JL Audio M6450 Owner's Manual
Thank you for purchasing a JL Audio amplif ier for
your marine sound system.
Your amplifier has been designed and manufactured to exacting
standards in order to ensure years of musical enjoyment in your vessel.
For maximum performance and extended warranty
coverage, we highly recommend that you have your new amplifier
installed by an authorized JL Audio dealer. Your authorized
dealer has the training, expertise and installation equipment to ensure
optimum performance from this product. Should you
decide to install the amplifier yourself, please take the time
to read this manual thoroughly so as to familiarize yourself
with its installation requirements and setup procedures.
If you have any questions regarding the instructions in this
manual or any aspect of your amplifier’s operation, please contact your
authorized JL Audio dealer for assistance. If you need further assistance,
please call the JL Audio Technical Support Department
at (954) 443-1100 during business hours.
OWNER’S MANUAL
M6450
six-channel marine amplifier
PLANNING YOUR INSTALLATION
It is important that you take the time to read
this manual and t hat you plan out your
installation carefully. The followi ng are some
considerations that you must take into account
when planning your installation.
Cooling Ef ficiency Consi derations:
The outer shell of your JL Audio amplifier
is designed to remove heat from the amplifier
circuit ry. For optimum cooling per formance,
this outer shell should be exposed to as large a
volume of air as possible. Enclosing the a mplifier
in a smal l, poorly ventilated cha mber can
lead to excessive heat build-up and degraded
performance. If an installation calls for an
enclosure around the amplifier, we recommend
that this enclosure be ventilated with the aid
of a fan. In normal applications, fan-cooling
is not necessa ry.
Mounting the amplifier upside down is
strongly discouraged.
If mounting the ampli fier under a seat,
make sure t here is at least 1 inch (2.5 cm) of
space above the amplif ier’s outer shell to per mit
proper cooling.
Safety Considerations:
Your amplifier needs to be installed in a dry,
well-ventilated envi ronment and in a manner
which does not i nterfere wit h your vessel’s factory
insta lled electronic dev ices. You should also take
the time to s ecurely mount the ampli fier using the
supplied screws so that it does not come loose in
the event of a col lision or a sudden jolt to the vessel.
Stupid Mistakes to Avoid:
• Check before drilli ng 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 wir ing outside or underneath
the vessel. This is an extremely dangerous
practice which can result in severe damage to
your vessel a nd person.
• Protect all system wires from sharp ed ges
(metal, fiberglass, etc.) by careful ly routing
them, ty ing them down and using grommets
and loom where appropriate.
• Do not mount the amplifier in the engine
compart ment or in any other area that w ill
expose t he amplifier circuitry to the elements.
While this amplif ier is specially desig ned
for marine applications, it is not waterproof
and it should not be mou nted where it is
likely to get wet.
JL AUDIO M6450 3
PROTECT YOUR HEARING!
We value you as a long-term customer. For
that reason, we urge you to pract ice restraint in
the operation of this product so as not to damage
your hearing and that of others in your vessel.
Studies have shown that continuous exposure to
high sound pressure levels can lead to permanent
(irreparable) hearing loss. This and a ll other
high-power ampli fiers are capable of producing
such high sound pressure levels when connected
to a speaker system. Please lim it your continuous
exposure to high volume levels.
While driving, operate your aud io system in
a manner that stil l allows you to he ar necessary
noises to operate your vessel safely (horns,
sirens, etc.).
SERIAL NUMBER
In the event that your amplifier requi res
service or is ever stolen, you will need to have
a record of the product’s serial number. Please
take the time to enter that number in the space
provided below. The serial number can be fou nd
on the bottom panel of the amplifier and on the
amplifier packaging.
Serial Number:
INSTALLATION APPLICATIONS
This ampl ifier is designed for oper ation in
vessels w ith 12 volt, negative-ground electr ical
systems. Use of this product in vessels with
positive ground and/or voltages other than 12V
may result in damage to the product and will void
the warranty.
This product is not certified or approved for
use in aircraft.
Do not attempt to “ bridge” the outputs of this
amplif ier with the outputs of a second amplif ier,
including an identical one.
