JL Audio M6600 User manual

Thank you for purchasing a JL Audio amplifier 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 vehicle.
For maximum performance, 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 [phone] during business hours.
OWNER’S MANUAL

PLANNING YOUR INSTALLATION
It is important that you take the time to read
this manual and that you plan out your
installation carefully. The following are some
considerations that you must take into account
when planning your installation.
Cooling Efficiency Considerations:
The outer shell of your JL Audio amplifier
is designed to remove heat from the amplifier
circuitry. For optimum cooling performance,
this outer shell should be exposed to as large a
volume of air as possible. Enclosing the amplifier
in a small, poorly ventilated chamber 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 necessary.
Mounting the amplifier upside down is
strongly discouraged.
If mounting the amplifier under a seat,
make sure there is at least 1 inch (2.5 cm) of
space above the amplifier’s outer shell to permit
proper cooling.
Safety Considerations:
Your amplifier needs to be installed in a dry,
well-ventilated 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.
Stupid Mistakes to Avoid:
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make sure that you will not be drilling through
the hull, a fuel tank, fuel line, wiring harness or
other vital vessel system.
t%POPUSVOTZTUFNXJSJOHPVUTJEFPSVOEFSOFBUI
the vessel. This is an extremely dangerous
practice which can result in severe damage to
your vessel and person.
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(metal, fiberglass, etc.) by carefully routing
them, tying them down and using grommets
and loom where appropriate.
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compartment or in any other area that will
expose the amplifier circuitry to the elements.
While this amplifier is specially designed
for marine applications, it is not waterproof
and it should not be mounted where it is
likely to get wet.
PROTECT YOUR HEARING!
We value you as a long-term customer. For
that reason, we urge you to practice 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 all other
high-power amplifiers are capable of producing
such high sound pressure levels when connected
UPBTQFBLFSTZTUFN1MFBTFMJNJUZPVSDPOUJOVPVT
exposure to high volume levels.
While driving, operate your audio system in
a manner that still allows you to hear necessary
noises to operate your vessel safely (horns,
sirens, etc.).
SERIAL NUMBER
In the event that your amplifier requires
service or is ever stolen, you will need to have
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take the time to enter that number in the space
provided below. The serial number can be found
on the bottom panel of the amplifier and on the
amplifier packaging.
Serial Number:
INSTALLATION APPLICATIONS
This amplifier is designed for operation in
vessels with 12 volt, negative-ground electrical
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.
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amplifier with the outputs of a second amplifier,
including an identical one.
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)
2 JL AUDIO M6600 JL AUDIO M6600 3

5IF.Ti+12 VDCwBOEiGroundw
connections are designed to accept 4 AWG power
wire. 4 AWG is a minimum power wire size for
this amplifier.
If you are installing the M6600 with other
amplifiers and wish to use a single main power
wire, use 2 AWG or larger main power wire
(depending on the overall current demands of all
the amplifiers in the system). This 2 AWG or
larger power wire should terminate into a
distribution block mounted as close to the
amplifiers as possible and should connect to the
M6600 with 4 AWG power wire.
Note: Smaller AWG numbers mean bigger
wire and vice-versa (1/0 AWG is the largest, 2
AWG is smaller, then 4 AWG, then 8 AWG, etc.).
To connect the power wires to the amplifier,
first back out the set screw on the top of the
terminal block, using the supplied 2.5 mm hex
wrench. Strip 1/2 inch (12 mm) of insulation from
the end of each wire and insert the bare wire into
the terminal block, seating it firmly so that no
bare wire is exposed. While holding the wire in
place, tighten the set screw firmly, taking care not
to strip the head of the screw.
The ground connection should be made using
the same gauge wire as the power connection.
Any wires run through barriers must be
protected with a high quality rubber grommet
to prevent damage to the insulation of the wire.
Failure to do so may result in a dangerous short
circuit.
Many vessels employ small (10 AWG - 6 AWG)
wire to connect the alternator’s positive
connection to the battery. To prevent voltage
drops, this wire should be upgraded to 4 AWG
when installing amplifier systems with main
fuse ratings above 60A.
It is common for the alternator to be grounded
through its chassis. If the alternator is not
grounded through its chassis and instead employs
a small (10 AWG - 6 AWG) wire to connect to
ground, this wire should also be upgraded to 4
AWG when installing amplifier systems with main
fuse ratings above 60A.
FUSE REQUIREMENTS
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 battery post
connection. The fuse value at each power wire
should be high enough for all of the equipment
being run from that power wire. If only the M6600
is being run from that power wire, we recommend
a 60A fuse be used. AFS (mini blade fuse), AGU
(big glass fuse) or MaxiFuse™ (big plastic-body
fuse) types are recommended.
No fuse is required or recommended directly
before the amplifier power connection. If one is
desired, we recommend the use of a 60A fuse.
