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MPC-XU Universal Crossover
For JBL MPC and MPA amplifiers
Owner’s Manual and Installation Guide
I. Description
The MPC-XU is a dual-channel universal crossover filter accessory for use with JBL MPC
and MPA power amplifiers.
The MPC-XU is user configurable to fulfill these functions:
active crossover
bandpass filter
subsonic filter
ultrasonic filter
The MPC-XU allows independent filtering of the two audio channels. The choices are:
high-pass filtering (selection of 19 frequencies)
low
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II. Installation CAUTION: The MPC-XU contains active components which can be damaged by electro- static discharge (ESD). Be sure to practice standard ESD precautions, and always ground yourself and your workstation before handling exposed circuit cards. Installing the MPC-XU requires PC board soldering skills. Only qualified service technicians should attempt it. Any authorized JBL service center can perform the installation. The MPC-XU installs on the amplifier input board of any JBL MPA or MPC
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NOISE SHIELD NOISE SHIELD #4-40 NUT TAB CH. 1 GAIN CONTROL INPUT PANEL PCB Figure 3 Figure 4 8 If you need to make any adjustments to the MPC-XU settings or if you need to record them, do so now, because the MPC-XU will be inaccessible once the noise shield is installed and the input panel is re-installed into the amplifier chassis. See Section III, Programming the MPC-XU, below. 9 Using a ¼-inch (6.3 mm) nutdriver, remove the outer 4-40 nut from the stud in the panel mounting bracket, next to
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Bypassing the filters To completely bypass the filter circuitry of a channel, set the jumpers on both Jx01 and Jx02 across pins 1 and 2, which are the upper two pins on their headers (see Figure 6). Note: If you neglect to place jumpers on either header, no signal will pass on that channel. Figure 6 Programming the low-pass filter Switch Sx01 in Switch Sx01 in Resistor network "×1" position "×10" position in RNx02 Bypass/enable headerTo use the low-pass filter, set the jumper on 8z 0 Hz 8K 00 H
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CD Horn Equalization (Boost)In addition to enabling the high-pass filter at Jx02, if you opt for CD horn equalization you must place a jumper at Jx03 as well. The MPC-XU offers two equalization curves for CD horn correction: For +6 dB of boost at 20 kHz, place the jumper across pins 1 and 2 of Jx03. For +10 dB of boost at 20 kHz, place the jumper across pins 2 and 3 of Jx03. To bypass the CD Horn Equalization, do not place a jumper in one position or the other. P3 ins 1 & 2Pe ins 2 & Non
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Ultrasonic Filter Applications: An ultrasonic filter is useful for minimizing RF interference, oscillations, leakage or aliasing from digital devices, or other signals that are too high in pitch to hear but may wreak havoc in an amplifier system. Typical ultrasonic filters are set at 16 kHz or 20 kHz. Program settings: 1 Set Jx01 to enable the low-pass filter by placing jumper across pins 2 and 3. 2 Set Jx02 to disable the high-pass filter (if not using) by placing jumper across pins 1 and 2. 3
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MPC-XU 2-Way Active Crossover This configuration routes the frequencies below a particular frequency to amplifier Channel 1, which will driver the low-frequency speaker(s), and the frequencies above to Channel 2, which will drive the high-frequency speaker(s). Using the MPC-XU as a crossover requires that you drive both amplifier inputs with the same full-band signal. Program settings: 1 On the input module, set the amplifer mode to parallel. Alternately, you could use a Y- cable to provide the
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V. Warranty & Contacting JBL These products are designed and backed by JBL Professional, the world leader in sound reinforcement. For complete JBL warranty information, to order replacement parts or to ask for clarifications to this manual, contact JBL Professional: Within the United States: Contact the Applications Dept, JBL Professional, PO Box 2200, 8500 Balboa Blvd, Northridge CA 91329 USA. In the USA you may call Monday through Friday 8:00 a.m. to 5:00 p.m. Pacific Coast Time: (818) 894-885
