1200/2200 Sound Level Meter Operator’s Manual
5
General Overview
2.2.4 A/C/Z Switch:
The A/C/Z switch controls the frequency response (weighting) of all
measurements. (See Figure 9)
2.2.5 RANGE (dB) Switch:
The displayed range of the model 1200 is 70 dB and is switchable between
(30-100 dB),(50-120 dB), and (70-140 dB). After switching ranges allow
several seconds for the meter electronics to stabilize. If a range change is
necessary during a LEQ study, it is good practice to first set the meter to
LEQ PAUSE, change range and then set the meter to RUN. This will
avoid integrating any handling or switching noise into the LEQ
measurement.
2.2.6 RESET Button:
This button is used primarily to clear data from the memory of the
instrument. When pressed, the display will begin to count down from ‘02’.
If the button is pressed and held, the display will count down
’02,01, ---‘. When the dashes are displayed the instrument memory is
clear.
This button is also used as an up-arrow during setup. (see Operating
Procedure)
2.2.7 CAL Button:
This button has three functions; It initiates a calibration, toggles between
Run Time displays, and acts as a down arrow during setup. (see Operating
Procedure)
1200/2200 Sound Level Meter Operator’s Manual
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General Overview
2.3 Output Jack:
The model 1200 provides an output jack on the bottom of the meter for
measuring the weighted AC signal before the rms/log detector and the DC
output of that detector. Both signals are real time, i.e. LEQ is not
represented at the DC output. This jack may be connected to any load
without affecting the operation of the meter. Connection to low
impedance loads will require correction for the 1 Kohm impedance of
these outputs and will also decrease battery life.
The output jack takes a 3.5mm stereo plug. (See Figure 2, Output Jack
Connections.)
2.3.1 DC Output Function:
The SPL or PEAK level over the range selected is linearly represented by
a DC output. The output changes 16.7mV/dB or 1V/60dB. This output is
provided for connecting a 0 to 1 volt span data recorder. (See section 4.4
Data Recording)
2.3.2 AC Output Function:
This jack provides the amplified, frequency weighted AC signal at the
input of the RMS detector.
Figure 2. Output Jack Connections