TURNON LEAD
The M6600 uses a conventional +12V remote
turn-on lead, typically controlled by the source
unit’s remote turn-on output. The amplifier will
turn on when +12V is present at its iRemotew
input and turn off when +12V is switched off. If
a source unit does not have a dedicated remote
turn-on output, the amplifier’s turn-on lead can
be connected to +12V via a switch that derives
power from an ignition-switched circuit.
The M6600’s iRemotewturn-on connector is
designed to accept 18 AWG – 12 AWG wire. To
connect the remote turn-on wire to the amplifier,
first back out the set screw on the top of the
terminal block, using the supplied 2.5mm hex
wrench. Strip 1/2 inch (12mm) of wire and insert
the bare wire into the terminal block, seating it
firmly so that no bare wire is exposed. While
holding the wire in the terminal, tighten the set
screw firmly, taking care not to strip the head of
the screw and making sure that the wire (not the
insulation) is firmly gripped by the set screw.
PRODUCT DESCRIPTION
The JL Audio M6600 is a six-channel,
full-range audio amplifier utilizing patented
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for all channels.
The M6600 can be operated with a wide
variety of source units and system configurations.
TYPICAL INSTALLATION SEQUENCE
The following represents the sequence for a
typical amplifier installation, using an aftermarket
source unit. Additional steps and different
procedures may be required in some applications.
If you have any questions, please contact your
authorized JL Audio dealer for assistance.
1)%JTDPOOFDUUIFOFHBUJWFCBUUFSZQPTU
connection and secure the disconnected cable
to prevent accidental re-connection during
installation. This step is not optional!
2) Run positive and negative power wire
(minimum 4 AWG) from from the battery
location to the amplifier mounting location,
taking care to route it in such a way that it
will not be damaged and will not interfere
with vessel operation. Use 4 AWG or larger
power wire and a power distribution block
if additional amplifiers are being installed
with the M6600.
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post. Fuse the wire with 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.
%POPUJOTUBMMUIFGVTFVOUJMUIFQPXFSXJSF
has been connected to the amplifier.
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battery post. Use the same size power
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connection (minimum 4 AWG).
5) Run signal cables and remote turn-on wire
from the source unit to the amplifier
mounting location.
6) Run speaker wire from the speaker system
to the amplifier mounting location.
7) Securely mount the amplifier.
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wires to the amplifier. A fuse near the
amplifier is not necessary.
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the amplifier.
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settings to make sure that they are set
according to the needs of the system.
13) Install power wire fuse (60A for a single
M6600) and reconnect the negative
battery post terminal.
14) Turn on the source unit 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 settings.
15) Make necessary adjustments to the input
sensitivity controls to obtain the right
overall output and the desired balance in the
system. See Appendix A (page 12)
for the recommended input sensitivity
setting method.
16) Enjoy the fruits of your labor with your
favorite music.
POWER CONNECTIONS
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negative (ground) wire from the vessel's battery.
This will prevent accidental damage to the system,
the vessel and your body during installation.
4 JL AUDIO M6600 JL AUDIO M6600 5

INPUT SENSITIVITY CONTROLS
Once the appropriate iInput Voltagewrange
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Sens.wMPDBUFEJOFBDIiChannel Controlsw
section can be used to match the source unit’s
output voltage to the input stage of each pair of
amplifier channels for maximum clean output.
Rotating the control clockwise will result in
higher sensitivity (louder for a given input
voltage). Rotating the control counter-clockwise
will result in lower sensitivity (quieter for a given
input voltage.)
To properly set the amplifier for maximum
clean output, please refer to Appendix A (page
14) in this manual. After using this procedure,
ZPVDBOUIFOBEKVTUBOZPSBMMiInput Sens.w
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 maximum level established during
the procedure outlined in Appendix A (page
14). Doing so will result in audible distortion
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 multiple speakers, each
dedicated to reproducing a specific frequency
range. Filters are used to select which frequency
range is sent to each section of a speaker system.
The division of frequency ranges to different
speakers can be done with passive filters (coils
and/or capacitors between the amplifier outputs
and the speakers), which are acceptable and
commonly used for filtering between mid-
range speakers and tweeters. Filtering between
subwoofer systems and satellite speaker systems
is best done with active filters, which cut off
frequency content at the input to the amplifier.
Active filters are more stable than passive filters
and do not introduce extraneous resistance,
which can degrade subwoofer performance.
The active filter built into each channel section
of the M6600 can be used to eliminate potentially
harmful and/or undesired frequencies from
making their way through the amplifier sections
to the speaker(s). This serves to improve tonal
balance and to avoid distortion and possible
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substantially increase the longevity and fidelity of
your audio system.
1) “Filter Mode” Control: The M6600 employs a
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(one filter for channels 1&2, another filter for
channels 3&4 and a third filter for channels
5&6). Each of these filters can be configured
independently into one of two filter types
or defeated completely by way of the three-
position “Filter Mode” switches:
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the full range of frequencies present at the
inputs to feed the amplifier. This is useful
for systems utilizing outboard crossovers or
requiring full-range reproduction from one or
more of the M6600’s channel pairs.
