MULTICOM PRO MDX4400

Users Manual

Version 1.3 April 2001

www.behringer.com

ENGLISH

SAFETY INSTRUCTIONS
CAUTION: To reduce the risk of electric shock, do not remove the cover (or back). No user serviceable parts inside; refer servicing to qualified personnel.
WARNING: To reduce the risk of fire or electric shock, do not expose this appliance to rain or moisture. This symbol, wherever it appears, alerts you to the presence of uninsulated dangerous voltage inside the enclosurevoltage that may be sufficient to constitute a risk of shock. This symbol, wherever it appears, alerts you to important operating and maintenance instructions in the accompanying literature. Read the manual.
DETAILED SAFETY INSTRUCTIONS: All the safety and operation instructions should be read before the appliance is operated. Retain Instructions: The safety and operating instructions should be retained for future reference. Heed Warnings: All warnings on the appliance and in the operating instructions should be adhered to. Follow instructions: All operation and user instructions should be followed. Water and Moisture: The appliance should not be used near water (e.g. near a bathtub, washbowl, kitchen sink, laundry tub, in a wet basement, or near a swimming pool etc.). Ventilation: The appliance should be situated so that its location or position does not interfere with its proper ventilation. For example, the appliance should not be situated on a bed, sofa, rug, or similar surface that may block the ventilation openings, or placed in a built-in installation, such as a bookcase or cabinet that may impede the flow of air through the ventilation openings. Heat: The appliance should be situated away from heat sources such as radiators, heat registers, stoves, or other appliances (including amplifiers) that produce heat. Power Source: The appliance should be connected to a power supply only of the type described in the operating instructions or as marked on the appliance. Grounding or 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 or pinched by items placed upon or against them, paying particular attention to cords and plugs, convenience receptacles and the point where they exit from the appliance. Cleaning: The appliance should be cleaned only as recommended by the manufacturer. Non-use Periods: The power cord of the appliance should be unplugged from the outlet when left unused for a long period of time. Debris and Liquid Entry: Care should be taken that debris and/or liquids do not enter the enclosure through openings. Damage Requiring Service: The appliance should be serviced by qualified service personnel when: - The power supply cord or the plug has been damaged; or - Debris or liquid has entered 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 which is described in the operating instructions. All other servicing should be referred to qualified service personnel.

FOREWORD

Dear Customer, Welcome to the team of MULTICOM PRO users and thank you very much for expressing your confidence in BEHRINGER products by purchasing this unit. It is one of my most pleasant tasks to write this letter to you, because it is the culmination of many months of hard work delivered by our engineering team to reach a very ambitious goal: making an outstanding device better still. The MULTICOM has for quite a long time been a standard tool used by numerous studios and PA rental companies. The task to improve one of our best-selling products certainly meant a great deal of responsibility, which we assumed by focusing on you, the discerning user and musician. It also meant a lot of work and night shifts to accomplish this goal. But it was fun, too. Developing a product usually brings a lot of people together, and what a great feeling it is when everybody who participated in such a project can be proud of what weve achieved. It is our philosophy to share our joy with you, because you are the most important member of the BEHRINGER family. With your highly competent suggestions for new products youve greatly contributed to shaping our company and making it successful. In return, we guarantee you uncompromising quality (manufactured under the ISO9000 certified management system) as well as excellent technical and audio properties at an extremely favorable price. All of this will enable you to fully unfold your creativity without being hampered by budget constraints. We are often asked how we can make it to produce such high-grade devices at such unbelievably low prices. The answer is quite simple: its you, our customers! Many satisfied customers means large sales volumes enabling us to get better conditions of purchase for components, etc. Isnt it only fair to pass this benefit back to you? Because we know that your success is our success, too! I would like to thank all people whose help on Project MULTICOM PRO has made it all possible. Everybody has made very personal contributions, starting from the designers of the unit via the many staff members in our company to you, the user of BEHRINGER products.

My friends, its been worth the trouble! Thank you very much,

Uli Behringer

MULTICOM PRO
Interactive 4-channel compressor/limiter/peak limiter of the reference class s IKA (Interactive Knee Adaptation) compressor concept combines the advantages of hard knee and soft knee characteristics
s Switchable highpass filter in control signal path avoids low-frequency signals from dominating compressor action
s Compression characteristics switchable between IKA and hard knee characteristics
s IGC (Interactive Gain Control) peak limiter combines clipper with program limiter circuits

MDX4400

s Extremely low-noise operational amplifiers and high-grade VCAs
s High-quality detent potentiometers and backlit switches
s Stereo Couple function for channels 1/2 and 3/4 selectable with real totaling of RMS output
s Accurate 8-digit LED meters for input level, output level and gain reduction
s Operating level switchable from +4 dBu to -10 dBV
s Servo-balanced inputs and outputs featuring 1/4" jacks and XLR connectors
s Manufactured under ISO9000 certified management system

