MPA MK2 SERIES
SINGLE ZONE MIXER-AMPLIFIERS
Installation and User Guide
MPA MK2 Installation and User Guide V1.0
WARNING:
To reduce the risk of re or electric shock, do not expose this appliance to rain or moisture.
WARNING: SHOCK HAZARD – DO NOT OPEN
AVIS: RISQUE DE CHOC ELECTRIQUE – NE PAS OUVRIR
The lightning ash with the arrowhead symbol within an equilateral
triangle is intended to alert you to the presence of uninsulated
dangerous voltages within the product’s enclosure that may be of
sufcient magnitude to constitute a risk of electric shock.
The exclamation point within an equilateral triangle is intended to
alert the user to the presence of important operating and maintenance
(servicing) instructions in the literature accompanying the appliance.
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MPA MK2 Installation and User Guide V1.0
IMPORTANT SAFETY INSTRUCTIONS
1. Read these Instructions.
2. Keep these Instructions.
3. Heed all Warnings.
4. Follow all Instructions.
5. Do not use this apparatus near water.
6. Clean only with a dry cloth.
7. Do not block any ventilation openings. Install in accordance with the manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, heat registers, stoves or other apparatus (including ampliers) that
produce heat.
9. Do not defeat the safety purpose of the polarized or grounding - type plug. A polarized plug has two blades with one wider
than the other. A grounding type plug has two blades and a third grounding prong. The wide blade or the third prong are
provided for your safety. When the provided plug does not t into your outlet, consult an electrician for replacement of
the obsolete outlet..
10. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point
where they exit from the apparatus.
11. Only use attachments/accessories specied by the manufacturer.
12. Use only with the cart, stand, tripod, bracket or table specied by the manufacturer or sold with the apparatus,
when a cart is used, use caution when moving the cart/apparatus combination to avoid injury from tip-over.
13. Unplug this apparatus during lightning storms or when unused for long periods of time.
14. Refer all servicing to qualied service personnel. Servicing is required when the apparatus has been damaged in any
way, such as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.
Do not expose the apparatus to dripping or splashing, and ensure that no objects lled with water, such as vases,
are placed on the apparatus.
L’appareil ne doit être exposé aux écoulements ou aux éclaboussures et aucun objet ne contenant de liquide, tel
qu’un vase, ne doit être placé sur l’appareil.
The mains plug is used as the disconnect device and it should remain readily accessible during intended use. In order
to isolate the apparatus from the mains, the mains plug should be completely removed form the mains outlet
socket.
Le prise du secteur ne doit pas être obstruée ou doit être facilement accessible pendant son utilisation. Pour être
complètement déconnnecté de l’alimentation d’entrée, la prise doit être débranchée du secteur.
This apparatus is of Class 1 construction and must only be connected to a mains outlet socket with a protective
earthing connection.
Terminals marked with the symbol may use Class 2 Wiring, but voltages at these terminals may be of sufcient
magnitude to constitute a risk of electric shock. The external wiring connected to these terminals requires
installation by an instructed person or the use of pre-made leads or cords.
MPA MK2 Installation and User Guide V1.0
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Energy Efciency Certication
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MPA MK2 Installation and User Guide V1.0
The Cloud MPA120 MK2 and MPA240 MK2 Mixer-ampliers have been designed to meet the relevant
provisions of the US Environmental Protection Agency’s ENERGY STAR® Program.
The ENERGY STAR Program exists to identify products that contribute to the saving of energy and
the reduction of harmful emissions, thereby both saving you money and protecting the environment.
ENERGY STAR certication is your assurance that this product is energy efcient. You can verify its inclusion in the ENERGY
STAR Program at:
https://www.energystar.gov/productnder/product/certied-audio-video/results
MPA MK2 Installation and User Guide V1.0
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Contents
IMPORTANT SAFETY INSTRUCTIONS ................................................................................................................. 3
Energy Efciency Certication ......................................................................................................................................... 4
SAFETY INFORMATION .......................................................................................................................................... 8
Safety Notes regarding Installation ................................................................................................................................ 8
Conformities ........................................................................................................................................................................... 8
RoHS and WEEE declaration .......................................................................................................................................... 8
Safety Considerations and Information ......................................................................................................................... 8
Caution – High Voltage ................................................................................................................................................... 8
Caution – Mains Fuse ....................................................................................................................................................... 8
Caution – Servicing ........................................................................................................................................................... 8
OVERVIEW ................................................................................................................................................................ 9
Introduction ............................................................................................................................................................................ 9
Applicable Models ................................................................................................................................................................. 9
MPA MK2 Series main features ........................................................................................................................................ 9
What’s in the box ................................................................................................................................................................10
Schematic Diagram ............................................................................................................................................................ 11
Front panel description ..................................................................................................................................................... 12
Rear panel description .......................................................................................................................................................13
INSTALLATION ....................................................................................................................................................... 15
Hardware considerations ..................................................................................................................................................15
Ventilation ............................................................................................................................................................................15
Power Supply ........................................................................................................................................................................15
Fuses and ratings .............................................................................................................................................................15
Connections and Controls ................................................................................................................................... 16
Music Inputs .........................................................................................................................................................................16
Sensitivity & Gain Control ............................................................................................................................................16
Music Source Select .......................................................................................................................................................16
Music Level Control ....................................................................................................................................................... 16
Remote Control of Music Source and Level ........................................................................................................... 16
Music Equalisation .........................................................................................................................................................17
Music Priority ...................................................................................................................................................................17
Microphone Inputs ..............................................................................................................................................................17
Gain Control .....................................................................................................................................................................18
Microphone level control ..............................................................................................................................................18
Microphone Equalisation .............................................................................................................................................18
Paging control and mic priority ...................................................................................................................................... 19
Microphone Access Input .............................................................................................................................................. 19
Mic 1-over-Mic 2 priority ............................................................................................................................................19
Outputs ..................................................................................................................................................................20
Speaker Output ............................................................................................................................................................... 20
Connecting to Lo-Z loudspeakers ...............................................................................................................................20
Connecting to 70/100 V-line systems ......................................................................................................................20
Auxiliary Output ..............................................................................................................................................................21
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MPA MK2 Installation and User Guide V1.0
Facility Port ............................................................................................................................................................21
Connecting an active remote module .......................................................................................................................... 22
Music Mute (Fire Alarm Interface) ......................................................................................................................23
Auto Power Down ..............................................................................................................................................................23
Options and Additional Information ............................................................................................................................23
Multi-zone Applications ................................................................................................................................................23
Control of music source and level
via external DC .................................................................................................................................................................23
Using the Facility Port as an auxiliary input ...........................................................................................................24
APPENDIX ................................................................................................................................................................25
PCB jumper locations .........................................................................................................................................................25
Table of internal jumpers and default settings ......................................................................................................26
Troubleshooting ..................................................................................................................................................................27
EMC Considerations ..........................................................................................................................................................27
Earthing .................................................................................................................................................................................27
TECHNICAL SPECIFICATIONS .............................................................................................................................28
MPA MK2 Installation and User Guide V1.0
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SAFETY INFORMATION
Safety Notes regarding Installation
• Do not expose the unit to water or moisture.
• Do not expose the unit to naked ames.
• Do not block or restrict any air vent.
• Do not operate the unit in ambient temperatures above
35°C
• Do not touch any part or terminal carrying the hazardous
live symbol while power is supplied to the unit.
TThe “crossed out wheelie bin” symbol on the
product and represented above is there to remind
users of the obligation of selective collection of
waste. This label is applied to various products to
indicate that the product is not to be thrown
away as unsorted municipal waste. At the end of life, dispose
of this product by returning it to the point of sale or to your
local municipal collection point for recycling of electric and
electronic devices.
Customer participation is important to minimize the
potential effects on the environment and human health that
can result from hazardous substances that may be contained
in this product.