INPUT SECTION
The M6600’s input section allows you to send
signals to the amplifier section through the use of
two, four or six differential-balanced inputs.
Input connections are via three pairs of
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If you wish to send six discrete channels into
the M6600, simply use all six inputs and set the
iInput Modewswitch in the iChannel 5 & 6
Controlswsection to iDiscretew
If you wish to feed all six channels by using
only four channels of full-range input, set the
iInput Modewswitch in the iChannel 5 & 6
Controlswsection to iSumwand use only the
inputs to channels 1, 2, 3 & 4.
If you wish to feed all six channels by using
two channels of full-range input and two
channels of low-frequency input (subwoofer
output from the source unit), set the iInput
Modewswitch in the iChannel 5 & 6 Controlsw
section to iDiscretew It will be necessary to split
the full-range signals with y-adaptors and feed
these signals 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 six amplifier channels,
it will be necessary to split the two signals with
y-adaptors and feed these signals into the inputs
to channels 1, 2, 3 & 4. Set the iInput Modew
switch in the iChannel 5 & 6 Controlsw
section to iSumwand use only the inputs
to channels 1, 2, 3 & 4.
Input Voltage Range:
A wide range of signal input voltages can
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wide range is split up into two sub-ranges,
accessible via a switch located to the left of the
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5IFiLowwQPTJUJPOPOUIFiInput Voltagew
switch selects an input sensitivity range between
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voltage window. If you are using a source unit
with conventional preamp-level outputs, this is
most likely the position that you will use.
5IFiHighwQPTJUJPOPOUIFiInput Voltagew
switch selects an input sensitivity range between
800mV and 8V. This is useful for certain high-
output preamp level signals as well as speaker-
level outputs from source units not equipped with
preamp-level outputs.
To use speaker-level sources, splice the speaker
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plugs for each input pair. No line output converter
is needed in most cases.
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accept only line-level signals and may clip
(distort) if high-level signals are applied to it.
The output of the amplifier will decrease for a
given input voltage when the “Input Range”
switch is placed in the “High” position.
Conversely, the output will be higher with the
switch in the “Low” position. While this may
sound counter-intuitive, it is consistent with
the descriptions above.
6 JL AUDIO M6600 JL AUDIO M6600 7

SPEAKER OUTPUTS
The M6600’s speaker outputs are designed to
accept 16 AWG - 8 AWG wire.
Each pair of the M6600’s channels are designed
to deliver power into speaker loads equal to
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configuration and speaker loads equal to or greater
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Speaker loads below 2 ohms nominal per
channel are not recommended and may cause
the amplifier to initiate a protection mode
which reduces power output.
BRIDGING CONSIDERATIONS
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output of two amplifier channels to drive a single
load. When bridged, each channel produces
signals of equal magnitude, but opposite polarity.
The combined output of the two channels
provides twice the output voltage available from a
single channel. The M6600 has been designed for
bridging of its channel pairs without the need for
input inversion adaptors.
To bridge a pair of channels, use the iLeft +w
and iRight –wspeaker connectors only (the
iLeft –wand iRight +wremain unused). When
bridged, each channel will deliver optimum
power into a 4 ohm load.
When a pair of channels are bridged, they
will deliver 200W x 1 into a 4 ohm load or
150W x 1 into an 8 ohm load. Operating a
pair of bridged channels into a load lower
than 4 ohms is not recommended.
Because a bridged pair of channels requires
that both channels receive input, you need to
connect both left and right inputs to the source
unit. Connection of only one input will result in
reduced power output, increased distortion and
can cause the amplifier to overheat.
Do not do this!
When a pair of the M6600’s channels are
operating in bridged mode, the output will be in
mono (only one channel). This mono channel
can contain right channel only information,
left channel only information or the sum of
the information from both the right and left
channels. In order to achieve one of these options,
configure the inputs to that pair of channels in
one of these two ways:
1) Left Channel Only or Right Channel Only
Information: If you wish to send a left-only
or right-only signal to a pair of the M6600’s
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inputs. This option is useful when using a pair
of the M6600’s channels to drive left channel
speakers only and the other pair of the M6600’s
channels to drive right channel speakers only.
2) Left + Right Channel Information: When
bridged and fed by a stereo input, a pair of the
M6600’s channels will automatically combine
the left and right channels into a summed
mono (left + right) channel. This option
is useful when using a pair of the M6600’s
channels to drive a subwoofer system or a
summed mono center channel.
If you plan to use the “Pre-Outs” to feed
a stereo amplifier, you must connect a
stereo signal to the input of the amplifier.
A mono signal into the amplifier will result
in a mono signal out of the preamp output.
