How to install and
operate the DLS
Reference series
car audio amplifiers
RA20 & RA40.
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.
Contents
Features…………………………….. 2
Installation…………………….……. 2
Tools and materials needed………. 3
Amplifier installation kit………….... 3
Routing Wires…………………….... 3
Wiring:
Power and Outputs……………..…. 4
Input and controls………………..... 5
Input wiring..................................... 5
Input level control.......................... 6
Grand Bass..................………….... 6
Phase control................................. 6
Crossovers..................................... 6
RA20 speaker wiring:
Front speakers…...……………….... 7
Subwoofer…………………………... 7
RA40 speaker wiring:
Four speakers…………………….... 8
Two speakers + bridged subwoofer. 8
Two speakers in bridge mode......... 9
Testing……………………………….. 9
Troubleshooting……………………... 9
Professional tips…………………….. 10
Specifications………………………... 11
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
RA20
RA40
All models include
RCA inputs
High Level input
Continuos variable low pass and/or high-
pass crossovers
Grand bass feature 0 - +18 dB
Phase shift continously variabel 0-180 degr.
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 speakers.
RA20 & RA40
RA20
2 x 130 Watt RMS / 2 x 220 Watt max in 2 ohm
1 x 440 Watt RMS bridged
RA40
4 x 75 Watt RMS / 4 x 110 Watt max in 2 ohm
2 x 220 Watt RMS bridged
All above RMS power ratings at 13,8 Volt DC.
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.
Amplifier location
Important
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
trunk.
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.
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 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.
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.
2
RA20 & RA40
Tools and material needed
Tools:
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
Material:
Speaker wire: minimum
12 AWG = 4 mm2 for subwoofers
13 – 16 AWG = 1,5-2,5 mm2 for other
speakers
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.
Routing wires
Stereo
head unit
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
installations
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.
Use minimum AWG 5 = 16 mm2 cable, but if
possible buy AWG 4 = PL 21 mm2 cable for best
performance.
The ground cable must have the same size.
3
Wiring
RA20 & RA40
Power and Outputs
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 50 Amp fuse.
DLS
Connect with ring
terminal to
battery + terminal
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.
DLS FH1
fuse holder
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.
Connect to head
unit remote start
terminal or power
antenna lead
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.
Connect with ring
terminal to
chassis ground
Fuses
Use only two 25 ampere ATC
blade type fuses.
4
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.
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)
Input and controls
RA20 & RA40
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.
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
sockets.
Set the input selector switch
to position ”Low level”.
High Level Input for ch 1 & 2 on RA20 and RA40
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
RA40 high level input for ch 3 & 4.
The RA40 four channel amplifier is connected
likewise, however we have four 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
cables.
Green: Left +
Black: Left -
CH4 CH3
Hi level input
socket on
amp.
Hi level input plug.
Black: Right Grey: Right +
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”
Green: Left +
Black: Left -
CH2 CH1
Hi level input
socket on amp.
Hi level input plug.
Black: Right Grey: Right +
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.
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
NOTE!
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.
5
RA20 & RA40
Input Level control
The input level control, 7V – 0,2 V,
matches the output of your radio to
the input of the amplifier. After instal-
GAIN
lation is complete, make sure the in-
7V
put of the amplifier is turned down all
0,2V
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
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
BASS
control at 0 dB if you want it
to be inoperative. On RA40
this function is operative only
0
+18
dB
on channels 3 & 4.
Phase control
Crossovers
TheDLS Reference amplifiers include high pass filter
( HP) and low pass filters (LP). The highpass filter
can also be used as a subsonic filter.
All filters are continously variable and all filters can
be switched on and off.
The slope of all filters are 12 dB / octave.
The filter can be switched off if you want to run the
amplifier in full range mode.
This is the crossover configuration on RA20 & RA40:
RA20:
LP-filter 40 - 125 Hz
HP-filter 20 - 150 Hz
RA40 CH1 & 2: RA40 CH3 & 4:
HP-filter 20 -150 Hz HP-filter 20 - 150 Hz
LP-filter 40 - 125 Hz
High Pass Filter / Subsonic filter
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.
HP-filter
FREQUENCY
20
150
Hz
The phase control on RA20 &
RA40 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.
6
PHASE
0
180
DEGREE
Low Pass Filter
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 both RA20 and
RA40.
