Speaker Outputs - JL Audio Slash 300/4 Owner's Manual

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 the rear speakers to
reproduce more low-frequency content.
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 A
(page 14) of this manual.
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SPEAKER OUTPUTS

Even though you may have installed zillions of
amps in your day, please take the time to read this
section! The 300/4 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 300/4 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 300/4 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 you connect to it.
Because the 300/4 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.
JL AUDIO 300/4
!
I M P O RTA 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 300/4 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 RTA 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 RTA 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.
JL AUDIO 300/4
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 300/4 has been designed for bridging
of its channel pairs without the need for input
inversion adaptors.
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"
(not included.) 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.
Why a mono signal? If you are bridging a pair of
channels and use a stereo input, the only
information that will reach the amplifier stage is the
common-phase portion of the signal.This may be
useful for passively deriving a center-channel signal,
but is not going to give you a defined left or right
channel. If you are looking to reproduce a single
channel's signal, you must split the mono signal with
a "Y-Adaptor" and connect it to both left and right
RCA inputs for the bridged channel pair.
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