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attenuate frequencies above the selected filter
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useful for connection of subwoofer(s) to one
or more of the M6600’s channel pairs in a
bi-amplified system.
“HP” (High-Pass):$POGJHVSFTUIFGJMUFSUP
attenuate frequencies below the selected filter
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useful for connection of component speakers to
one or more of the M6600’s channel pairs in a
bi-amplified system.
2) “Filter Freq. (Hz)” The filter frequency
markings surrounding this rotary control
are for reference purposes and are generally
accurate to within 1/3 octave or better. If you
would like to select the filter cutoff frequency
with a higher level of precision, consult the
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Tuning Hint: If you are using the M6600
to drive a subwoofer system (iLPwmode), a
component satellite speaker system (iHPwmode)
PSCPUI)[JTBHPPECBTFMJOFiFilter Freq.
(Hz)wsetting. After properly adjusting the iInput
Sens.w, as outlined in Appendix A (page 14), you
can fine tune the iFilter Freq. (Hz)wcontrol to
achieve the desired system frequency response.
BASS BOOST CONTROLS
1) “Bass Boost”: Found in the iChannel 5 & 6
Controlswsection, this switch allows the user
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for channels 5&6. When the iBass Boostwis
activated, the inputs to iCH 5 (Left)wand iCH
6 (Right)ware summed to create a mono signal.
The iFilter Modewswitch in the iChannel
5 & 6 Controlswsection must be in the iLPw
position for the bass boost to be functional.
2) “Remote Bass Port”: This port allows you to
connect an optional remote boost knob (sold
TFQBSBUFMZBT+-"VEJP.PEFM3#$UIBU
can be mounted near the head unit. With
UIF3#$DPOOFDUFEUIFCPPTUJTOPMPOHFS
MJNJUFEUPPSE#BMMPXJOHBWBSJBCMF
SBOHFPGUPE#PGCPPTUUPCFTFMFDUFE
8 JL AUDIO M6600 JL AUDIO M6600 9

SYSTEM CONFIGURATIONS
The M6600 is a flexible amplifier, well-suited
for a multitude of system configurations. In
this section, the most likely configurations are
explained in detail.
Once you have selected your desired
configuration, you can use the amplifier panel
drawing on pages 18 & 19 to mark the required
switch positions for easy reference.
BIAMPLIFIED SYSTEMS
#JBNQMJGJFETZTUFNTBSFEFGJOFEBTTZTUFNT
in which separate amplifier channels drive low-
GSFRVFODZ-'BOEIJHIGSFRVFODZ)'TQFBLFST
and are separately filtered to send appropriate
frequency ranges to each speaker system.
The most common application of bi-
amplification in marine audio is to drive a
subwoofer system from one or more amplifiers or
channels and component speakers from separate
amplifiers or channels.
The M6600 is designed to work as the only
amplifier in a bi-amplified system.
Bi-Amplified System with the M6600
In this configuration, channels 5&6 of the
M6600 will drive subwoofers (stereo 75W x 2 at 2
ohms or bridged 150W x 1 at 4 ohms) with low-
QBTTGJMUFSJOH$IBOOFMTBOEDIBOOFMT
will drive component speakers in stereo (75W x 4
at 2 ohms) with high-pass filtering.
Input connection options for a bi-amplified system
with one M6600 are as follows:
A) No User Adjustability:
Required: a basic source unit or processor
with one pair of stereo outputs.
Input Connections: a single pair of stereo source
VOJUPVUQVUTFBDITQMJUXJUIBi:"EBQUPSw
allowing the left signal to be sent to the
iCH 1 (Left)wBOEiCH 3 (Left)wJOQVUTBOE
UIFSJHIUTJHOBMUPCFTFOUUPUIFiCH 2 (Right)w
BOEiCH 4 (Right)wJOQVUTPGUIF.TFMFDU
iSumwPOUIFiInput Modewswitch in the
iChannel 5 & 6 ControlswTFDUJPO
Result: UIFSFMBUJWFMFWFMPGUIF-'BOE)'
DIBOOFMTXJMMCFGJYFECZUIF.TiInput
Sens.wTFUUJOHTBOEXJMMOPUCFVTFSBEKVTUBCMF
from the front of the vehicle.
B) Fade Front vs. Rear with no Subwoofer
Level Control:
Required: a basic source unit or processor with
two pairs of stereo outputs.
Input Connections: one pair of stereo source unit
PVUQVUTJTDPOOFDUFEUPUIFiCH 1 (Left)wBOE
iCH 2 (Right)wJOQVUTBOEUIFTFDPOEQBJS
of stereo source unit outputs is connected
UPUIFiCH 3 (Left)wBOEiCH 4 (Right)w
JOQVUTPGUIF.TFMFDUiSumwPOUIF
iInput ModewTXJUDIJOUIFiChannel 5 & 6
ControlswTFDUJPO
Result: UIFSFMBUJWFMFWFMPGUIF-'BOE)'
DIBOOFMTXJMMCFGJYFECZUIF.TiInput
Sens.wTFUUJOHTBOEXJMMOPUCFVTFSBEKVTUBCMF
from the front of the vehicle.
