Remote Control to navigate to the RC LOCK
Off option to enable the front panel IR sensor or
choose RC LOCK On to disable the front panel
IR sensor. See Figure 07
• Pushing ENTER will make the selection and
reboot the MX123
Figure 07– Setting the Remote Control Lock
