Bi-AmpLIFIED SYSTEMS

Bi-amplified systems are defined as systems in which separate amplifier channels drive low- frequency (LF) and high-frequency (HF) speakers and are separately filtered to send appropriate frequency ranges to each speaker system.

The most common application of bi-amplification in mobile audio is to drive a subwoofer system from one or more amplifiers or channels and component speakers from separate amplifiers or channels.

The HD900/5 can be easily configured to drive a complete bi-amplified system consisting of a subwoofer and four main speakers or a subwoofer and two main speakers.

Bi-Amplified System with one HD900/5 driving four main speakers plus subwoofer (5-Channel Mode)

In this configuration, the “Front” channels of the HD900/5 will drive front component speakers (stereo 100W x 2 @ 4Ω) with high- pass filtering. The “Rear” channels will drive rear component speakers in stereo (100W x 2

@4Ω) with high-pass filtering. The subwoofer channel will drive the subwoofer system

(500W x 1 @ 1.5-4Ω) with low-pass filtering. Once the input sections have been configured

appropriately, go to the “Front Channel Controls” Section. Select “12dB” or “24dB” on the “High-Pass Filter” and an appropriate “Filter Freq.” (80-90 Hz is a good starting point).

Next, turn your attention to the “Rear Channel Controls” Section and select “12dB” or “24dB” “High-Pass Filter” switch and an appropriate “Filter Freq.” (again, 80-90 Hz is a good starting point).

Finally, in the “Subwoofer Channel Controls” Section, select “12dB” or

“24dB” on the “Low-Pass Filter” Switch and a “Filter Freq.” of 80-90 Hz.

After proper adjustment of the HD900/5’s

“Input Range” and “Input Sens.” controls, you can fine tune filter frequencies

and slopes and attenuate each channel section to achieve proper balance.

Bi-Amplified System with one HD900/5 driving two main speakers plus subwoofer (3-Channel Mode)

In this configuration, the “Front” channels of the HD900/5 will be bridged to drive the left front component speaker system (150W x 1 @ 4Ω) with high-pass filtering. The “Rear” channels will be bridged to drive the right front component speaker system (150W x 1 @ 4Ω), also with high-pass filtering. The “Subwoofer” channel will drive the subwoofer system

(500W x 1 @ 1.5-4Ω) with low-pass filtering. For information on proper bridging

techniques refer to the section titled “Bridging Considerations” in this manual (page 14).

Once the input sections have been configured appropriately, go to the “Front Channel Controls” Section. Select “12dB” or “24dB” on the “High-Pass Filter” and an appropriate “Filter Freq.” (80-90 Hz is a good starting point).

Next, turn your attention to the “Rear Channel Controls” section and set it exactly the same as you set the “Front Channel Controls”.

Finally, in the “Subwoofer Channel Controls” section, select “12dB” or “24dB” on the “Low-Pass Filter” switch and a “Filter Freq.” of 80-90 Hz.

After proper adjustment of the HD900/5’s “Input Range” and “Input Sens.” controls, you can fine tune filter frequencies and slopes and attenuate each channel section to achieve proper balance. Keep in mind that the left and right front speakers will have independent “Input Sens.” controls in this configuration, and these need to be carefully matched for proper stereo performance.

12 JL Audio - HD900/5 Owner’s Manual