Manual

a loop of slack cable should be isolated and
tied off so that it does not become another
way for vibrations to reach the microphone.
Unlike a wind screen, a shock mount will not
affect the characteristics of a microphone. In
many kinds of work it is well justified to use a
shock mount ”by default.”
Overload
When dealing with problems of overload, it is
useful to think of your recording equipment
as a series of circuit stages. The goal is to find
the first stage that is being overloaded, and to
attenuate the signal at the input to that stage.
Reducing the gain at any earlier stage would
add unnecessary noise, while reducing it at a
later stage would not solve the problem.
A condenser microphone represents two cir-
cuit stages: the capsule and the amplifier. In
practice, capsules are rarely overloaded except
by explosions or very strong wind; the only
sound pressure levels that could overload a
SCHOEPS capsule are so extreme – ca. 150 dB
SPL – that they would quickly damage human
hearing. Properly powered SCHOEPS CMC
amplifiers can normally handle 130+ dB sound
pressure levels, depending on the capsule type.
Such levels rarely occur in unamplified sound,
though their equivalents can be caused by wind
when directional capsules are used. In addition,
proper powering should not be taken for
granted; insufficient or incorrect microphone
powering has proved to be the cause of many
otherwise mysterious “overload” problems.
If wind and powering can be excluded as
possible issues, however, overload is far more
likely to occur in the input circuitry of mixers,
preamps or recorders than in SCHOEPS CMC
series microphones. This is true particularly
with consumer audio equipment, though even
today some professional equipment is still
designed primarily for use with dynamic micro -
phones or with earlier, less sensitive condenser
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 extra hiss is
preferable to the risk of hard clipping. Level
meters and overload indicators don’t generally
detect input overload even in fully professional
equipment; they operate only at later stages
of the circuitry.
If overload occurs where powering, high
sound pressure levels and wind are not the
problem and an input sensitivity control cannot
be turned down, the next logical step is to
plug in a balanced resistive ”pad” (attenuator)
such as the SCHOEPS MDZ 10 or MDZ 20 at
the preamp input. If the sound quality
improves, leave the pad in place; as long as a
microphone isn’t being overloaded, it is always
better to pad the preamp input than the
microphone. Only if there are extreme sound
pressure levels should a capacitive attenuator
(SCHOEPS PAD 10 or PAD 20) be used.
Low-frequency disturbances such as wind
and solid-borne vibration may not be directly
audible as such, but infrasonic noise can still
cause overload in some stage of the signal
chain. A windscreen then becomes the first
line of defense. But low-frequency noise can
also be effectively suppressed in SCHOEPS
Colette microphones with the Active Filter
CUT 60, inserted between the capsule and
amplifier. This filter has the side effect of raising
a CMC amplifier’s gain to that of the +5 dB
option (see pages 4 and 5), but given the
enormous levels of noise which can be gener-
ated by wind, they are helpful far more often
than not. Alternatively, the simpler lowcut filters
LC 60 or LC 120 can be placed at the input of
a phantom-powered preamp.
Overload which does not otherwise seem
to make sense may actually be a symptom of
incorrect or inadequate microphone powering.
Powering systems and their requirements are
discussed near the beginning of this manual
on page 5.
The least expensive, most helpful trouble -
shooting tools are:
– a known good microphone cable
– a simple pop screen such as the SCHOEPS
B 5 (or for outdoor recording, a wind
screen such as the SCHOEPS W 5)
– a balanced, in-line resistive attenuator (”pad”)
such as the SCHOEPS MDZ 10 or MDZ 20
– an ordinary multimeter
SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: [phone] · Fax: [phone]
www.schoeps.de · [e-mail]
Possible Problems
Capsules
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