Boss Audio Systems MR250.4 User manual

User's Manual
2 CHANNEL BRIDGEABLE MOSFET
MARINE POWER AMPLIFIER
4 CHANNEL BRIDGEABLE MOSFET
MARINE POWER AMPLIFIER

---
o~s
USER'S MANUAL
~
Two Channel
MR400.2
High
Power MOSFET
Marine
Audio Amplifier
Four Channel
MR250.4
High
Power MOSFET
Marine
Audio Amplifier
Congratulations on your
purchase of a :lO~:S Marine
oWIlX'n~
Amplifier.
It has been designed, engineered
and manufactured
to bring you
the highest level
of performance
and quality, and will afford you
years
of listening pleasure.
Thank you for making
!9.~ Marine your choice for
marine audio entertainment!
page
CONTENTS
2 Introduction
2 What is included?
3 Features
3
About 2 Ohm operation
4 General
precautions
4 Protection circuitry
5 Installation precautions
5 Fuses
6
Mounting the amplifier
6
Connecting the amplifier
8
Low level input wiring
9 High level input wiring
10 Power and speaker wiring
2 Channel Amplifier
12 Power and speaker wiring
4 Channel Amplifier
14 Troubleshooting
5
Specifications
MMne MOSFET A.rnpl1fier Us.er's Manual - poge 1

Introduction
With the ~~ Marine MOSFET
amplifier series, we are introducing
two new amplifiers, designed
specifically for marine audio
installations. This new series includes
a 2-channel amplifier and a 4-channel
amplifier.
All
iiO~S Marine models feature both
highp;"S's and low pass crossovers.
For further flexibility
in the use of a
subwoofer. a variable bass
boost
control has been included. You can
control the subwoofer level with the
remote level control module.
These
!9~ Marine amplifiers are
constructed using a special corrosion
resistant coating on the printed circuit
board
to prevent damage from the
high humidity
of the marine
environment.
•
~ Marine understands that
amplifiers are placed
in many different
kinds
of installations, so we have also
Included
an Input sensitivity control to
help you integrate the amp into your
system regardless
of the nature of your
input source.
What is included?
When first unpacking your new
amplifier, please check first that the
package contains all
of the items
below. Ifsomething
is missing, contact
the store where you purchased the
player.
•
Marine amplifier
• HIgh input wire with connector
• Four (4) mounting screws
Features
Your new !9~1 Marine amplifier
features the following:
• Class
A-B operation
• Bridgeable outputs
• TriMode capable
• MOSFET PWM (Pulse Width
Modulated) Power Supply
• 2 Ohm stable stereo operation
with output power increase
• Thermal and speaker short
protection
• Soft turn-on cirCUit
•
Remote turn-on/turn-off circuit
• Variable input gain control
• Variable low and fixed high pass
crossovers
• Variable bass boost (0 to +18dB)
• Exclusive
protective coating on
PC board to provide damage from
humidity
• Gold plated RCA low level and
high level inputs
• LED power and protection
indicators
• Silver anodized heatsink
• Remote subwoofer level control
About 2 Ohm operation
Your'30~S Marine amplifier has be€n
desig'n~70 operate efficiently at loads
down to 2 Ohms. This means that you
can install four 8 Ohm speakers per
channel, when using parallel wiring.
Increasing the number of woofers per
channel at low frequencies (below
100t-fz) produces an acousticcoupling
effect. This acoustic coupling effect
increases your power output
by about
3dB per speaker. or the equivalent
of
an additional 10Wper speaker.
When operating at 2 Ohms. the
amplifiers will increase their
outpul
power by approximately 50%. The
current
draw will also increase by
about the same amount, so be sure
you have enough current to run the
amplifiers into a 2 Ohm load.
If you lack adequate current, your
music reproduction will be distorted.
Mu ..... ne MOSFET ArnpllflOJ User's Manual - pagf:!' 3
Manno MOSFET Ampllnlll' U ..... s Manual -page 2

