Behringer MULTIGATE PRO XR4400 Manual - Page 13

13 MULTIGATE PRO XR4400 User Manual 6.3 Applications 7. Specifications 6.3.1 Suppressing crosstalk in multi-track applications One of the most frequent applications of an expander/gate is the elimination of unwanted crosstalk between single channels during recording or playback. In particular, when recording acoustic drum sounds, this type of application is frequently used, because here several microphones closely positioned next to each other are used. The high sound pressure levels of the individual instruments lead to crosstalk in adjacent microphones. Frequency cancellations and a non-defined sound ("comb filter" effect) are the result. It has proven wise to use a separate microphone for each drum instrument and to "gate" each microphone channel. Insert the BEHRINGER MULTIGATE PRO into the recording channel of the snare drum, for example, and adjust the device so that it responds only to hits on the snare drum. Each single microphone should be optimally positioned before, and the threshold of the respective channel should be set so that the drum sound can be separated cleanly, just as if the instrument were played alone. 6.3.2 Reducing crosstalk in stage microphones The MULTIGATE PRO can be used in a variety of live/stage and multimicrophone applications: a moderately set expander can effectively suppress background noise, or the noise build-up that is typically produced by compressors as well as crosstalk between microphones, etc. without causing other unwanted side effects. Typically, an expander can be used to process vocal tracks. Particularly when using a compressor, the distance between singer and microphone is of crucial importance: As the distance increases, more and more disturbing background noise is picked up. You should therefore use the expander function to fade out unwanted interference noise "inaudibly" during signal pauses. In live situations you can eliminate bleeding, for instance, from drum to piano tracks, or clean your recordings from other acoustic "pollution". If you do not have enough microphones (or MULTIGATE PRO!) to record each instrument separately, try forming so-called subgroups: comprise the snare and middle toms, side toms, kick drum and cymbals in one group using the subgroup facilities on your mixing console. The goal is to position the group's microphones and to adjust the expander so that with each hit on a specific instrument only one microphone opens, thus transmitting only one specific instrument, while the remaining microphones remain muted. 6.3.3 Reducing feedback in stage microphones As soon as a singer sings into his/her microphone, background noise is masked and thus not perceived. During signal pauses, however, the microphone picks up the noise from PA and monitor speakers, which can lead to torturing feedback. By inserting the MULTIGATE PRO into the vocal channel and by adjusting it to mute the microphone when it is not in use, you can reduce the risk of feedback in this particular channel. Basically, this configuration should be used for all stage microphones. Audio Input Connectors Type Impedance Max. Input Level CMRR Audio Output Connectors Type Impedance Max. Output Level System Specifications Frequency Response Noise THD IMD Crosstalk Gate Section Type Threshold Attack Hold Release Range Expander Section Type Attack Ratio Side-Chain Filter Frequency BW (Bandwidth) XLR and 1/4" jack RF filtered, servo-balanced input 50 kOhm balanced, 25 kOhm unbalanced +21 dBu balanced and unbalanced typ. 40 dB, >55 dB @ 1 kHz XLR and 1/4" jack Electronically servo-balanced output stage 60 Ohms balanced, 30 Ohm unbalanced +21 dBu, +20 dBm balanced and unbalanced 18 Hz to 30 kHz, +/- 3 dB >95 dBu, unweighted, 22 Hz to 22 kHz 0.008% typ. @ +4 dBu, 1 kHz, Gain 1 0.01% typ. SMPTE