Contents
How to install and operate the
DLS Marine Audio amplifiers MRA22
& MRA31
Welcome!
This owners manual is written in easy english and
uses a lot of drawings to simply the installation and
use of the above amplifiers.
Your DLS amplifiers must be installed correctly in
order to work well. This manual will show you how
to install the amplifier like a pro. Please read the
entire manual before beginning the installation.
Install the amplifier yourself if you feel confident with
our instructions and if you have the proper tools.
However if you feel unsure, turn over the installation job to someone better suited to it.
Installation…………………….……. 2
Tools and materials needed………. 3
Amplifier installation kit………….... 3
Wiring
Power and Remote……………..…. 3
Input and controls
Input wiring Hi & Low level……….. 4
Parallel input.................................. 4
Hi/Low input switch........................ 4
Fuses / Protect light....................... 4
Input level control........................... 5
Phase control................................. 5
Crossovers…………....................... 5
MRA 22 speaker wiring:
Front speakers…...……………….... 6
Subwoofer…………………………... 6
MRA 31 speaker wiring:
Front speakers…...……………….... 7
Subwoofer…………………………... 7
Testing……………………………….. 8
Troubleshooting……………………... 8
Professional tips…………………….. 9
Specifications………………………... 10
Warranty Service
This amplifier is covered by warranty, depending
on the conditions in the country where it is sold. If
the amplifier is returned for service, please include
the original dated receipt with the product.
For technical assistance ask the shop where the
product was sold or the distributor in your very country.
You can always phone the DLS Helpdesk in Sweden
+ 46 31 84 00 60 or send an e-mail to info@dls.se.
Information can also be found on our WEB-site
www.dls.se
Technical Assistance
All models include
RCA inputs
High Level input
Continuos variable low pass and high
pass crossover
Remote turn on / off
Automatic remote turn on/ off on high level
input without connecting any remote wire
Electronic protection circuitry against
short-circuit, DC offset and thermal overload.
Bridgeable design to direct full power to
one or two subwoofers etc.
IMPORTANT!
While these amplifiers are specially designed
for marine applications, they are not
waterproof and should not be mounted where
it is likely to get wet.
The cover is made to resist moisture as well
as the PC-board.
Installation
Before you begin installation
Before you begin you need to read the manual, to have
some tools, cables and other material available. There
is one such list of material on the following page.
MRA22, MRA31
Amplifier location
Important
Allow air circulation around the amplifier.
The DLS Marine Audio amplifiers have a compact
design that allows great flexibility in mounting.
Safety Considerations:
Your amplifier must be installed in a dry, wellventilated environment and in a manner which
does not interfere with your vessel’s factory
installed electronic devices. You should also take
the time to securely mount the amplifier so that it
does not come loose in the event of a collision or
a sudden jolt to the vessel.
Check before drilling any holes in your vessel
to make sure that you will not be drilling through
the hull, a fuel tank, fuel line, wiring harness or
other vital vessel system.
Do not run system wiring outside or
underneath the vessel. This is an extremely
dangerous practice which can result in severe
damage to your vessel and person.
Protect all system wires from sharp edges
(metal, fiberglass, etc.) by carefully routing
them, tying them down and using grommets
and loom where appropriate.
Do not mount the amplifier in the engine
compartment or in any other area that will
expose the amplifier circuitry to the elements.
Do not mount the amplifier upside down!
This is the best way to
mount the amplifier to get
good cooling.
Disconnect Battery
Before starting the installation, always disconnect
the negative terminal of
the battery.
DLS logo on amplifier cooling flange
The DLS logo on top of the amplifier is attached
with two 1 mm hex. screws. The logo can be removed and twisted 90 or 180 degrees, and then
screwed back in wanted position. The logo can be
mounted in four different ways to match your installation.
Removal of side flanges
In order to attach the amplifier to the surface and
connect speaker and power cables, the side
flanges must be removed. This is done by removing the hex screws on top of the amplifier. Use a
3 mm hex key.
Remove these
screws using a 3
mm hex. key for
removal of side
flange. Remount
after attaching the
amplifier and
connection of the
speaker and power
cables.
2
Wiring
MRA22, MRA31
Tools and material needed
Tools:
Flat and Phillips screwdrivers
Wire cutter, Wire stripper
Electric drill with drills
Crimping tool
Digital multimeter or test lamp
Material:
Speaker wire: minimum
12 AWG = 4 mm2 for subwoofers
13 – 16 AWG = 1,5-2,5 mm2 for other
speakers
Stainless metal screws for mounting the
amplifier to the amplifier board and the
amplifier board to the vessel, and some
extra for fuse holder.