2 JL AUDIO M6450
Input Voltage
Selection
(pg. 6)
Channels 3 & 4
Preamp Input Jacks
(pg. 6)
Power
Status
Indicator
(pg. 9)
Ch. 1 & 2 Filter
Frequency
Selector
(pg. 8)
Ch. 1 & 2 Input
Sensitivity
Control
(pg. 6)
Protection Status
Indicator
(pg. 9)
Ch. 1 & 2
Filter Mode
Selection
(pg. 7)
Ch. 3 & 4
Filter Mode
Selection
(pg. 7)
Ch. 3 & 4
Input Sensitivity
Control
(pg. 6)
Ch. 3 & 4
Filter Frequency
Selector
(pg. 8)
Channels 1 & 2
Preamp Input Jacks
(pg. 6)
Channels 5 & 6
Preamp Input Jacks
(pg. 6)
Bass Boost
On/Off Switch
(pg. 8)
Jack for
Remote Bass
Control Knob
(pg. 8)
Ch. 5 & 6
Input Sensitivity
Control
(pg. 6)
Ch. 5 & 6
Filter Frequency
Selector
(pg. 8)
Ch. 5 & 6
Filter Mode
Selection
(pg. 7)
Input Mode
Switch
(pg. 6)
Remote Turn-On
Connector
(pg. 5)
Chassis Ground
Connector
(pg. 5)
+12 V Power
Connector
(pg. 4)
Channels 5 & 6
Speaker Outputs
(pg. 8)
Channels 3 & 4
Speaker Outputs
(pg. 8)
Channels 1 & 2
Speaker Outputs
(pg. 8)
The M6450’s “+12 VDC ” and “Ground”
connect ions are designed to accept 4 AWG power
wire. 4 AWG is a minimum power wire size for
this amplifier.
If you are install ing the M6450 with other
amplif iers and wish to use a single main power
wire, use 2 AWG or larger main power wi re
(depending on the overall current demands of all
the ampli fiers in the system). This 2 AWG or
larger power w ire should terminate i nto a
distribution block mounted as close to t he
amplif iers as possible a nd should connec t to the
M6450 with 4 AWG power wire.
Note: Smaller AWG numbers mean bigger
wire and v ice-versa (1/0 AWG is the largest, 2
AWG is sma ll er, the n 4 AW G, t hen 8 AWG, etc .).
To connect the power wires to the a mplifier,
first back out the set screw on the top of t he
termina l block, using the supplied 2 .5 mm hex
wrench. St rip 1/2 inch (12 mm) of insu lation from
the end of each w ire and insert the bare wire i nto
the termi nal block, seating it f irmly so that no
bare wire is exposed . While holding the wi re in
place, tig hten the set screw firmly, taki ng care not
to strip the head of the screw.
The ground connection should be made using
the same gau ge wire as t he power connection.
Any wires run th rough bar riers must be
protected with a high quality rubber grom met
to prevent damage to the insulation of the wire.
Failure to do so may result in a d angerous short
circuit.
Many vessels employ small (10 AWG - 6 AWG)
wire to connect the alternator’s positive
connection to the batter y. To prevent voltage
drops, this wire should be upgraded to 4 AWG
when installing amplif ier systems with main
fuse ratings above 60A.
It is common for the alternator to be grounded
through its chassis. If the a lternator is not
grounded t hrough its chassis a nd instead employs
a small (10 AWG - 6 AWG) wire to con nect to
ground, this wire should also be upgraded to 4
AWG when insta lling amplif ier systems with main
fuse rat ings above 60A.
FUSE REQUIREM ENTS
It is absolutely vital that the main power wire(s)
to the amplifier(s) in the system be fused within
18 inches (45 cm) of the positive batter y post
connect ion. The fuse value at each power wire
should be hig h enough for all of the equ ipment
being ru n from that power wire. If only the M6 450
is being run from that power wire, we recommend
a 60A fuse be u sed. AFS (mini blade f use), AGU
(big glass fuse) or Max iFuse™ (big plastic-body
fuse) ty pes are recommended.
No fuse is required or recommended direct ly
before the ampl ifier power connection. If one is
desired, we recommend the u se of a 60A fuse.
TURNON LE AD
The M6450 u ses a conventional +12V remote
turn-on lead, ty pically controlled by the source
unit’s remote tur n-on output. The a mplifier will
turn on when +12V is present at its “Remote”
input and turn off when +12V is switched off. If
a source unit does not have a dedic ated remote
turn-on out put, the amplifier’s turn-on lead ca n
be connected to +12V via a switch that derives
power from an ig nition-switched circuit.
