SCHOEPS V4 U - Handbuch (Seite 12)

2) Use only high-quality cables with a high
degree of shield coverage and low shield
resistance, e.g. SCHOEPS K EMC 5U.
3) Keep all cables as short as possible.
4) Dress audio cables away from power cables.
If they must cross, it should be at right angles.
5) At the preamp or mixer input, the shield of
the microphone cable should connect to
the chassis ground in the shortest, lowest-
impedance way possible. This coupling can
be capacitive rather than galvanic; see AES
standard AES48-2005.
Vibration
If noise from mechanical vibration is likely to
reach a stand- or boom-mounted micro-
phone, a shock mount (elastic suspension,
e.g. SCHOEPS USM V4) should be used, and a
loop of slack cable isolated and clamped or
tied off so that it does not become another
way for vibrations to reach the microphone.
When properly set up, the cable should not
“pull” on the microphone.
Overload
… practically never happens with the V4 U,
because of its very high maximum SPL. Only
strong air currents (e.g. from plosive consonants
very close to the microphone) can cause very
high signal amplitudes and possible overload.
The input circuitry of a mixer, preamp or
recorder can be overloaded even when the
microphone itself is not. This is true particularly
with consumer audio equipment, though
even today some professional equipment is
still designed primarily for use with dynamic
microphones or with earlier, less sensitive con-
denser microphones. If an input sensitivity
control is available, it should be set low enough
to avoid input overload, but not so low as to
cause excess noise (though a few dB of hiss is
generally preferable to hard clipping). Level
meters and overload indicators may not detect
input overload even in fully professional
equipment; often they operate only at later
stages of the circuitry.
If overload occurs when microphone power-
ing, high sound pressure levels and air currents
are not the problem, and an input sensitivity
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Avoiding Interference
12
English
Simultaneous Connection to Multiple Inputs
If a microphone has to be connected to multi-
ple inputs simultaneously, an active microphone
splitter should be used in order to preserve the
loading and powering conditions for the
microphone, as well as to prevent interference.
In no event may the outputs of several micro-
phones be connected in parallel to a single input.
Ma xi mum Cable Length
In the typical application of a studio vocal
microphone, cables of just a few meters are
used. The V4 U can be connected to cables up
to 300 m in length. The practical limit depends
on the electrical capacitance of the cable, which
is sometimes an unknown quantity. The lower
this capacitance is per unit length, the longer
the cable can be. All SCHOEPS cables have very
low capacitance (100 pF/m between the con-
ductors).
The main risks with excessively long micro-
phone cables are gradual losses at high fre-
quencies due to the cable capacitance, some
reduction in the ability to handle very high
sound pressure levels, and increased pickup of
interference.
Notes on Electromagnetic Compatibility
The SCHOEPS V4 U microphone is virtually
immune to magnetic, electric and electromag-
netic fields.
Due to the wide dynamic range of studio
microphones, the smallest signal amplitudes
are in the microvolt range (1/1,000,000 Volt).
A microphone can therefore never be expect-
ed to be immune to all possible disturbances
in all circumstances, but the following sugges-
tions can help to reduce any noise induction:
1) Keep both the microphone and the cable
away from known sources of interference
such as monitors, digital equipment (com-
puters), RF emitters (mobile phones and
other personal communication devices that
emit radio frequency energy), power trans-
formers, power lines, SCR dimmers, switch-
ing power supplies, etc.