6
| JL Audio - 300/4
v3
Owner’s Manual
7
on each “Input Voltage” 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 output
from source units and small amplifiers. To use
speaker-level sources, splice the speaker output
wires of the source unit or small amplifier
onto a pair of RCA plugs for each input pair
or use the JL Audio ECS Speaker Wire to RCA
adaptor (XD-CLRAIC2-SW).
I M P O R TA N T
!
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 correct
as described.
3) Input Sensitivity Adjustment: Located next
to the “Input Voltage” switch in each input
section is a rotary control labeled “Input
Sens.”. Once the appropriate “Input Voltage”
range has been selected, this control 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 each pair
of amplifier channels for maximum clean
output, please refer to Appendix A (page 14)
in this manual. After using this procedure,
you can then adjust the relative level of each
channel pair by adjusting the input sensitivity
downward on either or both channel pairs, if
they require attenuation to achieve the desired
system balance. Do not increase the “Input
Sens.” setting for 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. Be aware that
both “Input Sens.” adjustments will have to
be made, regardless of how many input cables
are feeding the amplifier. These controls will
allow you to set the appropriate relative levels
for front and rear channels and any other
amplifier channels in the system.
CrossoVer Controls
Crossovers are groups of individual electronic
filters which allow only certain frequency
ranges to pass through them by attenuating
frequencies outside the selected range. These
filters allow the user to specify what frequency
range will be sent out of each channel section
of the amplifier. This, in turn, allows each
speaker system to only reproduce a range of
frequencies it is well-suited for, resulting in
reduced distortion and improved fidelity.
Front and rear Filter section:
Bridged
Left
Right
+12VDC
Ground Remote
Front Filter Controls
Front Input Section
Front Speaker Outputs
Bridged
Left
Right
Rear Speaker Outputs
Left Ch.
Right Ch.
Filter Freq. (Hz)
Filter Slope
Freq. Range
Input Voltage
Input Sens.
Input Mode
12dB | 24dB
Filter Mode
Off | LP | HP
x1 | x10
Low | High
Rear Input Section
Left Ch.
Right Ch.
Input Voltage
Input Sens.
Low | High
2ch | 4ch
50
60
75
95
130
200
500
300/4
v3
Four-Channel Full-Range Amplifier
Rear Filter Controls
Filter Freq. (Hz)
Filter Slope
Freq. Range
12dB | 24dB
Filter Mode
Off | LP | HP
x1 | x10
50
60
75
95
130
200
500
Bridged
Left
Right
+12VDC
Ground Remote
Front Filter Controls
Front Input Section
Front Speaker Outputs
Bridged
Left
Right
Rear Speaker Outputs
Left Ch.
Right Ch.
Filter Freq. (Hz)
Filter Slope
Freq. Range
Input Voltage
Input Sens.
Input Mode
12dB | 24dB
Filter Mode
Off | LP | HP
x1 | x10
Low | High
Rear Input Section
Left Ch.
Right Ch.
Input Voltage
Input Sens.
Low | High
2ch | 4ch
50
60
75
95
130
200
500
300/4
v3
Four-Channel Full-Range Amplifier
Rear Filter Controls
Filter Freq. (Hz)
Filter Slope
Freq. Range
12dB | 24dB
Filter Mode
Off | LP | HP
x1 | x10
50
60
75
95
130
200
500
The 300/4v3 employs two separate, but
identical filter sections for its front and rear
channel pairs. These sections consist of the
following controls
1) “Filter Mode” Control: This switch allows you
to configure the filter into one of two filter
types or to defeat it completely:
“Off”: Defeats the filter for that channel
section completely, allowing the full range of
frequencies present at the inputs to feed that
pair of channels. This is useful for systems
utilizing outboard crossovers or requiring full-
range reproduction from that pair of channels.
“LP” (Low-Pass): Configures the filter to
attenuate frequencies above the selected
filter frequency. Useful for connection of
subwoofer(s) to that channel section.
“HP” (High-Pass): Configures the filter to
attenuate frequencies below the selected
filter frequency. Useful for connection
of component speakers to that channel
section in a bi-amplified system.
ground Connection
The chassis ground connection must be made
using 4 AWG pure copper wire and should be
kept as short as possible, while accessing a solid
piece of sheet metal in the vehicle. The surface of
the sheet metal should be sanded at the contact
point to create a clean, metal-to-metal connection
between the chassis and the termination of
the ground wire with a brass or copper power
ring. For optimal grounding, we recommend
the use of a JL Audio ECS master ground
lug (XB-MGLU). Alternatively, a sheet metal
screw or bolt can be used with a star washer.
