MLA-XLR
MIDI Line Amplifier
Users Manual
MLA-XLR, MLA-1 and MLA-10 are trademarks of JLCooper Electronics.
All other brand names are the property of their respective owners.
MLA-XLR User’s Manual, First Edition
Part Number 932090
2002 JLCooper Electronics, 142 Arena Street, El Segundo, CA 90245 USA
Table of Contents
Table of Contents.......................................................................... 1
Description..................................................................................... 2
Connections................................................................................. 3
Figure 1 – Connecting 2 MLA-XLRs..................................... 3
Using with MLA-1 or MLA-10.................................................... 3
Connection to MLA-1 and MLA-10 ............................................ 4
Table 1 - MLA-XLR Line Out to MLA-10............................ 4
Table 2 - MLA-10 to MLA-XLR Line In............................... 4
Table 3 - MLA-XLR Line Out to MLA-1.............................. 4
Table 4 - MLA-1 to MLA-XLR Line In................................. 4
Electrical Interface ..................................................................... 5
Table 5 - XLR Pinout.............................................................. 5
Troubleshooting ............................................................................ 5
Care and Service........................................................................... 5
JLCooper Electronics Limited Factory Warranty.................... 6
1
Description
The MLA-XLR is designed to act as a single channel, bidirectional, long distance amplifier or driver for MIDI signals.
While the normal MIDI protocol specifies a maximum cable
distance of about 50 feet, this is sometimes not sufficient for some
installations. The reason for this restriction is based on simple
physics. MIDI uses a simple electrical interface known as a
current loop. This lends itself to immunity from noise and ground
loops while allowing for cost effective implementation.
Although successful installations of 100 feet or more have been
made, this is usually the exception rather that the rule.
Additionally, this requires high quality, shielded, low capacitance
cable. Much more than 100 feet of MIDI transmission requires
some buffering or amplification.
The MLA-XLR takes a MIDI input and converts it to a balanced,
differential signal using the RS-422 specification. At the other
end, another MLA-XLR detects the signal using a sensitive
receiver that has a high degree of noise immunity. Connecting the
two MLA-XLRs are two standard, shielded, twisted pair
microphone cables.
The combination of a low impedance, differential driver coupled
with a sensitive differential receiver signal lends itself to long
distance, error free installations required in professional
applications. It is now possible to send your MIDI signal through
1000 feet of cable or more. Using lower gauge, high quality, low
capacitance, shielded, twisted pair cables, it is possible to reach
distances of 4000 feet!
Since the MIDI signal is converted into a non-MIDI signal, an
installation requires a MIDI Line Amplifier at each side. The
MLA-XLR is compatible with the JLCooper MLA-1 and MLA10.
2
Setting up the MLA-XLR
PS
PS
Connections
The MLA-XLR is refreshingly simple to use. There are no settings
to configure. Just plug in the power supply and connect two MLAXLRs together with a pair of standard mic cables. Then, connect
your MIDI gear as you would normally. Do not use ground lifters,
signal splitters or audio transformers on the XLR cables between
the MLA-XLRs.
MLA-XLR
Figure 1 – Connecting 2 MLA-XLRs
XLRMIDI
MLA-XLR
MIDI
Using with MLA-1 or MLA-10
The MLA-XLR can be used with the MLA-1 and MLA-10 with
some custom wiring. See the following page for details.
As with the MLA-1 and MLA10, the MLA-XLR can drive
multiple MLA-XLRs, MLA-1s and MLA-10s. However, the
usable distance will decrease with each additional receiver.
Note: As with any amplifier, do not connect multiple outputs
together. This can damage your MLA-XLR, MLA-1 or MLA-10.
The MLA-XLR cannot supply power or derive its power from an
MLA-1 or MLA-10.
3
Connection to MLA-1 and MLA-10
MLA-XLR
Line Out
MLA-10
Port 1
MLA-10
Port 2
MLA-10
Port 3
1 * * * *
2 9 11 13 15
3 10 12 14 16
Table 1 - MLA-XLR Line Out to MLA-10
MLA-XLR
Line In
MLA-10
Port 1
MLA-10
Port 2
MLA-10
Port 3
1 * * * *
2 1 3 5 7
3 2 4 6 8
Table 2 - MLA-10 to MLA-XLR Line In
MLA-XLR
Line Out
MLA-1
Port 1
MLA-1
Port 2
MLA-1
Port 3
1 * * * *
2 1 3 5 7
3 2 4 6 8
Table 3 - MLA-XLR Line Out to MLA-1
MLA-10
Port 4
MLA-10
Port 4
MLA-1
Port 4
MLA-XLR
Line In
MLA-1
Port 1
MLA-1
Port 2
MLA-1
Port 3
MLA-1
Port 4
1 * * * *
2 9 11 13 15
3 10 12 14 16
Table 4 - MLA-1 to MLA-XLR Line In
* Pin 17, 18, 19 or 20 can be used to terminate the shield.
