BBE Maxcom User Manual
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OWNERS MANUAL
i
The symbol is used to indicate that some
hazardous live terminals are involved within
this apparatus, even under the normal
operating conditions.
The symbol is used in the service
documentation to indicate that a specific
component shall be only replaced by the
component specified in that documentation
for safety reasons.
Protective grounding terminal.
Alternating current /voltage.
Hazardous live terminal.
ON: Denotes the apparatus is turned on.
OFF: Denotes the apparatus is turned off, because
it uses the single pole switch, be sure to unplug the
AC power to prevent any electric shock before you
proceed with your service.
WARNING: Describes precautions that should be
observed to prevent the danger of injury or death to
the user.
CAUTION: Describes precautions that should be
observed to prevent danger of the apparatus.
WARNING
• Power Supply
Ensures the source voltage matches the voltage of
the power supply before turning ON the apparatus.
Unplug this apparatus during lightning storms or when
unused for long periods of time.
• External Connection
The external wiring connected to the output hazard ous live terminals requires installation by an instructed
person, or the use of ready-made leads or cords.
• Do not Remove any Cover
There are maybe some areas with high voltages inside,
to reduce the risk of electric shock, do not remove any
cover if the power supply is connected. The cover
should be removed by qualified personnel only.
No user serviceable parts inside.
• Fuse
To prevent a fire, make sure to use fuses with specified
standard (current, voltage, type). Do not use a different
fuse or short circuit the fuse holder.
Before replacing the fuse, turn OFF the apparatus
and disconnect the power source.
• Protective Grounding
Make sure to connect the protective grounding to
prevent any electric shock before turning ON the
apparatus. Never cut off the internal or external
protective grounding wire or disconnect the wiring of
protective grounding terminal.
• Operating Conditions
This apparatus shall not be exposed to dripping or
splashing and that no objects filled with liquids, such
as vases, shall be placed on this apparatus.
To reduce the risk of fire or electric shock, do not
expose this apparatus to rain or moisture.
Do not use this apparatus near water. Install in
accordance with the manufacturer’s instructions.
Do not install near any heat sources such as radiators,
heat registers, stoves, or other apparatus (including
amplifiers) that produce heat.
Do not block any ventilation openings.
No naked flame sources, such as lighted candles,
should be placed on the apparatus.
IMPORTANT SAFETY INSTRUCTIONS
• Read these instructions.
• Heed all warnings.
• Follow all instructions.
• Keep these instructions.
Only use attachments/accessories specified by the
manufacturer.
• Power Cord and Plug
Do not defeat the safety purpose of the polarized or
grounding type plug. A polarized plug has two blades
with one wider than the other. A grounding type plug
has two blades and a third grounding prong. The
wide blade or the third prong are provided for your
safety. If the provided plug does not fit into your outlet,
consult an electrician for replacement of the obsolete
outlet. Protect the power cord from being walked
on or pinched particularly at the plug, convenience
receptacles, and the point where they exit from the
apparatus.
• Cleaning
When the apparatus needs a cleaning, you can blow
off dust from the apparatus with a blower or clean
with a rag etc. Don’t use solvents such as benzol,
alcohol, or other fluids with very strong volatility
and flammability for cleaning the apparatus body.
Clean only with a dry cloth.
• Servicing
Refer all servicing to qualified personnel. To reduce
the risk of electric shock, do not perform any servicing
other than that contained in the operating instructions
unless you are qualified to do so.
Servicing is required when the apparatus has been
damaged in any way, such as the power supply cord
or plug is damaged, liquid has been spilled or objects
have fallen into the apparatus, the apparatus has
been exposed to rain or moisture, does not operate
normally, or has been dropped.