General precautions
Before installing and l/sing YO(1r new
3\)~ Marine amplifier, please be-
~~ familiar with a'll the informa-
tion contained in this mal1ua/~
Please keep this manual in a safe
place for future reference.
• Do not open or attempt to repair this
unit yourself. Dangerous high voltages
are present which may result
In electric
shock. Refer any repairs
to a qualified
service technician.
• To avoid risk of electronic shock or
damage to the amplifier,
do not permit
any
of this equipment to become damp
orwet from water ordrinks. If this does
occur, immediately unplug the power
wires and send the amplifier to your
local dealer or service center as soon
as possible.
• If there is smoke
or any peculiar odor
present during
use or ifthere is damage
to any of the component enclosures.
immediately unplug the power cord
and send the amplifier to your local
dealer
or service center as soon as
possible.
SHOCK HAZARD! Do not open the case
of this product. There are dangerous
voltages present within the unit. There are
no user-serviceable parts within the unit.
Martnc MOSFET Ampllftor User's Manual· page 4
Protection Circuitry
This amplifier incorporates special
protection circuitry
Which will disable
the amplifier if any
of the following
should occur:
• Input overload
• Short circuit
• Extremely high temperatures
If any of these conditions
Is detected,
the amplifier will
go into a self-
preservation mode, and the PROTECT
LED on the model number badge
on
top of the amplifier will be illuminated.
What should I do if my amplifier
PROTECTLED
is illumInated?
If you observe that the PROTECT LED
is on, please check the system carefully
to determine what has caused the
protection
c1rcuit to engage.
To reset the amplifier when it is in
PROTECT mode, turn the power off to
the system (usually
by turning off the
head unit or other signal source which
feeds the amplifier) and then turn it on
again.
If the amplifier has shut down due to
thermal overload. you should first allow
it
to cool down before restarting.
If the shut
down was due to either an
input overload or a short circuit, be sure
to correct these conditions before
attempting
to power up the amplifier
again.
Installation precautions
Before you drill or cut any holes,
investigate your car's layout very
carefully.
Take special care when you
work near the gas tank, fuel lines,
hydraUlic lines and electrical wiring.
Never operate the amplifier when it
is
unmounted. Attach all audio system
components securely within the
amplifierto prevent damage, especially
in an accident.
Do not mount this amplifier so thai
wire connections are unprotected,
in
a pinched condition, in contact with
any metal surfaces
in your marine
vessel,
or likely to be damaged by
nearby objects.
Before making
or breaking power
connections
in your system,
disconnect the marine vessel battery.
Confirm that your head unit
or other
equipment
is turned off while
connecting the inputjacks and speaker
terminals.
If you need to replace the power fuse,
replace it only with a fuse identical to
that supplied with the amplifier. Using
a fuse of a different type or rating may
result
in damage to your audio system
or your amplifier which is not covered
by the manufacturer's warranty.
Fuses
Power fuses protect both the amplifier
and the electrical system of your car
from fault conditions. If you must
replace a fuse
in your Marine amp, use
a fuse of exactly the same type and
rating. Us,ng a different type or rating
of fuse may result in damage to your
amp or marine vessel or cause a fire.
MarIne MOSFET Amplifier User's Manual -page 5

