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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 crossoverChannel 1: 100 Hz low-pass; Channel 2: 100 Hz high-pass or full-range.
subsonic filterprogrammable; preset @ 20 Hz to protect against damage from infrasonic signals.
ultrasonic filterprogrammable; preset @ 20 kHz to protect against damage from ultrasonic signals.
CD horn EQfor 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 amplifiers 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 amplifiers 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, youll find two rows of solder pad holesone
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.
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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 1s 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 provisionsswitches or
headersfor 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 OperationWith 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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Figure 4
ni201ShctiwS
noitisop"1×"
zH02K021
zH03K28
zH04K65
zH05K74
Subsonic (high-pass) filter
frequency table
Bridged Mode OperationWith the amplifier in bridged mono mode and driving a highpower subwoofer system, the MPC-X100 can be used as a subwoofer filter, taking full-range
audio from Channel 1s input and sending on a 100 Hz low-pass signal to the amplifier
circuitry. For correct operation, bypass Channel 2 on the MPC-X100 board and use only
Channel 1s input and processing.
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 4). Note: If
you neglect to place jumpers on either header, no signal will pass on that channel. To
bypass Channel 2 for bridged mode operation, set the jumpers on headers J201 and J202
across pins 1 and 2.
Channel 1 (subwoofer): Programming the subsonic (high-pass) filter
Bypass/enable headerTo use the subwoofer channels high-pass subsonic filter, set the
krowtenrotsiseR
401NRni
jumper on header J102 across pins 2 and 3, which are the lower two pins. If you do not want
any subsonic filtering, bypass the filter by setting the jumper across pins 1 and 2. Note:
Subwoofers tend to sound best when used with suitable filtering, which prevents the
amplifier and speaker from wasting power trying to reproduce frequencies that are too
low. For best performance it is recommended that you bypass the high-pass filter only
if there is suitable filtering elsewhere in the audio signal path.
Setting frequencyTo set the corner frequency (at which the output is 6 dB down) of the
high-pass filter, set switch S102 to ×1 (down) and choose the appropriate resistor network
value for RN104. Use the high-pass table to select the right combination. See the appendix of
this manual for keys to identifying the correct resistor network. Note: Switch S101 should
also be set to ×1 (down).
ni102ShctiwS
noitisop"1×"
•
•
•
•
•
zH052zH0052K33
zH005zH0005K81
zH008zH0008K21
zH0061zH00061K6.5
zH0002zH00002K7.4
Ultrasonic (low-pass) filter
frequency table
Inserting the resistor networkThe factory preset frequency is 20 Hz. If there is a resistor
network already installed in the socket, carefully pull it straight out. Insert the pins of the new
resistor network into the socket holes and carefully press the network into the socket. Be
careful to avoid bending the pins of the resistor network. Orientation of the resistor network
is unimportant, as long as all 8 pins are well seated in the socket.
Channel 2: Programming the ultrasonic (low-pass) filter and CD horn EQ
ni102ShctiwS
noitisop"01×"
zH008K021
zH0001K28
zH0021K86
zH0061K65
zH0002K74
The high-pass frequency is fixed at 100 Hz and cannot be changed.
Bypass/enable headerTo use the low-pass ultrasonic filter, set the
krowtenrotsiseR
202NRni
jumper on J201 across pins 2 and 3, which are the lower two pins. But if you
do not wish to use the low-pass filter and want to bypass it instead, set the
jumper across pins 1 and 2. Note: Ultrasonic filtering is recommended to
reduce susceptibility to RF and other types of interference.
To engage the 100 Hz high-pass filter, place a jumper across pins 2 and 3 of
header J202. To bypass the filter for full-range audio, place the jumper across
pins 1 and 2. Note: if you need CD horn equalization, you must engage
the 100 Hz high-pass filter also.
Setting frequencyTo set the corner frequency (at which the output is
6dB down) of the low-pass ultrasonic filter section, choose the appropriate
resistor network value and switch setting for RN202 and S201, respectively.
(Sx01 is a ×10 range switch. In its upper position, the frequency range is ×10;
in the lower it is ×1.) Use the low-pass table at left to select the right combination. See the appendix of this manual for keys to identifying the correct
resistor network. Note: Switch S202 should always be set to ×1 (down).
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(subwoofer)
noitcnuFredaeH
All operation
Bypass subsonic
:1lennahC
Enable subsonic
All operation
Bypass ultrasonic
Enable ultrasonic
Bypass 100 Hz high-pass
Enable 100 Hz high-pass
:2lennahC
Bridged mono
Inserting the resistor networkThe factory preset frequency is 20 kHz. If there is a
resistor network already installed in the socket, carefully pull it straight out. Insert the pins of
the new resistor network into the socket holes and carefully press the network into the socket.