TABLE OF CONTENT

1. INTRODUCTION....6
1.1 Technical Background.... 1.1.1 Noise As A Physical Phenomenon... 1.1.2 What Are Audio Dynamics?... 1.1.3 Compressors/Limiters.... 7 9
2. THE DESIGN CONCEPT.... 10
2.1 High Quality Components And Design... 10 2.2 Inputs And Outputs.... 10 2.2.1 Balanced Inputs And Outputs.... 10

3. INSTALLATION.... 11

3.1 3.2 3.3 3.4 Rack Mounting.... 11 Mains Voltage..... 11 Audio Connections.... 11 Selecting The Operating Level... 12

4. CONTROLS.... 13

4.1 The Front Panel Control Elements... 13 4.4 Rear Panel Control Elements Of The MULTICOM PRO... 15

5. APPLICATIONS.... 16

5.1 Compression/Leveling/Limiting/Clipping.... 5.2 Compressor Section.... 5.2.1 Initial Settings For The Compressor Section... 5.2.2 The MULTICOM PRO As A Sound Effects Unit... 5.2.3 The Muffling Effect Of A Compressor... 5.3 Peak Limiter Section.... 5.3.1 Initial Settings For The Peak Limiter Section... 19
6. SPECIAL APPLICATIONS.... 20
6.1 Using The MULTICOM PRO For Recording And Cassette Duplication.. 6.1.1 The MULTICOM PRO In Digital Recording And Sampling.. 6.1.2 The MULTICOM PRO In Mastering... 6.2 The MULTICOM PRO as a protective device.... 6.2.1 Protection Of A System With A Passive Crossover.. 6.2.2 Protection Of A System With An Active Crossover... 6.2.3 Improving The Sound Of A Processor System... 6.3 The MULTICOM PRO In Broadcast.... 21 22
7. SPECIFICATIONS.... 23 8. WARRANTY..... 25

1. INTRODUCTION

In purchasing the MULTICOM PRO, you have acquired an extremely efficient and universal dynamics processor. The unit was particularly designed for those applications most frequently used in practice. Despite the extremely complex internal circuitry, the unit has a control surface which is clearly laid out and easy to understand. With the MULTICOM PRO, BEHRINGER have developed an innovative and easy-to-use dynamics processor which meets the high demands that are made on such a device both in live and studio applications. The units most outstanding features are the precision and flexibility of its functions. Quad compressor/limiters are actually not a new invention. Usually, four simple compressor sections are packed into one enclosure, representing however a compromise in terms of operation and functionality. An excessive number of controls complicates the operation of the unit and a lack of control functions restricts the units range of application. The BEHRINGER MULTICOM PRO is a compact quad compressor/limiter based on the successful BEHRINGER Interactive Technology. Integrated AUTO processors automatically derive attack and release times from the programme material and provide you with transparent and inaudible compression. In 1 RU package the unit consists of four independent high-precision compressor sections with sidechain filters and four peak limiters, each offering all the required controls. With rack space at a premium both in the studio and in sound reinforcement, the MULTICOM PROs unique high density design and clean uncluttered layout makes it a truly useful audio tool for all applications. The MULTICOM PRO is a perfect and extremely cost-effective solution for all your multi-channel dynamic applications. Advanced BEHRINGER Technology Compared to its predecessors, the MULTICOM PRO offers several advanced features such as the extended LED meters, the sidechain filter, the controlable peak limiter per channel and the couple function for two channels. Additionally, we have succeeded in refining the audio properties as well as the circuit topology. For the first time, the MULTICOM PRO MDX 4400 uses SMD technology (Surface Mounted Device). These sub-miniature components known from aerospace technology allow for an extreme packing density, plus improve the units reliability. IKA (Interactive Knee Adaptation) Compressor Our proven IKA (Interactive Knee Adaptation) circuit successfully combines the concept of a hard knee compressor with the characteristics of a soft knee approach. This program-dependent regulation scheme forms the prerequisite both for inaudible and musical program compression and for creative and highly effective dynamics processing. With its IKA circuit the MULTICOM PRO is capable of delivering outstanding musical results both in studio and live PA applications. Additionally, the MULTICOM PROs sidechain filter allows for limiting the influence low-frequency signal portions usually have on the control logic, so that the compression ratio is mainly determined by those frequencies that are essential to the loudness perceived by the listenerthe midrange frequencies. AUTO COMPRESSOR Circuitry The response of a compressor and the quality of dynamics processing largely depend on the control times, i.e., the attack and release functions. In particular, in the field of musical compression of complex composite signals, programme-dependent control times are necessary. The interactive AUTO processor derives the attack and release times automatically from the programme material, a function that avoids misadjustment of the control times, which is a problem often encountered in conventional designs. In addition the AUTO processor allows for a high compression of the dynamic range without any audible side effects, such as pumping, breathing etc. IGC (Interactive Gain Control) Peak Limiter A further remarkable feature of the BEHRINGER MULTICOM PRO is the IGC (Interactive Gain Control) Limiter, an intelligent combination of a clipper and a program limiter. Above an adjustable threshold the peak limiter begins to function and restricts signal peaks radically (clipper). If however, the threshold of the limiter was surpassed for more than a few milliseconds, the IGC circuit automatically kicks in and reduces the level of the 6 1. INTRODUCTION

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.

