MDX1400

AUTOCOM PRO

www.behringer.com

BEHRINGER

BEHRINGER AUTOCOM

2001 BEHRINGER

AUTOCOM PRO MDX1400

BEHRINGER Soft Knee

Hard Knee

BEHRINGER AUTOCOM PRO AUTOCOM PRO ( BEHRINGER OT-1 AC )

BEHRINGER AUTOCOM PRO

AUTOCOM PRO 180

BEHRINGER OT-1

BEHRINGER AUTOCOM PRO (-10 dB) AUTOCOM PRO

Operating Level (+4 dB)

4.1: AUTOCOM PRO
BEHRINGER AUTOCOM PRO 8 COUPLE COUPLE 30 LED

AUTOCOM PRO SC RETURN

SC MON 1

SC FILTER

COUPLE I/O-METER 2 2

OUTPUT

IN/OUT PROCESS

SC EXT

+15 d Threshold LED ( FAST SLOW SLOW ) SLOW FAST + LED
AUTOCOM PRO MDX1400 - dB ) Hard Knee Soft Knee (IKA) +20 dB (INTERACTIVE

INTERACTIVE 1:1 1:

4 ATTACK RELEASE

MANUAL 20 dB

SC RETURN

(Out) ( )

30 dB (12 IN ( ) ) -10 dBV +4 dB I/O METER OUT ( OPERATING LEVEL

4.5: AUTOCOM PRO

(3. ) AUTOCOM PRO XLR ( ) OT-1 ( ) XLR 6.3 mm
AUTOCOM PRO MDX1400 AUTOCOM PRO (+4 dB) AUTOCOM PRO (-10 dB)
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)
SC EXT SC MON INTERACTIVE SC FILTER AUTO I/O METER IN/OUT OPERATING LEVEL COUPLE +4 dBu -10 dBV Interactive Knee Adaptation
Gain Reduction Input/Output Level Expander/Gate Threshold Compressor Threshold

LED LED + -

Threshold Threshold LED 3
: 1/2/4/6/9/12/15/18/21/24/27/30 dB : -30/-24/-18/-12/-6/-3/0/+3/+6/+9/+12/ +18 dB LED 2 Interactive Threshold +
BEHRINGER Transformator OT-1

/ U.K./

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

50 - 60 Hz

20 W 100 - 120 V ~ : T 250 mA H 200 - 240 V ~ : T 125 mA H IEC
1 (44.5 mm) 2.2 kg 3.4 kg

(482.6 mm)

(217 mm)

AUTOCOM PRO MDX1400 Gate section can be used as an independent unit to eradicate noise offering almost limitless possibilities within this application. The BEHRINGER Dynamic Enhancer One of the most common negative effects of broadband compressors is the dulled or squashed sound that is produced when it is applied to composite music, since high-energy low frequency instruments cause a compressor to reduce the overall gain. Any high frequency instrument which occurs at the same time will also be reduced in level. This spectral intermodulation causes the squashed sound effect. The solution to this problem is the new AUTOCOM PROs Dynamic Enhancer which allows for selective replacement of high-end loss accrued through use of compression. Since the Enhancer tracks the amount of compression, enhancement will not be added when no compression throughout the mix without any additional outboard enhancer etc.
The following instructions should familiarize you with the special terms used first, so that you can get to know all the functions of the unit. After you have read the instructions carefully, please put them away safely, so that you can refer to them again if necessary.

1.2 Before you begin

Your BEHRINGER AUTOCOM PRO was carefully packed in the factory and the packaging is 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 during transit.
If the unit is damaged, please do not return it to BEHRINGER, 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.
The BEHRINGER AUTOCOM PRO 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 space around the unit for cooling and please do not place the ULTRA-GRAPHPRO on high temperature devices such as power amplifiers etc. to avoid overheating. Before you connect your AUTOCOM 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 AUTOCOM 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! The mains connection of the AUTOCOM PRO is made by using the enclosed 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, never remove or disable the ground conductor of the unit or of the AC power cable.

