JBL MPC-X100 User Manual

I. Description

MPC-X100 100 Hz Subwoofer Crossover

For JBL MPC and MPA amplifiers
Owner’s Manual and Installation Guide

The MPC-X100 is a dual-channel 100 Hz crossover filter accessory for use with JBL MPC
and MPA power amplifiers.

The MPC-X100 is user configurable to fulfill these functions:

 active crossoverChannel 1: 100 Hz low-pass; Channel 2: 100 Hz high-pass or full-range.
 subsonic filterprogrammable; preset @ 20 Hz to protect against damage from infrasonic signals.
 ultrasonic filterprogrammable; preset @ 20 kHz to protect against damage from ultrasonic signals.
 CD horn EQfor use in systems with uncompensated constant-directivity horns.

Each channel has an electronically balanced input and bypassable low-pass and high-pass
sections. Each filter circuit uses a 4-pole (24 dB/oct) Linkwitz-Riley alignment.

An alternative to the MPC-X100, the MPC-XU is a universal crossover with selectable
crossover frequency.

*TD-000084-00*

TD-000084-00

Rev. A

The MPC-X100 installs onto the amplifiers input card, where its settings are not easily
accessible to the user. This makes the MPC-X100 ideal for installed or rental sound systems,
since it practically eliminates the danger of unauthorized tampering with crossover setting or
incorrect crossover output connections, as well as the loudspeaker damage that may result
from such user tampering.

Installing the MPC-X100 involves soldering a 10-pin and a 12-pin header into corresponding
holes on the input card, a process that only qualified technical persons should attempt. We
recommend that you enlist an authorized JBL service center to perform the task. See the
installation section of this manual for more information.

Figure 1 shows a block diagram of both channels of the MPC-X100:

100 Hz
Linkwitz-Riley
Low-Pass Filter

Channel 1

(subwoofer)

Programmable
Linkwitz-Riley
Low-Pass Filter

(factory preset @ 20 kHz)

Channel 2

(high-pass or full-range)

Figure 1. Block diagram of the MPC-X100

jumper block:3-pin

jumper block:3-pin

jumper block:3-pin

resistor network RN202
& switch S201

header J101

header J101

header J201

Programmable
Linkwitz-Riley
High-Pass Filter

(factory preset @ 20 Hz)

resistor network RN104

100 Hz
Linkwitz-Riley
High-Pass Filter

jumper block:3-pin
header J203

Subwoofer
Output

jumper block:3-pin

header J102

High-pass or
Full-range
Output

jumper block:3-pin

header J202

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II. Installation

CAUTION: The MPC-X100 contains active components which can be damaged by electro­static discharge (ESD). Be sure to practice standard ESD precautions, and always ground
yourself and your workstation before handling exposed circuit cards.

Installing the MPC-X100 requires PC board soldering skills. Only qualified service technicians
should attempt it. Any authorized JBL service center can perform the installation.

The MPC-X100 installs on the amplifier input board of any JBL MPA or MPC amplifier.

Tools needed:

Soldering iron
¼-inch (6.3 mm) nutdriver
Phillips screwdriver
Wire cutters
Rosin-core solder
Desoldering iron or other suitable desoldering equipment (Do not use desoldering braid; it can

damage the solder pads on the input board and might not remove solder adequately.)

CAUTION: Preparing the input board for installation of the MPC-X100 involves removing
solder from feed-through holes on a 2-sided circuit board. Excessive heat can damage the
solder pads you will be working on. Proper equipment and experience with desoldering
delicate PC board circuitry is essential to successfully perform the procedure. Damage caused
by improper installation is not covered under warranty.

Input panel

CH2 CH1

10 10

12

88

66

14

44

18 18

22

24

0

-dB -dB

CH2 INPUT CH1

12

14

GROUND

STEREO

24

0

PARALLEL BRIDGE LEVELLEVEL

INPUT

Figure 2a. The input panel’s location
on the rear panel of the amp

1 Turn off the amplifier and disconnect the AC power cord from the AC source. Disconnect

all cables from the amplifiers input panel.

