Dls MRA31, MRA22 User Manual

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.

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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 [e-mail].
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:

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 Flat and Phillips screwdrivers

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 Wire cutter, Wire stripper

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 Electric drill with drills

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 Crimping tool

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 Digital multimeter or test lamp

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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.

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 Electrical insulation tape

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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