SM Pro MBC502 User manual

MBC502
500 series Optical compressor
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Operating Manual
V1.1
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Contents
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1 Safety instructions .........................................................................................................3
2 Foreword .........................................................................................................................4
2.1 Important Notes: ......................................................................................................4
3 Introduction.....................................................................................................................5
3.1 Unboxing...................................................................................................................5
3.2 Connecting ...............................................................................................................5
4 Optical Compressor .......................................................................................................6
5 Channel controls ............................................................................................................6
5.1 Level..........................................................................................................................6
5.2 Mute...........................................................................................................................6
5.3 Rotary compression control ...................................................................................6
5.4 Rotary attack encoder .............................................................................................6
5.5 Rotary release encoder ........................................................................................... 6
5.6 Master Level ............................................................................................................. 6
5.7 Gain Reduction Display...........................................................................................6
5.8 Compression on/off switch .....................................................................................6
6 Master level.....................................................................................................................7
7 Frequency .......................................................................................................................7
8 Let’s play.........................................................................................................................8
9 Specs...............................................................................................................................8
10 Warranty........................................................................................................................ 9
10.1 Warranty Registration............................................................................................9
10.2 Warranty..................................................................................................................9
10.3 Return Authorization Number...............................................................................9
10.4 Warranty Regulations ............................................................................................9
10.5 Claim for Damages ..............................................................................................10
10.6 Other Warranty Rights.........................................................................................10
11 FCC and CE Regulation .............................................................................................11
12 Correspondence.........................................................................................................11

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1Safety instructions
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CAUTION: Please ensure power to your 500 series power chassis is OFF before installing or
removing your 500 series modules. Hot Swapping, (exchanging of 500 series modules with the
power on) is NOT recommended. If the power is on whilst exchanging modules, the pins on the
modules multipin connector may short and burn the regulator. For this reason, hot swapping of
modules is not covered under the SM Pro Audio warranty.
DETAILED SAFETY INSTRUCTIONS:
All safety and operation instructions of this manual should be read and adhered to before
operation.
Retain Instructions:
Please retain all safety and operating instructions for future reference.
Follow instructions:
All operation and user instructions should be followed.
Water, liquid and Moisture:
The appliance should not be used near water, rain or other liquids. Make sure that no liquid can
leak, spill or otherwise seep into the appliance.
Ventilation:
Please place the appliance so no obstacles interfere or impede the flow of air through the
ventilation openings.
Heat:
The appliance should be situated away from other heat sources such as heaters, radiators, ovens,
or other appliances that produce heat.
Power Source:
Make sure your appliance is set to the correct voltage for the country in which it will
be use before switching the device ON.
Grounding and Polarization:
Precautions should be taken so that the grounding or polarization means of an appliance is not
defeated.
Power-Cord Protection:
Power supply cords should be routed so that they are not likely to be walked on, pinched,
damaged, worn, or rubbed by any other device or obstacle.
Cleaning:
The appliance should be cleaned only with a light soft cloth. Do not use any damaging
or corrosive products on the unit.
Periods of inactivity:
The power cord of the appliance should be unplugged from the outlet when left unused
for a long period of time or in case a lightning storm occurs.
Damage Requiring Service:
The appliance should be serviced by qualified service personnel when:
• The power supply cord or the plug has been damaged; or
• Objects have fallen, or liquid has been spilled into the appliance; or
• The appliance has been exposed to rain; or
• The appliance does not appear to operate normally or exhibits a marked change in
performance; or
• The appliance has been dropped, or the enclosure damaged.
Servicing:
The user should not attempt to service the appliance beyond that is described in the Operating
Instructions.
All other servicing should be referred to qualified service personnel.! !

