CX261 Installation and User Guide v1.5
16
Microphone Limiter
The microphone channel incorporates a limiter circuit to
prevent amplifier and speaker overloading and also to help
maintain more constant speech volume when the system is
used by different announcers. The limiter is set to restrict the
mic signals to a nominal 0 dBu, and if the mic gain and level
are set correctly, should be inaudible in operation on normal
speech. There are no internal or external controls.
Use of Mic 1 input with a telephone
system
MIC 1 input may be reconfigured to accept an audio input
directly from a compatible telephone system.
The
MIC/TEL
button on the rear panel ([9] at page 9
)
should be in the TEL position (in) for this application. This
inserts a transformer in series with the input connector to
provide full electrical isolation from the telephone system,
together with an independent gain control stage.
The
TEL GAIN
preset gain control ([10] at page 9
)
should be adjusted with a test call from the telephone system.
Note that the front panel
MIC 1 LEVEL
control is still
operational.
Main Outputs
In normal operation, the music level will be set by the front
panel
MUSIC LEVEL
control, or by a corresponding control
on a remote plate. Follow the procedure described previously
(page 15
) to adjust the music level in each zone.
Stereo/mono operation
The CX261 is a 2-channel device, and is intended to be used
where full stereo reproduction of music sources is desirable. If
the installation does not require full stereo operation (which
will generally be dictated by room layout and loudspeaker
placement), mono mode should be selected. Mono mode
is enabled by moving internal jumper J4 from STEREO to
MONO.
In mono mode, the
LEFT
and
RIGHT
outputs will carry
identical programme at the same level. Either or both may be
used as wished.
Note that stereo music sources should still be connected to
both L and R line inputs in the normal way. However, when
mono operation is enabled, any mono music sources may be
connected to either L or R only.
MOH/Auxiliary Output
The signal level at the MOH/Aux output can be set
independently, via the rear panel preset
MOH LEVEL
control ([13] at page 9
). The output level is zero with the
control fully anticlockwise. Note that the signal at this output
is NOT altered by the front panel
MUSIC LEVEL
control
or the rear panel
MUSIC EQ
preset adjustments.
Source Selection
If the output is to be used as an auxiliary mono feed, it will
generally need to follow the normal music source selection.
This is the factory default configuration. If Music Priority is
enabled (see “Line 6 priority”
), the MOH/Auxiliary output
will switch to Line 6 along with the main outputs if the input
becomes active.
However, when in use as an MOH source, it is generally
more desirable for the music source (typically a CD jukebox
or music server) to remain constant, and not vary with the
front panel
MUSIC SOURCE
control. For this purpose, the
source for the auxiliary/MOH output can be altered, by moving
internal jumper J8 from
SEL
to
LINE 2
. The music source
that is intended to provide the Music On Hold programme
should be connected to
LINE 2
. See “PCB jumper location
and settings” on page 20 for location of the internal jumper.
In either case no microphone signals are present at the
MOH/auxiliary output, thus announcements made via the
microphone inputs do NOT interrupt music programme at
this output, regardless of any priority settings.
Priorities
The CX261 offers several options for determining what
happens to music signals when announcements are made. The
options are selected via internal jumpers, and should be set
to suit the requirements of the installation when the system
is installed. See page 20 for location of the internal jumpers.
Line 6 priority
Line input 6 can be set to have priority over other music
inputs. When set, the CX261 will automatically switch the
music source to Line 6 when the signal level at Line 6 input
exceeds -30 dBu (approx.) The input set by the source
selection switch is temporarily deselected until the signal at
Line 6 input stops, when it resumes, smoothly increasing in
level to its former volume. The restoration time is selectable,
options are 3, 6 or 12 seconds.
This facility is useful with sources such as spot announcement
players, jukeboxes, digital sound stores or similar, as audio
from these sources will always automatically replace any
previously selected programme for its duration.
Music Priority is set by moving internal jumpers J5A and
J5B from OFF to ON. See page 20 for location of internal
jumpers.
The factory default restoration time is 3 seconds. This may be
too short in some cases; for example, if a jukebox was to take