3.1 Rack Mounting

The BEHRINGER MULTICOM PRO fits into one standard 19" rack unit of space (1 3/4"). 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 please do not place the MULTICOM PRO on high temperature devices such as power amplifiers etc. to avoid overheating.

3.2 Mains Voltage

Before you connect your MULTICOM PRO to the mains, please make sure that your local voltage matches the voltage required by the unit! The fuse holder on the female mains connector has 3 triangular markers, with two of these triangles opposing each other. Your MULTICOM PRO is set to the operating voltage printed next to these markers, and can be set to another voltage by turning the fuse holder by 180. CAUTION: this instruction does not apply to export models exclusively designed, e.g. for 115 V operation!

3.3 Audio Connections

The audio inputs and outputs on the BEHRINGER MULTICOM PRO are fully balanced. If possible, connect the unit to other devices in a balanced configuration to allow for maximum interference immunity.
Please ensure that only qualified persons install and operate the VIRTUALIZER. During installation and operation the user must have sufficient electrical contact to earth. Electrostatic charges might affect the operation of the MULTICOM PRO!

Output

Ground

Pin 2 = (+) Signal

Shield (+) Signal + Hum (-) Signal + Hum

Positive (+)Hum + Signal

Negative (-)Hum + Signal 2 x Signal

Pin 3 = (-) Signal

RFI and Hum

= Signal + 6 dB

Fig. 3.1: Compensation of interference with balanced connections
Unbalanced use of mono 1/4" jack plugs

Tip = Signal

Balanced use of stereo 1/4" jack plugs
Tip = hot (+ve) Ring = cold (-ve)

Sleeve = Ground / Shield

Tip Sleeve Strain relief clamp

Ring Sleeve

Strain relief clamp For connection of balanced and unbalanced plugs, ring and sleeve have to be bridged at the stereo plug.

Balanced use with XLR connectors
1 = Ground / Shield 2 = hot (+ve) 3 = cold (-ve)
Input For unbalanced use pin 1 and pin 3 have to be bridged
Fig. 3.2: Different plug types
Never use unbalanced XLR connections with microphone cables, as this would short-circuit any phantom power transmitted over these cables!
3.4 Selecting The Operating Level
With the Operating Level switch on the rear of the BEHRINGER MULTICOM PRO you can adjust the internal operating level of the unit. Thus, the MULTICOM PRO can be adapted perfectly to various levels (e.g. both the typical home recording level of -10 dBV and the professional level of +4 dBu). The level meters are referenced automatically to the selected level, i.e. an optimum operating range of the meters will always be ensured.

4. CONTROLS

Fig. 4.1: MULTICOM PRO front panel The BEHRINGER MULTICOM PRO has four identical channels. Each channel is equipped with 4 backlit pushbuttons, 4 rotary controls and 17 LEDs. The COUPLE switches are for stereo operation of two channels.
4.1 The Front Panel Control Elements
Fig. 4.2: Control elements on the front panel
The THRESHOLD control sets the threshold point for the compressor section. It has a range of -40 to +20 dB. If the channel is switched to INTERACTIVE mode (Interactive Knee Adaptation), a Soft Knee characteristic is applied to the signal exceeding the threshold point by a maximum of 10 dB. Above 10 dB, the signal would experience Hard Knee compression. The RATIO control determines the ratio between the input and output level for all signals exceeding the threshold point. If the INTERACTIVE mode is used, this control determines the ratio between input and output levels for signals exceeding the threshold point by more than 10 dB. The control range can be adjusted from 1:1 to oo:1. The OUTPUT control allows for the increase or decrease of the output signal by a maximum of 20 dB. Thus, a level loss due to the compression or limiting process can be compensated for. Please note when using the THRESHOLD control of the Peak Limiter section, that the OUTPUT control of the Compressor section precedes the Peak Limiter section. If the OUTPUT control is set too high, this can result in continuous peak limiting (see item 9 THRESHOLD control). The IN/OUT switch activates the corresponding channel. This switch acts as a so-called hard-bypass switch, which means that when the switch is OUT, the input jack is directly linked to the output jack. Normally, this switch is used to perform a direct A/B comparison between the unprocessed and the compressed or limited signals. Press the INTERACTIVE switch to change from Hard Knee to IKA characteristics. IKA provides a very subtle and musical compression of the program material and should therefore be used whenever compression should be more or less inaudible. The SC FILTER switch activates a highpass filter in the sidechain path and thus limits the influence of low frequencies on the MULTICOM PROs control processes. 4. CONTROLS 13

