JL Audio XD600/1, XD400/4 owner manual Filter Controls, Most speakers are not designed to reproduce

Filter Controls

Most speakers are not designed to reproduce

the full range of frequencies audible by the human ear. For this reason, most speaker systems are comprised of multiple speakers, each dedicated to reproducing a specific frequency range. Filters are used to select which frequency range is sent to each section of a speaker system. The division of frequency ranges to different speakers can be done with passive filters (coils and/or capacitors between the amplifier outputs and the speakers), which are acceptable and commonly used

for filtering between mid-range speakers and tweeters. Filtering between subwoofer systems and satellite speaker systems is best done with active filters, which cut off frequency content at the input to the amplifier. Active filters are more stable than passive filters and do not introduce extraneous resistance, which can degrade subwoofer performance.

The active filter built into each channel section of the XD400/4 can be used to eliminate potentially harmful and/or undesired frequencies from making their way through the amplifier sections to the speaker(s). This serves to improve tonal balance and to avoid distortion and possible speaker failure. Correct use of these filters can substantially increase the longevity and fidelity of your audio system.

1)“Filter Mode” Control: The XD400/4 employs a 12dB per octave filter for each pair of channels (one filter for channels 1&2, another filter for channels 3&4 and a third filter for channels 5&6). Each of these filters can be configured independently into one of two filter

types or defeated completely by way of the three-position “Filter Mode” switches:

 “Off”: Defeats the filter completely, allowing the full range of frequencies present at the inputs to feed the amplifier. This is useful for systems utilizing outboard active crossovers or requiring full-range reproduction from one or more of the XD400/4’s channel pairs.

 “LP” (Low-Pass):Configures the filter to attenuate frequencies above the selected filter frequency at a rate of 12dB per octave. This is useful for connection of subwoofer(s) to one or more of the XD400/4’s channel pairs in a bi-amplified system.

 “HP” (High-Pass):Configures the filter to attenuate frequencies below the selected filter frequency at a rate of 12dB per octave. This is useful for connection of component speakers to one or more of the XD400/4’s channel pairs in a bi-amplified system.

2)“Filter Freq. (Hz)” The filter frequency markings surrounding this rotary control are for reference purposes and are generally accurate to within 1/3 octave or better. If you would like to select the filter cutoff frequency with a higher level of precision, consult the chart in Appendix B (page 15).

Tuning Hint:  If you are using the XD400/4 to drive a subwoofer system (“LP” mode), a component satellite speaker system (“HP” mode) or both, 80 Hz is a good baseline “Filter Freq. (Hz)” setting. After properly adjusting the “Input Sens.”, as outlined in Appendix A (page 14), you can fine tune the “Filter Freq. (Hz)” control to achieve the desired system frequency response.