C) Fade Subwoofer Level vs. HF Level:
Required: a basic source unit or processor with
two pairs of stereo outputs.
Input Connections: the first stereo pair of source
VOJUPVUQVUTFBDITQMJUXJUIBi:"EBQUPSw
BMMPXJOHUIFMFGUTJHOBMUPCFTFOUUPUIFiCH
1 (Left)wBOEiCH 3 (Left)wJOQVUTBOEUIF
right signal to be sent to the iCH 2 (Right)w
and iCH 4 (Right)wJOQVUTPGUIF.
The second stereo pair of source unit outputs
is connected to the iCH 5 (Left)wBOE“CH
6 (Right)wJOQVUTTFMFDUiDiscretewPOUIF
iInput ModewTXJUDIJOUIFiChannel 5 & 6
ControlswTFDUJPO
Result: in this mode, the user has the ability to
fade or control the level of the LF channels
SFMBUJWFUPUIF)'DIBOOFMTWJBUIFTPVSDF
unit’s fader control without exceeding the
maximum clean output level set by each
BNQMJGJFSTFDUJPOTiInput Sens.wDPOUSPMT
AMPLIFIER STATUS INDICATOR LIGHTS &
PROTECTION CIRCUITRY
There are two status indicator lights on the
input / control end of the amplifier.
1) “Power” (Green): lights to indicate that the
amplifier is turned on and operating normally.
2) “Protect” (Red): Indicates that the amplifier
protection circuitry has been activated to
prevent product failure due to a short-circuit
or a dangerously low impedance connected
UPUIFBNQMJGJFSPVUQVUT$POOFDUJOHUIF
speaker outputs to an impedance lower than
2 ohms stereo (4 ohms bridged) will cause
this protection mode to activate. When this
protection mode is activated, the amplifier will
reduce it maximum power output to protect its
circuitry, which will manifest itself as increased
distortion. When the problem is corrected, the
amplifier will return to normal operation.
Advanced Rollback Thermal protection
Unlike conventional thermal protection
systems, which shut down an amplifier when it
overheats, this system protects the amplifier by
gradually reducing power output if the amplifier’s
safe operating temperature is exceeded. The
amplifier will continue to operate and return
to normal power output once its temperature
returns to a normal range.
Low-Voltage protection:
If the vessel’s supply voltage drops below 10
volts, the entire amplifier will shut itself off to
protect its internal circuitry. The green iPowerw
indicator will turn off when this occurs. The
amplifier will turn back on when voltage climbs
back above 10 volts. This may happen in a rapid
cycle when bass-heavy program material causes
a weak charging system to dip below 10 volts
momentarily. If this is happening in your system,
turn your audio system off and have your power
wiring, ground connections and charging
system inspected.
SERVICING YOUR JL AUDIO AMPLIFIER
If your amplifier fails or malfunctions, please
return it to your authorized JL Audio dealer so
that it may be sent in to JL Audio for service.
There are no user serviceable parts or fuses inside
the amplifier. The unique nature of the circuitry
in the JL Audio amplifiers requires specifically
USBJOFETFSWJDFQFSTPOOFM%POPUBUUFNQU
to service the amplifier yourself or through
unauthorized repair facilities. This will not only
void the warranty, but may result in the creation
of more problems within the amplifier.
If you have any questions about the installation or
setup of the amplifier not covered in this manual,
please contact your dealer or technical support.
JL Audio Technical Support:
[phone]
9:00 AM– 5:30 PM (Eastern Time Zone)
Monday - Friday
10 JL AUDIO M6600 JL AUDIO M6600 11

D) Subwoofer Level Control Only:
Required: a source unit or processor with
one pair of stereo outputs and dedicated
subwoofer outputs.
Input Connections: the stereo pair of source
VOJUPVUQVUTFBDITQMJUXJUIBi:"EBQUPSw
BMMPXJOHUIFMFGUTJHOBMUPCFTFOUUPUIFiCH
1 (Left)wBOEiCH 3 (Left)wJOQVUTBOEUIF
SJHIUTJHOBMUPCFTFOUUPUIFiCH 2 (Right)w
BOEiCH 4 (Right)wJOQVUTPGUIF.5IF
source unit’s dedicated subwoofer outputs are
DPOOFDUFEUPUIFiCH 5 (Left)wBOE
iCH 6 (Right)wJOQVUTTFMFDUiDiscretewPO
UIFiInput ModewTXJUDIJOUIFiChannel 5 &
6 ControlswTFDUJPO
Result: in this mode, the user has the ability to
control the absolute level of the LF channels
SFMBUJWFUPUIF)'DIBOOFMT
E) Independent level control of all three
channel pairs:
Required: a source unit or processor with
two pairs of stereo outputs and dedicated
subwoofer outputs.
