! IMPORTANT

Make sure you observe correct polarity in making the “High-Level Input” connections. Failure to do so will result in a complete loss of signal (no bass).

The connections for the “High-Level Inputs” plug wires are as follows from left to right on the plug:

White: Left Positive (+)

White/Black: Left Negative (–)

Black: Common Ground (rarely used)*

Gray: Right Positive (+)

Gray/Black: Right Negative (–)

*The only time you will use the “Common Ground” connection is with some older (pre- 1980’s) factory systems or head units that ground their speakers to chassis ground. To use this connection, ground the black wire on the plug to chassis ground and only connect the Left and Right Positive plug wires to the factory radio outputs.

! IMPORTANT

If you plan to use the preamp outputs 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.

“INPUT SENSITIVITY” (GAIN) ADJUSTMENT Located next to the input connectors is a rotary

control labeled “Input Sens.”. This rotary control can be used to match the source unit’s output voltage to the input stage of the amplifier for maximum clean output.

mplifier nputs

LEFT

min max

60

Input Sens.

LP Filter Fr

RIGHT

Rotating the control clockwise will result in higher sensitivity (louder for a given input voltage). Rotating the control counter-clockwise will result in lower sensitivity (quieter for a given input voltage). To properly set the amplifier for maximum clean output, please refer to Appendix A (page 12) in this manual. After using this procedure, you can then adjust the level of the amplifier by adjusting the input sensitivity downward, if the amplifier requires attenuation to achieve the desired system balance.

Do not increase the “Input Sens.” setting for any amplifier in the system beyond the maximum level established during the procedure outlined in Appendix A (page 12). Doing so will result in audible distortion and possible speaker damage.

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JL Audio J2250.1 owner manual Mplifier nputs