Behringer MDX1400 - Manual (Page 13)

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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 Se tting
THRESHOLD control OFF
RELEASE switch 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