Larson Davis System 824, Справочное руководство

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11/8/00 Using ID Setting Files 7-7
effect is that you can measure lower-level sounds
effectively. The degree of benefit varies depending
upon the weighting or filter that you are using.
High Range is not available for elec-
tret or direct transducer types (see
“Transducer Setting” below).
High - The instrument’s sensitivity is reduced by
20dB, which has the effect of moving the instru-
ment’s available dynamic range upward relative to
the “normal” range. Therefore you can measure
higher-level sounds effectively. The benefit varies
depending upon the weighting or octave filter that
you are using.
NOTE: The Range setting is not meant to
be switched dynamically in real time—in
part because selecting the “High” option
requires a stabilization period. Further-
more, the System 824’s large dynamic
range (110dB) often makes dynamic
range switching unnecessary. The Range
setting merely allows you to move the
available dynamic range either up or
down when you need to measure
extremely high or low sound levels.
Transducer Setting - (SSA,
LOG, ISM)
Transducer sets the desired transducer. This setting provides
the following three settings:
NOTE: Using an electret microphone
with the polarization voltage supplied
with the “condnsr” option, will change
the microphones sensitivity and fre-
quency response characteristics.
Condnsr - This indicates that the microphone
being used is an air condenser type and the System
824 will generate the appropriate polarization
voltage to make it function properly.
NOTE: The frequency characteristics of
the 2541 & 2560 microphones change
sufficiently enough in high range as to no
longer meet Type 1 standards. Thus we
recommend using the normal sensitivity
microphones, such as 2540 & 2559 to
measure high amplitude signals.
Elctret - This indicates that the microphone being
used is an “electret” (pre-polarized) microphone.
The instrument will not generate any polarization
voltage.
Direct - This indicates that no microphone is
being used and that electrical signals are being
injected directly into the preamp. The instrument
will not generate any polarization voltage.