LP-filter
FREQUENCY
40
125
Hz
RA20
Speaker wiring RA20
RA20 is a 2-channel stereo amplifier. It can be
connected either as a stereo amplifier for fullrange
speakers, or as a mono amplifier for subwoofers
connected in bridge mode.
Two fullrange speakersconnected in stereo
mode
+
-
Filter settings
-
+
One subwoofer connected in mono bridge
mode
+
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
The HP-filter is here used as
subsonic filter to take away
the very deepest frequencies
from the subwoofer. The
typical setting is around 25 –
40 Hz.
-
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.
The LP-filter should be OFF
(switch in OUT-position).
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
Hz.
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.
7
RA40
Speaker wiring RA40
RA40 is a 4-channel stereo amplifier. It can be
connected either as a stereo amplifier for two pairs
of fullrange speakers, or as a 3 channel amplifier
with one pair of fullrange speakers in stereo, and
one subwoofer connected in mono bridge mode.
Four fullrange speakers to RA40. One pair in
front and one pair in rear.
Front speakers Rear speakers
Filter settings channel 1 & 2
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.
Two fullrange speakers and one subwoofer to
RA40
+
Rear or front speakers Rear subwoofer
Filter settings channel 1 & 2
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.
Filter settings channel 3 & 4
-
Filter settings channel 3 & 4
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 HPF-filter (IN-position).
The typical setting is then around 60 – 80 Hz.
The LP-filter switch should be in OUT-position.
8
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
Hz.
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.
Two fullrange speakers connected in bridge
mode to RA40
+
Left speaker Right speaker
Filter settings channel 1, 2, 3 & 4
-
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 HPfilter. The typical setting is then
around 60 – 80 Hz. The LP-filter
should be in OUT-position.
+
-
RA20 & RA40
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.
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.
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.
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.
9
RA20 & RA40
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. Rewire ground wire from source unit to
clean position on chassis.
3. Check all power connections to ensure that
they are clean and tight.
4. Check quality of system ground connection.
5. 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. Check quality of earth strap connection from
battery negative terminal to chassis.
3. 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.
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: 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.
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
10
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.
Specifications
DLS CLASSIC RA20 RA40
Number of channels 2 4
Working mode AB AB
Power output at 13,8 Volt, 20 Hz - 20 kHz, max 0,1 % THD
RMS power out, 4 ohm 2 x 130 W 4 x 75 W
RMS power out, 2 ohm 2 x 220 W 4 x 110 W
RMS power out, 4 ohm bridged 1 x 440 W 2 x 220 W
THD @1 W < 0,1% < 0,1%
Signal to noise ratio, A-weighted >100 dB >100 dB
Damping factor >200 >200
Frequency response +/- 0,5 dB 10 Hz - 50 kHz 10 Hz - 50 kHz
Input impedance, low level >10 kohm >10 kohm
Input impedance, high level 330 ohm 330 ohm
High level input with auto start Yes Yes
Input sensitivity 0,2 - 7V 0,2 - 7V
Pre amp configuration on Front channel:
Filter high pass 20 - 150 Hz* 20 - 150 Hz*
Filter low pass 40 - 125 Hz* No
Phase shift 0- 180 degrees contiously Yes No
Grand bass adjustable gain @ 40 Hz 0 - +18 dB No
Pre amp configuration on Rear channel:
Filter highpass No 20 - 150 Hz*
Filter lowpass No 40 - 125 Hz*
Phase shift 0- 180 degrees contiously No Yes
Grand bass adjustable gain @ 40 Hz No 0 - +18 dB
* can be switched in/out
Filter slope 12 dB/octave 12 dB/octave
Protection current & thermal current & thermal
Max cable size, DC input 4 AWG, 21 mm
Max cable size, speakers 5 AWG, 16 mm
Power consumption:
Idle 0,6 A 0,9 A
Maximum 50 A 50 A
Fuse 2 x 25 A 2 x 25 A
Dimensions HxWxD(mm) 59x359x245 59x359x245
Dimensions (inch) 2,33x14,1x9,65 2,33x14,1x9,65
Weight 3,8 kg (8,4 lbs) 4,0 kg (8,8 lbs)
2
4 AWG, 21 mm
2
7 AWG, 10 mm
2
2
RA20 & RA40
NOTE!
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.
(In bridge mode the amplifier sees a four ohm
speaker as a two ohm load).
We follow a policy of continuous advancement in
development.
For this reason all or part of specifications & designs
may be changed without prior notice.
11
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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