Mounting the amplifier
1. Find a suitable location in the marine
vessel
in which to mount the amplifier.
2. Make sure there is sufficient air
circulation around
the intended
mounting location.
3. Mark the location for the mounting
hole screws by positioning the amplifier
where you wish to install it. Use a
scribe or mounting screw, inserted
through each of the amp's mounting
holes, to mark the mounting surlace.
If the mounting surlace is carpeted,
measure the hole centers and mark
with a felt tip pen.
4. Drill pilot holes in the mounting
surface for the mounting screws. Place
the
amplifier in position, and attach
the amplifier to the mounting surlace
securely uSing screws.
Connecting the amplifier
Before dOing <my wiring, look through
this
marual and identify the diagrams
to follow for power. input and speaker
connections for your particular
installation.
Be sure you understand
all the connections before you proceed.
1. Connect the power ground terminal
to tr.e closest point on the chassis of
the marine vessel. Keep tris ground
wire to less than 39" (100 em) h length.
Use 8
gauge (or heavier) wire.
2. Connect the remote terminal 10 the
remote
output of the head unit uSing
16
gauge (or heavier) wire.
3. Connect an empty fJse holder within
18" (45 em)
of the car battery. and run
8 gauge (or heavier) cable from this
fuse to the amplifier location.
4. Check that trfJ fuse holder is empty.
Then COllnect the fuse
holder to the
"BAn +. connection on the amplifier.
5. If multip:e amplifiers are being used
in
your system, either:
• Run a separate
pair of cables from
the battery
and a chassis ground pOint
to each amplifier. Each (+) cable must
have its own inline fuse.
-or-
• Run a #0
or #2 cable from the fuse
holder at the
battery to a distribution
block at or near the amplifier's location,
Then run separate
cables from the
amplifier
to this distribution block and
to independent chassis ground points.
6,
Connect all line inputs and outputs (if
used) using high-quality cables. Connect
all speakers,
following the diagrams in
this manual. Be sure to observe proper
polarity to avoid audio phase problems.
7. Insert tuse(s) into the battery fuse
holder(s).
8. Recheck all connections before
powering up the amplifier.
9. Sel all level controls to min,imum
position,
and set all crossover
controls/switches to the desired
frequency
poillts.
10. Power up the head unit and the
amplifier. Then
s~t the volume control
on the nead unit to about 3/4 volume,
and adjust the amplifier's input level
control(s)
to just below the 'level of
distortion.
11. Further fine tuning
of the various
controls may be necessary
to obtain best
results.
Don't .misuse the
level cont:rol_!
Do not mistakethe input level control
for a volume control' It is designed
ONLY to match the output level of
your audio sOurce to the input level
of your amplifier.
Do nol adiust this input level to
maximum unless your input level
requires il.
Ignoring
thElse instructions will result
in an input overload to the amplifier,
and excessive al:Jdio cjistortion. It
can also cause the protectiolfl circuit
to .engage.
Marine MOSFET Amplifier User's Manual· page 7
Marine MOSFET Ampli~Ol Usel'~ Manual· page 6

(1]) (
Low Level Input Wiring
High Level Input Wiring
Low-level (RCA) input wiring is preferred for best audio performance, Always use The high level input(s) should only be used when your head unit lacks RCA outputs,
a high-quality RCA cable for best audio pertormance. If the RCA
outputs are not present, connect the speaker outputs from the receiiver
to the high level input
connector of the amplifier. Be sure to observe polarity to
NOTE: Do not connect BOTH the high !evel and low level inputs from your
avoid audio phase problems,
receiver to your amplifier at the same time!
NOTE: Do not connect BOTH the high level and low level inputs from your
,
receiver to your amplifier at the same timet
2-Channel Amplifier
2-Channel Amplifier
MR400.2 1"'"' -----"
MR400.2
J 7
Optlonnl remote
ulJwoofer level conlrQI
(sold
~epamtelvl
To Audio
Outputs of head
unit or signal
processor
IObO;;;:;z;x::) I
l+ l~ R· R ...
Optional remote
ubwoofcr lellel contro
(sold separately)
To Speaker Terminals
of head unit
4-Channel Amplifier
Optlonal remote
"ubwoofer level control
MR250.4
(sold separately)
4-Channel Amplifiers
MR250.4
@
'\
!
TO FRONT Audio Outputs
To Speaker
of head unit or
10l:=J I
Terminals
signal processor
of head unit
To REAR Audio Outputs of
headl unil or
signal processor
~~ ~~ c.;: ;~ Optlonlll remote
I [] subwooler level control
01 ~ (sold se!l"arately)
1::Ic:::JCJC:::lt::lO
Ma"ne MOSFET AmpRfier User's Manual· p8ij8 8 MarlneMOSFET Amplifier User"s
Manual" page 9