Electrical insulation tape
Amplifier installation kit:
If available, buy an amplifier installation kit. It
contains normally all you need. This is what you
have to buy if you buy the items separately.
Power cable,minimum 8 AWG = 10 mm
for MRA22, 4 AWG = 21 mm2 for MRA 31.
1 pc of fuseholder to install close to the
battery + fuse 50 Ampere.
15 AWG = 1,5 mm2 wire for remote turn on /
off cable from radio / CD.
RCA-cable for input from radio.
Different lengths are available.
Two ring crimp terminals –one
for connection to the battery plus and one
for the battery minus connection.
Two heavy fork crimp terminals to connect
+ and – to amplifer – but you do only need
them if you use heavy cable or to make the
installation look nicer.
Four to ten fork crimp terminals to
connect the speaker cables – but you do
only need them if you use heavy cables or
want the installation to look nicer.
One fork crimp terminal to connect the
remote wire to the amplifier, but you need it
only to make it look nicer.
Four to eight splicers to connect speaker
cables to high level input cable, if high level
input is used.
Wire ties
2
Connect power and remote
Connect the fuse holder as close to the vessel
battery + as possible, using AWG 8 = 10 mm2 or
heavier cable. Use a ring crimp terminal cable to
connect to battery +. Apply silicon grease to the fuse
to prevent corrosion. Use a 50 Amp fuse for both
amplifiers.
To head unit
remote
DLS FH1
fuse holder
Connect the battery cable by a crimp fork terminal
(spade ) to the +12 Volt on the amplifier. Do likewise
with the negative cable. If you use a AWG 8 = 10
2
mm
or thinner cable, you can do without the crimp
terminal and put the cable right into the connector.
Be sure to use a rubber grommet or a plastic
insulating tube where the cable passes places when
it can easily be jammed. Use wire ties to secure to
existing cables.
Remote terminal ( REM )
For RCA cable signal input:
Connect the radio power antenna lead = remote
turn on/off from the car stereo to the amplifier remote
connection. This turns on the amplifier when the
car stereo is turned on.
You can either use the built in remote cable in the
RCA cable itself or use a separate cable.
We recommend to use a separate remote wire and
run the RCA lead separate from remote wire, power
cables and speaker cables.
You can either use a crimp fork terminal or insert
the cable directly into the amplifier terminal. If there
is no remote voltage available from the stereo, you
must connect to the ignition key through the radio
or any accessories fuse.
If amplifier installation kits are available with different size of power cable, chose the most heavy
power cable to improve sound quality and to allow
more amplifiers to be installed now or later.
These are the minimum sizes we recommend for
the amplifiers:
MRA22 10 mm2 (7 AWG)
MRA31 21 mm2 (4 AWG)
This is for cable lengths up to 5 meters.
The ground cable must have the same size.
For High Level input:
We recommend you to connect the remote wire as
described above. The amplifier will produce soft on
/ soft off operation this way. You must set the Hi
level/Low level switch to High level position in this
case.
In the case that there is no remote voltage available
from the car stereo or you want to simplify the installation, the amplifier can be turned on/ turned off
by the high level input voltage. This is done when
the Hi level/Low level switch is set to Hi level position. There is a small disadvantage that this function
gives soft turn on operation but some pop sound
when switching off.
3
Input and controls
MRA22, MRA31
Input Wiring
Inputs may be low level from the RCA output of the car
stereo or high level from the car stereo speaker output. Low level = RCA is to prefer for the best sound
quality.
Important
On MRA22 use either the low level or high level
input, do not use both at same time.
Low level input
Use a pair of shielded stereo audio cables with RCA
type jack. RCA cables are
available in different lengths
up to 5,5 meters.
Avoid placing the RCA cable
close to speaker cables,
power cables and remote
control cable. Connect to input socket A/B.
MRA31 has also a separate input (C) for the mono
sub channel.
High Level Input
Connect left and right speaker wires coming from
the car stereo to the high level input as shown. You
must connect both plus and minus as the inputs
are balanced, connecting plus only gives lower level
and bad sound quality. By changing the polarity of
plus and minus, you can change the phase.
