JL Audio HD900/5 Amplifier INPuTS, Input Mode Switch, Ch. Input Mode, Input Voltage Switch

AMPLIFIER INPuTS

The HD900/5 has three separate input sections, one for the “Front” left and right channels, another for the “Rear” left and right channels and one for the Subwoofer Channel. Each section consists of a pair of RCA-type input jacks on

the Connection Panel of the amplifier and input controls on the Control Panel of the amplifier: a single “Input Voltage” switch, an “Input Mode” switch and three individual “Input Sens.” rotary controls (one in each channel section).

“Input Mode” Switch

The “Input Mode” switch is located under the “General Setup” heading at the far right of the control panel. This switch allows operation of all five amplifier channels with only one pair of input signals (2 ch.) or with independent front and rear input signal pairs (4 ch.) or with discrete front, rear and subwoofer signal pairs (6 ch.).

“6 Ch.” Input Mode

In this mode, you will connect separate pairs of input cables to the “Front”, “Rear” and “Sub” amplifier inputs, allowing you full channel control from the source unit. If the source unit only provides a mono (single) subwoofer output, use a y-adaptor cable to feed both the “Left” and “Right” subwoofer inputs of the HD900/5 with the mono signal. Failure to do so will result in reduced gain and possible distortion.

“4 Ch.” Input Mode

In this mode, you will connect separate pairs of input cables to the “Front” and “Rear” amplifier inputs and leave the “Sub” inputs unused. The subwoofer channels will receive signal from the sum of the signals at the “Front” and “Rear” inputs so that front-to-rear fading of the main channels does not significantly affect the subwoofer level.

“2 Ch.” Input Mode

To operate all five channels of the HD900/5 with a single pair of stereo inputs, select the “2 Ch.” position on the “Input Mode” switch and connect a single pair of input cables to the “Front” input jacks only. The “Rear” and “Sub” input jacks will remain unused.

In this mode, the amplifier will route the signals connected to the “Front” inputs to the Front, Rear and Subwoofer channels. Front-to-rear fading will not be available.

“Input Voltage” Switch

A wide range of signal input voltages can be accommodated by each of the HD900/5’s differential- balanced inputs (200mV – 8V RMS). This wide range is split up into two sub-ranges, accessible via the “Input Voltage” switch located next to the “Input Mode” switch under the “General Setup” heading.

The “Low” position of the “Input Voltage” switch selects an input sensitivity range between 200mV and 2V for all the amplifier channels. This means that the “Input Sens.” rotary controls will operate within that voltage window. If you are using an aftermarket source unit, with preamp- level outputs, this is most likely the position that you will use (regardless of what voltage output capability is claimed by the source unit).

The “High” position of the “Input Voltage” switch selects an input sensitivity range between 800mV and 8V. This is for use with speaker-level outputs from source units and small amplifiers found in many OEM (factory-installed) systems. To use speaker-level sources, splice the speaker output wires of the source unit or small amplifier onto a pair of RCA plugs for each input pair or use the JL Audio ECS Speaker Wire to RCA adaptor (XB-CLRAIC2-SW). It is not necessary (or advisable) to use “Line Output Converters” with your HD900/5.

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