2. CONTROLS

Fig. 2.1: AUTOCOM PRO front panel The BEHRINGER AUTOCOM PRO has two identical channels. Each channel is equipped with 8 backlit push-buttons, 7 rotary controls and 26 LEDs. The COUPLE switch is for stereo operation:
By engaging the COUPLE switch the AUTOCOM PRO is converted to stereo mode, where the controls of the left channel take over the control of both audio channels. The control signal for the control characteristic consists of either the sum of the left and right audio signal or the sum of the external audio signals, which are being fed into both SC RETURN connectors. By pressing the COUPLE switch, you override all the controls and switches of channel 2 with the exception of the IN/OUT, SC EXT, SC MON, SC FILTER and I/O METER switches as well as the OUTPUT and PROCESS controls. As a result, the controls of channel 1 take over the functions of channel 2. Should you wish to use the SC EXT function in stereo mode, then be sure that both SC RETURN jacks are connected to the external control signal, and that the SC EXT switches on both channels are engaged.
2.1 Expander/Gate Section
Fig. 2.2: Control elements of expander/gate section
Use the THRESHOLD control to determine the threshold point below which expansion occurs. The range of this control is from OFF to +10 dB. When a signal above the threshold value is applied, the - LED lights up, while the + LED lights up when expansion occurs. To optimally adapt the expander/gate to the program material, the RELEASE switch allows for selecting a SLOW or FAST release time. When you engage this switch, the expander responds with a slow release. As a general rule, percussive material with little or no ambience is processed using the FAST release mode, whereas signals with long decay or with heavy ambience require the SLOW release mode. 2. CONTROLS

2.2 Compressor Section

Fig. 2.3: Control elements of the compressor section
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 ATTACK control determines the rate by which the compressor responds to the signal which exceeds the threshold. This control can be adjusted from 0.1 to 200 milliseconds. The RELEASE control determines the rate that the compressor returns to unity gain after falling below the threshold level. This control can be adjusted from 0.05 to 4 seconds. By activating the AUTO switch, the ATTACK and RELEASE controls are disabled and the attack and release rates are automatically derived from the program material. This function allows for unobtrusive musical compression of signals or mixes with widely varying dynamics. Only if set to MANUAL the settings of the attack and release controls will function. 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. When activated, the SC EXT switch severs the connection between the audio input and the sidechain path, whilst at the same time allowing an external signal to be sourced at the SC RETURN jack on the rear panel. Using the SC MON switch will enable you to connect the sidechain control signal to the audio output, whilst at the same time muting the audio input. This function provides you with the ability to monitor the sidechain signal that is returned via inserted equalizers or other external processors. The SC MONITOR function will assist you with tuning equalizer parameters for example. Please note when the SC MON switch is engaged, the audio processing facility of the respective channel is disabled. When this function is active, a visual indication will be provided by the switches LED, which will blink. The IN/OUT switch activates the corresponding channel. This switch acts as a so-called hard-bypass, 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 is expected to be more or less inaudible. 2. CONTROLS 9

3. APPLICATIONS

In this section, several typical applications of the BEHRINGER AUTOCOM PRO are discussed. The following basic settings can resolve most dynamic problems. They are the ideal starting point. Please take the time to study the application examples carefully, in order to be able to make full use of the AUTOCOM PROs capabilities in the future. Main Applications And Initial Settings The main applications of the BEHRINGER AUTOCOM PRO can be divided into three categories: 1. The EXPANDER/GATE section is used to eliminate interference and to suppress background noise and leakage on individual tracks in multitrack recording. 2. The COMPRESSOR section is used to compress the program material and to create special effects and unusual sounds, which are used for recording and musical performance. 3. The subsequent DYNAMIC ENHANCER section is designed to freshen the signal after compression.
3.1 Compression/Levelling/Limiting/Clipping
Now that the functions of the individual sections have been clearly explained, we would like to acquaint you with more terms and relationships of the dynamics process. Compression A compressor converts a large dynamic level into a restricted range. The extent of the resulting dynamic level is dependent on the threshold, attack, release and ratio settings. As it is the desired effect of a compressor to increase a low level signal, generally the threshold is set low. The inaudible compression mode requires fast attack and release times and low ratios. The faster the chosen control times and the higher the compression ratio, the greater the effect on the short term dynamics. This fact is often used to achieve audible and creative sound effects. Levelling The levelling mode is used to keep output level constant, i.e. to compensate for long term gain changes, without affecting the short term dynamics. Normally, the threshold is set quite low in order to be able to increase low level signals. Levelling requires slow attack and release times, combined with a high ratio. Because of the very slow response time, levelling has no effect on signal peaks or short term changes in average level. Limiting The limiting function requires a fast attack time and a high ratio and release time setting, which is dependent on the specific use and the desired sound effect. As it is usually the task of a limiter to limit only high signal peaks, the threshold is usually set at a high level. The dynamics are reduced dependent on the ratio setting and the degree by which the threshold point was exceeded. If the attack time is adjusted to control only the average level without affecting signal peaks above the threshold, this is referred to as the program limiter. For this purpose the attack time will be set above 20 ms. If the attack time is further reduced in order to also control signal peaks, this is defined as the peak limiter. 3. APPLICATIONS 11