• Do not perform any internal adjustments unless you
are qualied to do so and fully understand the hazards
associated with mains-operated equipment.
• The unit has no user-serviceable parts. Refer servicing to
qualied service personnel.
• If the moulded plug is cut off the AC power lead for
any reason, the discarded plug is a potential hazard and
should be disposed of in a responsible manner.
Conformities
This product conforms to the following European EMC
Standards:
BS EN 55035:2017 (Immunity)
BS EN 55032:2015 (Emissions)
BS EN 6100-3-2:2-14 (Harmonics)
This product has been tested for use in commercial and light
industrial environments. If the unit is used in controlled
EMC environments, the urban outdoors, heavy industrial
environments or close to railways, transmitters, overhead
power lines, etc., the performance of the unit may be
degraded.
The product conforms to the following European electrical
safety standard:
BS EN 62368-1:2014
Please dispose of this product and its packaging in accordance
with local and national disposal regulations, including those
governing the recovery and recycling of waste electrical
and electronic equipment. Contact your local waste
administration, waste collection company or dealer.
Safety Considerations and Information
The unit must be earthed. Ensure that the mains power
supply provides an effective earth connection using a threewire termination.
Caution – High Voltage
Do not touch any part or terminal carrying the hazardous live
symbol while power is applied to the unit. Terminals to
which the hazardous live symbol refers require installation by
a qualied person.
Caution – Mains Fuse
The MPA MK2 contains no user-replaceable fuses. Mains
over-current protection is provided by the fuse in the IEC
receptacle; only replace this fuse with one of an identical
type and rating.
If the replacement fuse blows immediately it indicates that
the mixer amplier has developed a fault, which should be
referred to competent service personnel.
This product is compliant with the relevant provisions of
Energy Star® Eligibility Criteria Ver 3.0 for AudioVideo products.
RoHS and WEEE declaration
Cloud Electronics Limited manages its business and
collaborates with its suppliers to comply with the European
Union restriction of the use of certain hazardous substances
in electrical and electronic equipment, RoHS Directive
(2002/95/EC), that came into force on 1st July 2006, and
similar restrictions in other jurisdictions.
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MPA MK2 Installation and User Guide V1.0
Caution – Servicing
The unit contains no user-serviceable parts. Refer servicing to
qualied personnel. Do not perform servicing unless you are
qualied to do so. Disconnect the power cable from the unit
before removing the top panel and do not make any internal
adjustments with the unit switched on. Only reassemble the
unit using bolts/screws identical to the original parts.
OVERVIEW
• Separate HF/LF EQ adjustments (rear panel) for mic signals
and music source
Introduction
The Cloud MPA MK2 Series are audio mixer-ampliers with
applications in Licensed, Retail, Leisure and similar venues.
Two models are available to suit different output power
requirements (120 or 240 watts); otherwise the models have
identical facilities.
The mixer-ampliers have inputs for six stereo line signals and
two microphone signals. Front panel controls are provided for
music source selection, music level and microphone levels. A
multi-function Facility Port allows the connection of remote
active input modules.
An extensive selection of pre-set controls is located on the
rear panel; primary unit conguration options are selectable
using rear panel DIP switches. Certain installation options are
set using internal PCB jumpers.
The units are also compatible with standard Cloud remote
control plates from the RL and RSL Series.
Applicable Models
This Installation and User Guide describes the installation
and operation of the following models:
Cloud MPA120 MK2: 120 W mono amplier for 4
ohm loudspeakers or 100/70 V-line loudspeaker
systems
Cloud MPA240 MK2: 240 W mono amplier for 4
ohm loudspeakers or 100/70 V-line loudspeaker
systems
All references to “MPA MK2” throughout this Installation and
User Guide may be taken as being applicable to both models.
• Paging control on Mic 1 input via short-to-ground access
connection
• Mic 1 congurable as high-voltage input for paging from
existing 70/100 V-line system
• High-voltage input alternatively selectable to Line 5
input: permits existing background music to be routed via
MPA MK2
• Selectable VOX mic-over-music priority on all mic Inputs
• Automatic Mic 1-over-Mic 2 priority in Page mode; may be
overridden by internal jumper
• Selectable LINE 6 priority with choice of release times
• Selectable pre-announcement chime
• Music Mute control input (N/O and N/C) for interface to
an emergency system
• Facility port for connection of LM-2, L-1 or M-1 remote
input modules via screened Cat 5 cable; LM-2 also allows
remote control of music level and line input selection
• Facility Port supports BT-1 Bluetooth input module
• Compatible with standard Cloud remote control plates:
RL-1 Series (music level) and RSL-6 Series (music level and
source selection)
• Power amplier protection circuitry
• Power amplier input limiter
• Transformerless output stage can be congured to drive
either 70/100 V-line systems directly, or low impedance
loudspeakers (4/8 ohms)
• Switchable 65 Hz low-pass lter: reduces transformer
saturation in 70/100 V-line systems
• Aux output from pre-amp (balanced, line level)
MPA MK2 Series main features
• Provide amplication and simple control of music, mic
sources and paging in a single unit
• Two versions: output power ratings of 120 or 240 W
• Integral two-channel microphone mixer with per-input
sensitivity adjustment
• Front panel controls for music source, music level and level
of each mic input
• Six (unbalanced) stereo line inputs with individual
sensitivity adjustment
• Two balanced mic inputs – 12 V phantom power available
on either or both
• Fixed 100 Hz hi-pass mic channel lter
• Separate microphone limiter circuit to prevent power stage
limiter from ducking music signal in the presence of high
mic levels
• Automatic power-down function (user-selectable)
• ENERGY STAR Certication applied for
• Convection cooled (MPA120 MK2); forced-air cooling with
variable speed control (MPA240 MK2)
• 1U 19” rack mounting unit
Available Options:
• LM-2 remote active mic/line input module with music
source selection and volume controls
• BT-1 remote Bluetooth wireless audio input module
• L-1 remote active line input module
• M-1 remote active mic input module
• RL Series remote control plates for music volume
• RSL Series remote control plates for music source selection
and level
• PM-1 single zone paging mic
MPA MK2 Installation and User Guide V1.0
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What’s in the box
Please check the shipping carton for damage before opening.
If there is damage, please contact your Cloud agent and the
shippers.
The packing carton should contain the following items:
• MPA MK2 mixer amplier
• IEC mains lead (AC cord) with moulded plug appropriate
to the territory
• Set of mating plug-in screw-terminal connectors
• Set of four plastic feet, with xings
• This manual
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MPA MK2 Installation and User Guide V1.0
Schematic Diagram
MPA MK2 Installation and User Guide V1.0
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Front panel description
27 3 1
4568 8
1. MIC 1 and 2 LEVEL – level controls for Mic Inputs 1 and 2.
2. MUSIC SOURCE – selects active Line Input (1 to 6).
3. MUSIC LEVEL – adjusts level of selected Line Input.
4. PEAK – red LED: illuminates if either Mic or Line signal levels are too high.
5. MUSIC MUTE – red LED: illuminates when external Music Mute is active.
6. STATUS – bicolour LED indicates as follows:
INDICATION MEANING
Off
Green
Red
Flashing green
Flashing red
7. Space for source idents.
8. Ventilation slots (MPA120 MK2 only), or forced-air cooling air intakes (MPA240 MK2 only) – do not block.
Power off
Normal operating mode
Standby (APD) mode
Power reduction due to high temperature
Fault condition - outputs muted
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MPA MK2 Installation and User Guide V1.0
Rear panel description
13
2919
12 16 20 22 25 24
14 15 17 21 27 26 23
18 9
9. LINE 1 to LINE 6 – stereo line inputs for music sources.
10. GAIN 1 to GAIN 6 – level trims for each line input.
11. MUSIC EQ – LF and HF EQ adjustment for music channel.
12. MIC 1 INPUT – balanced input for Mic 1.
13. HI-Z SPK INPUT – alternative high-voltage input, for connection to 70/100-V line speaker systems.
14. GAIN 1 – level trim for Mic input 1.
15. ACCESS – external paging control input for Mic 1.
16. MIC 2 – balanced input for Mic 2.
17. GAIN 2 – level trim for Mic 2.
2811 10
18. MIC EQ – LF and HF EQ adjustment for mic channel.
19. SETTINGS – 4-pole DIP switch for conguring Mic Input 1:
SWITCH NAME FUNCTION
SW1 MIC/PAGE
SW2 PRIORITY
SW3 ACC/VOX PRI.