Input Connections: one pair of stereo source
VOJUPVUQVUTJTDPOOFDUFEUPUIFiCH 1
(Left)wBOEiCH 2 (Right)wJOQVUTUIF
second pair of stereo source unit outputs is
DPOOFDUFEUPUIFiCH 3 (Left)wBOEiCH
4 (Right)wJOQVUTBOEUIFTPVSDFVOJUT
dedicated subwoofer output is connected
UPUIFiCH 5 (Left)wBOEiCH 6 (Right)w
JOQVUTTFMFDUiDiscretewPOUIFiInput
ModewTXJUDIJOUIFiChannel 5 & 6
ControlswTFDUJPO
Result: in this mode, the user has the ability to
control the absolute level of the LF channels as
XFMMBTCPUIQBJSTPG)'DIBOOFMT
When using a source unit’s dedicated
subwoofer output, set the “Input Sens.” of any
channels receiving input from the subwoofer
output with the source unit’s subwoofer level
control set at 3/4 of full output. See Appendix A
(page 14) for details.
Crossover Setup for Bi-Amplified System
with one M6600:
Once the input sections have been configured
BQQSPQSJBUFMZHPUPUIFiChannel 5 & 6
Controlsw4FMFDUiLPwMPXQBTTPOUIFiFilter
ModewTXJUDIBOEBOBQQSPQSJBUFiFilter Freq.w
)[JTBHPPETUBSUJOHQPJOU
/FYUUVSOZPVSBUUFOUJPOUPUIFiChannel 1 &
2 ControlswBOEiChannel 3 & 4 ControlswBOE
TFMFDUiHPwIJHIQBTTPOUIFiFilter Modew
TXJUDIFTBOEBOBQQSPQSJBUFiFilter Freq.wBHBJO
)[JTBHPPETUBSUJOHQPJOU
"GUFSQSPQFSBEKVTUNFOUPGUIFiInput Sens.w
controls for all three channel pairs using the
method shown in Appendix A (page 14), you can
fine tune filter frequencies and attenuate any pair
of channels to achieve proper balance. For precise
GJMUFSGSFRVFODZJOGPSNBUJPOSFGFSUP"QQFOEJY#
(page 15).
12 JL AUDIO M6600 JL AUDIO M6600 13

APPENDIX C:
M6600 Specifications
General Specifications:
Recommended Fuse Value:60A
Recommended Fuse Type:AFS, AGU or MaxiFuse™
Input Sections:
No. of Inputs:Three Stereo Pairs
Input Type:Differential-balanced with RCA jack inputs
Input Range:Switchable from 200mV - 2V RMS to
800mV - 8V RMS (except CH 5&6 inputs which are fixed
at 200mV-2V).
Amplifier Section:
Amplifier Topology:Class A/B with patented Absolute
Symmetry™ dual N-Channel MOSFET output design
Power Supply:Unregulated MOSFET switching type
Rated Power at 14.4V with less than
1% THD+Noise (20Hz - 2kHz)
Stereo, all channelsdriven:
75W RMS x 6 @ 4 ohms, 100W RMS x 6 @ 2 ohms
Bridged, all channelsdriven:
150W RMS x 3 @ 8 ohms, 200W RMS x 3 @ 4 ohms
Rated Power @ 12.5Vwith less than
1% THD + Noise (20Hz - 20 kHz)
Stereo, all channelsdriven:
55W RMS x 6 @ 4 ohms, 75W RMS x 6 @ 2 ohms
Rated Power Bridged, all channelsdriven:
110W RMS x 3 @ 8 ohms, 150W RMS x 3 @ 4 ohms
Signal to Noise Ratio: >104 dB referred to rated power
(A-weighted, 20 Hz-20 kHz noise bandwidth)
Frequency Response:10 Hz - 25 kHz (+0, -1dB)
Damping Factor:>200 @ 4 ohms per ch./50 Hz,
>100 @ 2 ohm per ch. /50 Hz
Slew Rate:± 22V/μs
Amplifier Filter:
Filter Type:State-variable, 12dB/octave Butterworth
with continuously variable cutoff frequency selection
from 50-200 Hz.
Configurable as Low-Pass or High-Pass. Defeatable.
Dimensions(LxWxH):
17. 7" x 9.25" x 2.50" (450mm x 235mm x 63.5mm)
APPENDIX B:
Precise Frequency Selection Chart
“FILTER FREQ” AMP FILTER
Detent Panel Actual
Number Marking Freq.
