How to install and
operate the DLS
Reference series
car audio amplifiers
RA25 & RA30.
Tools and materials needed……….
Amplifier installation kit…………....
Routing Wires……………………....
Power connection..……………..….
Input and controls……………….....
Input wiring.....................................
Input level control..........................
Grand Bass..................…………....
Phase control.................................
RA25 speaker wiring:
Front speakers…...………………....
Bridge connection…………………...
RA30 speaker wiring:
Two speakers + subwoofer …….....
Professional tips……………………..
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.
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.
Technical Assistance
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
Information can also be found on our WEB-site
RA25 & RA30
The amplifiers include
RCA inputs
High Level input
Variable low pass crossover (not RA25)
Variable high pass crossover
Grand bass feature 0 - +18 dB (not RA25)
Phase shift continously variabel 0-180 degr.
(not RA25)
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.
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.
Disconnect Battery
Before starting the installation, always disconnect
the negative terminal of
the battery.
Amplifier location
Allow air circulation around the amplifier.
The DLS Reference series of amplifiers have a
compact design that allows great flexibility in
mounting. You can mount it under a seat or in the
When you select a location, do remember that the
amplifier generates a lot of heat.
Choose a location where air can circulate freely
around the amplifier. Do not cover the amplifier
with carpets or hide behind trim panels.
Do not mount the amplifier in an inverted or upside
down position.
Check all locations and placements carefully
before making any cuts, drilling any holes or making any connections.
This is the best way to
mount the amplifier to get
the best cooling.
DLS logo on amplifier cooling flange
The DLS logo on top of the amplifier is attached
with two 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.
RA25 & RA30
Tools and material needed
Flat and Phillips screwdrivers
Wire cutter
Wire stripper
Electric drill with drills
Crimping tool
Digital multimeter or test lamp
Wire brush, scraper or a piece
of an abrasive sheet to remove
paint for a good ground connection
Grease to protect the ground
connection from oxidation
Routing wires
head unit
Speaker wire: minimum
12 AWG = 4 mm2 for subwoofers
13 – 16 AWG = 1,5-2,5 mm2 for other
Sheet metal screws for mounting the
amplifier to the amplifier board and the
amplifier board to the car + some extra
for fuse holder, amplifier ground etc.
Electrical insulation tape
½ inch thick plywood or particle board for
the amplifier to be mounted upon.
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
20- 25 feet = 6- 7.5 meter power cable,
minimum AWG 5 = 16 mm2 or heavier
1 pc of fuseholder to install close to the
car battery + fuse 50 Ampere.
20 feet of AWG 15 = 1,5 mm2 wire for
remote turn on / off cable from radio.
RCA-cable for input from radio.
- 20 feet or 5 meter for trunk installations
-12 feet or 2 – 3 meter for under seat
Two ring crimp terminals –one
for connection to the battery plus and one
for the amplifier ground connection.
Four to eight splicers to connect speaker
cables to high level input cable, if high level
input is used.
Wire ties
Insulating grommet or insulating tube
Professional Tip:
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.
If possible use AWG 4 = PL 21 mm2 cable for best
These are the minimum sizes we recommend for
the different models:
10 mm2 (7AWG)
21 mm2 (4AWG)
This is for cable lengths up to 5 meters.
The ground cable must have the same size.
RA25 & RA30
Power connections
Power terminal ( +12V)
Connect the fuse holder as close to the vehicle
battery + as possible, using AWG 5 = 16 mm2 or
heavier cable. Use ring crimp terminal cable to
connect to battery +. Apply silicon grease to the
fuse to prevent corrosion.
Use a 60 Amp fuse for cable
5AWG (16 mm2),
or 80 A fuse for cable
4AWG (21 mm2).
RA25 accepts max. AWG7
(10 mm2) in the power
Connect with ring
terminal to
battery + terminal
fuse holder
Connect the battery cable from the fuse holder to
the +12 Volt terminal on the amplifier.