AUTOCOM PRO MDX1400 Clipping In contrast to the two previously mentioned limiters, the clipping mode features infinitely fast control times, an infinite compression ratio and creates an unsurpassable barrier (brickwall) for all signals above a certain level. To be able to control the signal peaks, the clipping function radically cuts signals above the threshold, without affecting the amplitude of the original signal. If used in normal applications, this function remains inaudible and under certain circumstances it can even lead to an improved sound, because cutting the transients creates artificial harmonics. If misused, clipping can cause very obvious and distasteful distortion, which in an extreme manner, will convert the signals waveform into a square wave signal. This effect is often produced in guitar distortion devices (fuzz boxes).
3.2 Expander/Gate Section
The main task of the Expander/Gate is to inaudibly eliminate undesirable background noise from the usable signal. As additionally described in chapter 6.4, a downward expander automatically reduces the overall level for all signals below an adjustable threshold. The expander therefore operates in opposite way to that of a compressor/limiter. Expanders generally function with a flat ratio curve, so that the signal continually fades. Noise gates however, can be seen as high ratio expanders. If the signal falls below the threshold, it is radically attenuated. The BEHRINGER AUTOCOM PRO is equipped with a newly developed IRC (Interactive Ratio Control) Expander, the ratio of which is automatically adjusted dependent on the program material. The response characteristics of conventional expanders tend to cut into the signal abruptly and the result of this is unacceptable most of the time. Gain changes become audible. The IRC Expander is therefore equipped with a soft, interactive non-linear ratio curve, which is best suited to human hearing. Critical signals in the vicinity of the threshold level are processed with a minute expansion ratio, whereas signals that reduce in level will be subjected to an increasingly higher ratio, which will result in greater attenuation.
Output Gain 0 dB Threshold

IRC-Curve

Expander, 1:8

Noise Gate, 1:oo Input

Fig. 3.1: IRC curve characteristic of the Expander The result is expansion, which is less critical to adjust and which is more tolerant of useable signals, whose level is slightly above that of the noise floor. Expansion therefore occurs extremely soft with low ratio settings, while the known negative effects of expansion are inaudible. The Attack time of the IRC expander is set automatically and program-dependent, i.e. extremely short for quickly changing signals and slower for a more balanced program material. Since the expander/gate adapts itself automatically to the program material, you will note that the new IRC (Interactive Ratio Control) circuit produces considerably better results than conventional expanders. 3.2.1 Controlling Leakage In The Studio Expander/gates are most commonly used to suppress undesirable leakage of sound from one track to another during recording or playback. They are usually used when recording drum kits, where the mics are very close to each other. High volume levels of individual instruments often cause considerable leakage onto all the 12 3. APPLICATIONS