The 8-digit GAIN REDUCTION meter indicates how effectively the gain is reduced by the compressor, within a range from 1 to 30 dB. The 8-digit INPUT/OUTPUT LEVEL meter informs youdepending on the setting of the I/O METER switchabout the current input or output level, within a range from -24 to +18 dB. When the switch is set to IN (not engaged), the meter reads the input level, when it is OUT, the output level is displayed. The meter is referenced to the operating level (-10 dBV or +4 dBu) adjusted with the OPERATING LEVEL switch on the back. The peak limiter limits the signal to a level adjusted with the THRESHOLD control. Owing to its extremely fast response (Zero attack), the limiter is capable of limiting signal peaks without audible distortion. Whenever the signal is limited for more than 20 ms, the overall level is reduced for about 1 second to avoid heavy and thus audible signal distortion. When you use the peak limiter as a protective device against signal peaks, the THRESHOLD control should be set in combination with the OUTPUT control in the compressor section so that the peak limiter responds rarely or not at all. Thus, only real signal peaks will activate the limiter circuit. However, to produce creative sound effects, the peak limiter can be deliberately set to lower levels. The LIM LED lights up as soon as the limiter function is activated. The MULTICOM PRO converts two channels to stereo mode by engaging one of the COUPLE switches, where the left of the channels assumes the control of both audio channels, i.e. the control signal of channel 2 is replaced with that of channel 1. By pressing the COUPLE switch, you override all the controls and switches of channel 2 (or 4) with the exception of the IN/OUT and SC Filter switches as well as the peak limiters THRESHOLD control. The controls of channel 1 (or 3) take over all functions of channel 2 (or 4).
4.4 Rear Panel Control Elements Of The MULTICOM PRO
Fig. 4.5: Control elements of the rear panel
FUSE HOLDER / VOLTAGE SELECTOR. Please make sure that your local voltage matches the voltage indicated on the unit, before you attempt to connect and operate the MULTICOM PRO. Blown fuses may only be replaced by fuses of the same type and rating. MAINS CONNECTION. Use the enclosed power cord to connect the unit to the mains. Please also note the instructions given in the INSTALLATION chapter. AUDIO IN. These are the audio inputs of your MULTICOM PRO, available both as balanced 1/4" jack and XLR connectors. AUDIO OUT. These are the audio outputs of your MULTICOM PRO. Matching phone jack and XLR connectors are wired in parallel. With the OPERATING LEVEL switch you can adapt the MULTICOM PRO to various operating levels, i.e. you can select both the -10 dBV home recording level and the professional studio level of +4 dBu. The level meters are referenced automatically to the selected level, i.e. an optimum operating range of the meters will always be ensured.

5.2 Compressor Section

The task of a compressor is to reduce the dynamic range of program material and to control the overall level. The extensive controls of the Compressor section, provide a great range of dynamic effects: from musical and soft compression to limiting signal peaks, right up to extreme and effective compression of the overall dynamics. For example, a low ratio and very low threshold setting can be used to achieve soft and musical processing of the general dynamics of the program material. Higher ratios, together with low threshold settings, create relatively constant volume (leveling) for instruments and vocals. High threshold levels generally limit the overall level of a program. Ratios greater than 6:1 effectively prevent the output level from significantly exceeding the threshold point (provided that the OUTPUT control is in the 0 dB position). Please note that the compression of the entire program material (achieved by low threshold settings) sounds less natural with higher ratio settings. Ratio settings in the range of 4:1 and lower, effect the dynamics of the program material less and are often used to compress the sound of a bass guitar, a snare drum or a vocal. Sensitive and moderate settings are generally used in mixing and for leveling of program material in broadcast.
Output Threshold Gain 0 dB
Ratio 2:1 Hard Knee Ratio 4:1 Limiter oo:1 IKA Curve
Fig. 5.1: IKA characteristic of the compressor section
The new IKA (Interactive Knee Adaptation) circuit prevents aggressive compression, created by high ratios, from sounding too unnatural. This is achieved with an interactive control function, which begins above the threshold level and introduces a Soft Knee curve characteristic in the range up to 10 dB above the threshold point. Beyond this range, the signal is subjected to linear (Hard Knee) compression. With the threshold control completely turned to the right, the threshold value is +20 dB. Since such a value will not be reached in practice, you can use it to disable the compressor section and work exclusively with the limiter circuits.
MULTICOM PRO MDX4400 5.2.1 Initial Settings For The Compressor Section
C ontrol IN/OUT swi tch INTERAC TIVE swi tch SC FILTER swi tch THRESHOLD control RATIO control OUTPUT control Setti ng IN IN OUT +20 dB 3:dB

