JL Audio HD900/5 - Manual (Page 14)

14 | JL Audio - HD900/5 Owner’s Manual
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 HD900/5 has been designed
for bridging of its two main channel pairs without
the need for input inversion adaptors.
The mono subwoofer channel cannot be
bridged to another mono channel.
To bridge either pair of main 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” (sold
separately), because a bridged pair of channels
requires that both amplifier channels of the
bridged pair receive input. Connection of
only one RCA input will result in reduced
power output, increased distortion and
can cause the amplifier to overheat.
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.
speaker connector Plugs
There are three speaker connector plugs on the
HD900/5: one for the front channels, one for the
rear channels and one for the subwoofer channel.
To connect the speaker wires to the amplifier,
unplug the speaker connector plugs from the
amplifier chassis (pull back firmly) and back out
the set screws on each connector plug, using the
supplied 2.5 mm hex wrench. Strip 3/8 inch (10
mm) of insulation from the end of each wire and
insert the bare wire into the receptacle on the
speaker connector plug, seating it firmly so that
no bare wire is exposed. While holding each wire
in place, tighten each set screw firmly, taking care
not to strip the head of the screw.
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.