SW4 CHIME TONE
MIC 1 mode – congures MIC 1 input for paging use
Enables mic-over-music priority
Selects paging priority mode – VOX or ACC (ACC = contact closure)
Enables pre-announcement chime tone
20. FACILITY PORT – RJ45 socket for connection of remote active input/control modules such as the LM-2, BT-1, L-1 and M-1.
This port may also be used as an additional balanced line input.
21. RSL-6 – for connection of RL-1 or RSL-6 remote control plates.
22. LOCAL/REMOTE – press to enable the RSL-6 port and the remote control functions of the Facility Port: disables front panel
music controls.
23. SPEAKER OUTPUT – connect to either low-Z loudspeakers or to 70/100 V-line distribution system.
MPA MK2 Installation and User Guide V1.0
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24. SPEAKER SETTINGS – 3-pole DIP switch for setting output conguration:
SWITCH NAME FUNCTION
SW1 65 HZ
SW2 SPK Z
SW3 SPK Z
25. AUXILIARY OUTPUT – balanced line level output for feeding additional ampliers, etc.
26. MUSIC LEVEL – adjust level of music at AUXILIARY OUTPUT.
27. MUSIC MUTE – Emergency control input for muting music.
28. IEC mains input with mains switch and integral fuseholder.
29. Ventilation slot (MPA120 MK2 only), or forced-air cooling air exhaust (MPA240 MK2 only) – do not block.
Enables 65 Hz high-pass lter (use with 70/100 V-line operation)
Congures output for low-Z or 70/100 V-line operation
When SW2 = LO Z: selects output impedance to suit 4 ohm or 8 ohm loudspeakers
When SW2 = HI-Z: selects 70 V-line or 100 V-line operation
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MPA MK2 Installation and User Guide V1.0
INSTALLATION
Hardware considerations
The MPA MK2 mixer-amplier is built in a 1U-high 19” rack
mount enclosure. It is recommended that it is installed in a
19” rack wherever possible. The units are only 150 mm deep,
but it is recommended that at least 100 mm of additional
rack depth should be available to allow for rear connectors
and cabling.
Power Supply
The MPA MK2 has an internal power supply of the “universal”
type, and will operate on all AC mains supplies of between
85 V and 265 V, 45 to 65 Hz. An IEC mains cable with a plug
appropriate for each country is supplied with the unit. MPA
MK2 mixer-ampliers are very energy-efcient and consume
less than 10 W in Idle mode; see the Technical Specications
on page 28 for more details.
Fuses and ratings
The choice of installation location will be dictated by the
specics of the system and building layout. It is recommended
that wherever possible, the MPA MK2 should be mounted
adjacent to as many of the music sources (CD players, music
servers, TV receiver boxes, etc.) as practical.
When deciding the mixer-amplier’s location, bear in mind
that access to it (particularly the rear panel) will probably
be required even if a full complement of remote controls is
being tted as part of the system, as certain adjustments can
only be made on the unit itself.
Ventilation
The MPA120 MK2 is convection-cooled and is silent in
operation.
The higher-powered MPA240 MK2 is convection cooled
below 45°C, and force-air cooled by a variable-speed fan
above this temperature, which reaches its maximum speed
at a temperature of 65°C. Airow is from front to rear.
Both models have two sets of ventilation slots in the front
panels and one set in each of the rear, top and both side
panels: ensure that these are kept unobstructed by cabling
or any other items. It is recommended that a 1U blank panel
is tted above the MPA MK2 to aid heat dissipation; slotted
panels are not recommended in the case of the MPA240 MK2
as they defeat the action of forced-air cooling.
The only externally-accessible fuse is the AC mains
fuse integral with the IEC receptacle on the rear panel.
Only replace a fuse with one of exactly the same type.
The IEC receptacle has space for a spare fuse; one is supplied
with the unit.
The table below gives the correct fuse type:
Fuse Type Fuse size Rating
T4AH 250V 20 mm x 5 mm 4 A
If a replacement fuse blows immediately, it indicates that
the mixer-amplier has developed a fault, which should be
referred to competent service personnel.
Internally, a 20mm x 5mm time-delay 2.5 A fuse protects the
amplier power output module. This is a service component,
and should not require attention. Failure of this fuse indicates
a fault condition, which should be immediately referred to a
competent technician or authorised service centre.
MPA MK2 mixer ampliers have been designed to operate in an
ambient temperature range of 0°C to 35°C. While satisfactory
operation outside of this recommended temperature range may
be achievable in a particular installation, no guarantee can be
given regarding full adherence to the performance specications
(see the Appendix section of this manual). Installers should
always endeavour to t the MPA MK2 in a location where the
recommended temperature range is not exceeded. To help
achieve this, we recommend that the MPA MK2 is not rackmounted immediately above other equipment which generates
heat (e.g., older designs of power amplier).
If the unit is to be used free-standing (i.e., not mounted in
a rack), the push-rivet plastic feet supplied in the accessory
pack should be tted to the bottom of the enclosure.
MPA MK2 Installation and User Guide V1.0
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Connections and Controls
123
REMOTE MUSIC
CONTROL
CONNECTOR
123
REMOTE SOURCE & LEVEL CONTROL WIRING
RSL-6
USE TWO-CORE SCREENED CABLE
Music Inputs
The unit has six stereo line inputs; these inputs are suitable
for most music sources such as compact disc players, music
servers, laptops, satellite receivers and the like. Each stereo
input is summed internally to mono.
Remote Control of Music Source and Level
MPA MK2 mixer-ampliers are compatible with standard
Cloud remote control plates: RSL-6 Series (music source
select and level) and RL-1 Series (level only).
Either type of plate may be connected at the rear 3-pin, 5
mm-pitch screw terminal connector (RSL-6), using the wiring
shown below:
All inputs are unbalanced, and use 3-pin 3.5 mm-pitch screw
terminal connectors. The input impedance is 47 kohms.
Connect as shown below:
AUDIO
SOURCE
RIGHT CHANNEL
LEFT CHANNEL
S L R
LINE 6 input can be congured to have automatic priority the
other music sources: see Music Priority, page 17.
Sensitivity & Gain Control
All six stereo line inputs have a preset GAIN control on the
rear panel adjacent to the respective input sockets. The
control has a range of 20 dB allowing the input sensitivity to
be varied from -12 dBu (195 mV) to +8 dBu (2.0 V).
The GAIN control should be adjusted so that all the input
sources are operating at approximately the same volume,
and that the front panel MUSIC LEVEL control has a useful
range of control.
REMOTE LEVEL CONTROL WIRING
RL-1
123
SINGLE-CORE SCREENED CABLE MAY BE USED
REMOTE SOURCE & LEVEL CONTROL WIRING
123
RSL-6
USE TWO-CORE SCREENED CABLE
REMOTE MUSIC
CONTROL
CONNECTOR
123
REMOTE MUSIC
CONTROL
CONNECTOR
123
Music Source Select
The front panel MUSIC SOURCE rotary switch is used to
select the desired music signal. Remote control of source
selection is possible with a remote control plate (RSL-6), or
active input module (LM-2), see below and page 22.
Music Level Control
A front panel mounted MUSIC LEVEL control is provided.