Tab. 5.1: Initial settings for the compressor section Rotate the THRESHOLD control counterclockwise until an appropriate amount of gain reduction is indicated on the GAIN REDUCTION meter. This operation will be accompanied by an audible drop in output level. The OUTPUT control should now be turned clockwise to reinstate the output level. The level of the unprocessed and the processed signal can be compared by pressing the I/O METER switch and observing the INPUT/OUTPUT LEVEL meter. Final adjustments of the RATIO control can then be made to suit your particular requirements. The experienced user will be in a position to specify parameters while in bypass mode and thus realize the effect before the unit is actually switched into operation. This is important in live situations, where a signal needs to be managed efficiently by the engineer, without the convenience of continual A/B comparison. 5.2.2 The MULTICOM PRO As A Sound Effects Unit In the early 1960s, musicians began looking at the recording process as a way to create new sounds. The pumping effect which had been avoided by earlier engineers suddenly became fashionable and was utilized as a creative tool, laying the groundwork for many of the sounds which are now considered indispensable in contemporary music. The compressor is used in this role because you can hear it working, and control of the dynamic range is of secondary importance. The BEHRINGER MULTICOM PRO, with its extensive range of functions, is well suited to this application. Sound effects of this kind can be achieved using extreme settings. To achieve this, set the THRESHOLD control to a fairly low level, the RATIO control to almost maximum to obtain the desired effect. Experiment with all the controls in order to get a feel of their function! 5.2.3 The Muffling Effect Of A Compressor Quite often, compressors are sometimes accused of muffling the sound, whilst at the same time reducing the dynamics. This fact should be investigated further. Bass frequencies contain most of the energy within music and therefore cause the compressor to reduce the overall dynamics. If the music also contains high frequencies along with the bass frequencies, these are also reduced in level. This is the reason why: in an extremely compressed recording of drums, the cymbals and high-hats are acoustically swamped by the sound of the snare or the bass drum. The same effect is experienced when processing reverberated or ambient sounds. The solution commonly used to this basic problem is either to reduce the compression ratio or to slow down the attack time, so that the increasing high frequency transients pass through the compressor unhindered before the compressor takes effect. The MULTICOM PRO MDX4400 offers a solution to this problem that is by much more elegant. The SC Filter switch allows you to activate a highpass filter in the control signal path of the compressor. This filter makes sure that midrange and treble range frequencies are taken into account to a greater extent, and that a lowfrequency signal triggers less compression than a midrange/treble signal of comparable level. A major advantage of this design can be seen in the fact that the frequency response of the overall signal is not modified below the threshold adjusted with the Threshold control.

MULTICOM PRO MDX4400 In pop music the dynamics of both kick drum and bass guitar are usually processed individually. The sidechain filter is therefore ideally suited to apply overall compression in the mixdown, to compress the music while increasing its loudness, but without having to accept the drawbacks described above. Please note that we offer a whole series of high-grade equalizers and enhancers/exciters, which are perfect tools to give any dynamics-processed signal the finishing acoustic touch. Please ask for detailed information!

5.3 Peak Limiter Section

As a section of its own and independent of the remaining control functions, the peak limiter enables you to limit the maximum peak level on the MULTICOM PROs output. It has been designed for use in combination with the compressor section. Independently of all compressor functions, you can protect subsequent devices against signal peaks, short-time overload and excess modulation (radio stations, etc.).

Peak Limiting

Program Limiting Release Input

Threshold

Output 5 ms ms approx. 1 s t/ms
Fig. 5.3: IGC characteristic of the limiter section The diagram illustrates the functioning of the IGC limiter. The solid graph represents the output signal, while the dashed graph above shows the input signal response. The areas between the graphs represent the amount of gain reduction (bright areas are clipping areas, i.e. signal peaks are radically cut off, dark areas show the effect of the program limiter). The limiter is activated when the adjusted threshold is exceeded for more than 20 ms, so as to limit audible clipping to a very short moment. About 1 s after the signals has dropped below the threshold again, the reduction is set to 0 dB, so that input and output signals are identical again (unity gain). 5.3.1 Initial Settings For The Peak Limiter Section
C ontrol THRE S HOLD control S etti ng OFF
Tab. 5.3: Initial settings for the peak limiter section The THRESHOLD control of the Peak Limiter sets the threshold level, so that subsequent units are protected from overloading. If the LIM comes on regularly or is on constantly, the OUTPUT control of the compressor section must be turned down, as this control sets the level of the signal, which is routed to the Peak Limiter section. If this technique leads to an undesired drop in the overall level, it is recommended that you increase the compression: either, reduce the threshold level, or increase the compression ratio with the RATIO control. The OUTPUT control will compensate for a renewed drop in level.