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2Foreword
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Dear Customer,
Thank you for purchasing this SM Pro Audio product. Our MBC502 has been designed as a tool
for use in home & professional studios, P.A. rental companies, Schools and in many other
situations where audio products would be used.
With vast experience in the audio industry over a long period of time, and along with valuable
suggestions from our customers, our engineers have developed a product that we know you will be
satisfied with. We guarantee you uncompromising quality as well as excellent technical and audio
properties at an extremely affordable price.
We hope you enjoy making music with SM Pro Audio!
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2.1 Important Notes:
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Every effort has been made to ensure all information provided in this manual is accurate at the
time of writing.
SM Pro Audio is not liable for any incorrect information contained in this manual and extends no
liabilities in regard to this manual other than those required by local law.
SM Pro Audio may update the contents of this manual at any time without prior notice. The latest
version of this manual is available from the SM Pro Audio website at all times.
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3Introduction
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MBC502 is a 500 series module that occupies 2 slots in your 500 series rack. It is a dual band
optical compressor with a Linkwitz-Riley 4th order (24dB/octave) crossover.
Each channel – low frequency and high frequency offer control over level, compression amount,
attack and release times. Switches allow you to mute one channel so that the other can act as a
filter, with the filters centre frequency determined by the frequency selector knob. The VU meter
displays the master output level, while gain reduction is shown on the LED meters. Last but not
least: The MBC502 audio circuit uses LME49720 ultra-low distortion/low noise Op Amps, for clear,
defined audio input and output quality.
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3.1 Unboxing
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Your SM Pro Audio MBC502 was carefully packed in the factory and the packaging was designed
to protect the unit from rough handling. Nevertheless, we recommend that you carefully examine
the packaging and its contents for any signs of physical damage, which may have occurred in
transit.
If the unit is damaged, please do not return it to us, but notify your dealer and the shipping
company immediately, otherwise claims for damage or replacement may not be granted. Shipping
claims must be made by the consignee.
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3.2 Connecting
The SM Pro Audio MBC502 is a 500 series compatible module, which connects to a 500 series
power chassis via the rear multipin slot. Please ensure the power is off before slotting your
module into your 500 series power chassis.Below is the feature layout of the multipin
connector.
Terminal 1 CHASSIS
2 OUTPUT 1 + (+4 Level)
3 OUTPUT 2 + (-2 Level)
4 OUTPUT -
5 GND
6 STEREO LINK
7 INPUT 2 - (-2 Level)
8 INPUT 1 - (+4 Level)
9 INPUT 2 + (-2 Level)
10 INPUT 1 + (+4 Level)
11 GAIN TRIM RESISTOR
12 +16V DC
13 GND
14 -16V DC
15 +48V DC

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4Optical Compressor
Why Optical Compression?
Optical compressors have a smooth gradual release curve making them pleasing to the ear, very
musical. This style of release is not usually found on a solid state or tube compressor. In simple
terms, the MBC502 optical compressor splits the signal between a sensor (resistor) and an LED
light. The light then acts as an attenuator on your volume path, controlling the amount of gain
reduction. The audio itself does not have any processing as such.
5Channel controls
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Controls for each channel are:
5.1 Level
The rotary knob control at the top of the MBC502 (labelled 0 to 10), controls the
amount of output level on each channel. !
5.2 Mute
The white push buttons marked LOW MUTE & HIGH MUTE mutes the audio
signal for its respective channel. The corresponding LED with light up when the
channel is muted.!
5.3 Rotary compression control
The (COMP) rotary compression control, sets the amount of compression. It
expresses the difference between the input level change and the output level
change. The higher the amount of compression, the smaller the dynamic range.!
5.4 Rotary attack encoder
The (Att) rotary attack control allows for adjustment in milliseconds. Attack is the
time it takes the compressor module to respond to the corresponding input signal
before gain reduction occurs. Short attack times quickly bring down the level of
the loud, fast transients in the audio signal; long attack times let more sound
through before the compressor engages, resulting in a punchier sound.!
5.5 Rotary release encoder
The (Rel) release control sets the time in seconds it takes for the compressor
module gain to return to the point of no gain reduction in the absence of audio
program material. Short release times create a more exaggerated effect
(“breathing”), whereas long release times have a more gradual decay.!
5.6 Master Level
The Master Level VU Meter displays the audio level.
5.7 Gain Reduction Display
The GR display shows the amount of gain reduction on each channel.
5.8 Compression on/off switch
The white buttons under the GR LEDS are the channel compressor on/off
switches. Simply turns the compressor stage on or off for each channel.!
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6Master level
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The Master level (labelled 0 to 10) is a rotary control that simply
controls the Master input level to the compressor. Above the Master
level is a Bypass switch. When tuned on, the LED will light and only the
original signal will be heard without any compression.
7Frequency
The Frequency rotary control is the sweep that selects the frequency at
which the low and high band compressor is crossed over. The MBC502
employs a Linkwitz-Riley 4th order (24dB/octave) crossover.
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8Let’s play
The MBC502 opamps are in DIP8 sockets, this simply means that users can interchange between
different types of opamps to achieve different results, and we would be happy if you report the
results to us as well. Please note that any damage caused in this process cannot be covered under
warranty.
9Specs
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Audio Inputs
Mic input connector XLR balanced
Impedance 3k Ohms
Mic input gain 10dB to 60dB
Phase reversal switchable
Phantom power + 48V, switchable
Instrument input con. 1/4“ jack unbalanced
Instrument input gain 0dB to 45dB
Audio Outputs
Connectors XLR & 1/4“ jack
Type Balanced & Unbalanced
Amplitube Frequency Response
Line in 6Hz to 40kHz within 1dB
Compressor
Photoresistive servo operated
Ratio Variable 1:1 - 10:1
Attack 1 ms – 100 ms
Release 0,1 s – 3 s
Filter
Xover: 70Hz – 3.6kHz
Slope: 24 dB
Meter
VU meter -20 dBu – + 3 dBu
Performance
THD (Unweighted) 1kHz 0.022%
Power Supply
198ma from standard 500 series power chasis.
SM ProAudio is constantly striving to maintain the highest professional standards. As a result of
these efforts, modifications may be made from time to time to existing products without prior notice.
Specifications and appearance may differ from those listed or shown.