The M6450’s “Remote” turn-on connector is
designed to accept 18 AWG – 12 AWG wire . To
connect the remote turn-on wire to the amplif ier,
first back out the set screw on the top of t he
termina l block, using the supplied 2 .5mm hex
wrench. Strip 1/2 inch (12mm) of wire and inser t
the bare wire into the termina l block, seating it
firmly so that no bare wire is exposed. While
holding the w ire in the termina l, tighten the set
screw firmly, tak ing care not to strip the head of
the screw and maki ng sure that the wire (not the
insulat ion) is firm ly gripped by the set screw.
JL AUDIO M6450 5
PRODUCT DE SCRIPTION
The JL Audio M6 450 is a six-channel,
full-range audio amplifier utili zing patented
Absolute Symmetry™ Class A/B technolog y
for all cha nnels.
The M6450 c an be operated with a w ide
variet y of source units and system configurat ions.
TYPICAL I NSTALLATION SEQUE NCE
The followi ng represents the sequence for a
typical ampli fier installation, using an af termarket
source unit. Additional steps a nd different
procedures may be required in some applications.
If you have any quest ions, please contact your
authoriz ed JL Audio dealer for assist ance.
1) Disconnect the negative battery post
connection and secure the disconnected c able
to prevent accidental re-connection dur ing
installation. This step is not optional!
2) Run positive a nd negative power w ire
(minimum 4 AWG) from from the bat tery
location to the a mplifier mounting location,
taki ng care to route it i n such a way that it
will not be damaged and wil l not interfere
with vessel operation. Use 4 AWG or larger
power wire and a power dist ribution block
if additional ampli fiers are being installed
with the M6450.
3) Connect power wire to the positive bat tery
post. Fuse t he wire w ith an appropriate fuse
block (and connectors) within 18 inches (45
cm) wire length of the positive battery post.
This fuse is essential to protect the vessel.
Do not insta ll the f use unt il the power wire
has been connected to the amplif ier.
4) Connect negat ive power wire to the negative
battery post. Use the same siz e power
wire as t he wire connected to t he “+12V ”
connection (minimum 4 AWG).
5) Run signa l cables and remote turn-on w ire
from the source unit to the amplif ier
mounting location.
6) Run speaker wire from t he speaker system
to the ampli fier mount ing location.
7) Securely mount t he amplif ier using the
supplied screws.
8) Connect the positive and negative power
wires to the amplif ier. A fuse near the
amplif ier is not necessary.
9) Connect the remote turn-on wire to
the amplifier.
10) Connec t the input cables to the amplifier.
11) Con nect the speaker w ires to the amplif ier.
12) Careful ly review the ampli fier’s control
settings to make sure that they are set
according to the needs of t he system.
13) Install power wire f use (60A for a single
M6450) and reconnect the negative
battery post terminal.
14) Turn on the source u nit at a low level
to double-check that the amplifier is
configured correctly. Resist the temptation
to crank it up until you have verified the
control set tings.
15) Make necessa ry adjust ments to the i nput
sensitiv ity controls to obtai n the rig ht
overall out put and the desired balance in t he
system. See Appendix A (page 12)
for the recommended input sensit ivity
setti ng method.
16) Enjoy the f ruits of your labor wit h your
favorite music.
POWER CONNECTIONS
Before installing the amplifier, disconnect the
negative (ground) wire from the vessel's battery.
This will prevent ac cidental damage to t he system,
the vessel and your body du ring instal lation.
4 JL AUDIO M6450
INPUT SENSITIVITY CONTROLS
Once the appropriate “Input Voltage” range
has been selected, t he controls labeled “Input
Sens.” located in each “Channel Controls”
section can be used to match the sou rce unit’s
output voltage to the input stage of each pair of
amplif ier channels for maximum clean output.
Rotating t he control clockwise will re sult in
higher sensitivit y (louder for a given input
voltage). Rotating t he control counter-clockw ise
will re sult in lower sensitivit y (qu ieter for a given
input voltage.)
To properly set the ampli fier for maximum
clean output, please refer to Appendix A (page
14) in this manua l. After using t his procedure,
you can then adjust any or all “Input Sens.”
levels downward if this is required to achieve the
desired system balance.
Do not increase any “Input Sens.” setting for
any channel(s) of any amplifier in the system
beyond the ma ximum level established during
the procedu re outlined in Appendix A (page
14). Doing so will result in audible d istortion
and possible speaker damage.
