User manual JL AUDIO 250-1

[. . . ] JL AUDIO 250/1 monoblock subwoofer amplifier o w n e r 's m a n u a l Thank you for purchasing a JL Audio amplifier for your automotive sound system. Your amplifier has been designed and manufactured to exacting standards in order to ensure years of musical enjoyment in your vehicle. For maximum performance and extended warranty coverage, we highly recommend that you have your new amplifier installed by an authorized JL Audio dealer. Your authorized dealer has the training, expertise and installation equipment to ensure optimum performance from this product. [. . . ] Depending on the subwoofer system and the vehicle, different slopes may be required to produce a smooth transition to the mid-bass speakers in the system. Experiment to find the slope which best matches the acoustic requirements of your system. Hint: A trunk mounted sub whose output has to "fight" through a rear deck or a back seat often benefits from the 12 dB/octave slope which lets more upper bass content pass through. A sub that fires directly into the listening environment is more likely to benefit from a 24 dB/octave slope. The above hint is not "set-in-stone". . . You should always listen to the system carefully to determine the best choice as vehicle acoustics and other factors play a big role in choosing the most appropriate filter slope. !!CAUTION The signal level of the "Preamp Output" is affected by the setting of the "Input Voltage Range" switch (of the input section chosen by the "Signal From" switch). See Appendix B (page 13) for details on "Input Voltage" settings. All "slave" amplifiers should get this switch set to "Low". See Appendix C (page 14) for details. 1) "Infrasonic Filter": The infrasonic filter is a 24 dB/octave high-pass filter, with a fixed cutoff frequency of 30 Hz. This filter is designed to conserve amplifier power and protect subwoofer systems without audibly affecting the sub-bass output. With ported enclosures, the use of the infrasonic filter is highly recommended to protect the speaker(s) from excessive excursion below box tuning. With sealed enclosures, the use of the filter is less necessary, but can still help protect the speaker system. The infrasonic filter can be completely defeated by selecting the "Off" position on the "Infrasonic Filter" switch. This bypasses all signal from flowing through the circuit. 2) "LF (Low-frequency) Boost": This feature allows the user to control the boost of a fixed "Q", fixed-frequency equalization band centered at 48 Hz. The "LF Boost" control knob determines how much boost (in dB) you are adding to the bass signal. A range of 0 - 15 dB of boost is available. If no boost is desired, rotate the "LF Boost" knob fully counterclockwise. 1) "Full-Range": This is a pass-through mode for the preamp output, delivering the same signal that is being fed to the "Amplifier Input Section" (If the input signal is full-range, the preamp output will be full-range). This signal is not affected by the "Bass Control" processing selected for the amplifier. 2) "Low-Pass": The preamp output delivers the same mono-summed signal that is feeding the 250/1's amplifier section when the "Amp LP Filter" is engaged, including all the low-pass filtering and "Bass Control" processing that is selected. JL AUDIO 250/1 JL AUDIO 250/1 !I M P O RTA N T The "Bass Control" section will only operate when the amplifier's filter is activated with the "Amp LP Filter" switch in the "12dB" or "24dB" position. It will not work with this switch in the "Off" position. This is to prevent cascading the processing of multiple amplifiers when configured in a master/slave arrangement as shown in Appendix C (page 14). If you are using an external active crossover and would like to use the "Bass Control" features, set the "Amp LP Filter" switch 9 8 on "12dB" and rotate the frequency selection knob fully clockwise to the "200 Hz" position. This will activate the "LF Boost" and "Infrasonic Filter" controls without significantly affecting the crossover point selected by the external active crossover. !I M P O RTA N T Speaker loads below 1. 5 nominal are not recommended and may cause the amplifier output to distort excessively. Speaker connections to the 250/1 are straightforward and take place at the far right of the front panel. You will notice that there are two "+" positive connections and two "­" negative connections. This is to facilitate multiple speaker wiring. The two positive and two negative connections are connected in parallel inside the amplifier. [. . . ] 5-volts or more should be measured at the speaker outputs. This output level can vary greatly between amplifiers but it should not be in the millivolt range with the source unit at half volume. If you are reading sufficient voltage, check your speaker connections as explained above. (continued on next page) 16 JL AUDIO 250/1 JL AUDIO 250/1 17 APPENDIX D: TROUBLE SHOOTING (CONT. ) APPENDIX E: 250/1 Specifications GENERAL SPECIFICATIONS: Recommended Fuse Value: 30A Recommended Fuse Type: AGU or MaxiFuseTM INPUT SECTION: Input Type: Differential-balanced with RCA jack inputs Input Range: Switchable from 200mV - 2V RMS to 800mV - 8V RMS PREAMP OUTPUT: 2-Channel, selectable as full-range (pass-through) or low-pass or high-pass filtered (tracks with the amplifier low-pass filter cutoff frequency) BASS CONTROL SECTION: Bass EQ: Single-band, fixed frequency/"Q" centered at 48 Hz with boost adjustment from 0 dB to +15 dB, defeatable Infrasonic Filter: 24 dB/octave Butterworth high-pass filter with 30 Hz cutoff frequency, defeatable DIMENSIONS: (LxWxH): 10. 25" x 9. 25" x 2. 36" (260mm x 235mm x 60mm) Due to ongoing product development, all specifications are subject to change without notice. CROSSOVER SECTION: Amplifier Low-Pass Filter: State-variable, 12 dB/octave Butterworth or 24 dB/octave Linkwitz-Riley with continuously variable cutoff frequency selection from 40 - 200 Hz, defeatable "MY AMPLIFIER'S OUTPUT FLUCTUATES WHEN I TAP ON IT OR HIT A BUMP" Check the connections to the amplifier. [. . . ]