Preamp Outputs - JL Audio HD750/1 Owner's Manual

OUTPUT POLARITY CONTROL
Depending on the distance relationship of
the mid-bass speakers and the subwoofers in a
system, it can be desirable to reverse the polarity
of the subwoofer system in order to produce
a better transition between subwoofer and
midbass speaker output. This is normally done
by swapping the positive and negative wires
connected to the subwoofer(s).
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High
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Output
Polarity
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PREAMP OUTPUTS
The HD750/1 incorporates a pass-through
preamp output section, so that additional
amplifiers can easily be connected to the same
signal(s) feeding the HD750/1. These preamp
output signals are accessible via a stereo pair
of RCA-type jacks, labeled "Preouts", on the
Connection Panel.
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Preouts R,
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Amplifier
The "Output Polarity" switch on the HD
750/1 allows you to quickly peform this polarity
inversion without touching any wires. Simply
flip the switch from the "0" (normal) to the "180
deg." (reversed) position.
Neither switch position is "correct" for every
system. Experiment to determine which polarity
produces the best overall bass performance
in your system, listening in particular to the
mid-bass smoothness and impact to make your
determination. If you change crossover slopes
or crossover filter frequencies, you may need to
revisit this control as these can affect the phase of
the speaker systems in the overlap region.
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JL Audio - HD750/1 Owner's Manual
The term "pass-through" refers to the fact that
the Preamp Output signals are not affected by any
crossover filter or input sensitivity setting selected
on the HD750/1 (if the input signal is full-range,
the Preamp Output will be full-range). These
preamp output signals are buffered to prevent
noise and are always preamp level, regardless of
the level of signals feeding the HD750/l's inputs.