SAFETY RELATED SYMBOLS
CONTENTS
MAXCOM SPECIFICATIONS ………………………………………………………………………… iii
AUDIO INPUT …………………………………………………………………………………………… iii
INTRODUCTION ………………………………………………………………………………………… 1
FEATURE LIST ……………………………………………………………………………………………………………… 1
THE DESIGN CONCEPT ……………………………………………………………………………… 2
THE VCA …………………………………………………………………………………………………………………… 2
INPUTS ……………………………………………………………………………………………………………………… 2
INSTALLATION …………………………………………………………………………………………… 3
UNBALANCED/BALANCED OPERATION ……………………………………………………………………………… 4
MAINS CONNECTION …………………………………………………………………………………………………… 4
CONTROLS ……………………………………………………………………………………………… 5
FRONT PANEL LAYOUT OF THE MAXCOM …………………………………………………………………………… 5
REAR PANEL …………………………………………………………………………………………… 7
THE BACK PANEL LAYOUT OF THE MAXCOM ……………………………………………………………………… 7
OPERATION …………………………………………………………………………………………… 8
EXPANDER/GATE SECTION …………………………………………………………………………………………… 8
COMPRESSOR SECTION ……………………………………………………………………………………………… 8
BBE SECTION ……………………………………………………………………………………………………………… 10
COMPRESSION EFFECT …………………………………………………………………………………………………10
THE LIMITING EFFECT ……………………………………………………………………………………………………10
APPLICATIONS ………………………………………………………………………………………… 11
MAIN APPLICATIONS AND INITIAL SETTINGS ………………………………………………………………………… 11
EXPANDER/GATE SECTION …………………………………………………………………………………………… 11
THE COMPRESSOR FUNCTION …………………………………………………………………………………………13
LIMITER FUNCTION ………………………………………………………………………………………………………14
SPECIAL APPLICATIONS ……………………………………………………………………………… 15
THE MAXCOM AS A PROTECTIVE DEVICE …………………………………………………………………………… 15
EXTERNAL SIDECHAIN APPLICATIONS ……………………………………………………………………………… 16
SERVICE ……………………………………………………………………………………………………………………19
WARRANTY …………………………………………………………………………………………………………………19
MAINTENANCE …………………………………………………………………………………………………………… 19
ii
MAXCOM SPECIFICATIONS
AUDIO INPUT
Type ………………………………Active balanced XLR and 1/4” jack
Impedance …………………………60k ohm balanced
Maximum input level ……………+21 dBu balanced and unbalanced
AUDIO OUTPUT
Type ………………………………XLR and 1/4” jack
Impedance …………………………1K ohm unbalanced
Maximum output level ……………+21 dBu
Frequency response ……………20Hz to 20KHz
THD N% @ 1kHz, 4dBu …………0.05%
IMD (SMPTE) @ 10dBu …………0.01%
Noise & Hum unity gain …………93dBu
Noise & Hum, fully off ……………97dBu
Crosstalk @ 20kHz ………………85dBu
CMR @ 1kHz ……………………60dB
COMPRESSOR SECTION
Type ………………………………Interactive Compressor
Threshold …………………………Variable from -40dB to 20dB
Ratio ………………………………Variable from 1:1 to LIM
Attack ……………………………Variable from 0.1ms to 200ms
Release ……………………………Variable from 0.05s to 4s
GATE SECTION
Type ………………………………Interactive Expander/Gate
Threshold …………………………Variable from OFF to 15dB
SONIC MAXIMIZER SECTION
POWER SUPPLY …………………………AC 115V/230Vac 60/50Hz; DC 24V
DIMENSIONS ……………………………483mm (W) x 217mm (D) x 44mm (H)
19.01˝ (W) x 8.54˝ (D) x 1.73˝ (H)
WEIGHT ……………………………………3kg (6.61lb)
SPECIFICATIONS
iii
1
INTRODUCTION
Congratulations and thank you for your purchase of the BBE MAXCOM. You have acquired an extremely efficient
and universal dynamics processor. It’s unique circuit design makes MAXCOM the ultimate dynamics processor:
intelligent program recognition, interactive expander/gate and a fourth generation BBE® Sonic Maximizer™.
FEATURE LIST
• SONIC MAXIMIZER
Loudspeakers have difficulty working with the electronic signals supplied by an amplifier. These difficulties
cause such major phase and amplitude distortion that the sound reproduced by speaker differs significantly from
the sound produced by the original source.
In the past, these problems proved unsolvable and were thus delegated to a position of secondary importance
in audio system design. However, phase and amplitude integrity is essential to accurate sound reproduction.
Research shows that the information which the listener translates into the recognizable characteristics of a live
performance are intimately tied into complex time and amplitude relationships between the fundamental and
harmonic components of a given musical note or sound. These relationships define a sound’s “sound”.
When these complex relationships pass through a speaker, the proper order is lost. The higher frequencies are
delayed. A lower frequency may reach the listener’s ear first or perhaps simultaneously with that of a higher
frequency. In some cases, the fundamental components may be so time-shifted that they reach the listener’s
ear ahead of some or all of the harmonic components.