Be careful to avoid bending the pins of the resistor network. Orientation of the resistor
network is unimportant, as long as all 8 pins are well seated in the socket.
CD Horn Equalization (Boost)In addition to enabling the 100 Hz high-pass filter at
J202, if you opt for CD horn equalization you must place a jumper at J203 as well. The MPCX100 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 J203.
For +10 dB of boost at 20 kHz, place the jumper across pins 2 and 3 of J203.
To bypass the CD horn equalization, do not place a jumper across any pins on J203.
2&1sniP3&2sniPenoN
The table at left is a summary of the jumper
settings for the MPC-X100.
101JX
201JX
201JX
301JX
102JX
102JX
202JX
202JX
tsoobnrohDCelbasiD302JX
zHk02@Bd6+,tsoobnrohDC302JX
zHk02@Bd01+,tsoobnrohDC J203 X
J201, J202
J203
X
X
IV. Typical configurations
Subsonic Filter (Infrasonic Filter)
Applications: Subsonic filters are commonly used in sound installations to filter out rumbles
and other inaudible or unwanted low frequency signals and to protect speaker tuned vented
speakers from damage due to excessive energy below the tuning frequency.
For a subsonic filter, determine the lowest useable frequency that the speaker can safely
handle and set the high-pass filter to that frequency. Typical subsonic filters are set at 50 Hz,
40Hz, 30 Hz or 20 Hz.
Program settings:
1 Set J102 to enable the high-pass filter by placing jumper across pins 2 and 3.
2 No jumper on J103.
3 Insert proper resistor network in RN104 socket.
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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 J201 to enable the low-pass filter by placing jumper across pins 2 and 3.
2 No jumper on J203 unless you need CD horn equalization.
3 Insert proper resistor network in RN202 socket.
CD Horn Equalization Filter
Applications: A constant directivity horn requires a 6 dB per octave boost at high frequen-
cies to provide a flat frequency response. On the MPC-X100 you must use the CD horn
equalization in conjunction with the 100 Hz high-pass filter.
Program settings:
1 Set J202 to enable the 100 Hz high-pass filter by placing jumper across pins 2 and 3.
2 Set J203 to select the EQ curve you desire: across pins 1 and 2 to +6 dB at 20 kHz, or
across pins 2 and 3 for +10 dB at 20 kHz.
F=
100 Hz
C
MPC-X100
Full-range
speaker system
Subwoofer
2-Way Active Crossover
This configuration routes the frequencies below 100 Hz to amplifier Channel 1, which will
driver the subwoofer(s), and the frequencies above to Channel 2, which will drive the fullrange (typically, woofer + high frequency as passive 2-way, or woofer + midrange + high
frequency as passive 3-way) speaker(s). Using the MPC-X100 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 same signal to both channel inputs.
Channel 1:
2 Subsonic (infrasonic) filterIf you need subsonic (infrasonic) filtering, set J102 to enable the
high-pass filter by placing jumper across pins 2 and 3, and insert a resistor network into RN104
corresponding to the roll-off frequency you desire. If you do not want subsonic (infrasonic) filtering, set J102 to disable the high-pass filter by placing jumper across pins 1 and 2.
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Channel 2:
3 Set J202 to enable the Channel 2s 100 Hz high-pass filter by placing jumper across pins 2
and 3.
4 CD horn EQIf you need equalization for a constant-directivity horn, set a jumper on
J203 for the amount of boost you need. If you do not want CD horn equalization, do not
place any jumper on J203.
5 Ultrasonic filteringIf you need ultrasonic filtering, set a jumper on J201 across pins 2 and 3
to enable Channel 2s Low-pass filter and insert a resistor network into RN202 that
corresponds to the desired roll-off frequency. If you do not want any ultrasonic filtering,
set the jumper on J201 across pins 1 and 2 to bypass the low-pass filter.
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) 894-8850.
In other areas throughout the world: Contact the JBL Professional Distributor in you country.
A list of JBL Professional Distributors and U.S. Service Centers can be attained from the JBL
Professional website: www .jb lpro.com.
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Appendix
Identifying resistor networks
Use this chart to identify the values of the resistor networks. See the tables on page 4 to find
the correct values for the desired filter frequencies.
Useonlythesethreedigitsto
determineresistancecode.
Disregardtheother
numeralsandletters.
RESISTANCE
2.7K
3.9K
4.7K
5.6K
6.8K
8.2K
10K
12K
15K
18K
20K
22K
27K
33K
39K
47K
56K
68K
CODE
272
392
472
562
682
822
103
123
153
183
203
223
273
333
393
473
563
683
JBL Professional 8500 Balboa Boulevard, P.O. Box 2200 Northridge, California 91329 U.S.A.
A Harman International Company MPC-X100 MANUAL 3/99
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