RCA Output
Input Output
Use RCA Outputs to
AA
connect additional
amplifiers (not available on
MRA31).
BB
Hi / Low level input switch
To ensure best possible performance from the
amplifiers a switch is installed to select between Hi
and Low input.
When using High Level input:
Push in the button to position
”Hi Level”
When using Low level input:
Hi level
Low level
Push out the button to position
”Low Level”
If the switch is set to wrong position, the amplifier
still works, but the risk for disturbances or distortion
increases.
Fuses
MRA31 uses two 30 ampere
ATC blade type fuses.
MRA22 uses one 25 A fuse.
MRA 22, MRA31
High Input
(C/D Ch)
Hi level input
plug on amp.
White: A ch.+
White/Black: A ch.Grey/Black: B ch.Grey: B ch.+
MRA31
On MRA31 the high level signal is fed internally to
channel C when using high level input.
Automatic turn on when using high level input.
With the Hi/Low input swich set to Hi, the amplifier
turns on automatically on high input. You dont need
to connect a separate remote wire from your head
unit.
Parallel input on MRA31
Parallel Input
MRA31
Off PC
On MRA31 the PC position
internally connects the A/B input
with the input for channel C.
Power Light / Protect light
The power light (green ) comes on when
Power
(Green)
Protect
(Red)
the amplifier is turned on.
The protect light ( red ) comes on
when the amplifier shuts down from
overheating, or a short circuit ( speaker failure)
4
MRA22, MRA31
Input Level control
The input level control, 5V – 0,25 V,
matches the output of your radio to
Level
the input of the amplifier. After installation is complete, make sure the input of the amplifier is turned down all
5V
0,25V
the way ( counter-clockwise at 5V ).
Play a tape or CD, make sure all bass or treble
settings or equalizer are flat, and turn the volume of
the radio up until you just start to hear distortion.
Turn the volume control down just a bit. On the
amplifier increase the input level control ( clockwise
or to the right ) until you just start to hear distortion,
then back the level control just a bit. Now your radio
and amplifier levels are matched.
Phase control MRA31
The phase control on MRA31 can be set
continuously from 0 - 180 degrees. This is very
useful when you want to adjust the bass sound for
best front stage image. Start on 0 and turn the control
slowly clockwise until you experience that the bass
sound is coming from the front. If you dont get the
result you want, also try to
phase reverse the subwoofer
connections and make
a new adjustment.
NOTE: This function is intended for car use and
may not be fully functional in boats. Set the control
to 0.
PHASE
0 180
High Pass Filter (HPF)
HPF
50Hz 220Hz
Filter freq. range:
15Hz
500Hz
MRA22: 15-150 Hz
MRA31: 50 - 150 Hz
Off On
The HPF (high pass filter) blocks very low
frequencies from reaching the speakers. It is mostly
used at say 60 Hz to protect small speakers (like 6
inch and smaller) from deep bass. It can also be
used as subsonic filter to take away the very
deepest frequencies from a bass box. The typical
setting is then around 25 – 40 Hz.
The filter can be switched off if you want to run the
amplifier in full range mode.
Low Pass Filter (LPF)
LPF
80Hz 200Hz
500Hz
50Hz
Off On
The LPF (low pass filter) mostly used for
subwoofers. It will allow low frequencies only and
blocks higher frequencies. A typical setting is 50 –
80 Hz. The filter can be switched in and out.
Filter freq. range:
MRA22: 50-500 Hz
MRA31: 50 - 120 Hz
Crossovers
Both amplifiers include high pass filter
( HPF ) and low pass filters ( LPF).
All filters are continously variable and all filters can
be switched on and off. MRA31 also include a
subsonic filter.
Subsonic filter MRA31
The Subsonic filter blocks the very
deepest frequencies from reaching the
subwoofers. It has a fixed frequency
of 25 Hz and can be switched On / Off.
For sub channel C only.
Subsonic
Off On
5
Speaker wiring MRA 22
MRA22
Two fullrange speakers to MRA22
Filter settings
HPF
50Hz 220Hz
One subwoofer connected in bridge mode to
MRA22
NOTE!
4 ohm minimum load when using bridge mode
connection. Lower impedances may damage the
amplifier. In bridge mode the amplifier sees a 4
ohm load as 2 ohm.
Filter settings
HPF
50Hz 220Hz
500Hz
15Hz
Off On
With the HPF-filter in OFF position the amplifier
allows the speakers to play fullrange. If you for
some reason want to limit the low bass
reproduction switch on the HPF-filter.