Remote control of music level is possible with a remote
control plate (RSL-6 or RL-1), or active input module (LM-2),
see below and page 22.
Use two-core (RSL-6 or RL-1) or single-core (RL-1 only)
screened cable to connect the remote level plate (max length
100 metres).
Setting the LOCAL/REMOTE button adjacent to the
RSL-6 connector to REMOTE (button IN) activates the remote
control plate and disables both the front panel level and
source select controls. If an RL-1 is being used, the internal
jumper J10 should be moved from its default ‘SW’ setting to
‘FR’, to override the disabling of the front panel source select
switch. See page 25 for location of jumpers.
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MPA MK2 Installation and User Guide V1.0
Music Equalisation
Two MUSIC EQ controls are provided for the music signals.
These preset controls are located on the rear panel adjacent
to the line input sockets. The HF (treble) control has a range
of ±10 dB at 10 kHz and the LF (bass) control has a range of
±10 dB at 50 Hz.
Note that these controls also affect any signal applied to the
unit via the Facility Port: see page 21.
Microphone Inputs
Two microphone inputs are provided; the microphone preampliers are an electronically balanced, transformerless
design congured for optimum low noise performance. The
input impedance is greater than 2 kohm and is suitable for
microphones in the 200 ohm to 600 ohm range.
Inputs are via separate 3-pin, 3.5 mm-pitch screw terminal
connectors on the rear panel.
Music Priority
A jukebox, digital sound store or other audio source can
be given automatic priority over all other music inputs by
connecting it to Line Input 6 and moving internal jumpers
J1A and J1B from OFF (factory default position) to ON. When
this priority is enabled, the unit will operate normally until a
signal is detected at Line Input 6, when the selected source
(typically background music) is muted, allowing the source
connected to Line 6 to replace it. Once the signal on Line
Input 6 stops, the selected source will smoothly restore to
its former level. The time taken for the restoration is factoryset to 3 seconds, but may be set to 6 or 12 seconds with
internal jumper J2. (3s is suitable for announcements, but the
longer times may be more appropriate if a jukebox or similar
is connected to Line Input 6.) See page 25 for location of
jumpers.
Note that Line 6 priority does not apply to the Facility Port.
Remote active modules connected to the MPA MK2 Facility
Port will normally have priority (but in the case of the LM-2,
see the Installation Guide for further information).
Mic Input 1 - connections
Mic Input 1 can be congured for paging or announcements.
By default, the mic input is independent and is simply
mixed with Mic Input 2 and the selected line input: when
recongured for paging, it operates as a standard Cloudtype paging input, with selectable mic-over-line priority
and triggering by either contact closure or automatic signal
detection. It is then compatible with paging microphones
using zone selection by contact-closure such as the Cloud
PM1 single-zone microphone. See page 19 for more details.
Mic Input 1 has two separate physical inputs: a standard
balanced input and a high-voltage transformer-isolated input
for connection to 70/100 V-line systems. Both inputs are on
the MIC 1/HI-Z/PAGE connector.
IMPORTANT: Cloud recommend that no attempt is made
to connect sources to the balanced and high-voltage
inputs simultaneously.
Balanced input
The connector uses the lower three pins of the 2 x 3-pin 3.5
mm-pitch screw terminal type on the rear panel [12]. Use the
wiring shown below:
HI-Z SPK INPUT
0V
SCREEN
1
MIC 1 INPUT
100V
2 3
70/
HOT
COLD
12 V phantom power is available at the mic input, and is
activated by setting internal jumper J3 to the ON position.
See page 25 for locations of internal jumpers. Care should
be taken to ensure that phantom power is activated only
when the microphone connected to the input requires it –
i.e., a capacitor or electret type; other types of microphones
(such as dynamic) may be damaged if a DC voltage is applied
to them.
MPA MK2 Installation and User Guide V1.0
17
Hi-Z input
Mic Input 1 is provided with a second, alternative method of
connection, which by default is routed to the mic channel
when selected. This is a high impedance, transformer-isolated
input which can be connected directly to a 70 V-line or
100 V-line loudspeaker system. When congured in this way,
the mic input can be used to route paging announcements
from a building-wide PA or PA/VA system into the area
covered by the MPA MK2.
The high-voltage input is enabled by moving internal PCB
jumpers J6A, J6B and J6C. All three jumpers must be moved
together. See page 25 for details of jumper locations.
The high-voltage input may alternatively be routed
internally to the music channel, where it replaces Line Input
5. This means the MPA MK2 can be fed, for example, with
background music from a 70/100 V-line system, allowing it
to be fully integrated with an existing building system. Also,
the music level may be controlled remotely in the same
way as when any other input is used for music sources. The
internal routing of the Hi-Z input - to the mic channel or
Line 5 - is determined by internal jumpers J7A and J7B. The
factory default is for the high-voltage input to be routed
to the mic channel: moving the jumpers will route it to the
music channel. Both jumpers must be moved together. See
page 25 for details of jumper locations.
Note that when the high-voltage input is enabled, the
balanced mic input [12] will be disconnected; if J7A and J7B
are moved to the LINE position, Line Input 5 will also be
disconnected.
To use the high-voltage input, connect a 70 V-line or 100
V-line system feed to the 70/100V input, as shown below.
The Hi-Z input uses two pins of the upper 3-pin section of
the connector.
Mic Input 2 - connections
Connect microphones as shown below:
HOT
SCREEN
2 3
1
COLD
12 V phantom power is available at Mic input 2, and is
activated by setting internal jumper J4 to the ON position.
See page 25 for locations of internal jumpers. Care should
be taken to ensure that phantom power is activated only
when the microphone connected to the input requires it –
i.e., a capacitor or electret type; other types of microphones
(such as dynamic) may be damaged if a DC voltage is applied
to them.
Gain Control
Each mic input has a preset GAIN control ([14] and [17])
adjacent to the input connector.
The GAIN control for Mic Input 1 is operative whichever of the
two input types is in use, though with different gain ranges:
• Balanced mic input - gain range 40 dB, from 10 dB to 50 dB.
• Hi-Z input – gain range 10 dB, from 10 dB to 20 dB
Note that the GAIN control is still functional when the
Hi-Z input is routed internally to Line 5 by moving jumpers
J7A and J7B.
HI-Z SPK INPUT
0V
1
MIC 1 INPUT
100V
2 3
70/
Note that the 70/100 V input is suitable for use with either
70 V-line or 100 V-line systems. The GAIN control may be
used to adjust for the 3 dB difference in level between the
two systems.
Microphone level control
A front panel LEVEL control [1] is provided for each mic input
and these provide the user with a means of adjusting the
volume of each, or the announcements from a PA/VA system
if Mic Input 1’s high voltage connections are in use. The rear
panel GAIN controls ([14] and [17]) should be set at a level
where distortion does not occur even when the front panel
LEVEL control is fully clockwise. If the mic level is set too
high, the front-panel PEAK LED [4] will illuminate. Note that
this LED also indicates excessive music level.
Microphone Equalisation
The two microphone inputs are summed together and are
routed to the power stage via a xed high pass lter and
an adjustable EQ section. The xed lter attenuates the
signal below 100 Hz, which helps to reduce the effects of
microphone handling noise.
The two preset MIC EQ controls [18] are on the rear panel
adjacent to the mic inputs; the LF and HF controls provide ±10
dB of adjustment below 100 Hz and above 5 kHz respectively.
After installation, some test announcements should be made,
ideally by the people who will normally make them. The Mic
EQ should be adjusted if necessary to maximise voice clarity.
18
MPA MK2 Installation and User Guide V1.0
Paging control and mic priority
Mic Input 1 can be recongured to operate as a paging input
with the SETTINGS DIP switch.
For normal (non-paging) operation, all four switches should
be in the ‘up’ position. The priority functions operate as
described below whichever of Mic Input 1’s connection
options is in use (balanced or Hi-Z).