6.2 The MULTICOM PRO as a protective device
Sound system distortion is usually a result of amplifiers and loudspeakers being driven beyond their limitations by signals clipping. The signal limitations that occur lead to unpleasant distortion that is dangerous to the speakers. 20 6. SPECIAL APPLICATIONS
MULTICOM PRO MDX4400 A speaker diaphragm is required to accelerate, slow down, smoothly change direction and accelerate again in normal operation. Distorted operation (clipping) leads to instant acceleration, instant stop, change of direction and instant acceleration again. Since speaker diaphragms are subject to the laws of physics, they will not take this kind of punishment for long: the diaphragm will either break up or its voice coil may overheat. In addition to the damage caused by sustained overload, the speaker may also be damaged by an occasional high level overload, e.g. the sound of a microphone falling onto a hard floor. Even if this type of transient does not destroy a speaker outright, it may damage the speaker surround in such a way, as to cause mechanical abrasion and future failure. It is recommended that you use the BEHRINGER MULTICOM PRO in order to protect the speaker. Brick Wall peak limiters are not normally necessary for PA systems, as amplifiers and loudspeakers are tolerant of short signal peaks. Nevertheless, conventional limiters have to be generally driven far beyond the headroom limit of an amplifier, in order to limit the level and length of the transients responsible for overloading the system. The disadvantage of this principle is that the units full range cannot be completely used. If an increase in the average level of up to 3 dB is attained with the MULTICOM PROs IGC Peak Limiter, this means that you effectively double the power amplification. The MULTICOM PRO can act in this way to convert a PA system of 5,000 Watts into a distortion free 10,000 Watts system. The following instructions will help you to integrate the unit into your system. 6.2.1 Protection Of A System With A Passive Crossover If your sound system incorporates a passive crossover network (included in the loudspeaker case), insert the BEHRINGER MULTICOM PRO between your mixing console output and the power amplifier input. It is used as the last link in the chain preceding the power amp. Thus, you can effectively avoid the technical knockout of the midrange/tweeter range caused by high-energy bass signals! This statement, as paradox as it may seem at first, can be explained with the fact that especially low-frequency signals with high amplitudes can overload the power supplies in the amplifier(s). The resulting clipping (cutting off of signal peaks) produces high-energy distortion (upper harmonics), which is abruptly added to the midrange/tweeter signals. For this reason, weak power amps, in particular, must be protected by a limiter in their input dynamics. 6.2.2 Protection Of A System With An Active Crossover For systems using active crossovers, there are two ways to use the BEHRINGER MULTICOM PRO. The unit may be inserted between the console output and the crossover input. In this application, the BEHRINGER MULTICOM PRO will process the entire audio frequency spectrum. Alternately, the MULTICOM PRO can be inserted between the output of an active crossover and the input of a power amplifier. In this application it will only affect a specific range of frequencies. This application is particularly suited to protect the most fragile components of a multi-way speaker system against harmful signal peaks. For example, when your tweeters keep on going up in smoke all the time, the entire system should be operated at lower sound pressure levels or the tweeters should be replaced by other models. Using the MULTICOM PRO in the corresponding tweeter band avoids overloading and thus damage to the speakers. 6.2.3 Improving The Sound Of A Processor System A processor system is understood as a PA system which contains a special active crossover whose outputs are linked via separated power amplifiers to the loudspeakers. Each band has its own limiter whose task it is to limit dangerous signal peaks to a certain level. This process avoids overloading the subsequent power amplifier or destruction of the loudspeaker. In some units, the crossover frequencies in the crossover unit are further changed during high signal levels to achieve a loudness contour suited to the human hearing. But in many cases, this function leads more to a disturbance than to an improvement of the sound quality. If the MULTICOM PRO is preceding this system, the signal peaks can be eliminated before they reach the limiters of the processing system. The sound quality therefore remains natural and free of side effects caused by the changing frequencies of the crossover.

6.3 The MULTICOM PRO In Broadcast
The main aim of processing sound recordings for commercial radio and television is to achieve a maximum transmission volume at all costs. Owners of these radio and television stations strive to get bigger audience ratings, because principally, radio programs whose reception is louder than the average are preferred by the listener. By achieving a bigger audience, the broadcast station gains more money from the increasing number of promotion companies placing adverts. What is volume? Volume is defined as the relationship between the average level of program material to peak-to-peak level, in response to amplitude and duration. The higher the average level and the time it remains at a high level, the louder the program material will be perceived by the listener. If you want to run your broadcast station at maximum average volume, proceed as mentioned in chapter 6.1.2 The MULTICOM PRO In Mastering. Please make sure that the maximum peak level is below the threshold of the transmitters limiter, otherwise this could lead to very hard and audible use of the transmisson limiters. Keep in mind that a heavy increase in average volume by means of compression always leads to a loss in dynamics and an increased perception of side effects. The moderate use of the compressor and the Peak Limiter sections of the MULTICOM PRO result in higher average volumes, free of distortion.

7. SPECIFICATIONS

AUDIO INPUT Connectors Type Impedance Nominal Operating Level Max. Input Level CMRR AUDIO OUTPUT Connectors Type Impedance Max. Output Level SYSTEM SPECIFICATIONS Bandwidth Frequency Response Noise THD IMD Crosstalk Stereo Coupling COMPRESSOR SECTION Type Threshold Ratio Threshold characteristics Auto characteristics Auto Attack Time Auto Release Time Output PEAK LIMITER SECTION Type Threshold Ratio Stage 1 Limiter Type Attack Release Stage 2 Limiter Type Attack Release FUNCTION SWITCHES INTERACTIVE CONTOUR I/O METER IN/OUT OPERATING LEVEL COUPLE XLR and 1/4" jack RF filtered, servo-balanced input 50 kOhm balanced, 25 kOhm unbalanced +4 dBu/-10 dBV switchable +21 dBu balanced and unbalanced typ. 40 dB, >55 dB @ 1 kHz XLR and 1/4" jack Electronically servo-balanced output stage (optional transformer-balanced). 60 Ohms balanced, 30 Ohm unbalanced +21 dBu, +20 dBm balanced and unbalanced