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10 Warranty
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10.1 Warranty Registration
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To be protected by this warranty, please register your purchase using our online registration form
at http://www.smproaudio.com/index.php/en/service/register
10.2 Warranty
SM ProAudio warrants the mechanical and electronic components of this product to be free of
defects in material and workmanship for a period of three (3) years from the original date of
purchase, in accordance with the warranty regulations described below. If any defects occur within
the specified warranty period that are not caused by normal wear or inappropriate use, SM Pro
Audio shall, at its sole discretion, either repair or replace the product through its local distributor.
Warranty claims other than those indicated above are expressly excluded.
10.3 Return Authorization Number
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To obtain warranty service, the buyer must: a. return the product to its place of purchase, or b.
contact your local distributor, or c. email [e-mail] BEFORE returning the product.
All warranty requests must be accompanied by a description of the problem and an original
purchase receipt. If you have previously registered your purchase (via the SM Pro Audio web site),
you will then be issued with a return authorization number. If you have not previously registered
your purchase, then you must forward a proof of purchase document (retail dealers invoice) before
a return authorisation can be provided.
The product must then be returned in its original shipping carton, together with the return
authorization number.
10.4 Warranty Regulations
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Any product deemed eligible for repair or replacement by SM Pro Audio under the terms of this
warranty will be repaired or replaced in the best possible manner.
If the product needs to be modified or adapted in order to comply with applicable technical or
safety standards on a national or local level, in any country which is not the country for which the
product was originally developed and manufactured, this modification/adaptation shall not be
considered a defect in materials or workmanship.
The warranty does not cover any such modification/adaptation, irrespective of whether it was
carried out properly or not. Under the terms of this warranty, SM Pro Audio shall not be held
responsible for any cost resulting from such a modification/adaptation.
Free inspections, maintenance/repair work and replacement of parts are expressly excluded from
this warranty, in particular if caused by inappropriate use. Likewise, the warranty does not cover
defects of expendable parts caused by normal wear of the product. Expendable parts are typically
pots, potentiometers, switches and similar components.
Damages/defects caused by the following conditions are not covered by this warranty:
Misuse, neglect or failure to operate the unit in compliance with the instructions given in the user or
service manuals.

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Connection or operation of the unit in any way that does not comply with the technical or safety
regulations applicable in the country where the product is used.
Damages/defects that are caused by any other condition beyond the control of SM Pro Audio.
Any repair carried out by unauthorized personnel will void the warranty.
Products which do not meet the terms of this warranty will be repaired exclusively at the buyer‘s
expense. SM Pro Audio will inform the buyer of any such circumstance. If the buyer fails to submit
a written repair order within 4 weeks after notification, SM Pro Audio will return the unit C.O.D. with
a separate invoice for freight and packing. Such cost will also be invoiced separately when the
buyer has sent in a written repair order.
10.5 Claim for Damages
Failure of SM Pro Audio to provide proper warranty service shall not entitle the buyer to claim
(consequential) damages. In no event shall the liability of SM Pro Audio exceed the invoiced value
of the product.
10.6 Other Warranty Rights
This warranty does not exclude or limit the buyer‘s statutory rights provided by national law, in
particular, any such rights against the seller that arise from a legally effective purchase contract.

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11 FCC and CE Regulation
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two
conditions: (1) this device may not cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause undesired operation.
Caution: Any changes or modifications in construction of this device with are not expressly
approved by the party responsible for compliance, could void the user's authority to operate
equipment.
Note: This equipment has been tested and found to comply with the limits for a Class A digital
device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable
protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instruction manual, may cause harmful interference to
radio communications. Operation of this equipment in a residential area is likely to cause harmful
interference in which case the user will be required to correct the interference at his/her own
expense. If necessary, consult an experienced radio/television technician for additional
suggestions.
12 Correspondence
For technical support, warranty claims, and all other enquiries, please contact your local SM Pro
Audio distributor.
Contact details of all SM Pro Audio distributors list can be found online at
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The information contained in this manual is subject to change without notice. No part of this
manual may be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying and recording of any kind, for any purpose, without the express written
permission of SM Pro Audio.
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ALL RIGHTS RESERVED © 2013 SM Pro Audio