JL Audio 450/4V2 User Manual

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24  |  JL Audio - 450/4
v2
 Owner’s Manual  
25
“My amplifier shuts off once in a while, usually at higher volumes”
 Check 
 
your voltage source and grounding point. The power supply 
of the 450/4v2 will operate with charging system voltages 
down to 10V. Shutdown problems at higher volume levels 
can occur when the charging system voltage drops below 
10V. These dips can be of very short duration making them 
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To ensure proper voltage, inspect all wiring and termination 
points. It may also be necessary to upgrade the ground 
wire connecting the battery to the vehicle’s chassis and the 
power wire connecting the alternator to the battery. Many 
vehicles employ small (10 AWG - 6 AWG) wire to ground the 
battery to the vehicle’s chassis and to connect the alternator to 
the battery. To prevent voltage drops, these wires should  be 
upgraded to 4 AWG when installing amplifier systems with 
main fuse ratings above 60A. Grounding problems are the 
leading cause of misdiagnosed amplifier “failures.”
“My amplifier turns on, but there is no output”
 Check 
 
the input signal using an AC voltmeter to measure the 
voltage from the source unit while an appropriate test tone is 
played through the source unit (disconnect the input cables 
from the amplifier prior to this test). The frequency used 
should be in the range that is to be amplified by the amplifier  
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range / high-pass application).  A steady, sufficient voltage 
(between 200mV and 8.0-volts) should be present at the 
output of the signal cables. 
 Check 
 
the output of the amplifier. Using the procedure explained in 
the previous check item (after plugging the input cables back 
into the amplifier) test for output at the speaker outputs of 
the amplifier. Unless you enjoy test tones at high levels, it is 
a good idea to remove the speaker wires from the amplifier 
while doing this.  Turn the volume up approximately half 
way. 5V or more should be measured at the speaker outputs.  
This output level can vary greatly between amplifiers but it 
should not be in the millivolt range with the source unit at 
half volume. If you are reading sufficient voltage, check your 
speaker connections as explained below.
 
Check  to ensure that the speaker wires are making a good 
connection with the metal inside the terminal block.  The 
speaker wire connectors are designed to accept up to 8 AWG 
wire.  Make sure to strip the wire to allow for a sufficient 
connection with the metal inside the terminal block.
“How do I properly set the input sensitivity on my amplifier”
 Please 
 
refer to Appendix B (page 22) to set the input sensitivity for 
maximum, low-distortion output.
“My amplifier doesn’t turn on”
 Check 
 
the fuse, not just visually, but with a continuity meter. It is 
possible for a fuse to have poor internal connections that 
cannot be found by visual inspection. It is best to take the 
fuse out of the holder for testing. If no problem is found with 
the fuse, inspect the fuse-holder. 
 Check 
 
the integrity of the connections made to each of the 
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that no wire insulation is pinched by the terminal set screw 
and that each connection is tight. 
 Check 
 
to make sure there is +12V at the “Remote” connection of the 
amplifier. In some cases, the turn-on lead from the source unit 
is insufficient to turn on multiple devices and the use of a relay 
is required.  To test for this problem, jump the 
i+12VDCw wire 
to the 
iRemotew terminal to see if the amplifier turns on. 
 
“I get a distorted / attenuated sound coming out of the speaker(s)”
 Check 
 
the speaker wires for a possible short, either between the 
positive and negative leads or between either speaker lead 
and the vehicle’s chassis ground. If a short is present, you  
will experience distorted and/or attenuated output. The  
iLow Ωw light will illuminate in this situation. It may be 
helpful to disconnect the speaker wires from the amplifier 
and use a different set of wires connected to a test speaker. 
 Check 
 
the nominal load impedance to verify that each channel  
of the amplifier is driving a load equal to or greater than  
1.5 ohms in stereo mode (3 ohms bridged). 
 Check 
 
the input signal and input signal cables to make sure signal 
is present at the “Amplifier Inputs” and the cables are not 
pinched or loose. It may be helpful to try a different set of 
cables and/or a different signal source to be sure.
“My amplifier’s output fluctuates when I tap on it or hit a bump”
 Check 
 
the connections to the amplifier. Make sure that the 
insulation for all wires has been stripped back far enough to 
allow a good contact area inside the terminal block. 
 
Check  the input connectors to ensure that they all are making good 
contact with the input jacks on the amplifier. 
APPENDIX C:  TROUBLE SHOOTING