20 Hz to 20 kHz, +0/-0.5 dB 0.35 Hz to 200 kHz, +0/-3 dB >-95 dBu, unweighted, 22 Hz to 22 kHz 0.008 % typ. @ +4 dBu, 1 kHz, Gain 1 0.04 % typ. @ +20 dBu, 1 kHz, Gain 1 0.01 % typ. SMPTE <-100 dB, 22 Hz to 22 kHz True RMS detection
IKA (Interactive Knee Adaptation) Compressor variable (-40 dB to +20 dB) variable (1:1 to oo:1) variable (Interactive or Hard Knee) Wave Adaptive Compressor typ. 15 ms at 10 dB, 5 ms at 20 dB, 3 ms at 30 dB program dependent, typ. 125 dB/s variable (-20 to +20 dB) IGC (Interactive Gain Control) Peak Limiter variable (+4 dB to OFF (+22 dBu)) oo:1 Clipper zero zero Program Limiter program dependent, typ. < 5 ms program dependent, typ. 20 dB/s
Enables the Interactive Knee Adaptation characteristics. Allows for frequency dependent detection. Switches between input and output for the Level Meter. Bypass switch. Changes the internal reference level from +4 dBu to -10 dBV. Linking channels 1&2 or 3&4 for stereo operation. Channel 1 (or 3) becomes master.
MULTICOM PRO MDX4400 INDICATORS GAIN REDUCTION INPUT/OUTPUT LEVEL Peak Limiter Threshold Function switch POWER SUPPLY Mains Voltages 8 element LED display: 1/3/6/10/15/20/25/30 dB 8 element LED display: -24/-18/-12/-6/0/+6/+12/+18 dB 1 LED for Indication of Limiter function LED indicator for each
Fuse Power Consumption Mains Connection PHYSICAL Dimension Net Weight Shipping Weight
USA/Canada 120 V ~, 60 Hz U.K./Australia 240 V ~, 50 Hz Europe 230 V ~, 50 Hz General Export Model 100 - 120 V ~, 200 - 240 V ~, 50 - 60 Hz 100 - 120 V ~: T 630 mA H 200 - 240 V ~: T 315 mA H max. 32 W Standard IEC receptacle 1 3/4" (44.5 mm) * 19" (482.6 mm) * 8 1/2" (217 mm) 2.2 kg 3.4 kg
BEHRINGER 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 illustrated.

8. WARRANTY

1 WARRANTY CARD/ONLINE REGISTRATION To be protected by the extended warranty, the buyer must complete and return the enclosed warranty card within 14 days of the date of purchase to BEHRINGER Spezielle Studiotechnik GmbH, in accordance with the conditions stipulated in 3. Failure to return the card in due time (date as per postmark) will void any extended warranty claims. Based on the conditions herein, the buyer may also choose to use the online registration option via the Internet (www.behringer.com or www.behringer.de). 2 WARRANTY 1. BEHRINGER (BEHRINGER Spezielle Studiotechnik GmbH including all BEHRINGER subsidiaries listed on the enclosed page, except BEHRINGER Japan) warrants the mechanical and electronic components of this product to be free of defects in material and workmanship for a period of one (1) year from the original date of purchase, in accordance with the warranty regulations described below. If the product shows any defects within the specified warranty period that are not due to normal wear and tear and/or improper handling by the user, BEHRINGER shall, at its sole discretion, either repair or replace the product. 2. If the warranty claim proves to be justified, the product will be returned to the user freight prepaid. 3. Warranty claims other than those indicated above are expressly excluded. 3 RETURN AUTHORIZATION NUMBER 1. To obtain warranty service, the buyer (or his authorized dealer) must call BEHRINGER (see enclosed list) during normal business hours BEFORE returning the product. All inquiries must be accompanied by a description of the problem. BEHRINGER will then issue a return authorization number. 2. Subsequently, the product must be returned in its original shipping carton, together with the return authorization number to the address indicated by BEHRINGER. 3. Shipments without freight prepaid will not be accepted. 4 WARRANTY REGULATIONS 1. Warranty services will be furnished only if the product is accompanied by a copy of the original retail dealers invoice. Any product deemed eligible for repair or replacement by BEHRINGER under the terms of this warranty will be repaired or replaced within 30 days of receipt of the product at BEHRINGER. 2. 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, BEHRINGER shall not be held responsible for any cost resulting from such a modification/adaptation. 3. Free inspections and maintenance/repair work are expressly excluded from this warranty, in particular, if caused by improper handling of the product by the user. This also applies to defects caused by normal wear and tear, in particular, of faders, potentiometers, keys/buttons and similar parts. 4. Damages/defects caused by the following conditions are not covered by this warranty: s misuse, neglect or failure to operate the unit in compliance with the instructions given in BEHRINGER user or service manuals. s 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. s damages/defects caused by force majeure or any other condition that is beyond the control of BEHRINGER. 5. Any repair or opening of the unit carried out by unauthorized personnel (user included) will void the warranty. 6. If an inspection of the product by BEHRINGER shows that the defect in question is not covered by the warranty, the inspection costs are payable by the customer. 7. Products which do not meet the terms of this warranty will be repaired exclusively at the buyers expense. BEHRINGER will inform the buyer of any such circumstance. If the buyer fails to submit a written repair order within 6 weeks after notification, BEHRINGER will return the unit C.O.D. with a separate invoice for freight and packing. Such costs will also be invoiced separately when the buyer has sent in a written repair order. 5 WARRANTY TRANSFERABILITY This warranty is extended exclusively to the original buyer (customer of retail dealer) and is not transferable to anyone who may subsequently purchase this product. No other person (retail dealer, etc.) shall be entitled to give any warranty promise on behalf of BEHRINGER. 6 CLAIM FOR DAMAGES Failure of BEHRINGER to provide proper warranty service shall not entitle the buyer to claim (consequential) damages. In no event shall the liability of BEHRINGER exceed the invoiced value of the product. 7 OTHER WARRANTY RIGHTS AND NATIONAL LAW 1. This warranty does not exclude or limit the buyers statutory rights provided by national law, in particular, any such rights against the seller that arise from a legally effective purchase contract. 2. The warranty regulations mentioned herein are applicable unless they constitute an infringement of national warranty law.

