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Фрагмент инструкции
For precise filter frequency information refer to Appendix B (page 15). Multi-Amplifier SYSTEMS Using the “Preamp Outputs” of the XD400/4, it is easy to configure many different multi-amplifier systems. The most common type involves the addition of a subwoofer amplifier, such as the XD600/1. Common configurations of such a system are described below. Bi-Amplified System with one XD400/4 in four-channel mode and a separate subwoofer amplifier This configuration requires that the separate subwoofer amplifier has a built-in low-pass filter. (All JL Audio amplifiers have this feature.) In this configuration, channels 1&2 of the XD400/4 will drive front component speakers in stereo with high-pass filtering. Channels 3&4 will drive rear component speakers in stereo, also with high-pass filtering. The separate amplifier will drive the subwoofer system with low-pass filtering (80 Hz is a good starting point). Here are three possible configuration options: A) Fade Subwoofer Level vs. HF Level: Req uired: a source unit or processor with front and rear pairs of stereo outputs. Inp ut Connections: one stereo pair of source unit outputs is connected to the “CH 1 (Left)” and “CH 2 (Right)” inputs of the XD400/4 (select “2 Ch.” on the “Input Mode” switch). The second stereo pair of source unit outputs is connected to the subwoofer amplifier inputs. Res ult: with this option, the user has the ability to fade the level of the subwoofer amplifier’s input relative to the HF channels, but cannot control front-to-rear fading of the HF channels. The relative level of the front and rear HF channels will be fixed by the XD400/4’s “Input Sens.” settings and will not be user adjustable from the front of the vehicle. B) Subwoofer Level Control Only: Req uired: a source unit or processor with left, right and dedicated subwoofer outputs. Inp ut Connections: The main stereo pair of source unit outputs is connected to the “CH 1 (Left)” and “CH 2 (Right)” inputs of the XD400/4 (select “2 Ch.” on the “Input Mode” switch). The source unit’s dedicated subwoofer output is connected to the subwoofer amplifier inputs. Res ult: with this option, the user has the ability to control the absolute level of the subwoofer channel relative to the HF channels, but cannot fade the front and rear HF channels relative to each other. Set the subwoofer amplifier’s “Input Sens.” with the source unit’s subwoofer level control set at 3/4 of full output. C) Front to Rear HF Fading and Subwoofer Level Control: Req uired: a source unit or processor with front and rear pairs of stereo outputs plus a dedicated subwoofer output. Inp ut Connections: one stereo pair of source unit outputs is connected to the “CH 1 (Left)” and “CH 2 (Right)” inputs of the XD400/4. The second stereo pair of source unit outputs is connected to the “CH 3 (Left)” and “CH 4 (Right)” inputs of the XD400/4 (select “4 Ch.” on the “Input Mode” switch). The source unit’s dedicated subwoofer output is connected to the subwoofer amplifier inputs. Appendix A: Input Sensitivity Level Setting Following the directions below will allow the installer to adjust the input sensitivity of each amplifier channel pair simply and easily in just a few minutes using equipment which is commonly available in installation bays. Necessary Equipment • Digital AC Voltmeter • CD with a sine-wave test tone recorded at 0 dB reference level in the frequency range to be amplified for that set of channels (50 Hz for subwoofer channels, 1 kHz for a midrange application). Do not use attenuated test tones (-10 dB, -20 dB, etc.). The Nine-Step Procedure 1) Disconnect the speaker(s) from the amplifier’s speaker output connectors. 2) Turn off all processing (bass/treble, loudness, EQ, etc.) on the source unit, processors (if used) and amplifier. Set fader control to center position and subwoofer level control to 3/4 of maximum (if used to feed the XD400/4). 3) Turn both “Input Sens.” controls all the way down. 4) Set the source unit volume to 3/4 of full volume. This will allow for reasonable gain overlap with moderate clipping at full volume. 5) Using the chart on this page, determine the target voltage for input sensitivity adjustment according to the nominal impedance of the speaker system connected to the amplifier outputs. 6) Verify that you have disconnected the speakers before proceeding. Play a track with an appropriate sine wave (within the frequency range to be amplified by the XD400/4) at 3/4 source unit volume. 7) Connect the AC voltmeter to the speaker output connectors of the amplifier. If the channel pair is operating in stereo, it is only necessary to measure one channel. If bridged, make sure you test the voltage at the correct connectors (L+ and R–). 8) Increase the “Input Sens.” control until the target voltage is observed with the voltmeter. 9) Once you have adjusted the XD400/4 to its maximum low-distortion output level, reconnect the speaker(s). The “Input Sens.” controls can now be adjusted downward if the a...
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