This change in the phase and amplitude relationship on the harmonic and fundamental frequencies is techni
cally called “envelope distortion.” The listener perceives this loss of sound integrity in the reproduced sound as
“muddy” and “smeared.” In the extreme, it can become difficult to tell the difference between musical instruments, for example, an oboe and a clarinet.
BBE Sound, Inc. conducted extensive studies of numerous speaker systems over a ten year period. With this
knowledge, it became possible to identify the characteristics of an ideal speaker and to distill the corrections
necessary to return the fundamental and harmonic frequency structures to their correct order. While there are
differences among various speaker designs in the magnitude of their correction, the overall pattern of correction
needed is remarkably consistent.
The BBE Process is so unique that 42 patents have been awarded by the U.S. Patent Office.
• INTERACTIVE COMPRESSOR
The Interactive Compressor successfully combines the concept of a “Hard Knee” compressor with the charac
teristics of a “Soft Knee” approach. The “Soft Knee” mode with its “Soft” control characteristics is the basis of the
“inaudible” and “musical” compression of the program material, while the “Hard Knee” function is a prerequisite
both for creative and efficient dynamics processing and for limiting signal peaks reliably and precisely. This function is required to protect subsequent equipment against distortion.
• THE AUTO FUNCTION
The MAXCOM incorporates an AUTO function for intelligent program detection. With the help of the AUTO func
tion, the attack and release times are derived automatically from the program material. Adjustment errors can
therefore be effectively prevented. This feature lets you compress the signal heavily and “musically” in dynamic
range without any audible “pumping”, “breathing” or other side effects, providing you with optimum results.
• MANUALLY ADJUSTABLE ATTACK AND RELEASE CONTROLS
The response of a compressor and the quality of the dynamics processing largely depend on the control times, i.e.,
the attack and release functions. When processing signals from individual instruments such as drum, guitar etc.,
and when using the compressor to protect the audio system against signal transients, it is imperative that the control
times be user-adjustable. The MAXCOM offers this feature by providing both ATTACK and RELEASE controls.
• ADAPTIVE EXPANDER/GATE
A basic problem in the use of a compressor is the fact that the noise floor is highly amplified during quiet sections
or when there are music pauses. This effect is exaggerated when the compression ratio is inappropriate. An
adaptive Expander/Gate has been integrated into the MAXCOM. The gate is automatically adjusted dependent
on the program material. The result is an expander which is less critical of adjustment and which is more tolerant
in the presence of those signals which appear slightly above the noise floor.
INTRODUCTION
2
THE DESIGN CONCEPT
THE VCA
At the heart of the MAXCOM lies an industry standard state-of-the-art VCA (Voltage Controlled Amplifier). With
its excellent specifications (noise, THD, control feedthrough, linearity, slew rate and temperature stability) the
precision VCA used in the MAXCOM is considered one of the best in VCA technology. The “control feedthrough”
used in VCA terminology is a very critical parameter for the crosstalk of the control voltage into the audio path.
Slow changes of the control voltage lead to a slow DC offset at the audio output of the VCA and are mostly in
audible. Fast controls however, will result in awkward switching noise (“clicks”).
INPUTS
• BALANCED INPUTS
As standard, the MAXCOM comes with electronically servo-balanced inputs. This circuit design features automatic hum and noise reduction for balanced signals and thus allows for trouble-free operation even at high
operating levels. Externally induced mains hum etc. will be effectively suppressed. The automatic servo-function
recognizes the presence of unbalanced connectors and adjusts the nominal level internally to avoid level differences between the input and output signals (correction 6 dB).
• SIDECHAIN INPUTS
Each of the two channels of the MAXCOM incorporates a separate SIDECHAIN insert facility. Using an external
equalizer, this additional feature allows for frequency selective operation. Therefore, the unit can be used as a
de-esser or feedback suppressor.
• AUDIO PATH
The audio signal passes first through an electronically balanced input stage and is then directed through the
VCA which actually governs the dynamic process. The VCA’s output feeds the resulting signal into the Sonic
Maximizer. The subsequent potentiometers control the amount of Sonic Maximizer Process and Lo Contour
control which will be used in the main path. The amplifier and output driver leads the signal via the Bypass switch
to the output connector.