AUTOCOM PRO MDX1400 adjacent mics and results in conflicting frequency and phase coherence problems, as well as unspecified sounds (comb filter effects). It is vitally important that every instrument is recorded into a separate mic and that each mic is individually gated. Patch the BEHRINGER AUTOCOM PRO into a snare drum channel for example and adjust it so that triggering only occurs on snare hits. Each mic should be set to its maximum operating level, monitored (see SC MON switch) and the THRESHOLD level set so that each snare hit sounds acoustically clean and seperate, as though it was played on its own. The optimum use of the Expander/Gate depends principally on microphone technique. Be particularly careful, when high frequency instruments are located to the side or rear of a cardioid microphone. Most cardioids exhibit a sharply rising off-axis response characteristic at higher frequencies. If there is only a 2 or 3 dB difference between the on-axis and off-axis response in the 5 to 10 kHz region, cymbals may leak excessively into the tom mics and you may have hi-hat spilling all over the snare mic. Please make full use of the directional characteristic of the mics, to acoustically exclude all other instruments as much as possible. Make sure that you do everything possible to achieve source separation with good microphone technique. Otherwise the Expander/Gate is not able to undertake clear acoustic separation. Sometimes, it is necessary to prevent the Expander/Gate from responding to low frequencies (rumbles etc.), especially if a singer is moving the microphone around on a mic-stand. More information about this topic in chapter 5.2. 3.2.2 Initial Settings For The Expander/Gate Section
Control THRESHOLD control RELEASE switch Se tting OFF SLOW
Tab. 3.1: Initial settings for the expander/gate section Begin with very low threshold levels, so that the signal can pass through the unit unaffected. Now turn the control clockwise until all unwanted noise is removed and only the sound of the desired instrument can be heard. To adapt the unit to the program material properly, you can additionally choose between a SLOW or FAST release time. In the depressed position, the unit works at a slow release time. Percussive material with little or no reverb, is processed in fast mode, whereas the slow mode is advantageously used for signals with long durations or signals with heavy ambience. You will find that a fast release time (FAST mode) is preferable for acoustic separation of most percussive sounds, whilst cymbals and tom toms, normally benefit from the SLOW mode. If the controls are set correctly, the drum sounds will be dry, sharp and clearly defined. If you do not have enough mics (or AUTOCOM PRO channels!) to record each instrument separately, try to create sub-groups: put the snare and mid-toms together, and group the side-toms, bass drum and cymbals together with the help of a mixing console. The aim is to set up the Expander/Gate and to position the group mics so that each strike on an instrument opens a specific mic and so only that instrument is recorded, whilst the other mics remain muted. 3.2.3 Reducing Leakage In Stage Mics The AUTOCOM PRO has many uses in live-work, on stage and in multi-miking situations: a well set up Expander/Gate can effectively suppress background noise, compressor type pumping noise and microphone leakage etc. without producing any undesirable side effects. Expander/gates are commonly used for processing vocals. When specifically used with a compressor, the distance and position of the mic in relation to the singer is very critical: the further the distance, the more sensitive the mic is to background noise. Use the Expander/Gate section in the slow release mode to inaudibly eliminate background noise, that occurs in pauses between singing. When used in live situations, leakage of miked instrumentation is substantially reduced, as well as other acoustic contaminants in various recording situations. 3. APPLICATIONS 13

AUTOCOM PRO MDX1400 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. For using the AUTOCOM PRO as a Limiter, you should set RATIO to oo:1, INTERACTIVE to off and use short Attack and max. Release Times. Use the THRESHOLD control to set the threshold level for limiting. 3.3.2 The AUTOCOM 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 AUTOCOM 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 and use the ATTACK and RELEASE controls to obtain the desired effect. Experiment with all the controls in order to get a feel of their function! 3.3.3 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 AUTOCOM PRO MDX1400 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 low-frequency 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. 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.

3.4 Dynamic Enhancer Section
In addition to the above mentioned method with the sidechain filter the AUTOCOM PRO offers another alternative solution: the Dynamic Enhancer. It eliminates the problems without creating any additional negative side effects. As the signal level rises towards the threshold point where compression will occur, high frequency enhancement is added at the same degree to which the input signal is compressed. The AUTOCOM PRO accurately tracks the amount of compression in order to compensate with the same amount of dynamic enhancement, even if there are heavy signal variations. When there is no compression taking place, the Dynamic Enhancer is inoperative and therefore, no additional noise or signal equalization is added to the signal. For more versatility, a PROCESS control allows you to control the available amount of dynamic enhancement. The range lies between Off and 6. The typical dynamic enhancement function is shown in the following figure:

Output

No Gain Reduction

With Enhancer

-20 dB 20 dB Gain Reduction Without Enhancer

Frequency

Fig. 3.3: The frequency response with and without dynamic enhancer
3.4.1 Initial Settings For The Dynamic Enhancer Section Turn the PROCESS control beginning from Off to a value, where you have the impression of a correct frequency response at compression. Also check out the combination with the sidechain filter.
Control PROCESS control Se tting OFF
Tab. 3.3: Initial settings for the dynamic enhancer section

4. SPECIAL APPLICATIONS

4.1 Using The AUTOCOM PRO For Recording And Cassette Duplication
In the recording and duplication field the goal should always be to achieve an optimum recording level onto the recording media. Too low or too high recording levels lead to side effects such as noise, distortion etc. In mastering and multitrack recording, as well as in duplication, one should always take care to utilize the full dynamic range of the tape recorder, DAT recorder etc. Principally, it is possible to control the recording level by riding faders, which means with low level signals, the gain is increased, whereas the amplitude of high level signal is reduced. It is obvious that this method is insufficient because, especially in live recordings, the expected signal levels cannot be anticipated correctly. Especially with multitrack recordings, which are run under hectic circumstances, the signal level of all channels cannot be monitored and controlled at the same time. Generally, with manual control, it is not possible to achieve satisfying recording results. An automatic gain control system achieves better and more constant results. Use the AUTOCOM PRO by starting with the initial settings, and use its dynamic control functions in order to be able to drive an analog, as well as a digital recording, up to the limit of its maximum dynamic range while remaining noise- and distortionfree.

AUTOCOM PRO MDX1400 4.1.1 The AUTOCOM PRO In Digital Recording And Sampling In an analog recording, too low recording levels lead to an increased noise level, whereas too high levels will cause a compressed and squashed sound. In extreme cases, it will cause distortion due to tape saturation. In contrast to analog, side effects in the digital field always become extremely audible: with decreasing level, a tape previously recorded with insufficient level loses resolution: the recording sounds hard and loses atmosphere. With excessive level, the recording sounds harsh and heavily distorted. In order to avoid these effects, the AUTOCOM PRO as a limiter should be placed before for example a sampler. As a result of this process, a digital recording or a sampling event can be optimally set in level without any problem. 4.1.2 The AUTOCOM PRO In Mastering The mastering process is one of the most critical processing steps in recording. In this production step, it is the goal to achieve a maximum level copy of the recording, without any noise or distortion. In many applications it is further required to produce a high average volume. In the field of commercial media for example, this is apparent especially with records and cassettes which are processed with high average volumes. Quite often in these cases, dynamics suffer drastically, because the program material has been compressed and limited too heavily. Using the Compressor section of the AUTOCOM PRO as a limiter allows you to drastically increase the overall volume, without audibly affecting the dynamics. Proceed as follows: Limit the dynamics of the program material by 6 dB using the AUTOCOM PRO as a Peak Limiter (Ratio 1:oo). By softly clipping just the transients, the real audio signal will not be limited, resulting in a higher headroom. The overall gain can now be increased by 6 dB, which leads to a higher volume. More than 6 dB should not be limited, otherwise side effects could become audible. This effect is particularly noticeable with DAT recorders, whose level indicators achieve a response time of less than 1 ms. Set the DAT recorder at unity and now reduce the LEVEL control of the peak limiter until a gain reduction of 6 dB is indicated. The cut signal peaks cause a reduced recording level of about 6 dB, which is visible on the level indicators of the DAT recorder. Now increase the recording level of the recorder back to unity. The result is a clearly louder recording without any loss of sound.
4.2 The AUTOCOM 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. 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 AUTOCOM 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 AUTOCOM PRO as a Limiter, this means that you effectively double the power amplification. The AUTOCOM 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. 4.2.1 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 AUTOCOM 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 18 4. SPECIAL APPLICATIONS