Be sure to use a rubber grommet or a plastic
insulating tube where the cable passes the firewall
or other places when it can easily be jammed.
Use ty-wraps to secure to existing cables in the
engine compartment.
Ground Terminal ( GND )
Connect to a good chassis ground. The ground
connection should be clean, unpainted metal to
provide a good electrical connection. Use a wire
brush, a scraper or a piece of an abrasive sheet to
clean the metal. Use a lock washer or two to secure
contact. Protect with silicon grease or by paint
applied afterwards.
Remote terminal ( REM )
For RCA cable signal input:
Set the input selector switch to position ”Low level”.
Connect the radio power antenna lead = remote
turn on/off from the car stereo to the amplifier
remote connection. This turns on the amplifier
whenever 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 as seen
on page 4.
Sometimes a small disturbance may enter the
amplifier coming from the remote voltage , through
the built in remote wire and into the RCA cable.
Thus we recommend to use a separate remote wire
and run the RCA lead separate from remote wire,
power cables and speaker cables.
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.
Set the ”High level auto
start” switch to position
Connect to head
unit remote start
terminal or power
antenna lead
For High Level input:
Set the input selector switch to position ”High level”.
We recommend you to connect the remote wire as
described above. The amplifier will produce soft
on / soft off operation this way. If you use a remote
wire, set the switch ”High level auto start” to position OUT.
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 ”High level auto start” switch is set to IN
- position.
Connect with ring
terminal to
chassis ground
Use only two 35 ampere ATC
blade type fuses on RA30, or
one 25 A on RA25.
Power Light / Protect light
The power light (green ) comes on when
the amplifier is turned on.
The protect light ( red ) comes on
when the amplifier shuts down from
overheating, or a short circuit ( speaker failure)
Input and controls
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
Low level input
Use a pair of shielded stereo audio cables with RCA
type jack. Most trunk-mount amplifiers need a 20
feet RCA cable ( appr 5 – 6 meters). Most under
the seat installations require 12 feet ( 2 – 3 meters)
RCA cables. Avoid placing the RCA cable close to
speaker cables, power
cables and remote control
cable. Connect to RCA input
Set the input selector switch
to position ”Low level”.
On RA30 the Low level input for your front system is
connected to channel 1 & 2.
The input for the subwoofer channel is connected
to input 3 & 4.
High Level Input for ch 1 & 2 on RA25 and RA30
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.
High level input socket for CH 1 & 2
Hi level input
socket on amp.
Green: Left +
Black: Left Black: Right Grey: Right +
Hi level input plug.
Automatic turn on when using high level input.
With the ”Input selector switch” set to High level
and the ”High level Auto Start” switch set to IN,
the amplifier turns on automatically on high input.
You don´t need to connect a separate remote wire
from your head unit.
If you want to use high level
input but use a remote start
wire, just set the ”High level
Auto Start” switch to OUT.
RA25 & RA30
RA30 high level input for ch 3 & 4.
The RA30 three channel amplifier is connected
likewise, however we have three channels.
You can feed all four channels using high level input, or feed two channels from RCA and two
channels using high level input from rear speaker
CH 3&4 high level inputs feeds the sub channel.
Hi level input
socket on
Green: Left +
Black: Left Black: Right Grey: Right +
Hi level input plug.
High / 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
”High Level”
When using Low level input:
Push out the button to position
”Low Level”
Hi level auto start switch
To ensure best possible performance from the
amplifiers when used with high level input a switch
is installed to select between Automatic amplifier
start and remote wire start.
When using High Level input with
automatic start:
Push the button to position IN
When using High level input with
remote wire start:
Push out the button to position OUT
Some head units use BTL output IC:s that have a
constant 12 Volt + on the speaker terminal, also
when shut off (the Power LED indicator lights
constantly even when the head unit is off). In this
case you have to use a separate remote wire
connected to the REMOTE-terminal instead.