• SIDECHAIN PATH
The audio signal is simultaneously directed to the SIDECHAIN. By further processing of this input signal, both
Expander and Compressor Audio Detectors result in a conversion of the audio signal into rectified control volt
ages. The subsequent Auto Gate and Auto Compressor circuit govern the control characteristics of the gate
and the compressor. They automatically derive the attack and release times from the input signal and therefore
generate a musical and unobtrusive signal processing. The final control voltage is then routed to the VCA.
• SIDECHAIN INPUT
An external signal can be fed into the SIDECHAIN connector which allows the unit to be controlled externally. By
using the SIDECHAIN insert on the back panel the link to the audio signal will be automatically interrupted and
the MAXCOM can now be used for example as a frequency selective compressor (de-esser etc.).
DESIGN CONCEPT
3
INSTALLATION
Your MAXCOM was carefully packed at 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.
• RACK MOUNTING
The MAXCOM fits into one standard 19” rack unit of space. Please allow at least an additional 4” depth for the
connectors on the back panel. Be sure that there is enough air space around the unit for cooling and, to avoid
overheating, please do not place the MAXCOM on high temperature devices such as power amplifiers.
• CONNECTORS
The MAXCOM can be installed using standard 1/4” and XLR jacks. Although the inputs are fully balanced, the
automatic servo-functions allow them to operate with unbalanced source/loads. Audio outputs use 1/4” and XLR
jacks also, but they are unbalanced.
INSTALLATION
4
• IMPEDANCE
The input has an impedance of 60k Ohms and can be driven by most input sources.
UNBALANCED/BALANCED OPERATION
90% of all mistakes in audio installations can be attributed to incorrect and defective audio connections! In order
to utilize the MAXCOM to its full potential, please pay special attention to the following section. For better under
standing, the technical difference between unbalanced and balanced systems must be clarified:
• THE UNBALANCED SYSTEM
Unbalanced operation is characterized by a single conductor shielded cable with the center conductor carrying
the signal and the shield at ground.
• THE BALANCED SYSTEM
A balanced operation is defined as a two conductor shielded cable, where each of the two center conductors carry
the signal but of opposite phase. They have equal but inverted potential differences from that of the ground.
The advantage of the balanced system is based on the effect that the differential amplifier in a subsequent
device suppresses all equal phased noise which has been induced during its transmission down the cable link.
However, the original signal will be amplified and retain all its original integrity.
In this way audio signals can be transmitted without interference or loss across long distances. Balanced or
unbalanced systems require different wiring. Please read the next section carefully and pay close attention to
the correct wiring requirements of the units in the audio chain.
• THE CORRECT WIRING FOR BALANCED OPERATION
If the Unit preceding the MAXCOM uses output balancing we recommend that you use balanced audio con
nections. This will avoid interferences such as mains hum etc. For maximum hum rejection, you should avoid
common grounding, which means grounding the MAXCOM input and output.
We recommend that you connect the shield of the input cable to the ground of the signal source, making sure that the
shield is not connected to the MAXCOM input connector. At
the output, the shield of the cable is connected to the ground
of the MAXCOM, but making sure that the shield of the corresponding cable’s end is not connected to the ground of the
subsequent unit. Generally speaking, the shield connection
will be tied to the source units, but not to destination units. If
you still develop hum, it may be helpful is some cases to connect the shield on the input of the subsequent device also.
MAINS CONNECTION
The mains connection in the MAXCOM is made by using a mains cable and a standard IEC receptacle. It meets
all of the international safety certification requirements. Please make sure that all units have a proper ground
connection. For your own safety it is advisable not to remove the ground connection within the unit or at the supply, or fail to make this connection at all. The audio ground of the MAXCOM is internally capacitor decoupled to
isolate it from the supply earth. It is therefore not advantageous to attempt ground loop problem solving using
this method.
• OPERATING VOLTAGE
Before you switch on the MAXCOM, check that the AC mains voltage match that one shown on the back panel
of the unit.
• SAFETY FUSE REPLACEMENT
A safety fuse protects the unit from serious defects. If the fuse blows, this is a warning sign and always indicates
that the circuit is overloaded. The fault must always be repaired before the fuse is replaced.
If the safety fuse is faulty and needs replacing after the unit is repaired, please make sure that you replace it only
with the identical type and rating. NEVER use fuses of different ratings or cover faulty fuses with aluminium foil.
This can cause fire and electric shocks and will endanger your life and the lives of others.
INSTALLATION
END UNIT
The correct wiring of the balance system
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