98271 User Manual

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10 | JL Audio - M400/4 Owner’s Manual

STATUS LED / PROTECTION CIRCUITRY

There is a single multi-color LED on the top

surface of the amplifier to indicate the amplifier’s

operating status.

1 ) F l a s h i n g G r e e n : amplifier is powering up,

audio output is muted.

2) Constant Green: amplifier is on and

functioning normally, audio output is active.

3) Constant Red: Indicates that the

amplifier has exceeded its safe operating

temperature, putting the amplifier into a

self-protection mode, which reduces the

peak power output of the amplifier. When its

temperature returns to a safe level, the red

light will return to green and the amplifier will

return to full-power operating mode.

4) Constant Amber (yellow): Indicates

that an over-current condition has occurred

and is accompanied by a muting of the affected

channel(s). Because the muting behavior may be

very short in duration, it may manifest itself as

an audible, repetitive ticking 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 wiring. The latter can result

from a short circuit between the positive and

negative speaker wires or between either speaker

wire and a power wire. The “Status LED” will

remain amber for a few seconds, even if the over-

current condition is of a very short duration.

This functionality can be used to diagnose a

short-circuit by only connecting one channel at

a time. The “Status LED” will turn amber when

you connect the channel that is experiencing the

problem and turn the volume up.

SPEAKER OUTPUTS

The M400/4’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 M400/4’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 M400/4 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). When

bridged, each channel will deliver optimum

power into a 4 ohm load.

When a pair of 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.

Because a bridged pair of channels requires

that both channels receive input, you need to

connect both left and right inputs to the source

unit. 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 M400/4’s channels are

operating in bridged mode, the output will be in

mono (only one channel). This mono channel

can contain right channel only information,

left channel only information or the sum of

the information from both the right and left

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 M400/4’s

channels, use a “Y-Adaptor” to split the single

channel signal into both left and right RCA

inputs. This option is useful when using a

pair of the M400/4’s channels to drive left

channel speakers only and the other pair of

the M400/4’s channels to drive right channel

speakers only.

2) Left + Right Channel Information: When

bridged and fed by a stereo input, a pair of the

M400/4’s channels will automatically combine

the left and right channels into a summed

mono (left + right) channel. This option is

useful when using a pair of the M400/4’s

channels to drive a subwoofer system or a

summed mono center channel.

5) LED off / Amplifier Shuts Off Unexpectedly

The only condition that will shut down

an undamaged M600/6 completely is if battery

voltage or remote turn-on voltage drops below

10 volts. The “Status LED” will turn off when

this occurs. The amplifier will turn back on

when voltage climbs back above 11 volts. If this

is happening in your system, have your charging

system and power wiring inspected.

For more information on troubleshooting this

amplifier, refer to Appendix D (pages 16, 17).

SERVICING YOUR JL AUDIO AMPLIFIER

If your amplifier fails or malfunctions, please

return it to your authorized JL Audio dealer so

that it may be sent in to JL Audio for service.

There are no user serviceable parts or fuses inside

the amplifier. The unique nature of the circuitry

in the JL Audio amplifiers requires specifically

trained service personnel. Do not attempt

to service the amplifier yourself or through

unauthorized repair facilities. This will not only

void the warranty, but may result in the creation of

User Manual - Page 6