RA25 & RA30
Input Level control
The input level control, 7V – 0,2 V,
matches the output of your radio to
the input of the amplifier. After installation is complete, make sure the input of the amplifier is turned down all
the way ( counter-clockwise at 7V ).
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.
Grand bass 40 Hz
RA30 CH 3 & 4:
LP-filter 40 - 125 Hz
Subsonic filter 25 Hz
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.
20 150
Low Pass Filter
Phase control
RA30 CH 1 & 2:
HP-filter 45 -125 Hz
High Pass Filter / Subsonic filter
Grand Bass is used to increase the bass volume
with a center frequency of 40 HZ. You can select
the amplification between 0 dB ( no amplification )
and +18 dB (full amplification).
This function is used to
compensate for the bass box
function and to adjust for your
own taste of bass. Set level
control at 0 dB if you want it
to be inoperative. This
function is operative only on
RA30, channels 3 & 4.
The phase control on RA30 sub
channel 3&4 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.
The DLS Reference amplifiers include high pass
filter (HP) and low pass filters (LP). The highpass
filter on RA25 can also be used as a subsonic filter.
The slope of all filters are 12 dB / octave.
The high pass filters can be switched off if you want to
run the amplifier in full range mode.
This is the crossover configuration on RA25 & RA30:
HP-filter 20 - 150 Hz
0 180
The LP-filter ( low pass filter) is
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-OUT
and is available on RA30 sub
channel only.
40 125
Speaker wiring RA25
RA25 is a 2-channel stereo amplifier. It can be
connected either as a stereo amplifier for fullrange
speakers, or as a mono amplifier for a single driver
connected in bridge mode.
Two fullrange speakers connected in stereo
One speaker connected in mono bridge mode
Filter settings
With the HP-filter in OUT position the amplifier
allows the speakers to play fullrange. If you for
some reason want to limit the low bass
reproduction switch IN the HP-filter. The typical
setting is then around 60 – 80 Hz.
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.
Bridge mode can be used to connect a center
channel speaker.
You can also run a front system in bridge mode
using two RA25 amplifiers, one for each channel.
If you want to use the RA25 for bridge mode
connection of a subwoofer, you must use an
external passive lowpass crossover.
Speaker wiring RA30
RA30 is a 3-channel stereo amplifier. It is normally
used to connect one pair of front/rear fullrange
speakers, and one or more subwoofers connected
to the mono sub channel.
Two fullrange speakers and one subwoofer to
Rear or front speakers
Rear subwoofer
RA30 is two ohm stable, so it is possible to connect
two front speaker systems, or two subwoofers, in
Filter settings channel 1 & 2 (front system)
With the HP-filter in OUT position the amplifier
allows the speakers to play fullrange. If you for
some reason want to limit the low bass
reproduction switch on the HP-filter. The typical
setting is then around 60 – 80 Hz.
Remote Bass lvel and phase control box
The RA30 includes a
remote control unit. With
this unit it is possible to
adjust the bass level and
phase on the subwoofer
channels 3&4, from the
front seat. Connect the
amplifier socket and the
socket on the remote box.
Filter settings channel 3 & 4
The LP-filter will allow low frequencies only and
blocks higher frequencies. A typical setting is 70 –
90 Hz. When used with a subwoofer the switch
should be in IN-position. Set the LP-filter to 70-90
GRAND BASS is used to increase the bass
volume with a center frequency of 40 HZ. You can
select the amplification between 0 dB ( no
amplification ) and +18 dB (full amplification).
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 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.
Remote Bass level and phase control.
With the remote control unit it is possible to adjust
the bass level and phase on the subwoofer
channels 3&4, from the front seat. The box with
it´s functions is activated when the IN-OUT switch
is set to IN-position. Connect the cable between
the amplifier socket and the socket on the remote
RA25 & RA30
Before you finish the installation, you should do the
following tests to make sure the wiring is correct and
everything is operating properly.
If problems occour during the installation, or later,
this guide might help you to find out whats´s wrong.
Reconnect Battery
When wiring is complete,
reconnect the battery
negative terminal.
