Preattenuation Pad; Highpass Filter - AKG C451 User Instructions

Application

Preattenuation Pad

Highpass Filter

20
If you are miking up an extremely loud sound
source or have placed the microphone ex
tremely close to an instrument, the diaphragm
may be ex posed to extremely high sound
pressure levels. As a result, the electrical
output signal of the transducer may become
high enough to overload the subsequent
impedance converter/preamplifier
introduce audible distortion. To minimize the
risk of getting audible distortion, use the
preattenuation switch on the microphone shaft
to switch in 10 dB (1:3) or 20 dB (1:10) of
preattenuation.
Low-frequency rumble or wind noise such as
air conditioning rumble,
structure-borne noise, etc. that usually pass
unnoticed may become a clearly audible
nuisance on a recording. To minimize low-
frequency noise, you can switch in the
highpass filter. Depending on the spectra of
the wanted and unwanted signals, set the
highpass filter switch on the microphone shaft
from flat to a corner frequency of 75 Hz or
150 Hz. In either position, the slope of the
filter is 12 dB/octave (1:4) downward.
-10
-20
and
traffic noise,
C451 65th Anniversary Edition
0
dB
lin
75 Hz
150 Hz