The typical setting is then 60 – 80 Hz.
LPF
80Hz 200Hz
500Hz
50Hz
Off On
The LPF-filter should be OFF.
500Hz
15Hz
Off On
The HPF filter is here used as subsonic filter to take
away the very deepest frequencies. The typical setting is around 25 – 40 Hz.
LPF
80Hz 200Hz
500Hz
50Hz
Off On
The LPF will allow low frequencies only and blocks
higher frequencies. A typical setting is 70 – 90 Hz.
6
Speaker wiring MRA 31
MRA31
Two fullrange
speakers to
channel A/B
With the HPF-filter in OFF
position the amplifier allows
the speakers to play
fullrange. If you for some
reason want to limit the low
bass reproduction turn on the
HPF-filter. The typical setting
is then around 60 – 80 Hz.
90Hz
50Hz
HPF
120Hz
150Hz
Off On
One (or two)
4 ohm
+ + C CH - -
subwoofers
to channel C
Filter settings channel C
The subsonic filter takes away the very deepest
frequencies. Turn on the subsonic filter if you want
to remove these frequencis.
The LPF will allow low frequencies only and blocks
higher frequencies. A typical setting is 60 – 80 Hz.
The phase control can be set continuously from 0
- 180 degrees. This is very useful when you want to
adjust the bass sound for best front stage image.
Start on 0 and turn the control slowly clockwise until
you experience the bass sound coming from the
front. If you dont get the result you want, also try to
phase reverse the subwoofer connections and make
a new adjustment.
NOTE: This function is intended for car use and may
not be fully functional in boats. Set the control to 0.
7
MRA22, MRA31
Testing
Before you finish the installation, you should do the
following tests to make sure the wiring is correct and
everything is operating properly.
Reconnect Battery
When wiring is complete,
reconnect the battery
negative terminal.
Test power wiring
1. Turn on the head unit but do not turn up the
volume. The amplifier power light should
come on. If not, check the remote and +12
volt wires. Also check the ground
connection.
2. Turn up the head units volume slightly. All
speakers should operate. if not, check wiring
connections at amplifier and speakers.
Test speaker connections
Make sure the speakers are connected correct.
Use the balance control on the head unit to make
sure right channel is on right speaker etc. If
speakers don´t play at all, one or both speaker
wires may be disconnected.
Troubleshooting
If problems occour during the installation, or later,
this guide might help you to find out whats´s wrong.
THE AMPLIFIER IS DEAD:
1. Check power lead, ground and remote
connections at the amplifier using a multi meter.
2. Check the battery terminal connections.
3. Check the power lead fuse or circuit breaker. If
fuse damage continues, inspect the power lead
for short circuits.
4. Check the amplifier protection fuses. Are these
broken change to new ones with the same value.
If short circuiting continues, contact your local
DLS dealer. A fault may exist in the amplifier.
5. To start the amplifier requires a remote voltage of
9-15 volt. Check the voltage with a multi meter.
AMPLIFIER PROTECTION FUSE BLOWS AT LOW
VOLUME :
1. One or more speaker cables are shorted. Make an
insulation test with a multi meter. The cables must not
have a connection to earth.
THE AMPLIFIER TURNS OFF AFTER 10 - 30 MINUTES.
The amplifier is overheating due to inadequate ventilation. Check mounting position is free from obstruction.
Do this:
1. Move the amplifier to a place with better ventil-
ation.
2. Install one or two fans to cool down the heat-
sink.
3. Overheating can also be caused by an
impedance load below the level permitted.
NO OUTPUT FROM ONE OR MORE SPEAKERS:
Check the following:
1. Balance control position.
2. Fader control position.
3. Speaker cable connections to both amplifier and
drivers.
4. Signal lead plugs and cables.
5. Change left and right signal lead plugs in the
amplifier to see if the problem moves to a different speaker, the lead has a fault.
If the problem remains, the speaker or amplifier
are at fault.
8
MRA22, MRA31
Professional Tip:Professional Tip:
NOISE PROBLEMS
WHINING NOISE VARYING WITH ENGINE
REVOLUTIONS:
Do this:
1. Rewire the power supply (12 V) to source
unit direct from battery.
2. Check all power connections to ensure that
they are clean and tight.
3. Check quality of system ground connection.
4. Install a Power Cap capacitor. This can be
helpful against most noise problems.
