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 |  JL Audio - XD400/4v2 Owner’s Manual  

Note: When the “Input Voltage” switch is in its 

“Low” position, the level of the “Preouts” signals 
matches the input signal levels (unity gain). When 
the “Input Level” switch is in the “high” position, 
the level of the input signal is attenuated –12 dB 
to produce a line level signal at the “Preouts”
This ensures a proper line level signal output 
under both conditions.

If you plan to use the “Preouts” to feed a stereo 

amplifier, you must connect a stereo signal to 

the input of the amplifier. A mono signal into 

the amplifier will result in a mono signal out of 

the preamp output.

SPEAKER OUTPUTS

The XD400/4v2’s speaker outputs are designed 

to accept 16 AWG - 8 AWG wire. To connect the 
speaker wires to the amplifier, first back out the 
set screws on the top of the terminal block, using 
the supplied 2.5 mm hex wrench. Strip 1/2 inch 
(12 mm) of insulation from the end of each wire 
and insert the bare wire into the terminal block, 
seating it firmly so that no bare wire is exposed. 
While holding the wire in place, tighten the set 
screw firmly, taking care not to strip the head of 
the screw.

Each pair of the XD400/4v2’s channels 

are designed to deliver power into speaker 
loads equal to or greater than 2 ohms when 
using a “stereo” configuration and speaker 
loads equal to or greater than 4 ohms 
when using a “bridged” configuration.

 

Speaker loads below 2 ohms nominal per 

channel (or 4 ohms bridged) are not 

recommended and may cause the amplifier  

to initiate a protection mode which reduces 

power output.

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 XD400/4v2 has been designed 
for bridging of its main channel pairs without the 
need for input inversion adaptors.

To bridge a pair of main channels, use the 

“Left +” and “Right –”speaker connectors only 
(the “Left –” and “Right +” remain unused). Each 
bridged channel pair will deliver optimum power 
into a 4 ohm load.

When a pair of the XD400/4v2’s channels are 

bridged, they will deliver 200W x 1 into a 4 ohm 

load or 150W x 1 into an 8 ohm load. Operating 

a pair of bridged channels into a load lower than 

4 ohms is not recommended.

A bridged pair of channels requires that 

both channels in the pair receive input. You 

must connect the mono or stereo source signal 

to both the left and right inputs of the bridged 

channel pair. Connection of only one input 

will result in reduced power output, increased 

distortion and can cause the amplifier to 

overheat. Do not do this!

When a pair of the XD400/4v2’s channels are 

operating in bridged mode, the output will be in 
mono (only one channel). This mono channel can 
contain only right channel information, only left 
channel information, or the sum of the signals 
from right and left input channels. In order to 
achieve one of these options, configure the inputs 
to that pair of channels in one of these two ways:

 

1)  Left Channel Only or Right Channel Only 

Information: If you wish to send a left-only or 
right-only signal to a pair of the XD400/4v2’s 
channels you must use a “Y-Adaptor” to split 
the single channel signal into both left and 
right RCA inputs of the bridged channel 
pair. This option is used when deploying a 

Summary of Contents for XD 400/4v2

Page 1: ...allation equipment to ensure optimum performance from this product Should you decide to install the amplifier yourself please take the time to read this manual thoroughly to familiarize yourself with...

Page 2: ...space provided below The serial number can be found on the bottom panel of the amplifier and on the amplifier packaging Serial Number INSTALLATION APPLICATIONS This amplifier is designed for operatio...

Page 3: ...ventilated environment and in a manner which does not interfere with your vehicle s safety equipment air bags seat belt systems ABS brake systems etc You should also take the time to securely mount th...

Page 4: ...eaker systems to the amplifier mounting location 6 Find a good solid metal grounding point close to the amplifier and connect the negative power wire to it using appropriate hardware use of the JL Aud...

Page 5: ...the set screw firmly taking care not to strip the head of the screw The ground connection should be made using 8 or 4 AWG wire and should be kept as short as possible while accessing a solid piece of...

Page 6: ...ventional 12 V turn on leads Depending on the characteristics of the audio signal one of the following methods may work better than the other We recommend trying DC Offset Sensing first as it does not...

Page 7: ...ts an input sensitivity range between 800mV and 8V This is useful for certain high output preamp level signals as well as speaker level output from source units and small amplifiers To use speaker lev...

Page 8: ...audio system Input Mode 2 Ch 4 Ch All 3 4 1 2 Sum Preouts From Remote Level Mode nal Input Voltage Low High e 1 Filter Mode Controls The XD400 4v2 employs 12dB per octave filters for each pair of cha...

Page 9: ...y added to the system This pass through preamp output can be configured two different ways using the switch labeled Preouts From 1 1 2 the preamp output delivers the same signal that is connected to t...

Page 10: ...put 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 outp...

Page 11: ...ticking or thumping noise in the output Over current conditions can be caused by a speaker impedance lower than the optimum load impedance range for the amplifier or a short circuit in the speaker wi...

Page 12: ...D400 4v2 s Input Sens settings and will not be user adjustable from the front of the vehicle B Fade Subwoofer Level vs HF Level Req uired a source unit or processor with two pairs of stereo outputs In...

Page 13: ...pair of source unit outputs is connected to the subwoofer amplifier inputs Res ult with this option the user has the ability to fade the level of the subwoofer amplifier s input relative to the HF ch...

Page 14: ...input sensitivity adjustment according to the nominal impedance of the speaker system connected to the amplifier outputs 6 Verify that you have disconnected the speakers before proceeding Play a track...

Page 15: ...tio 104 dB referred to rated power A weighted 20 Hz 20 kHz noise bandwidth 84 dB referred to 1W A weighted 20 Hz 20 kHz noise bandwidth Frequency Response 12 Hz 22 kHz 0 1dB Damping Factor 150 4 ohms...

Page 16: ...ay is required To test for this problem jump the 12VDC wire to the Remote terminal to see if the amplifier turns on I get a repetitive ticking or popping sound coming out of the speaker s Check the sp...

Page 17: ...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...

Page 18: ...JL Audio XD400 4v2 Owner s Manual INSTALLATION NOTES Use this diagram to document your amplifier s switch and control positions 4 Channel Amplifier Rem Offset Signal Input Voltage Low High Turn On Mo...

Page 19: ...19...

Page 20: ...etail and no warranties whether express or implied shall apply to this product thereafter Some states do not allow limitations on implied warranties therefore these exclusions may not apply to you Thi...

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