• SW1 – MIC/PAGE: in the MIC position (switch up), Mic
1 input operates as a standard microphone input. In the
PG position (switch down), it operates as a typical Cloud
paging input. In this mode, the Paging Access contacts
will need to be shorted in order for Mic 1 input to become
active.
Microphone Access Input
The paging access control input is on the 2-pin, 5 mm–
pitch screw-terminal ACCESS connector [15]. The ACCESS
input provides compatibility with “contact-closure” paging
microphones. In PAGE mode, Mic 1 input is muted as long
as the pins of the access connector are open-circuit. When
the pins are connected together, Mic 1 input becomes active.
The internal chime generator will also be activated if SW4 is
set to ON.
In either VOX or ACC mode, the music signal is faded back up
after the announcement is complete over a period of approx.
3 seconds.
• SW2 – PRIORITY: set to ON (switch down) to enable Mic-
over-Music priority. This can be selected in both MIC and
PAGE modes of Mic Input 1, i.e., regardless of the setting of
SW1. The priority function will reduce the level of signals
at both LINE and FACILITY inputs by 25 dB. In MIC mode
the priority trigger is always VOX; in PAGE mode the
priority can be either by access contacts or VOX mode, as
selected by SW3. Note that in MIC mode (SW1), Mic-overMusic priority is triggered by a signal at either mic input.
When Mic-over-Music priority is active, the music channel
is muted: when it is released, the music will fade up over
approximately 3 seconds. Note that this priority also mutes
any audio signal applied to the unit via the Facility Port.
• SW3 – ACCESS/VOX PRI.: Note that this switch is
only operational when SW1 is set to PG: with SW1 set
to MIC, priority triggering always uses VOX mode.
When SW3 is set to ACC (switch up), contact closure
priority triggering is selected: a short circuit at the ACCESS
connector [15] will trigger priority (see below for wiring
details), enabling the mic input while ‘ducking’ any line
input signals and muting Mic Input 2 (unless overridden
by internal jumper). With the switch down, VOX mode is
selected: a signal at Mic 1 input will automatically trigger
Mic-over-Music priority. In order for VOX mode to operate
when SW1 is set to PG, the two pins of the Paging Access
connector must be shorted together.
Mic 1-over-Mic 2 priority
If internal jumper J5 is set to ON (the default setting), Mic
Input 2 will be muted whenever the ACCESS connector pins
are shorted with PAGE mode selected (SW1 set to PG). This
ensures that Mic Input 1 will always have priority over Mic
Input 2 when Mic Input 1 is congured for paging.
If this default setting is overridden by moving J5 to OFF, Mic
Input 2 will remain active, and any signal at the input will be
mixed with the paging announcement.
• SW4 – CHIME: MPA MK2 mixer-ampliers have an internal
pre-announcement chime generator. With SW4 set to ON
(switch down), the chime is triggered by the ACCESS input
when Mic Input 1 is in Page mode (SW1 set to PG). The
default setting is OFF. An internal preset control is provided
to adjust the chime volume; the front panel level controls
have no effect on chime level. See page 25 for locations
of internal controls.
MPA MK2 Installation and User Guide V1.0
19
Outputs
Speaker Output
The power amplier stage is fully protected against DC
offset, output over-current, and is also thermally protected.
Activation of the protection circuitry shuts the power
amplier stage down until the fault condition clears. All
protection conditions will automatically self-clear if the
amplier is power-cycled. A switch-on delay function mutes
the output during power-up and power-down to protect
loudspeakers.
The MPA MK2 has both a low impedance output (4 ohms)
and a high voltage output for 70/100 V-line speaker systems.
Both outputs are available on the 3-pin 5 mm-pitch screwterminal SPEAKER OUTPUT connector [23].
Only one of the two output options can be used at a time.
The output type is selected with SPEAKER SETTINGS DIP
switch: select SW2 to LO-Z (switch down) for low impedance
operation or HI Z (switch up) for 70/100 V-line operation. The
switch is set to HI at the factory: set it to the down position if
the amplier is to be use with low impedance loudspeakers.
Connecting to 70/100 V-line systems
The MPA MK2 is a transformerless design and can directly
drive 70 V-line or 100 V-line loudspeaker systems. The power
amplier stage is rated at 120 W (MPA120 MK2) or 240 W
(MPA240 MK2).
Connect to a 70 V-line or 100 V-line speaker system by
setting SW2 to HI Z (switch up) and setting SW3 to either
70V (switch up) or 100V (switch down), as required.
Units will be factory-set to 70 V “out of the box”: a set of tick
boxes is included on the rear panel for installers to conrm
what the correct output conguration should be.
COM 4W
(a) Lo-Z (4 ohm) connection
HI Z / 8W
+
-
4 ohm
loudspeaker
Connecting to Lo-Z loudspeakers
For low-impedance operation, set SW2 to LO-Z (switch
down). The MPA MK2 can deliver its rated power into a 4
ohm or 8 ohm load: set SW3 to 4Ω/70V (switch up) or to
8Ω/100V (switch down) as appropriate. Installers tting
multiple low-impedance loudspeakers (generally 8 ohms)
should employ series and parallel wiring to produce a total
load impedance of either 4 or 8 ohms, but never less than 4
ohms under any circumstances.
For low-impedance operation, wire the SPEAKER OUTPUT
connector according to (a) or (b) in the diagram below.
COM
(b) Lo-Z (8 ohm) connection
COM
(c) Hi-Z connection
4W HI Z / 8W
HI Z / 8W
4W
+
-
+
-
8 ohm
loudspeaker
70 V-line
or 100 V-line
speaker
system
When driving 70/100 V-line loudspeaker systems there
is a risk of transformer core saturation at high levels and
low frequencies, which can produce distortion. To prevent
this, the MPA MK2’s output stage is provided with a 65 Hz
high-pass lter, which may be enabled by setting SPEAKER
SETTINGS switch SW1 to on (SWITCH down).
20
MPA MK2 Installation and User Guide V1.0
Auxiliary Output
The mixer-amplier is provided with an AUXILIARY OUTPUT
[25]. This may be used to drive an additional amplier, for
recording, or any other purpose where system “expansion”
is required. The connector is a 3-pin, 3.5 mm-pitch screw
terminal type.
The signal at the Auxiliary Output is balanced and line level,
and can thus be used to drive most external equipment
directly. The wiring is as follows:
132
Facility Port
The MPA MK2 mixer-amplier is provided with a FACILITY
PORT in the form of a rear panel RJ45 connector [20]. The
primary use of the Facility Port is for the connection of
remote active modules such as the LM-2 or BT-1, but it may
also be used as a general-purpose auxiliary balanced input
(see page 24 for more information on this application).
The various optional Cloud remote active modules operate
from DC power supplied by the MPA MK2. The current
consumed by each module is minimal and in the vast majority
of installations there will be no power supply issues.
scn
cold (-)
OUTPUT: BALANCED
CONNECTION
132
scn
(DON’T CONNECT PIN 2)
OUTPUT: UNBALANCED
CONNECTION
hot (+)
hot (+)
The signal at the AUXILIARY OUTPUT connector is a mix of
the music and mic channels. The music level at the output
can be adjusted with the MUSIC LEVEL control [26] adjacent
to the connector. By default, the music source will be that
present at the amplier’s main output. Alternatively, the
music source may be set to be always that connected to Line
Input 1, by moving internal jumper J9 from TRACK to LINE1.
If J9 is set to TRACK, the Auxiliary Output will be affected by
both Line 6 and Mic-over-Music Priorities: this will not be the
case if J9 is set to LINE1. See page 25 for details of PCB
jumper locations.
Note that the music signal at the Auxiliary Output is not
subject to the action of the Music EQ section, the 65 Hz highpass lter or the power stage’s dynamic clip protection.