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 BEHRINGER Spezielle Studiotechnik GmbH. BEHRINGER and MULITCOM are registered trademarks. ALL RIGHTS RESERVED. 2001 BEHRINGER Spezielle Studiotechnik GmbH. BEHRINGER Spezielle Studiotechnik GmbH, Hanns-Martin-Schleyer-Str. 36-38, 47877 Willich-Mnchheide II, Germany Tel. +49 (0) / 92 06-0, Fax +49 (0) / 92 06-30

MULTICOM PRO MDX4400

www.behringer.com
BEHRINGER BEHRINGER MULTICOM 2001 BEHRINGER Spezielle Studiotechnik GmbH
BEHRINGER MULTICOM PRO MULTICOM PRO MULTICOM PRO 4
BEHRINGER MULTICOM PRO MULTICOM PRO AC

BEHRINGER MULTICOM PRO

MULTICOM PRO 180
BEHRINGER MULTICOM PRO (-10 dB) MULTICOM PRO

Operating Level (+4 dB)

4.1: MULTICOM PRO
BEHRINGER MULTICOM PRO 4 COUPLE

17 LED 2

10 dB ) Hard Knee Soft Knee (IKA) -40 +20 dB (INTERACTIVE

INTERAC-

OUTPUT

( 4 4.

Hard Knee

MULTICOM PRO

30 dB (8 IN ( ) OPERATING LEVEL -24 dB +18 dB -10 dBV +4 dB ) I/O METER )

1&2( ) 3 3&4

4.3: MULTICOM PRO

6.3 mm

OPERATING LEVEL (+4 dB)

(-10 dB) MULTICOM PRO

XLR 6.3 mm RF-rejecting DC-decoupled 50 k / 25 k / +4 dB -10 dB +21 dBu/ 40 dB >55 dB @ 1 kHz

6.3 mm ( )

60 / 30 / +21 dBu +20 dBm/
6.3 mm RF-rejecting DC-decoupled >10 k +24 dBu
6.3 mm RF-rejecting DC-decoupled 2k +21 dBu

S/N (THD) IMD

20 Hz bis 20 kHz +0/-0.5 dB 0.35 Hz 200 kHz +0/-3 dB -95 dBu unweighted 22 Hz 22 kHz 0.008 % typ. @ +4 dBu 1 kHz 1 0.04 % typ. @ +20 dBu 1 kHz 1 0.01 % typ. SMPTE <-100 dB 22 Hz 22 kHz True RMS detection

Threshold

IRC (Interactive Ratio Control) (OFF +15 dB) (1:1 1:8) <1 ms / 50 dB (SLOW: 100 ms / 1 dB FAST: 100 ms / 100 dB)
IKA (Interactive Knee Adaptation) (-40 +20 dB) (1:1 :1) (Interactive Knee Hard Knee) ( ) (0.5 ms/20 dB 100 ms/20 dB) (0.05 ms/20 dB 5 s/20 dB) 15 ms/10 dB 5 ms/20 dB 3 ms/30 dB 125 dB/sec (-20 +20 dB)
INTERACTIVE SC FILTER I/O METER IN/OUT OPERATING LEVEL COUPLE
Interactive Knee Adaptation

+4 dBu

-10 dBV 1
Gain Reduction Input/Output Level Peak Limiter Threshold

LED LED LED

: 1/3/6/10/15/20/25/30 dB : -30/-24/-18/-12/-6/-3/0/+3/+6/+9/+12/+18 dB LED 1

/ U.K./

120 V ~ 60 Hz 240 V ~ , 50 Hz 230 V ~ 50 Hz 100 - 120 V ~ 200 - 240 V ~

50 - 60 Hz

14 W 100 - 120 V ~ : 200 - 240 V ~ : IEC
1 (44.5 mm) 2.2 kg 3.4 kg

(482.6 mm)

(217 mm)

BEHRINGER