5.4 Voice-Over Compression (Ducking)
The BEHRINGER AUTOCOM PRO can be used to automatically reduce music to a background level, when an announcer is speaking through a microphone. For this purpose, the BEHRINGER AUTOCOM PRO is used as an automatic fader and is controlled by the announcers microphone, which is connected to the SC RETURN input via a preamplifier. The music output and the announcers voice, are then mixed. This application is known as voice-over compression or ducking and is commonly used in discos, radio stations etc.
5.5 Triggering Additional Sounds From A Rhythm Track
This technique is used to give a rhythm track more punch. For this purpose, only the Expander/Gate section is required and the Compressor and Dynamic Enhancer sections are switched off. The bass guitar track is connected to the audio chain of the BEHRINGER AUTOCOM PRO, while the bass drum is connected to the SC RETURN input. By activating the SC EXT switch, the bass guitar is now triggered by the bass drum. Another application allows the sound of the bass drum to be supported or extended by other instruments (synthesizers etc.), where the bass drum is used to trigger a new sound, which is then mixed into the track.

6. TECHNICAL BACKGROUND

By employing current modern analog technology it is possible to manufacture audio equipment with a dynamic range of up to 125 dB. In contrast to analog techniques, the dynamic range of digital equipment is approximately 25 dB less. With conventional record and tape recorder technology, as well as broadcasting, this value is further reduced. Generally, dynamic restrictions are due to noisy storage and transmission media and also the maximum headroom of these systems.
6.1 Noise As A Physical Phenomenon
All electrical components produce a certain level of inherent noise. Current flowing through a conductor leads to uncontrolled random electron movements. For statistical reasons, this produces frequencies within the whole audio spectrum. If these currents are highly amplified, the result will be perceived as noise. Since all frequencies are equally affected, we term this white noise. It is fairly obvious that electronics cannot function without components. Even if special low-noise components are used, a certain degree of basic noise cannot be avoided. This effect is similar when replaying a tape. The non-directional magnetic particles passing the replay head can also cause uncontrolled currents and voltages. The resulting sound of the various frequencies is heard as noise. Even the best possible tape biasing can only provide signal-to-noise ratios of about 70 dB, which is not acceptable today since the demands of listeners have increased. Due to the laws of physics, improving the design of the magnetic carrier is impossible using conventional means.

Audio, in general, is only as good as the source from which it was derived. The dynamic range of signals will often be restricted by noise. Synthesizers, effects devices, guitar pickups, amplifiers etc. generally produce a high level of noise, hum or other ambient background hiss, which can disturb the quality of the program material. Normally these noises are inaudible if the level of the desired signal lies significantly above the level of the noise. This perception by the ear is based on the masking effect: noise will be masked and thus becomes inaudible as soon as considerably louder sound signals in the same frequency band are added. Nevertheless, the further the level that the desired signal decreases, the more the noise floor becomes a disturbing factor. Expanders or noise gates offer a solution for this problem: these devices attenuate signals when their amplitudes drop, thereby fading out the background noise. Relying on this method, gain controlling amplifiers, like expanders, can extend the dynamic range of a signal and are therefore the opposite of a compressor. In practice, it is shown that an expansion over the entire dynamic range is not desired. With an expansion ratio of 5:1 and a processed dynamic range of 30 dB, an output dynamic range of 150 dB will be the result, exceeding all subsequent signal processors, as well as human hearing. Therefore, the amplitude control is restricted to signals whose levels are below a certain threshold. Signals above this threshold pass through the unit unchanged. Due to the continuous attenuation of the signals below this threshold, this kind of expansion is termed downward expansion. The noise gate is the simplest form of an expander: in contrast to the expander, which continuously attenuates a signal below the threshold, the noise gate cuts off the signal abruptly. In most applications this method is not very useful, since the on/off transition is too drastic. The onset of a simple gate function appears very obvious and unnatural. To achieve inaudible processing of the program material, it is necessary to be able to control the signals envelope parameters. This is part of the many features of the AUTOCOM PRO.

7. AUDIO CONNECTIONS

7.1 Inputs And Outputs
7.1.1 Balanced Inputs And Outputs As standard, the BEHRINGER AUTOCOM PRO is installed with electronically servo-balanced inputs and outputs. The new 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). 24 7. AUDIO CONNECTIONS

approx. 1 " (44.5 mm) * 19" (482.6 mm) * 8 " (217 mm) approx. 2.2 kg approx. 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.

9. 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 AUTOCOM 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