2 Position the amplifier so the rear of the chassis is facing you. The input panel is located on

the left side of the rear panel. See Figure 2a.

LOW IMPEDANCE

AUDIO TRANSFORMER

CH1

CH1

070100

DIR. OUTPUT

ISOL.OUTPUT

70V

25V

BRIDGE

100V

MONO

LOW IMPEDANCE

AUDIO TRANSFORMER

CH2

CH2

070100

DIR. OUTPUT

ISOL.OUTPUT

70V

25V

BRIDGE

100V

MONO

Figure 2b. The input panel (MPC)

Wire jumpers: W303/304 and
W403/404 (MPC); or W305/
306 and W405/W406 (MPA)

Solder holes for MPC-XU

Figure 2c. The input panel (MPA)

3 Locate and remove the screws securing both the upper blank and the lower input panels to

the rear side of the chassis (2 screws on each mini panel). The upper blank panel will
simply drop off when its screws are removed.

4 Gently pull the lower input panel out from the amplifier. Once it is removed, you will

notice a ribbon cable connecting the input PC board to the amplifier. Disengage the
locking wing clamps on the ribbon header and carefully remove the ribbon head from the
socket on the board. Now the input panel assembly is completely free from the amplifier.

5 Desolder and remove the wire jumper pairs indicated in Figure 2b or 2c.

6 Under where the jumpers were located, youll find two rows of solder pad holesone

with 10 holes and another with 12 holes. Remove the solder from all 22 holes.

7 With the input panel facing you and the component side of the MPC-X100 board facing

away from you, carefully insert the header pins of the MPC-X100 fully into the socket
holes. Turn the assembly over and solder the MPC-X100 in place. Make sure all the header
pins are well soldered. Visually inspect for cold solder joints and verify that you have
sufficient clearance to re-install the ribbon connector on the top side of the assembly.
Finish by trimming the MPC-X100 header pins as required.

2

NOISE SHIELD

#4-40 NUT

CH. 1 GAIN CONTROL

NOISE SHIELD

INPUT PANEL PCB

TAB

Figure 3 Figure 4

8 If you need to make any adjustments to the MPC-X100 settings or if you need to record

them, do so now, because the MPC-X100 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-X100, 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 Channel 1s gain control potentiometer. Place the noise shield
over the circuit board of the MPC-X100 (Figure 3) and bend the grounding tab down so
its hole goes over the stud. Re-install the nut, and tighten it securely (Figure 4).

10 Reconnect the ribbon cable to the input board connector. Press the locking clamp wings

of the connector closed. You will feel them snap into place.

11 Carefully reposition the input board/MPC-X100 assembly into the amplifier chassis and

secure it by fastening the two mounting screws. Make sure the screws are tightened snugly,
but do not over-torque them. Re-install the upper blank panel.

Installation of the MPC-X100 is now complete, and the amplifier is now ready to be installed
into the system.

III. Programming the MPC-X100

Figure 3. The MPC-X100’s switches, jumpers, and resistor networks.

Setting input operating mode on amplifier or input card

The input board or accessory on which the MPC-X100 is installed has provisionsswitches or
headersfor setting the operating mode of the amplifier. In the signal flow, the MPC-X100 is
located after these switches or headers, so its operation is affected by the mode setting.

Stereo or Parallel Mode OperationWith the amplifier in stereo or parallel mode, the
MPC-X100 operates normally: Channel 1 provides a 100 Hz low-pass subwoofer signal to
Channel 1 of the amplifier, while Channel 2 provides either a 100 Hz high-pass or a full-range
signal. Most 2-way applications will require operating in parallel mode.

The MPC-X100 is preset for a 100 Hz crossover point; this
frequency cannot be changed. The circuit board has four
switches, six 3-pin headers, and two SIP resistor network
sockets, all used for programming the module (see Figure 3).
The numerical designations identify which channel the
switch, header, or socket is part of: those designated by a 3­digit number starting in a 1 (for example, headers J101) are
for Channel 1, while those starting in a 2 are for Channel 2.

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