I
Et7
Q
poweA
Chassl$
groUf'ld
point
to REMOTE TURN-ON
tennlnal 01 head unit
MINIMUM
SPEAKER
IMPEDANCE
40HMS
~
./'
Q
$
MINIMUM
SPEAKER
IMPEOANCE
4 OHMS
Power and Speaker Wiring
2-Channel Amplifier
MR400.2
Power and Speaker Wiring
2·,Chanhel Amplifie!i
"'11400.2
Two
Channel
R.IGHT
Speaker
Bridged
SPEAKER
IMPEDANCE
4-8 OHMS
$
Q
POW,liR
Ch.a;sls
ground
point
to REMOTE TURN-ON
18111'1 inal 0r head u ni l
~
Q
LEFT
Speaker
Mode
ttl
o
CJ c::J
FUSE
I Batlery I
ttl
Q
~I,.o,ll£l'n
Cha'"ssis
ground
point
to 'REMOTE TllRN·ON
~
Q
SUBWOOFER
ttl
Mode
torm lnal of I' cad unIt
Connecr the Negmive (-)
terminal
of 1M speaker to /he
o
c::J CJ
R(-) amplifier terminal.
FUSE I Battery I
COnnec! the posJtlve (+)
terminal of the spooker 10 !he
L(+)
amplifier terminal.
Tri-mode operation allows you to connect this amplifier to a pair- of main speakers
plus a sUlbwoofer on one pair
of output channels. The main speakers will operate
in STEREO while the subwoofer simultaneously operates In MONO.
To set up the amplifier to run In this mode, put the crossover switch in the FULL
position. Insert h'igh pass filter capacitors and a low pass fliller -nditJctor into the
wiring as
shown below. Be sure to check the table at the bottom of this page to
determine the correct capacitor ar.d inductor values for the crossover frequency
you wish 10 achieve,
Tri-Mode
LEFT Speaker
HIgh pass filter
RIGHT Spaaker
capacitors
o
c::::I c::J
SP'EAKER
FUSE I Ba tte ry I
IMPEDANCE
80HMS
Component values for
6dB Passive Crossover
FREQUENCY INDUCTOR CAPACITOR
80 Hz
7.5mH
470uF
tOO Hz 6.5mH
330uF
120 Hz
5.5mH
330uF
t50 Hz
4mH
220uF
Lowpass
filter Inductor
Marino MOSFET Amplifier Users Manual -page 10
Marine MOsFET AmplirJel USB(S Manual- page 11

Power and Speaker Wiring
4-Channel Amplifier
h
MR250.4
E:t)
Chassl.
ground
CH3
polnt
Sponker
to REMOTE TURN'ON
CH4 o
Speaker
FUSE
l~atte~1
SPEAKER
IMPEDANCE Connect rile Negative
(-J terminal of Ihe RIGHT
4-8 OHMS subwoofer to the CH4(-) amplifier tarmlnal.
RIGHT
Connact lhe Postive
(+) terminal of !he RIGH
Subwooler
subwoofer 10 the CH3(+) amplifIer terminal.
atidged
Mode
E:t)
o
Chnssfs
ground
poln!
LEFT
10 REMOTE TURN·ON
Subwoofer
terminal 01 head unit
o
D c::J
FUSE I
Battery I
SPEAKER
IMPEDANCE
4-8 OHMS
Mmine MOSFET Amplifier User's Manual - page' 2
terminal ot head unit
Connecllhe Negative (-J terminal of rhe LEFT
subwoofer
10 the CH2(·) amplifierterminal.
Connect the Pos/lVa
(+) terminal of the LEfT
subwoofer 10 the CH1(+J amplifier tarmlfl8.l.
Power and Speaker Wiring
4-Channel Amplifier
MR250.4
Tri-mode operation allows you to connect this amplifier to a pair of main speakers
plus a subwoofer on one pair of output channels. The main speakers will operate
in STEREO while the subwoofer simultaneously operates in MONO.
To set up the amplifier to run In this mode, put the crossover switches in the FULL
position. Insert high pass filter capacitors and a low pass filter inductor into the
wiring as shown below.
Be sure to check the table at the bottom of this page to
determine the correct capacitor and Inductor values for the crossover frequency
you wish to achieve.
Component values for
SPEAKER
6dB Passive Crossover
IMPEOANCE
elli •• ls
ground
point
MINIMU
SPEAKER
IMPEDANCE
40HM9
SPEAKER
IMPEDANCE
80HMS
Marino MOSFET AmplltierUser's Manual -P'lIIe 13
470uF
330uF
330uF
220uF
o
o 0
I Battery I
lo REMOTE nJRN-QN
term!nal of head unit
7.5mH
6.5mH
5.5mH
4/111-1
FUSE
FREOUENCY INDUCTOR CAPACrrOR
80 Hz
100 Hz
120 Hz
150 Hz
80HMS
Tri~Mode