Test power wiring
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
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 right. 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.
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.
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 is overheating due to inadequate ventilation. Check mounting position is free from obstruction.
Do this:
Move the amplifier to a place with better ventilation.
Install one or two fans to cool down the heatsink.
Overheating can also be caused by an
impedance load below the level permitted.
Check the following:
Balance control position.
Fader control position.
Speaker cable connections to both amplifier and
Signal lead plugs and cables.
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.
RA20 & RA40
Professional Tip:
Professional Tip:
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.
Do this:
Rewire the power supply (12 V) to source
unit direct from battery.
Rewire ground wire from source unit to
clean position on chassis.
Check all power connections to ensure that
they are clean and tight.
Check quality of system ground connection.
Install a Power Cap capacitor. This can be
helpful against most noise problems.
Do this:
Ensure that all equipment has a common
ground point.
Check quality of earth strap connection from
battery negative terminal to chassis.
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
If noise remains regardless of cable position,
try to use so called Quasi-balanced signal
cables. DLS PRO-cables are
Professional Tip:
Installing in trunk
When installing the amplifier in the trunk, run the
power wires along the same path as the other
vehicle wiring. Many cars have insulated channels
for wiring. you will have to remove the door sill trim
and the carpet.
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
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.
1,5 Volt
NOTE! Tweeters can not be tested this way,
double check the connections instead.
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:
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:
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 on
opposite sides of the car.
RA25 & RA30
Number of channels
Working mode
Power output at 13,8 Volt, 20 Hz - 20 kHz, max 0,1 % THD, all channels driven.
Power output, 4 ohm
Power output, 2 ohm
Power output, 4 ohm bridged
THD @1 W
Signal to noise ratio, A-weighted
Damping factor
Frequency response +/- 0,5 dB
Input impedance, low level
Input impedance, high level
High level input with auto start
Input sensitivity
Filter slope
2 x 70 W
2 x 110 W
1 x 220 W
< 0,1%
>100 dB
10 Hz - 50 kHz
>10 kohm
330 ohm
0,2 - 7V
12 dB/octave
2 x 70 W + 1 x 265 W
2 x 100 W + 1 x 365 W
< 0,1%
>100 dB
10 Hz - 50 kHz
>10 kohm
330 ohm
0,2 - 7V
12 dB/octave
Pre amp configuration on Front channel:
Filter high pass
* can be switched in/out
20 - 150 Hz*
45 - 125 Hz*
Pre amp configuration onRA30 sub channel:
Filter lowpass
Fixed 25 Hz subsonic filter
Phase shift 0- 180 degrees contiously
Grand bass adjustable gain @ 40 Hz
Remote bass level and phase control
* can be switched in/out
40 - 125 Hz
0 - +18 dB
current & thermal
7 AWG, 10 mm2
7 AWG, 10 mm2
current & thermal
4 AWG, 21 mm2
10 AWG, 6 mm2
7 AWG, 10 mm2
0,6 A
25 A
25 A
2,6 kg (5,7 lbs)
0,9 A
70 A
2 x 35 A
4,4 kg (9,7 lbs)
Max cable size, DC input
Max cable size, front speakers
Max cable size, sub output
Power consumption:
Dimensions HxWxD(mm)
Dimensions (inch)
The amplifiers are two (2) ohm stable. In stereo
mode it´s possible to load the amplifier down to two
ohm on each channel.
In mono bridge mode it´s possible to load with one
four ohm fullrange speaker or subwoofer.
The sub channel on RA30 can handle 2 ohm loads,
for example two 4 ohm subwoofers in parallel.
In bridge mode connection an amplifier sees a four
ohm speaker as a two ohm load.
We follow a policy of continuous advancement in
For this reason all or part of specifications & designs
may be changed without prior notice.
DLS Svenska AB
P.O. Box 13029
SE-40251 Göteborg, Sweden
Tel: +46 31 840060
Fax: +46 31 844021
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