FILTER CONTROLS
Most speakers are not designed to reproduce
the full range of frequencies audible by the
human ear. For this reason, most speaker
systems are comprised of mu ltiple speakers, each
dedicated to reproducing a specific f requency
range. Filters are used to select which frequency
range is sent to each section of a speaker system .
The division of frequency ra nges to different
speakers can be done with passive filters (coils
and/or capacitors between the amplifier outputs
and the speakers), which a re acceptable and
commonly us ed for filtering between midrange speakers and tweeters . Filteri ng between
subwoofer systems and satellite spe aker systems
is best done with active filters, which cut off
frequency c ontent at the input to t he amplifier.
Active filters are more s table tha n passive filters
and do not introduce extra neous resistance,
which can degrade subwoofer performance.
The active filter bu ilt into each channel section
of the M6450 can be used to elim inate potentially
harmf ul and/or undesired frequencies from
maki ng their way t hrough the amplifier sec tions
to the speaker(s). This serves to improve tonal
balance and to avoid distor tion and possible
speaker failure . Correct use of these filters can
substant ially increase the longevity and f idelity of
your audio system.
1) “Filter Mode” Control: The M6450 employs a
12dB per octave filter for each pair of channels
(one filter for channels 1&2, another filter for
channels 3&4 and a thi rd filter for channels
5&6). Each of the se filters can be config ured
independent ly into one of two filter types
or defeated completely by way of the threeposition “Filter Mode” switches:
“Off”: Defeats t he filter completely, allowing
the full range of f requencies present at the
inputs to feed the amplifier. This is useful
for systems ut iliz ing outboard crossovers or
requiri ng ful l-range reproduction from one or
more of the M6450’s channel pai rs.
JL AUDIO M6450 7
INPUT SECTION
The M6450’s input section al lows you to send
signal to t he amplifier section through the use of
two, four or six differential-balanced inputs.
Input connect ions are via three pa irs of
traditional RCA-type jacks.
If you wish to send six discrete channels into
the M6450, simply use a ll six inputs and set the
“Input Mode” switch in t he “Channel 5 & 6
Controls” section to “Discrete”.
If you wish to feed all si x channels by using
only four channels of full-range input, set the
“Input Mode” switch in t he “Channel 5 & 6
Controls” section to “Sum” and use only the
inputs to channels 1, 2, 3 & 4.
If you wish to feed all si x channels by using
two channels of full-range input and two
channels of low-frequency input (subwoofer
output from the source unit), set the “Input
Mode” switch i n the “Channel 5 & 6 Controls”
section to “Discrete”. It will be necessary to split
the full-range signals w ith y-adaptors and feed
these sig nals into the inputs to channels 1, 2, 3 &
4. The dedicated subwoofer signal should be sent
to channels 5 & 6.
If you wish to use only two channels of input
to deliver signal to all si x amplifier cha nnels,
it will be necessa ry to split the two sig nals with
y-adaptors and feed these signals into the input s
to channels 1, 2, 3 & 4. Set t he “Input Mode”
switch in the “Channel 5 & 6 Controls”
section to “Sum” and use only the inputs
to channels 1, 2, 3 & 4.
Input Voltag e Range:
A wide range of signal i nput voltages ca n
be accommodated by theM6450’s CH 1&2 and
CH 3&4 input sect ions (200mV – 8V). This
wide range is split up into t wo sub-ranges,
accessible v ia a switch located to the lef t of the
Input Connectors.
The “Low” position on the “Input Voltage”
switch selects an input sensitiv ity range between
200mV and 2V. This means that the “Input
Sens.” rotary control will oper ate with in that
voltage window. If you are using a sou rce unit
with convent ional preamp-level outputs , this is
most likely the position that you wi ll use.
The “High” position on the “Input Voltage”
switch selects an input sensitiv ity range between
800mV and 8V. This is usef ul for certain highoutput preamp level signals as well as speakerlevel outputs from source units not equipped w ith
preamp-level out puts.
To use speaker-level sources, splice the speaker
output wires of the source unit onto a pair of RCA
plugs for each input pa ir. No line output converter
is needed in most cases.
The CH 5&6 input section is designed to
accept only l ine-level signals and may clip
(distort) if hig h-level signa ls are applied to it.
The output of the ampl ifier will decrease for
a given input voltage when the “Input R ange”
switch is placed in the “High” position.
Conversely, the output will be higher with the
switch in t he “Low” position. Wh ile this may
sound counter-intuitive, it is consistent with
the descriptions above.
6 JL AUDIO M6450
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