Behringer SHARK FBQ100 Manual - Page 9

9 SHARK FBQ100 User Manual Gallery Speaker Stage Stage Speaker Gallery Fig. 2.6: Sound reinforcement application with different speaker positions 2.4 The noise gate function The main task of a Noise Gate is to separate unwanted background noise from wanted signals and remove noise "inaudibly". A so-called downward Expander automatically reduces the overall level of all signals below an adjustable threshold and thus expands the dynamic range of the program material. In live or stage applications and multi-microphone systems, in particular, the SHARK has a variety of possible uses: as a moderately and accurately set Gate it efficiently suppresses background noise, compressor-induced noise build-up and crosstalk between microphones, without producing any unpleasant side effects. A typical Gate application is the processing of vocal tracks. Especially when using a Compressor, the distance between microphone and singer is critical: as the distance increases, more and more disturbing background noise is picked up. Use the Gate function to fade out unwanted interference "inaudibly" during music pauses. In live applications, e.g. crosstalk of drum and piano tracks can be suppressed or acoustically "contaminated" recordings can be cleaned. When a singer sings into a stage microphone, the background noise is masked and hence not perceived. During music pauses, however, the microphone picks up the noise produced by the P.A. system and monitor speakers, which can lead to unpleasant feedback. When you insert the SHARK in a vocal channel and adjust it so that it mutes the channel, as long as the microphone is not in use, susceptibility to feedback can be reduced enormously. Basically, all stage microphones should be treated in this way. The GATE LEARN function helps you adjust the Gate threshold. Use this function before the concert and after the sound check. If the adjusted value yields unsatisfactory results, the UP/DOWN buttons can be used to fine-tune the Gate, until it closes only during signal pauses and suppresses interference efficiently. 2.5 The low cut filter in the SHARK In miking it is quite common to fade out low-frequency signal portions such as stage rumble, pop sounds or other types of interference. Frequencies of that kind often have high amplitudes and not only affect the sound image but can also damage power amps and/or loudspeakers. The SHARK is equipped with a tunable high pass filter that features a very high slope. Press the LOW CUT button to tune the cutoff frequency from 20 Hz through 150 Hz with the UP/DOWN buttons, so that interference noise is faded out as perfectly as possible, while the wanted signals remains unaffected. 2.6 The compressor function In broadcast and recording applications, signal levels often exceed the headroom of signal-processing devices, which means that the dynamic range must be reduced to avoid distortion. This is usually accomplished by the use of Compressors or Limiters, which use an automatic gain control circuit to reduce the signal level during loud passages. In this way, it is possible to compress the dynamics of a microphone channel from 90 dB to 50 dB or less, which ensures the troublefree further processing of signals, e.g. in broadcast, stage or recording applications. The Compressor monitors the program material using an adjustable threshold and continuous level control process, i.e. above threshold the signal gain is reduced, depending on threshold overshoot. Usually, the threshold is set to somewhere below the operating level to allow for a musical compression of the upper level range. The FBQ100 allows you to set two Compressor parameters. The first one, DENSITY, compresses the program material in a range from 0 (bypass) through 100 (max. compression). The second parameter, SPEED, allows you to adjust the Compressor function in the time domain. Here, you can set the control speed of the Compressor from 10 through 1000 msec. Use small values to make the Compressor respond to smallest level differences, and high values to process dynamics "inaudibly". 3. Installation 3.1 Audio connections As standard, the BEHRINGER FBQ100 is installed with electronically servobalanced 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. Output Pin 1 Pin 2 = (+) Signal Pin 3 = (-) Signal 2 1 3 Cable Shield (+) Signal + Hum (-) Signal + Hum 1 2 3 Input Ground Positive Negative RFI and Hum Fig. 3.1: Compensation of interference with balanced connections (+)Hum + Signal (-)Hum + Signal 2 x Signal = Signal + 6 dB