14
| JL Audio - 300/4
v3
Owner’s Manual
15
aPPendix a:
input sensitivity level setting
JL Audio amplifiers utilizing the Regulated
Intelligent Power Supply (R.I.P.S.) allow
delivery of their rated power when connected
to any load impedance from 1.5 - 4Ω per
channel and when connected to a charging
system with any voltage from 11 - 14.5V. This
design is beneficial for many reasons. One of
these reasons is ease of setup. Because each
JL Audio amplifier will always deliver the
same amount of power within its operational
range of impedances and supply voltages, the
maximum, unclipped output is very predictable.
This makes setting the gain structure via the
input sensitivity controls very simple. Following
the directions below will allow the user to adjust
the input sensitivity of the amplifier(s) simply
and easily in just a few minutes using equipment
which is commonly available in installation bays.
necessary equipment
• Digital AC Voltmeter
• CD with a sine-wave test tone recorded at
0 dB reference level in the frequency range
to be amplified for that set of channels
(50 Hz for subwoofer channels, 1 kHz for
a midrange application). The CleanSweep®
Calibration Disc contains the appropriate
test tones and is available for sale at
http://store.jlaudio.com Do not use attenuated
test tones (-10 dB, -20 dB, etc.).
the nine-step Procedure
(follow this procedure for each pair of channels)
1) Disconnect the speaker(s) from the
amplifier’s “Front Speaker Outputs” and
“Rear Speaker Outputs” connectors.
2) Turn off all processing on the source
unit (bass/treble, loudness, EQ, etc.).
Set fader control to center position
and subwoofer level control to 3/4 of
maximum (if used to drive the 300/4v3).
3) Switch the “Input Voltage” to “Low” and
turn the “Input Sens.” control on both sets of
channels all the way down.
4) Set the source unit volume to 3/4 of full
volume. If either set of channels is being
driven by a source unit’s dedicated subwoofer
output, also adjust the source unit’s subwoofer
level control to 3/4 of maximum output. This
will allow for reasonable gain overlap with
moderate clipping at full volume.
5) Using the listings on pages 16 & 17, find the
configuration that matches your specific
speaker impedance as connected to the
300/4v3. Note whether your channels are in
stereo or bridged and use the appropriate
listing section. Once you have found your
configuration, note the target voltage for input
sensitivity adjustment for each channel section.
This target voltage is listed in parentheses as
“(set to “x” volts)”.
6) Verify that you have disconnected the speakers
before proceeding. Play a track with an
appropriate sine wave (within the frequency
range to be amplified by each set of channels)
at 3/4 source unit volume.
7) Connect the AC voltmeter to the “Front
Speaker Outputs” or “Rear Speaker Outputs”
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 delivered for that set of
channels.If excessive voltage is read on either
set of channels with the control at minimum
(full counterclockwise), switch the appropriate
“Input Voltage” switch to “High” and re-adjust.
9) Once you have adjusted each set of channels
to its maximum low-distortion output level,
reconnect the speaker(s). The “Input Sens.”
controls can now be adjusted downward if either
or both sets of channels requires attenuation to
achieve the desired system balance.
I M P O R TA N T
!
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.
Please refer to input sensitivity level setting
reference listings on the next pages.
aPPendix b:
300/4v3 specifications
general specifications:
Recommended Fuse Value:
40A
Recommended Fuse Type:
AGU or MaxiFuse™
input sections:
No. of Inputs:
Two Stereo Pairs (Front, Rear)
Input Type:
Differential-balanced with RCA jack inputs
Input Range:
Switchable from 200mV - 2V RMS
to 800mV - 8V RMS
amplifier section:
Amplifier Topology:
Class A/B with patented Absolute
Symmetry™ dual N-Channel MOSFET output design
Power Supply:
Independent, pulse width modulation-reg-
ulated switching power supply with multistage impedance
optimizing circuitry.
Rated Power (Stereo):
75W RMS x 4 @ 1.5-4Ω (11V - 14.5V)
Rated Power (Bridged):
150W RMS x 2 @ 3-8Ω (11V - 14.5V)
THD at Rated Power:
<0.03% @ 4Ω per channel
(20 Hz-20 kHz)
Signal to Noise Ratio:
>108.5 dB referred to rated power
(A-weighted, 20 Hz-20 kHz noise bandwidth)
Frequency Response:
5 Hz - 30 kHz (+0, -1dB)
Damping Factor:
>200 @ 4Ω per ch. / 50 Hz, >100 @ 2Ω
per ch. / 50 Hz
Slew Rate:
± 25V/µs
Filter sections:
Front and Rear Filters (2):
State-variable, 12 dB/octave
Butterworth or 24 dB/octave Linkwitz-Riley low-pass or
high-pass with continuously variable cutoff frequency
from 50 - 500 Hz, switchable to a range of 500 - 5000 Hz,
via x10 switch. Defeatable.
dimensions (H x w x d):
2.36 in x 13.4 in x 9.25 in (60mm x 340mm x 235mm)
Due to ongoing product development, all specifications are subject to
change without notice.