Full counter-clockwise: 53
01............................53
02...........“50” ............53
03............................53
04............................54
05............................54
06............................55
07............................55
08...........“55” ............56
09............................56
10............................57
11............................58
12............................59
13............................62
14...........“60” ............65
15 ............................65
16 ............................66
17 ............................70
18 ............................73
19 ............................77
20 ...........“80” ............81
21 ............................84
22 ............................88
23 ............................94
24 ...........................101
25 ...........................104
26 .......... “120” ..........115
27 ...........................118
28 ...........................128
29 ...........................137
30 ...........................146
31 ...........................164
32 .......... “150” ..........177
33 ...........................193
34 ...........................197
35 ...........................209
36 ...........................213
37 ...........................216
38 .......... “200” ..........218
39 ...........................225
Full-clockwise: 225
APPENDIX A:
Input Sensitivity Level Setting
Following the directions below will allow the
installer to adjust the input sensitivity of each
amplifier channel pair simply and easily in just a
few minutes using equipment which is commonly
available in installation bays.
Necessary Equipment
t%JHJUBM"$7PMUNFUFS
t$%XJUIBTJOFXBWFUFTUUPOFSFDPSEFEBU
E#SFGFSFODFMFWFMJOUIFGSFRVFODZSBOHF
to be amplified for that set of channels
)[GPSTVCXPPGFSDIBOOFMTL)[GPSB
NJESBOHFBQQMJDBUJPO%POPUVTFBUUFOVBUFE
UFTUUPOFTE#E#FUD
The Nine-Step Procedure
1)%JTDPOOFDUUIFTQFBLFSTGSPNUIF
amplifier’s speaker output connectors.
2) Turn off all processing (bass/treble, loudness,
EQ, etc.) on the source unit, processors (if
used) and amplifier. Set fader control to center
position and subwoofer level control to 3/4 of
maximum (if used to feed the M6600).
3) Switch the iInput Voltagewswitch to iLoww
and turn the iInput Sens.wcontrol all the
way down.
4) Set the source unit volume to 3/4 of full
volume. This will allow for reasonable gain
overlap with moderate clipping at full volume.
5) Using the chart on this page, determine the target
voltage for input sensitivity adjustment according
to the nominal impedance of the speaker system
connected to the amplifier outputs.
6) Verify that you have disconnected the speakers
CFGPSFQSPDFFEJOH1MBZBUSBDLXJUIBO
appropriate sine wave (within the frequency
range to be amplified by the M6600) at 3/4
source unit volume.
7)$POOFDUUIF"$WPMUNFUFSUPUIFTQFBLFSPVUQVU
connectors of the amplifier. If the channel
pair is operating in stereo, it is only necessary
to measure one channel. If bridged, make sure
you test the voltage at the correct connectors
(L+ and R–).
8) Increase the “Input Sens.” control until the
target voltage is observed with the voltmeter.
9) Once you have adjusted the M6600 to its
maximum low-distortion output level,
reconnect the speaker(s). The “Input Sens.”
controls can now be adjusted downward if the
amplifier requires attenuation to achieve the
desired system balance.
Do not increase any “Input Sens.” setting for
any amplifier channel or channel pair in the
system beyond the maximum level established
during this procedure. Doing so will result in
audible distortion and possible speaker damage.
It will be necessary to re-adjust the
“Input Sens.” for the affected channels if any
equalizer boost is activated after setting the
“Input Sens.” with this procedure. This applies
to any EQ boost circuit, including source unit
tone controls or EQ circuits. EQ cuts will not
require re-adjustment.
Due to ongoing product development, all specifications are subject to
change without notice.
Nom.
Impedance
Target AC Voltage
Stereo Bridged
8 17.3 V 34.6 V
6 17.3 V 32.8 V
4 17.3 V 28.3 V
3 16.4 V not recommended
2 14.1 V not recommended
14 JL AUDIO M6600 JL AUDIO M6600 15

“My amplifier shuts off once in a while, usually at higher volumes”
Check your voltage source and grounding point. The power supply
of the M6600 will operate with charging system voltages
down to 10V. Shutdown problems at higher volume levels
can occur when the charging system voltage drops below
10V. These dips can be of very short duration making them
FYUSFNFMZEJGGJDVMUUPEFUFDUXJUIBDPNNPO%$WPMUNFUFS
To ensure proper voltage, inspect all wiring and termination
points. It may also be necessary to upgrade the vessel’s
battery wires. Many vessels employ small (10 AWG - 6 AWG)
wire to ground the battery and to connect the alternator to
the battery. To prevent voltage drops, these wires should be
upgraded to 4 AWG when installing amplifier systems with
main fuse ratings above 60A. Grounding problems are the
MFBEJOHDBVTFPGNJTEJBHOPTFEBNQMJGJFSiGBJMVSFT
“My amplifier turns on, but there is no output”
Check UIFJOQVUTJHOBMVTJOHBO"$WPMUNFUFSUPNFBTVSFUIF
voltage from the source unit while an appropriate test tone is
played through the source unit (disconnect the input cables
from the amplifier prior to this test). The frequency used
should be in the range that is to be amplified by the amplifier
FYBNQMF)[GPSBTVCCBTTBQQMJDBUJPOPSL)[GPSBGVMM
range / high-pass application). A steady, sufficient voltage
(between 0.2 and 8.0-volts) should be present at the output of
the signal cables.
