
The MPS1 is a music/paging unit which, when used with a public address amplifier,
allows for two speaker zones to be controlled from an external console microphone
or similar unit. The unit has an integral signal muting facility, as well as a switched 24v
DC output suitable for activation of a restoration relay.
The MPS1 is supplied in a metal case that can be wall, table or rack mounted. It is
powered by 240v (120v option available) 50/60 Hz AC mains and/or 24v DC supply.
Introduction:
2

Technical Specifications:
3
Specifications:
Zone switching: Main and auxiliary amplifier selection
Muting: 2 sets of change-over contacts (2 pole 2 way)
operated from a single input
Zone relay rating: DPCO 5 Amp 250v AC contact rating with
24v DC coil
Muting relay rating: DPCO 1 Amp 30V AC contact rating with
24v DC coil, SW 24v DC Out DPCO 1 Amp 30v
AC contact rating with
Relay rating: 24v DC coil
Visual status indication: By LED indicators mounted on PCB (for test
purposes only)
Connections: Screw terminals on PCB
Power requirements: 240v AC 50/60 Hz (120v option), and/or
24v DC
Power consumption: 6vA @ 240v AC, 75mA using 24v DC supply
Case dimensions: 180( L) x 120(W) x 50(H) mm
Weight: 1kg
• CIE-Group reserves the right to alter the above specifications without prior notice

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Description:
• Control In:
The CONTROL input requires switch
closure across the terminals P.T.T. (Press
To Talk) & 0V to activate zone control.
The switch will normally be a zone
select switch in a microphone console.
When activated three DPCO relay (RL1,
RL2, RL3) circuits will be energised
simultaneously, viz.: zone control, signal
muting and switched 24v DC out.
• Zone Control:
The zone control section consists of a
DPCO relay (RL3) which is activated by
switch closure across the ‘Press To Talk’
(P.T.T.) terminals. The main 100v speaker
line signal, zone 1, is connected to the
MAIN AMP IN terminals which are directly
connected on the printed circuit board to
the MAIN SPEAKER OUT terminals, i.e.
unswitched. The MAIN AMP IN terminals
are also connected to the Normally Open
contacts on the relay. When the relay is
activated, the main amplifier signal is
routed to the switched speaker output
terminals (SW SPEAKER OUT) as well as
the MAIN SPEAKER OUT terminals.
The AUX AMP IN terminals are connected
to the Normally Closed contacts on the
relay and allow a second amplifier, zone
2, to be connected. When the relay is
relaxed (de-energised) the AUX AMP IN
terminals are connected through to the
SW SPEAKER OUT terminals. An LED
adjacent to the relay illuminates when
the relay is activated, giving a visual
indication of its operation.
• Signal Muting:
A signal muting facility is supplied,
consisting of a DPCO relay (RL2) which
is activated by switch closure across
the ‘Press To Talk’ (P.T.T.) terminals. All
the contacts of the relay are brought out
to the SIGNAL MUTE terminal group.
The actual muting can be achieved in
several ways depending on the system
requirements, although typically the
signal (from tuner, tape deck, etc.,) would
be connected to the common terminal
(+ SIG OUT) and the ground or screen
to the normally open terminal (SCREEN).
When the mute relay is activated the
contacts close and the signal is short
circuited. It is important to check that the
source from the tuner, tape deck, etc.,
is suitably buffered so that shorting out
the signal will not damage the source.
If in doubt, the relay contacts should be
configured to open circuit the signal to
the amplifier.
As there are two sets of contacts
available, several muting arrangements
are possible. These include muting
balanced signals, muting two separate
signals, using one set of terminals to
trigger a chime.

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• Switched 24v DC Out:
The switched 24v DC output section
consists of a DPCO relay (RL1) which is
activated by switch closure across the
‘Press To Talk’ (P.T.T.) terminals. One set
of the relay contacts, when activated,
provides a switched 24v DC output supply
at the SWITCHED 24v DC OUT terminals.
The current available is shared with the
unswitched 24v DC output and is limited
to 250mA by a fuse (F2). This switched
output is ideally suited for activating a
restoration relay to increase the speaker
volume during paging. The second set of
the relay contacts are brought out to the
SPARE terminals. These may be used to
trigger a chime.
• 24v DC Out:
A 24v DC fused supply is available from
the unit, and is suitable for powering
ancillary equipment such as microphone
consoles, line amplifiers, tone generators
etc. The current available is shared with
the switched 24v DC output and is limited
to 250mA by a fuse (F2).
• 24v DC In:
The MPS1 can be powered from an
external 24v power supply via these
terminals. The unit has reverse current
protection, so that both the mains supply
and the external 24v can be connected
at the same time (e.g. when in systems
requiring battery backup).
• Mains Input:
The unit is supplied with a standard input
voltage of 240v 50/60Hz, although it can
be supplied with a 120v 50/60Hz input as
an option.

6
Connection Details:
• Main Speaker OUT:
The main amplifier speakers are
connected to these terminals.
• SW Speaker OUT:
The auxiliary amplifier speakers are
connected to these terminals.
• Signal MUTE:
These are simply the two sets of muting
relay contacts brought out to terminals.
The ± SIG IN terminals refer to Normally
Closed contacts, the SCREEN terminals
to Normally Open contacts and ± SIG
OUT to the Common contacts. For wiring
options see description ‘Signal Muting’.
• Switched 24V DC OUT:
A switched 24v DC supply fused at a
maximum of 250mA is available from
these terminals whilst the ‘Press To Talk’
(P.T.T.) control input is activated by switch
closure. The current available is shared
with the unswitched 24v DC output. A
spare set of potential free changeover
contacts are also brought out to
terminals, which are also activated whilst
the P.T.T. control input is present. For
wiring options see description ‘Switched
24v DC Out’.
• Control IN:
Switch closure across the P.T.T. & 0v
control input terminals will activate the
music/page switching, providing the
facility for zone control, signal muting
and switched 24v DC output.
• Main AMP IN:
The 100v output from the main amplifier
is connected to these terminals. In the
case of an unbalanced or polarised
system the ‘earthy’ or ground line
should be made to the - MAIN AMP IN
terminal.
• AUX AMP IN:
The 100v output from the auxiliary
amplifier is connected to these terminals.
In the case of an unbalanced or polarised
system the ‘earthy’ or ground line should
be made to the - AUX AMP IN terminal.

7
• 24v DC OUT:
A 24v DC fused supply at a maximum of
250mA is available from these terminals.
The current available is shared with the
switched 24v DC output.
• 24V DC IN:
An external 24v DC supply @ 1 Amp
continuous current rating should be
connected to these terminals, for either
powering the unit or for supply backup
purposes.
• Mains INPUT:
The mains power input should be
connected to these terminals. The Live
conductor should be connected to the
terminal marked ‘L’, the Neutral to the
terminal marked ‘N’ and the Earth to the
terminal marked ‘E’.
Ensure that the supply cord is held firmly
in place by the cable clamp adjacent
the terminals. The unit is supplied with a
standard input voltage of 240v 50/60Hz,
although it can be supplied with a 120v
50/60Hz input as an option.
For safety reasons this unit MUST be
connected to Earth.
The UK convention for mains supply
colour coding is:
LIVE - BROWN
NEUTRAL - BLUE
EARTH - GREEN/YELLOW
• WARNING:
Under no circumstances
should any wiring or maintenance be
carried out to the unit whilst mains
power is connected. All connections
are via knock out holes on the sides
of the box and onto screw terminals
located on the printed circuit board.

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CIE-Group Ltd Widdowson Close Blenheim Ind Est Bulwell Nottingham NG6 8WB England
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