I M P O R TA N T
!
Many vehicles employ small (10 AWG - 6
AWG) wire to ground the battery to the vehicle
chassis and to connect the alternator’s positive
connection to the battery. To prevent voltage
drops, these wires should be upgraded to 4
AWG pure copper wire when installing amplifier
systems with main fuse ratings above 60A.
turn-on lead
The 300/4v3 uses a conven12V 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 “Remote”
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 300/4v3’s “Remote” turn-on connector is
designed to accept 18 AWG – 8 AWG wire.
12 AWG is more than adequate for this purpose.
To connect the remote turn-on wire to the
amplifier, first back out the set screw on the top
of the amplifier, using the supplied hex wrench.
Strip 1/2 inch (12mm) of wire and insert the
bare wire into the receptacle on the front panel
of the amplifier, seating it firmly so that no bare
wire is exposed. When using smaller wire, it may
be necessary to strip 1 inch of insulation from
the wire and fold the bare wire in half prior to
insertion. 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 is firmly gripped by the set screw.
Front and rear inPut seCtions
The 300/4v3 has two separate input sections,
one for its front channels and another for its rear
channels. Each section contains a pair of RCA-
type input jacks, an “Input Voltage” switch and
an “Input Sens.” rotary control.
Bridged
Left
Right
+12VDC
Ground Remote
Front Filter Controls
Front Input Section
Front Speaker Outputs
Bridged
Left
Right
Rear Speaker Outputs
Left Ch.
Right Ch.
Filter Freq. (Hz)
Filter Slope
Freq. Range
Input Voltage
Input Sens.
Input Mode
12dB | 24dB
Filter Mode
Off | LP | HP
x1 | x10
Low | High
Rear Input Section
Left Ch.
Right Ch.
Input Voltage
Input Sens.
Low | High
2ch | 4ch
50
60
75
95
130
200
500
300/4
v3
Four-Channel Full-Range Amplifier
Rear Filter Controls
Filter Freq. (Hz)
Filter Slope
Freq. Range
12dB | 24dB
Filter Mode
Off | LP | HP
x1 | x10
50
60
75
95
130
200
500
Bridged
Left
Right
+12VDC
Ground Remote
Front Filter Controls
Front Input Section
Front Speaker Outputs
Bridged
Left
Right
Rear Speaker Outputs
Left Ch.
Right Ch.
Filter Freq. (Hz)
Filter Slope
Freq. Range
Input Voltage
Input Sens.
Input Mode
12dB | 24dB
Filter Mode
Off | LP | HP
x1 | x10
Low | High
Rear Input Section
Left Ch.
Right Ch.
Input Voltage
Input Sens.
Low | High
2ch | 4ch
50
60
75
95
130
200
500
300/4
v3
Four-Channel Full-Range Amplifier
Rear Filter Controls
Filter Freq. (Hz)
Filter Slope
Freq. Range
12dB | 24dB
Filter Mode
Off | LP | HP
x1 | x10
50
60
75
95
130
200
500
The “Front Input Section” also contains an
“Input Mode” switch to allow operation of all
four amplifier channels with one or two pairs of
input signals.
1) Input Mode Switch: If you wish to operate
all four channels of the 300/4v3 with a single
pair of stereo inputs, select the “2ch” position
on the “Input Mode” switch and connect a
single pair of input cables to the input jacks
in the “Front Input Section”. In this mode,
the amplifier will route the signals connected
to the front inputs to the rear inputs as well.
If you wish to use separate inputs for the front
and rear channel sections (to allow front-to-
rear fading, for example) and the source unit
is equipped with front and rear outputs, select
“4ch” on the “Input Mode” switch. In this
mode, you must connect separate pairs of input
cables to each input section.
2) Input Voltage Range: A wide range of signal
input voltages can be accommodated by each
of the 300/4v3’s input sections (200mV – 8V).
This wide range is split up into two sub-
ranges, accessible via switches located in each
input section of the amplifier. Be aware that
each input section’s “Input Voltage” switch
will have to be configured, regardless of how
many input cables are actually feeding the
amplifier. The “Low” position on each “Input
Voltage” switch selects an input sensitivity
range between 200mV and 2V. This means that
the “Input Sens.” rotary control will operate
within that voltage window. If you are using
an aftermarket source unit, with conventional
preamp-level outputs, this is most likely the
position that you will use. The “High” position