IMPORTANT: In order for the remote control functions on
an LM-2 module to operate, the rear panel LOCAL/REMOTE
button must be set to REMOTE (button IN). This will disable
the front panel MUSIC SOURCE and MUSIC LEVEL controls,
and control of music level and/or source selection will be
available from the remote module. The LOCAL/REMOTE
button should be left set to LOCAL (button OUT) when a
BT-1, L-1 or M-1 module is connected to the Facility Port.
The pinout of the Facility Port connector is given in the table
below:
PIN USE Cat 5 CORE*
1 Audio ‘cold’ phase (-) White + Orange
2 Audio ‘hot’ phase (+) Orange
3 Priority VCA control White + Green
4 + 12 V Blue
5 0 V White + Blue
6 -12 V Green
7 Music level control
White + Brown
(0 to 10 V)
8 Music source select
Brown
control (0 to 10 V)
SCN GND ref for system
Connector shell
music controls
* Standard wiring for pre-made cables
MPA MK2 Installation and User Guide V1.0
21
MIC LEVEL
5
4
3
2
1
MIC INPUT
6
0
MUSIC LEVEL
7
8
9
10
4
3
2
1
LINE INPUT
7
8
9
10
0
PRIORITY
6
5
3
4
2
5
6
1
MIC
6
5
7
4
8
9
3
2
10
1
0
LM-2
LM-2 mic/line input module, with music source
and level controls
Connecting an active remote module
The LM-2 is an active input module which allows a microphone
and a stereo line input in a remote location to be connected
to the MPA MK2. The module also includes the functions of
a Cloud RSL-6 Remote Control Plate, which allows remote
control of the MPA MK2’s music level and music source
selection.
The BT-1 is a Bluetooth remote audio input module which
enables compatible portable devices such as laptops, tablets
and smartphones to stream audio wirelessly to the module,
and thus into the audio system of the area where the module
is installed.
NOTE: The MPA MK2 is only compatible with the BT-1F
variant of the BT-1: do not attempt to connect variant BT-1E.
STATUS
PUSH
--
TO PAIR
2s 5s
BT-1
BT-1 Bluetooth wireless audio input module
MUSIC LEVEL
5
6
4
3
2
1
LINE INPUT
7
8
9
10
0
L-1
The L-1 and M-1 are remote active input modules which
allows a microphone (M-1) or stereo line level source (L-1)
to be connected within a zone and then routed to the zone’s
audio system. The M-1 includes a mic level control and a
switchable mic-over-music priority function; the L-1 is tted
with both phono sockets (RCA jacks) and a 3.5 mm 3-pole
jack socket, together with a music level control.
The active remote module should be connected to the MPA
MK2’s FACILITY PORT using screened Cat 5 cable. (Note
that as the cable carries analogue audio, only screened Cat 5
should be used.) The LM-2 includes controls for local music
level and source selection, the wiring for these functions
being catered for on the Facility Port. The maximum total
Cat 5 cable length should not exceed 100 m.
Connections:
LM-2: The LM-2’s upper PCB is tted with an RJ45 connector
labelled OUTPUT. Connect this to the FACILITY PORT using
screened Cat 5 cable with screened RJ45 connectors at
each end. Follow the colour coding shown in the table on
page 21. The metal screening of the connectors should be
bonded to the screen of the cable. Full details can be found in
the LM-2 Installation Guide.
22
L-1 line input module
MIC LEVEL
5
6
4
3
2
1
MIC PRIORITY
7
8
9
10
0
M-1
M-1 mic input module
MPA MK2 Installation and User Guide V1.0
As explained in the preceding section, before the LM-2’s
music source and level controls will operate, the LOCAL/
REMOTE button [22] must be set to REMOTE.
BT-1: Connect the RJ45 socket on the rear of the BT-1 to
the MPA MK2’s FACILITY PORT with screened Cat 5 cable
and shielded RJ45 plugs. Full details can be found in the BT-1
Installation Guide.
M-1 and L-1: Connect the RJ45 socket on the rear of the M-1
or L-1 to the MPA MK2’s FACILITY PORT with screened Cat 5
cable and shielded RJ45 plugs. Full details can be found in the
Installation Guide supplied with the module.
The Facility Port may alternatively be used as an additional
balanced line input for any other source; see page 24 for details.
Music Mute (Fire Alarm Interface)
In some installations (such as licensed premises or retail
outlets within a shopping mall), there may be a local authority
or re service requirement to mute the music signals from
a re alarm control panel when an alarm condition arises.
MPA MK2 mixer-ampliers include a facility to mute
the music signals only (i.e., mic inputs are still active), via
the MUSIC MUTE input. This is a 2-pin 5 mm-pitch screw
terminal connector on the rear panel [27], and the contacts
are fully isolated.
Activation of Music Mute is often via a relay mounted close
to the MPA MK2, powered by the re alarm control panel.
Other arrangements may exist depending on the design of
the re control system and the alarm system details should
be consulted when making the connection. MPA MK2 mixerampliers will mute the music on either a contact closure
at the Music Mute input (N/O) or an open-circuit (N/C).
Selection of N/O or N/C operation is made with internal
jumper J11. N/O is the factory default.
Options and Additional Information
Multi-zone Applications
Where the sound system specication calls for separate
control in several zones, multiple MPA MK2 mixer-ampliers
can be used.
Signal sources can be parallel-connected to several inputs as
required, but care must be taken to ensure the output stage
of the signal source is capable of driving the resulting lower
input impedance.
The impedance of the line inputs (music inputs) is 47 kohms
and it is reasonable to assume that most op-amp based signal
sources are able to drive a 10 kohm load, allowing up to ve
ampliers to be paralleled. The input impedance of the mic
inputs is 3.3 kohms, making them suitable for microphones
with a nominal impedance of 600 ohms or less. A single 600
ohm microphone could therefore typically be connected to
four paralleled mic inputs.
If these guideline gures cannot be adhered to, the use of
suitable mic or line distribution ampliers is recommended.
REMOTE MUSIC MUTE TERMINATIONS
RELAY
NORMALLY OPEN (N/O)
CONNECTION
MUSIC MUTE
INPUT
1 2
RELAY
NORMALLY CLOSED (N/C)
CONNECTION
MUSIC MUTE
INPUT
1 2
Note that any signal applied to the MPA MK2’s Facility Port –
either from a remote active module, or as a hard-wired direct
input, will be also muted by the action of Music Mute.
When Music Mute is active, the front panel red MUSIC MUTE
LED [5] illuminates.
Auto Power Down
The MPA MK2 is an extremely energy-efcient mixeramplier, but can be made even more so by enabling the
Auto Power-Down feature. When active, the signal level is
constantly monitored and if no input signals are measured
for 15 minutes, the unit enters a “Sleep” mode, minimising
power consumption. If an input signal is detected while in
Sleep Mode, the mixer-amplier “wakes up” in approximately
one second: if the signal is a line input, the volume will be
faded up over a period of three seconds.
To avoid any problems associated with differences in mains
supply earthing, we recommend that all MPA MK2 mixerampliers used in a multi-zone application should be colocated and connected to a common mains supply.
Note that when using multiple MPA MK2 mixer-ampliers
in a 19” rack, suitable ventilation arrangements must be
made to ensure that lower ampliers do not cause those
above to overheat (see Ventilation on page 15 for further
information).
Control of music source and level via external DC
It may be necessary in some installations to adjust the music
level and select music source in one or more zones from an
external AV control system. If the RSL-6 port is not required
for RL-1/RSL-6 Series remote control plates, they may be
used to receive DC voltages from the external system to
effect these adjustments.
Both music source selection and level can be controlled over
their full ranges with a DC voltage of 0 to +10 V. The pinout
of the RSL-6 port is as follows:
PIN USE
1 0 V ref.