CONSTANT WHINING NOISE:
Do this:
1. Ensure that all equipment has a common
ground point.
2. Disconnect signal cables from amplifier to
see if noise disappears. If so the leads are
picking up noise. Test this by laying a new
cable over the seats and reconnecting to the
amplifier. If the noise does not return, reroute original cable away from source of
interference.
3. Try to reduce the amplifiers input sensitivity.
If noise remains regardless of cable position,
try to use so called Quasi-balanced signal
cables. DLS PRO-cables are
Quasibalanced.
SPEAKER POLARITY CHECK.
All speakers in a car audio system should be
connected in phase (the same polarity). All speaker cones must move in the same direction. Out of
phase speakers will cause a lack of bass, and a
poor stereo soundstage.
Checking polarity:
Hold the - connection of the speaker wire to the terminal of a 1,5 Volt flashlight battery. Tap the +
wire on to the + terminal of the battery, and observe
the movement of the cone. The cone should move
outwards when the wire touches the battery, and
inwards when the battery is removed. If it is the
other way around, the speaker has been connected
backwards and it must be removed and connected
correctly.
If your system also has a subwoofer connected
through a passive 6 or 12 dB crossover, try to
connect this with various polarity and judge what
sounds best. The phase shift in passive crossovers
sometimes makes it necessary to change polarity.
+
Battery
1,5 Volt
+
-
-
NOTE! Tweeters can not be tested this way, double
check the connections instead.
Professional Tip:
Crimp connections
Purchase crimp connectors and crimping tool.
Connectors are color coded.
1. Strip 1/4 inch (6 mm) of insulation from the wire.
2. Insert into connector
3. Crimp tightly
Professional Tip:
Securing wires
Use wire ties to bundle together when possible.
(But never bundle speaker wires or signal cables
together with power wires.
Professional Tip:
Speaker and power wires
Do not run speaker and power wires next to each
other. Power wires can generate a ”siren” sound in
the speakers. Run speaker and power wires
separated from each other.
9
Specifications
DLS MARINE AUDIO MRA 22
Number of channels 2
Power output, 4 ohm (0,1% THD) 2 x 60 W
Power output, 2 ohm (0,2% THD) 2 x 100 W
Power output, 4 ohm bridged 1 x 200 W
Signal to noise ratio, A-weighted >100 dB
Damping factor >100
Frequency response 10 Hz - 35 kHz
Input impedance, low level >10 kohm
Input impedance, high level 100 ohm
High level input with auto start Yes
Low output (RCA output) Yes
Input sensitivity 0,25 - 5V
Filter high pass /subsonic 15-500 Hz*
Filter low pass 50-500 Hz*
* can be switched in/out
Power consumption, idle 0,5 A
Fuse 1 x 25 A
Dimensions HxWxD(mm) 70x230x268
Dimensions (inch) 2,92x9,06x10,55
Weight 2,7 kg
MRA22, MRA31
DLS MARINE AUDIO MRA 31
Number of channels 3
Power output, 4 ohm (0,1% THD) 2 x 65 W
Power output, 2 ohm (0,2% THD) 2 x 90 W
Power output, 4 ohm bridged 1 x 170 W
Power out mono sub ch. 4 ohm 1 x 170 W
Power out mono sub ch. 2 ohm 1 x 280 W
Signal to noise ratio, A-weighted >100 dB
Damping factor >100
Frequency response 10 Hz - 35 kHz
Input impedance, low level >10 kohm
Input impedance, high level 100 ohm
High level input with auto start Yes
Low output (RCA output) No
Input sensitivity 0,25 - 5V
Variable phase shift control CH C 0-180 degrees
Filter high pass CH A & B 50-150 Hz*
Filter low pass CH C 50-120 Hz*
Subsonic filter CH C Fixed 25 Hz*
* can be switched in/out
Power consumption, idle 1,0 A
Fuse 2 x 30 A
Dimensions HxWxD(mm) 70x357x268
Dimensions (inch) 2,92x14,06x10,55
Weight 4 kg
All output power ratings at 13,8 VDC
We follow a policy of continuous advancement in
development.
For this reason all or part of specifications & designs
may be changed without prior notice.
10
DLS Svenska AB
P.O. Box 13029
SE-40251 Göteborg, Sweden
Tel: +46 31 840060
Fax: +46 31 844021
E-mail: info@dls.se
www.dls.se
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