JL Audio 300w Filter Controls, system frequency response, Bass Boost Controls, Pre-OUTS

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 the G1300 can be used to eliminate potentially harmful and/or undesired frequencies from making their way through the amplifier section to the speaker(s). This serves to improve tonal balance and to avoid distortion and possible speaker failure. Correct use of this filter can substantially increase the longevity and fidelity of your audio system.

2)“Filter Mode” Control: The G1300 employs a 12dB per octave filter. This filter can be configured into one of two filter types or defeated completely by way of the three- position “Filter Mode” switch:

 “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 crossovers or requiring full- range reproduction from the G1300.

 “LP” (Low-Pass):Configures the filter to attenuate frequencies above the selected filter frequency at a rate of 12dB per octave. Useful for connection of subwoofer(s) to the G1300 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. Useful for connection of a coaxial or component satellite speaker system to the G1300 in a bi-amplified system.

3)“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 13).

Tuning Hint:  If you are using the G1300 to drive a subwoofer system (“LP” mode) or a component satellite speaker system (“HP” mode), 80 Hz is a good baseline “Filter Freq. (Hz)” setting. After properly adjusting the “Input Sens.”, as outlined in Appendix A (page 12), you can fine tune the “Filter Freq. (Hz)” control to achieve the desired

system frequency response.

BASS BOOST CONTROLS

1)“Bass Boost”: This switch allows the user to activate a 6 dB boost centered at 48 Hz.

The “Filter Mode” switch in the “Amplifier Controls” section must be in the “LP” position for the bass boost to be functional.

2)“Remote Bass Port”: This port allows you to connect an optional remote boost knob (sold separately, JL Audio Model RBC-1) that can be mounted in the front of the vehicle. With the RBC-1 connected, the boost is no longer limited to 0 or +6 dB, allowing a range of

0 - 12 dB of boost to be selected.

Pre-OUTS

The G1300’s “Pre-Outs” connectors output unprocessed (pass-through) left and right channel preamp level signals, permitting connection of additional amplifiers in a system.

The preamp output signals are identical to the input signals and are not affected by any settings in the “Amplifier Controls” or “Bass Boost Controls” sections. The signal level of the “Preamp Output” is line-level (low voltage), regardless of the position selected via the G1300’s “Input Voltage” switch. An additional amplifier connected to these preamp outputs should have its input voltage switch set to the “Low“ position.

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