8
| JL Audio - 300/4
v3
Owner’s Manual
9
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
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.
I M P O R TA N T
!
If you connect a load higher than 4Ω nominal
per channel in stereo mode (or 8Ω in bridged
mode), power will drop by half with every
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
!
Speaker loads below 1.5Ω nominal per channel
in stereo or 3Ω nominal in bridged mode are
not recommended and may cause the amplifier
output to distort excessively.
bridging Considerations
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.
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
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.
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.
sPeaker outPuts
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
channel speaker impedances for optimum output
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).
The operation of the R.I.P.S. circuitry is
entirely automatic and adjusts itself every time
the amplifier is turned on according to the
lowest impedance present at either front or rear
channels. There are no user controls to configure.
The system operates through three stages of
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.