INPUT SECTION The e1200 has one input section with two distinct input connection options. 1) A pair of traditional RCA type connections designed to accept input from source units with line level outputs. 2) A four-pin connector designed to accept input from amplified sources such as factory source units or source units not equipped with line level outputs. You may run a stereo or a mono signal into the inputs of the amplifier. The amplifier's input section automatically sums stereo signals to mono for the internal amplifier section. IMPORTANT! If you plan to use the “Pre-Outs” 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 preamp output. (It's a great amplifier, but it doesn't do magic). The amplifier will operate with only one input connection (left or right), but will require an increase in input sensitivity to overcome the loss of signal. If a mono input signal is to be run, we recommend that you use a “Y-adaptor” to split the mono signal into both inputs of the amplifier. JL AUDIO e1200 AMPLIFIER CONTROLS Input Sensitivity This control, labeled “Input Sens. ”, can be used to match the source unit's to the input stage of the e1200 maximum clean output. Rotating the control clockwise 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 10). After using this procedure, you can then adjust the “Input Sens. ” level downward if this is required to achieve the desired system balance. Do not increase any “Input Sens. ” setting for any channel(s) of any amplifier in the system beyond the maximum level established during the procedure outlined in Appendix A (page 10). Doing so will result in audible distortion and possible speaker damage. 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 mids 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 e1200 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. 1) “Filter Mode” Control: The e1200 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 e1200. “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 e1200 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 e1200 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 11). Tuning Hint: If you are using the e1200 to drive a subwoofer system ( “LP” mode) or a component satellite speaker system ( “HP” mode), 100 Hz is a good baseline “Filter Freq. (Hz)” setting. After properly adjusting the “Input Sens. ” , as outlined in Appendix A (page 10), you can fine tune the “Filter Freq. (Hz)” control to achieve the desired system frequency response. JL AUDIO e1200 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 “Channel 1 & 2” section must be in the “LP” positi...