Troubleshooting
If you experience operation or perionnance problems with this product, compare your
installation with the electrical wiring diagram
on the previous pages. If problems persist,
read the following troubleshooting tips which may help eliminate the problems.
SYMPTOM
POSSIBLE REMEDY
Amplifier will not
power up.
Checkto make sure you have a good ground connection.
Check that the Remote Input (Tum-On) has at least 3VDC.
Check that there Is battery
power on the (+) terminal.
Check that there
Is at least 12v.
Check all fuses, replace Ifnecessary.
Make sure that the Protection LED ls not illuminated. IfIt Is lit. shut off
the amplifierbriefly. and (hen repower It.
Protection LE.D
comes on when
amplifier is
powered up.
Check for short clrcwts on speaker leads.
Tum down the volume control on the head umt to preventoverdrlving.
Remote speaker leads, andreset the amplifier. If the Protection LED
stil,
comes on, then the ampllfTer Is faulty andneeds servicing,
No output.
Check that all fuses are OK.
Check thatamplifierIs properly grounded.
Check thaI the Remote Input (Tum· On) has at least 3VDC.
Check that the RCA audio cables are
plugged into the properInputs.
Check all speaker wiring,
Low output.
Reset the Level Control.
Check the Crossover Control settings.
Audio present in
only one channel.
Check the RCA Interconnect cables.
Check allspeaker Wiring.
High hiss in the
speakers.
Disconnect all RCA Inputs to the amplifiers, It the hiss disappears, thel
plug in the component dn"vmg the amplifier and unplug Its Inputs. If thE
hiss disappears a/ this point. go on until the faulty/noisy component is
found.
It
IS best to set the amplifier's Input level control as low as possible. Th
best sUbjective s/gna/-to-noise ratio is achieved In this manner. Try /0 s
the head unit as high 8S possible (I¥/lhout distortion) and the amp Inpu
level as low aspossIble.
Squealing noise
from speakers.
Check for improperly groundedRCA Interconnects,
Distorted sound.
Check that the Input Level Contrails set to match the signal level of the
head unit. Always try to set the Input Lavel as low as possIble.
Clleck that all crossover frequencies areproperly set.
Check for short circuits on the speaker leads.
Amplifier gets
very hot.
CllfICk that the minimum speaker Impedance tor the amp modelIs correct.
Check thaI there is
good aircirculatJon around the amp. In some
applications, it may be necessary to add and extemal cooling fan.
Engine noise
(static type)
This is usually caused by poor qualityRCA cables.which can pick up
radiated nOise. Use only the best quality cables. and route them away
from power cables
Engine noise
(alternator
whine)
Check that speaker leads are not shorted to the man'ne vessel chassis.
Check that the RCA grounds are notshortedto the marine vessel chassis.
Check that the head unit is properly grounded.
Specifications
MODEL
I\M$ POWER
into 4 Ohm5
'MAX POWER
into 2 Ohms
BRIOGE.O POWER
Into 4 Ohms
Min. speak·e.
,impedance
THO
Frequency response
Sl~na!·to-noi$e r ... tio
Channel separation
Damping factor
Crossover range
low pa ••
[high pass
[Bass Ibo'ost
IFuse rating
i{;lil1lenslorfS:
(1, 1·3/4" X 2-518;1 l< ... )
Two Chllnnel
Four Chenn'1l
MarIne Amplifier
Marine AmplifIer
MR400.2
MR.250.
125W x2
100Wx4
400W x 2 250W x4
SOOW x 1 500W
x2
2 Ohm Stereo/4 Ohm Mono Bridged ------
0.01%
6Hz-50kHz
103dB
90dS
125+
35HZ-155Hz
200Hz (fixed)
0- +1SdS
25A x
10-31S'
0.01%
6Hz-50kHz
103dB
gOdS
125+
35Hz.-155Hz
200Hz (fixed)
o -+18dS
15Ax2
13-1116'
All specifications subject to
change without notice.
e
t
Maline MOSFET Amplifier U..,,'. Manual -p3ge 14
Marine MOSFET Amplifier User'. Manual· page 15