2 Music level control (0 to +10 V)
3 Music source selection (0 to +10 V)
The MPA MK2 is shipped with the Auto Power Down function
disabled. It may be enabled by removing internal jumper J12.
See page 25 for location of PCB jumpers.
MPA MK2 Installation and User Guide V1.0
23
+12 V
CONTROL
SYSTEM
SOURCE CONTROL
LEVEL CONTROL
0 V REF
REMOTE
SOURCE+LEVEL
PORT
3k6
15k
3
2
1
0 V
46-80
MUSIC SOURCE
MUSIC VCA
SELECT
NOTE: If the control voltage source is not isolated from the
power earth, there is a small risk of creating a ‘ground loop’
by linking the mixer technical ground (0 V) to the ground
(0 V) of the equipment supplying the control voltages. To
minimise this risk, we suggest that all pieces of equipment be
in close proximity, and supplied from the same power outlet.
pull-up will cause ‘OFF’ to be selected. The output impedance
of the control voltage source should be low enough to
overcome the effect of this resistor.
Using the Facility Port as an auxiliary input
The Facility Port provides a balanced audio input. If the
port is not connected to a remote input module or remote
control plate, it may be used as an additional, balanced line
input. The signal applied at the Facility Port is mixed with the
other music inputs and is affected by the rear panel MUSIC
EQ controls [11]. The Facility Port signal has no independent
level control on the amplier; this must be adjusted at the
source. If Mic-over-Music priority is enabled (see “Paging
control and mic priority” on page page 19), a line input at
the Facility Port will be reduced in level by 25 dB in the same
way as the other Line Inputs, though this may be overridden
by moving internal jumper J8 from its default setting (ON) to
OFF. See page 25 for locations of PCB jumpers.
Music level
Music level in a zone may be varied over its full range by
applying a DC voltage of between 0 V and +10 V to pin 2,
the 0 V reference being connected to Pin 1. 0 V on pin 2
corresponds to maximum level and +10 V will produce
90 dB of attenuation. The rate of attenuation is approximately
175 mV/dB.
Note that there is an internal 3k6 “pull-up” resistor between
pin 2 and the internal +12 V rail. If pin 2 is left “oating”, this
pull-up will result in full attenuation. The output impedance
of the control voltage source should be low enough to
overcome the effect of this resistor.
Music source
Music source for a zone may be controlled by applying
various DC voltages of between 0 and +10 V to pin 3, the 0 V
reference being connected to pin 1. 0 V at pin 3 will select Line
input 6 and between +6 V and +7.2 V will select Line input
1. The other line inputs will be selected with intermediate
voltages. Taking pin 3 above +7.2 V will deselect all inputs,
making the zone effectively ‘off’ for music.
Connect an external balanced source to the Facility Port as
shown below:
1
2
hot (+)
3
OUTPUT (e.g., XLR)
cold (-)
BALANCED
Twin-core screened cable
FACILITY PORT (RJ45)
hot (+)
cold (-)
1
2
3
4
5
6
7
8
An unbalanced source may also be connected; the use of
balancing transformers is recommended.
The table below lists the DC voltages required at pin 3 to
select each line input. The third column is the value of a
resistor which should be connected between pins 1 and 3 to
permanently ‘force’ a zone to a particular line input.
INPUT DC VOLTAGE RESISTOR VALUE
OFF >+7.2 V Open-circuit
Line 1 +6.3 V 16k
Line 2 +5.1 V 10k
Line 3 +3.9 V 6k8
Line 4 +3.0 V 3k9
Line 5 +1.8 V 1k8
Line 6 0 V short-circuit
Note that there is an internal 15k “pull-up” resistor between
pin 3 and the internal +12 V rail. If pin 3 is left “oating”, this
24
MPA MK2 Installation and User Guide V1.0
APPENDIX
PCB jumper locations
The MPA MK2 has various internal jumpers, the setting of which may require alteration during installation. The diagram below
shows the locations of the internal jumpers (not to scale), all of which are located on the main PCB. The table below lists each
jumper and its purpose, together with the factory default setting.
All “user” jumpers have two possible positions; the black rectangle in the symbol on the diagram below indicates the default
setting. If any jumpers need to be changed, turn the MPA MK2 off and disconnect it from the mains. Undo the six screws
securing the top cover of the unit and remove it. Use a pair of small pliers to gently remove the jumpers from the PCB headers
and reposition them as required. Ret the top cover using the same screws.
J6B
J6A
J3
J5
PCB
J6C
J7B
J4
REAR PANEL
TO UPPER
PANEL PCB
TO FRONT
J12
J13
ONLY PRIMARY COMPONENTS SHOWN.
VIEWED FROM REAR OF UNIT.
MAIN PCB ONLY SHOWN.
NOT TO SCALE.
J9
J7A
J8
J10
J2
J1A
J1B
J11
TO POWER
STAGE
MPA MK2 Installation and User Guide V1.0
25
Table of internal jumpers and default settings
The table below lists each jumper and its purpose, together with location and factory default setting.
JUMPER DESCRIPTION EFFECT DEFAULT REMARKS
J1A & J1B must
J1A, J1B Line 6 priority OFF: Line Input 6 operates as other line inputs. OFF
3 SEC: selected music source resumes 3 seconds after
signal at Line Input 6 ends.
J2
J3
J4
J5
J6A
J6B
J6C
J7, J7B
J8
J9
J10
J11
J12 APD enable
J13 APD Test Mode For factory use only ABSENT
Line 6 priority
release time
Mic Input 1
phantom power
Mic Input 2
phantom power
Page Mic-over
Mic 2 priority
defeat
Hi-voltage input
enable
Hi-voltage input
internal routing
Mic-over-Facility
port priority
Aux Output music
source
Force front panel
music source
select
Music mute N/O
or N/C
6 SEC: selected music source resumes 6 seconds after
signal at Line Input 6 ends.
ABSENT: selected music source resumes 12 seconds after
signal at Line Input 6 ends.
OFF: Mic Input 1 phantom power off.
ON: 12 V phantom power available at Mic Input 1.
OFF: Mic Input 2 phantom power off.
ON: 12 V phantom power available at Mic Input 2.
OFF: Mic Input 2 will remain active when Mic 1 is in
PAGE mode and ACCESS port pins are shorted.
ON: Mic Input 2 will be muted when Mic 1 is in PAGE
mode and the ACCESS port pins are shorted.
MIC: Mic Input 1 is a normal balanced mic input.
100V: Mic Input 1 is congured for connection to 70/100
V-line speaker system.
MIC: Hi-voltage input is routed as Mic Input 1.
LINE: Hi-voltage input is routed as Line Input 5.
OFF: Mic signals will be mixed at full level with Facility
Port input.
ON: An input at Mic 1 or Mic 2 will cause a signal from
the Facility Port to duck.
TRACK: music source at Auxiliary Output is that selected
by MUSIC SOURCE control (or equivalent remote
control).
LINE1: music source at Auxiliary Output is always Line
Input 1
SW: when LOCAL/REMOTE switch is set to REMOTE,
front panel MUSIC SOURCE switch is disabled and music
source selection is made from remote control plate/
module.
FR: when REMOTE/LOCAL switch is set to REMOTE, front
panel MUSIC SOURCE control remains operative.
N/O: connect the pins of the MUSIC MUTE connector
together to mute Line Inputs 1 to 6 and the Facility Port.
N/C: remove a short-circuit across the pins of the MUSIC
MUTE connector to mute Line Inputs 1 to 6 and the
Facility Port.
PRESENT: APD (Automatic Power Down) inactive.
ABSENT: APD enabled
3 SEC
OFF
OFF
ON
MIC
MIC
ON
TRACK
SW
N/O
PRESENT
always be moved
together.
J6A, J6B & J6C
must always be
moved together.
J7A & J7B must
always be moved
together.
