Specifications

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mously to the character of any sound. With a shotgun
microphone, the pickup angle at high frequencies will
be narrower than at lower frequencies; as a result,
diffuse room sound will be picked up with a distinct
high-frequency rolloff, which can make the sound
rather dull. This tendency will be emphasized further if
a windscreen is used. For this reason a supercardioid is
often a better choice for indoor recording. Of course if
there is a special need to reduce the pickup of room
sound at high frequencies (for example, if there is
interfering high-frequency noise), a shotgun microphone
may still be preferable.
The tendency toward dull sound can be counteracted
with a high-frequency boost, which can also benefit
speech intelligibility. The SCHOEPS CMIT 5 offers a built-
in, switchable high-frequency boost of this kind.
The polar patterns of shotgun microphones often have
multiple narrow lobes of sensitivity. These can cause
disturbing comb-filter-like effects when the microphone
(or a sound source) is in motion, especially in indoor
recordings. Special care was taken to smooth out these
response lobes in the design of the SCHOEPS CMIT 5.
Since any off-axis sound will be picked up with
reduced high-frequency content, a shotgun microphone
must always ”track” (follow) a moving actor or other
sound source precisely – particularly if the microphone
is close to the person being followed and / or its inter-
ference tube is a longer one. Precise tracking is not
always easy, and even if it can be done perfectly, other
sound sources in the room (including noise sources
and other nearby voices) will still be picked up from
off-axis.
3. Since shotgun microphones are frequently used out-
doors and / or on booms, they should have a low-cut
filter available to suppress wind and handling noise.
The SCHOEPS CMIT 5 has a switchable low-cut filter of
this type.
In addition, any directional microphone will increase
its pickup of low and lower-midrange frequencies
when it is positioned near a sound source. To avoid
false boominess, a shotgun microphone should also
have a filter to compensate for this ”proximity effect.”
These two requirements involve different frequency
ranges and different ideal filter slopes, however, so a
single low-cut filter is always a compromise at best.
The SCHOEPS CMIT 5 has a switchable low-cut filter
with two different characteristics available: a relatively
sharp cutoff for suppressing room rumble or wind and
handling noise, or a more gradual slope that reaches
some what higher in frequency to compensate for
proximity effect.
4. For high frequency sound, shotgun microphones
increase the distance at which a good proportion of
direct sound may be obtained. But their use still makes
clear sense only when they are already close enough
for direct sound to predominate in the result. For out-
door recording this will not be an issue when there is
little or no reflected sound energy – but indoors, even
the lower fre quencies in a person’s voice will be restored
to normal by virtue of proximity effect, resulting in a
clear and full sound.
By choosing a microphone of high directivity it is also
possible to avoid acoustic feedback. If a loudspeaker is
set up within the reverberation radius*, it should, for
obvious reasons, be positioned where the microphone
has its minimum sensitivity. If the loudspeaker is
beyond the reverberation radius, its radiated sound
will reach the microphone after being reflected by the
walls, floor and ceiling of the room, arriving as rever-
berant sound from many directions. The microphone
will pick this up less strongly than the direct sound
from the source on the main axis.
Off-axis attenuation increases with greater micro-
phone directivity. The greater this is, the less danger
there will be of acoustic feedback. This is true only in
the direct sound field, however; in a diffuse sound
field (beyond the reverberation radius), a directional
microphone will offer no help for this problem.
When dealing with pressure-gradient transducers,
their greater sensitivity to wind and vibration should
be kept in mind. Suspensions that damp solid-borne
noise (elastic suspensions and / or sound-isolated stands)
are highly recommended, as well as popscreens and
windscreens wherever appropriate.
Interference Tube (”Shotgun”) Microphones
A ”shotgun” microphone has a pressure-gradient
transducer with an interference tube fitted in front. At
upper-midrange and high frequencies the tube sup-
presses off-axis sound; this effect is more pronounced
at higher frequencies, and can generally be made
greater with a longer interference tube. At mid range
frequencies and below, however, a shotgun micro-
phone cannot have greater directivity than a supercar-
dioid unless its interference tube is so long that it
would be impractical for most purposes.
For the sake of high-quality sound, it is desirable for
a microphone to have similar frequency response at all
angles of sound incidence. However, this may become
a secondary consideration when very high directivity is
required. It is somewhat like the situation with wind-
screens: Everyone knows that they affect the sound
quality, but sometimes they are necessary in order to
get a usable recording at all.
Here are some things which are worth knowing
about ”shotgun” microphones, including the SCHOEPS
CMIT 5:
1. For any given length of the interference tube, a shot-
gun microphone's design can be optimized for maxi-
mum directivity or for best sound quality, but unfortu-
nately not for both at the same time. The SCHOEPS
CMIT 5 has been optimized for best sound quality.
2. Room reflections and reverberance contribute enor-
*see next page
Principal Microphone Characteristics