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2) "Filter Slope" Control: This switch
allows you to select from two filter
slopes for that channel section.
"12dB": Configures the filter to attenuate
frequencies above or below the selected
filter frequency at a rate of 12 dB per octave
(Butterworth alignment).
"24dB": Configures the filter to attenuate
frequencies above or below the selected
filter frequency at a rate of 24 dB per octave
(Linkwitz-Riley alignment).
Depending on the speaker system and the
vehicle, different filter slopes may be required
to produce a smooth transition between the
sound of different speakers in the system.
Experiment to find the slope which best matches
the acoustic requirements of the system. The
sharper "24dB" setting will do a better job of
protecting small speakers with limited power
handling. The shallower "12dB" octave setting
allows for greater energy overlap with the rest of
the speaker system. In some cases, this results
in better overall response and sound quality.
3) "Freq. Range" Control: When thrown to
the right, this switch multiplies the cutoff
frequency selected by the rotary "Filter Freq.
(Hz)" control by a factor of 10. In the "x1"
position, the range of the rotary control is
50 - 500 Hz (as marked). In the "x10"
position, the range of the rotary control is
500 Hz - 5 kHz (5000 Hz).
4) "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
charts in Appendix D (page 18) of this manual.
8 | JL Audio - 300/4
Owner's Manual
v3
sPeaker outPuts
+12VDC
Ground Remote
Even though you may have installed zillions of
amps in your day, please take the time to read this
section! The 300/4v3 is not a typical amplifier and
care must be taken to balance the front and rear
300/4
v3
channel speaker impedances for optimum output
Four-Channel Full-Range Amplifier
from all four channels.
The 300/4v3 employs JL Audio's exclusive
Regulated, Intelligent Power Supply (R.I.P.S.)
design. This sophisticated power supply allows
the amplifier to produce its optimum power (300
watts) over a wide range of speaker impedances.
Unlike conventional amplifiers that require a
specific impedance to produce optimum power,
the R.I.P.S.-equipped 300/4v3 gives you the
freedom to use a variety of speaker configurations
that achieve final impedances between 1.5 – 4
Ohms nominal per channel (without sacrificing
power output or sound quality).
+12VDC
Ground Remote
Rear Filter Controls
The operation of the R.I.P.S. circuitry is
Freq. Range
Filter Slope
entirely automatic and adjusts itself every time
x1 | x10
12dB | 24dB
the amplifier is turned on according to the
95
Filter Mode
lowest impedance present at either front or rear
75
130
300 /4
60
200
v3
channels. There are no user controls to configure.
Four-Channel Full-Range Amplifier
Off | LP | HP
50
500
The system operates through three stages of
Filter Freq. (Hz)
impedance optimization, choosing the stage
most appropriate to the actual impedance of the
speakers connected to it.
Because the 300/4v3 utilizes a single power
supply, it will set itself up based on the lowest
impedance present at either the front or rear
amplifier channels. For example, if you connect
a 2 ohm load to each front channel and a 4 ohm
load to each rear channel, the amplifier will adjust
itself to deliver 75 watts x 2 to the front 2 ohm
loads, but will only deliver half its optimum power
(37.5 watts x 2) to the rear 4 ohm loads. If you
connect a 4 ohm load to all four channels or a 2
ohm load to all four channels, the amplifier will
deliver 75 watts x 4. See, we told you this amp
was different... Read on, there is more important
information to follow.
Rear Filter Controls
Rear Input Section
Rear Speaker Outputs
Freq. Range
Filter Slope
Input Voltage
Input Sens.
x1 | x10
12dB | 24dB
Low | High
95
Filter Mode
75
130
60
200
Left
Off | LP | HP
50
500
Bridged
Filter Freq. (Hz)
Left Ch.
Right Ch.
!
I M P O R TA N T
For optimum power output at all four channels,
connect the same impedance (between 1.5-4Ω)
on all four channels. On pages 16 and 17 are
charts showing the continuous (RMS) power
output capability of the 300/4v3 into various
combinations of front and rear impedances
(optimum output is shown in bold type). Please
refer to these charts so you know what to expect
in terms of power output.
Rear Input Section
Rear Speaker Outputs
Input Voltage
Input Sens.
!
I M P O R TA N T
Low | High
If you connect a load higher than 4Ω nominal
Left
per channel in stereo mode (or 8Ω in bridged
Right
mode), power will drop by half with every
Bridged
Left Ch.
Right Ch.
doubling of impedance above 4Ω stereo / 8Ω
mono. If you connect a load lower than 1.5Ω
nominal per channel in stereo mode (or 3Ω in
bridged mode, the amplifier protection
circuitry activates a "safe" mode which reduces
amplifier power to protect the circuitry from
failure (the yellow "Low Ω" LED lights to
indicate that this has happened). See page 10
for details.
!
I M P O R TA N T
Front Filter Controls
Front Input Section
Speaker loads below 1.5Ω nominal per channel
Freq. Range
Filter Slope
Input Voltage
Input Sens.
in stereo or 3Ω nominal in bridged mode are
x1 | x10
12dB | 24dB
Low | High
not recommended and may cause the amplifier
95
Filter Mode
75
130
output to distort excessively.
60
200
Right
Off | LP | HP
50
500
bridging Considerations
Filter Freq. (Hz)
Left Ch.
Right Ch.
Bridging is the practice of combining the
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 300/4v3 has been designed for
bridging of its channel pairs without the need for
input inversion adaptors.
Front Filter Controls
Front Input Section
Freq. Range
Filter Slope
Input Voltage
Input Sens.
Input Mode
x1 | x10
12dB | 24dB
Low | High
2ch | 4ch
95
Filter Mode
75
130
60
200
Off | LP | HP
50
500
Filter Freq. (Hz)
Left Ch.
Right Ch.
To bridge a pair of channels, use the "Left +"
and "Right –" speaker connectors only (the "Left
–" and "Right +" remain unused). Then connect
a mono signal to both left and right RCA inputs
for that channel pair. This requires an RCA
"Y-Adaptor" like the JL Audio ECS model
XD-CLRAICY-1F2M (sold separately).
When bridged, each channel pair will
deliver optimum power into a 3-8Ω load.
Operating bridged channel pairs into a load
lower than 3Ω is not recommended.
Because a bridged pair of channels requires
that both channels receive input, you need to
connect both left and right RCA inputs to the
bridged channel pair's inputs. Connection of
only one RCA input will result in reduced power
output, increased distortion and can cause the
amplifier to overheat. Do not do this! Instead, use
a "Y-Adaptor" to split the mono signal into both
left and right RCA inputs.
Front Speaker Outputs
Input Mode
2ch | 4ch
Left
Right
Bridged
Front Speaker Outputs
Left
Right
Bridged
9
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