DO NOT FIT A
JUMPER HERE
26
MPA MK2 Installation and User Guide V1.0
Troubleshooting
EMC Considerations
Fault conditions are indicated by the front panel STATUS LED
[6] ashing either red or green.
Status LED ashes GREEN - Output Power reduced
If the amplier temperature exceeds 70°C the output
power will be reduced linearly to maintain a safe operating
temperature for the internal components. This feature
prevents over-temperature shutdown from being triggered
and is indicated by a ashing GREEN status LED.
Status LED ashes RED - Over-temperature Shutdown
When the amplier temperature exceeds 85°C, the unit will
mute the speaker and auxiliary outputs: this state is indicated
by a ashing RED status LED. Power cycle the unit to clear.
Output power reduction or over-temperature shutdown can
occur if the amplier is incorrectly installed. In this event,
investigate the following points:
• Incorrect output setting for connected speaker load.
• Elevated ambient temperature (> 40°C)
• Ventilation requirements not met (no free space above
unit)
• Excessive signal input (PEAK LED illuminated constantly)
Status LED ashes RED - Amplier output protection
The MPA MK2 incorporates the following protection schemes
to prevent damage to the amplier or connected speakers:
• Short Circuit protection
• Over-current protection
• DC protection
If any of the three protection schemes is triggered, the unit
will mute the speaker and auxiliary outputs and ash the
STATUS LED RED. The speaker wiring should be checked for
faults. A power cycle is required to reset the unit.
MPA MK2 mixer-ampliers fully conform to the relevant
electromagnetic compatibility (EMC) standards and are
technically well behaved. You should experience no problems
interfacing units to other items of equipment and under
normal circumstances, no special precautions need to be
taken.
If the unit is to be used in close proximity to potential sources
of HF disturbance such as high power communication
transmitters, radar stations and the like, it is suggested that
input signal leads be kept as short as possible.
Always use balanced interconnections wherever possible. If
the MPA MK2 mixer- amplier is mounted in a 19” rack, do
not locate the unit in close proximity to a powerful amplier
of any kind, which may radiate a strong magnetic eld from
the power transformer.
Earthing
When several mains powered units are connected together
via their signal cables, there is a risk of one or more earth
loops which may cause an audible hum on the system even
with the gain controls set to minimum.
The 0 V rail of an MPA MK2 mixer-amplier is directly coupled
to the chassis ground. No interconnection problems should
be encountered, but if there is any hum or other extraneous
noise when source equipment is connected, the situation can
generally be remedied by observing the following guidelines:
• Always connect sources using balanced connections
wherever possible, with the cable screen only connected at
the receiving end (amplier input).
• Use audio isolating transformers (readily available from
trade suppliers) at the inputs if necessary. These will ensure
that the amplier is electrically isolated from the source
equipment.
• The signal source units should be located as close as possible
to the ampliers and the metal housing of the various units
should not be electrically connected together through the
equipment rack. If this is a problem, rack isolating kits are
available from specialist hardware suppliers. If the problem
persists, try to connect all interconnected units, including
power ampliers to a common power source to ensure a
common ground is provided.
MPA MK2 Installation and User Guide V1.0
27
TECHNICAL SPECIFICATIONS
Line Inputs
Frequency Response 20 Hz to 20 kHz, ±1 dB
Sensitivity 195 mV (-12 dBu) to 2.0 V (+8 dBu)
Input impedance 47 kohms
Headroom 16 dB
Noise <-90 dB (22 kHz bandwidth)
Equalisation HF: ±10 dB @ 10 kHz; LF: ±10 dB @ 50 Hz
Microphone Inputs
Frequency Response -3 dB @100 Hz (xed lter) to 20 kHz, ±1 dB
Sensitivity 2.54 mV (-50dBu) to 245 mV (-10 dBu)
Input Impedance 3.3 kohms (balanced)
Phantom Power 12 V, switchable per-input by jumpers
Headroom 16 dB
Noise (EIN) -126 dBu
Equalisation HF: ±10 dB @ 5 kHz; LF: ±10 dB @ 100 Hz
High voltage input
Frequency Response
Input Gain Control 10 dB to 20 dB
Noise <-90 dB (22 kHz bandwidth)
Facility Input
Frequency Response 20 Hz to 20 kHz, ±1 dB
Sensitivity 0.775 V (0 dBu)
Input impedance 10 kohms (balanced)
Headroom 18 dB
Noise Gate -60 dB
Main Output
Output Power (1 kHz continuous sine wave)
Minimum load
Frequency response
THD + N < 0.05% @ 1 kHz
Protection Fixed level signal limiter: DC, over-current and over-temperature protection
Auxiliary Output
Nominal output level 0 dBu (0.775 Vrms), balanced
Noise <-90 dB, 22 kHz bandwidth
via Mic I i/p -3 dB @100 Hz (xed lter) to 20 kHz, ±1 dB
Via Line 5 i/p 20 Hz to 20 kHz, ±1 dB
±0.5 dB, 20 Hz to 20 kHz 120 watts
<0.05% @ 1 kHz 240 watts
Low-Z output 4 ohms
70 V-line
High-Z output
100 V-line
Low-Z output 20 Hz to 20 kHz, ±1 dB
High-Z output 20 Hz to 20 kHz, ±1 dB (65 Hz lter off)
MPA120 MK2 41 ohms
MPA240 MK2 21 ohms
MPA120 MK2 66 ohms
MPA240 MK2 33 ohms
28
MPA MK2 Installation and User Guide V1.0
General
Power input Universal type, 85 to 265 VAC, 45 to 65 Hz
Fuse details 5 x 20 mm, time delay, 4 A
Normal operating temperature
Cooling
Power consumption
Heat Loss
0 °C to 35 °C (Note: performance and specications cannot be guaranteed
outside of this range)
MPA120 MK2 Natural convection
MPA240 MK2 Forced air cooling, variable speed
Standby
Idle
1
2
1/8th Power
1/3rd Power
Standby
Idle
1
2
1/8th Power
1/3rd Power
3
4
3
4
MPA120 MK2
MPA240 MK2
MPA120 MK2
MPA240 MK2
MPA120 MK2 29.9 W (40.6 VA)
MPA240 MK2 48 W (56.7 VA)
MPA120 MK2 59 W (67.1 W)
MPA240 MK2 104.6 W (112.5 VA)
MPA120 MK2
MPA240 MK2
MPA120 MK2
MPA240 MK2
MPA120 MK2 53.2 KJ/hr (50.5 BTU/hr)
MPA240 MK2 64.3 KJ/hr (60.9 BTU/hr)
MPA120 MK2 68.5 KJ/hr (64.0 BTU/hr)
MPA240 MK2 87.7 KJ/hr (83.2 BTU/hr)
482.6 mm x 44 mm (1U) x 150 mm
Net
Dimensions (W x H x D)
(less connectors & knobs)
19” x 1.75” (1U) x 5.9” (less connectors & knobs)
0.89 W (11.8 VA)
9.6 W (18.9 VA)
3.2 KJ/hr (3.1 BTU/hr)
34.5 KJ/hr (32.8 BTU/hr)
Shipping (Gross)
Weights
Notes re Power Consumption and Heat Loss measurements:
All measurements at 230 VAC 50 Hz power input
1. Standby: amplier in standby state (STATUS LED steady red)
2. Idle: amplier not in standby state (STATUS LED steady green), but no audio output
3. 1/8th. Power: constant sound level at one-eighth maximum rated output (audio mainly clean, only occasional clipping)
4. 1/3rd. Power: constant sound level at one-third maximum rated output (audio beginning to become compressed, limited or heavily clipped)
Net 2.15 kg / 4.8 lbs
Shipping (Gross) 3.2 kg / 7.2 lbs
560 mm x 60 mm x 290 mm
22” x 2.4” x 11.4”
MPA MK2 Installation and User Guide V1.0
29
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