4
Technical Reference
Electrical Interface
The MLA-XLR uses the EIA RS-422A electrical interface over an
XLR connector.
1 Shield
2 MIDI Data3 MIDI Data+
Table 5 - XLR Pinout
The XLR input has an internal 100Ω termination. This is done to
reduce errors caused by reflections in the cable.
Troubleshooting
If for some reason the MLA-XLR does not give you the expected
results, take a moment to do some investigating. The most
important concept is that you have your MLA-XLR connected
properly as outlined in Setting up the MLA-XLR. Take a moment to
double check this setup.
The MLA-XLR has three LEDs to aid you in troubleshooting your
setup. There is one green LED that indicates the presence of
power. Two red LEDs indicate the presence of MIDI activity.
Care and Service
If properly cared for, your MLA-XLR should provide years of
troublefree performance. While the MLA-XLR is built in a rugged
steel enclosure, please avoid dropping the MLA-XLR.
Clean with a soft, damp cloth. Do not allow liquids to get inside
the unit.
There are no user-serviceable parts in the MLA-XLR. Please refer
to the JLCooper Electronics Limited Factory Warranty for detailed
warranty and service information.
5
JLCooper Electronics Limited Factory Warranty
JLCooper Electronics ("JLCooper") warrants this product to be free of defects in
materials or workmanship for a period of 12 months from the date of purchase. This
warranty is non-transferable and the benefits apply to the original owner. Proof of
purchase in the form of an itemized sales receipt is required for warranty coverage. To
receive service under this warranty, customers in the United States should contact the
JLCooper factory at (310) 322-9990 and talk to a service technician. If necessary, a
Return Authorization number may be issued. For our customers outside the United States,
it is recommended that you first contact your Dealer or Distributor, since they may offer
their own service or support policy. If local support is not obtainable, please send a FAX
to JLCooper's Service Department at (310) 335-0110 with a detailed description of the
service required. Upon issuance of return authorization, the product should be properly
packed and shipped to: Service Department, JLCooper Electronics, 142 Arena Street, El
Segundo, CA 90245. Please include the following: copy of the sales receipt, your name
and address (no P.O. Boxes, please), a brief description of the problem, and any other
related items discussed with the service department and considered necessary to evaluate
the product or effect a repair. The return authorization number must be clearly written on
the outside of the package. JLCooper will at its option, without charge for parts or labor,
either repair or replace the defective part(s). Shipping costs are not covered by this
warranty. JLCooper's normal repair turn around time at the factory is approximately 15
business days from receipt of product to shipping. Your actual turn around time will
include return shipping. Actual turn around time will vary depending upon many factors
including the repeatability of the customer's reported complaint, the availability of parts
required for repair, the availability of related products needed to evaluate the product if
necessary. Priority services are available at additional cost. These should be discussed
with the service technician at the time the return authorization is issued.This warranty
provides only the benefits specified and does not cover defects or repairs needed as result
of acts beyond the control of JLCooper including but not limited to: abuse, damage by
accident/negligence, modification, alteration, improper use, unauthorized servicing,
tampering, or failure to operate in accordance with the procedures outlined in the owner's
manual; nor for natural or man-made events such as, but not limited to flooding,
lightning, tornadoes, earthquake, fire, civil unrest, war, etc.
THE DURATION OF ANY OTHER WARRANTIES, WHETHER IMPLIED OR
EXPRESS, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTY OF
MERCHANTABILITY, IS LIMITED TO THE DURATION OF THE EXPRESS
WARRANTY HEREIN. JLCOOPER HEREBY EXCLUDES INCIDENTAL AND
CONSEQUENTIAL DAMAGES, INCLUDING BUT NOT LIMITED TO: LOSS OF
TIME, INCONVENIENCE, DELAY IN PERFORMANCE OF THIS WARRANTY,
THE LOSS OF USE OF THE PRODUCT OR COMMERCIAL LOSS, AND FOR
BREACH OF ANY EXPRESS OR IMPLIED WARRANTY OF MERCHANTABILITY APPLICABLE TO THIS PRODUCT. JLCOOPER SHALL NOT BE LIABLE
FOR DAMAGES OR LOSS RESULTING FROM THE NEGLIGENT OR
INTENTIONAL ACTS OF THE SHIPPER OR HIS CONTRACT AFFILIATES. THE
CUSTOMER SHOULD CONTACT THE SHIPPER FOR PROPER CLAIMS
PROCEDURES IN THE EVENT OF DAMAGE OR LOSS RESULTING FROM
SHIPMENT. THIS WARRANTY SHALL BE GOVERENED BY THE LAWS OF THE
STATE OF CALIFORNIA.
6
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