Check the output of the amplifier. Using the procedure explained in
the previous check item (after plugging the input cables back
into the amplifier) test for output at the speaker outputs of
the amplifier. Unless you enjoy test tones at high levels, it is
a good idea to remove the speaker wires from the amplifier
while doing this. Turn the volume up approximately half
way. 5V or more should be measured at the speaker outputs.
This output level can vary greatly between amplifiers but it
should not be in the millivolt range with the source unit at
half volume. If you are reading sufficient voltage, check your
speaker connections as explained below.
Check to ensure that the speaker wires are making a good
connection with the metal inside the terminal block. The
speaker wire connectors are designed to accept up to 8 AWG
wire. Make sure to strip the wire to allow for a sufficient
connection with the metal inside the terminal block.
“How do I properly set the input sensitivity on my amplifier”
Please refer to Appendix A (page 14) to set the input sensitivity for
maximum, low-distortion output.
“My amplifier doesn’t turn on”
Check the fuse, not just visually, but with a continuity meter. It is
possible for a fuse to have poor internal connections that
cannot be found by visual inspection. It is best to take the
fuse out of the holder for testing. If no problem is found with
the fuse, inspect the fuse-holder.
Check the integrity of the connections made to each of the
i+12VDCwiGroundwBOEiRemotewUFSNJOBMT. Ensure
that no wire insulation is pinched by the terminal set screw
and that each connection is tight.
Check to make sure there is +12V at the “Remote” connection of the
amplifier. In some cases, the turn-on lead from the source unit
is insufficient to turn on multiple devices and the use of a relay
is required. To test for this problem, jump the i+12VDCwwire
to the iRemotewterminal to see if the amplifier turns on. If this
does not work, proceed to the next step.
“I get a distorted / attenuated sound coming out of the speaker(s)”
Check the speaker wires for a possible short, either between the
positive and negative leads or between either speaker lead
and the vehicle’s chassis ground. If a short is present, you
will experience distorted and/or attenuated output. The
iProtectwlight will illuminate in this situation. It may be
helpful to disconnect the speaker wires from the amplifier
and use a different set of wires connected to a test speaker.
Check the nominal load impedance to verify that each channel
of the amplifier is driving a load equal to or greater than
2 ohms in stereo mode (4 ohms bridged).
Check the input signal and input signal cables to make sure signal
is present at the “Amplifier Inputs” and the cables are not
pinched or loose. It may be helpful to try a different set of
cables and/or a different signal source to be sure.
“My amplifier’s output fluctuates when I tap on it or hit a bump”
Check the connections to the amplifier. Make sure that the
insulation for all wires has been stripped back far enough to
allow a good contact area inside the terminal block.
Check the input connectors to ensure that they all are making good
contact with the input jacks on the amplifier.
APPENDIX D: TROUBLESHOOTING
16 JL AUDIO M6600 JL AUDIO M6600 17

INSTALLATION NOTES:
Use this diagram to document your amplifier’s switch and control positions.
18 JL AUDIO M6600 JL AUDIO M6600 19

LIMITED WARRANTY  AMPLIFIERS USA
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period of two (2) years.
This warranty is not transferrable and applies only to the original purchaser from an authorized
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accident, misuse, abuse, product modification or neglect, failure to follow installation instructions,
unauthorized repair attempts, misrepresentations by the seller. This warranty does not cover incidental
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damage due to accident or normal wear and tear is not covered under warranty.
Warranty is void if the product’s serial number has been removed or defaced.
Any applicable implied warranties are limited in duration to the period of the express warranty as
provided herein beginning with the date of the original purchase at retail, and no warranties, whether
express or implied, shall apply to this product thereafter. Some states do not allow limitations on implied
warranties, therefore these exclusions may not apply to you. This warranty gives you specific legal rights,
and you may also have other rights which vary from state to state.
If you need service on your JL AUDIO product:
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Warranty expiration on products returned without proof of purchase will be determined from the
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For Service Information in the U.S.A. please call
JL Audio Customer Service: [phone]
9:00 AM– 5:30 PM (Eastern Time Zone)
JL Audio, Inc
10369 North Commerce Pkwy.
Miramar, FL 33025
(do not send product for repair to this address)
International Warranties:
Products purchased outside the United States of America are covered only
bythat country’sdistributor and not byJL Audio, Inc.
M6600MAN-02-2008
Absolute Symmetry™ Class A/B Amplifier Circuit is covered byU.S. Patent #6,294,959and is pending in the
countries listed below. Austria, Belgium, Brazil, Canada, China, France, Germany, Indonesia, Italy, Japan, Republic of Korea,
Mexico, Netherlands, Norway, Russian Federation, Singapore, Sweden, Switzerland, United Kingdom, and all other PCT countries.