Chapter 2 — Checking Procedure
Checking Procedure
2238 Mediator Integrating Sound Level Meter
Service Manual
Brüel&Kjær
14
Table 2.4 C-Weighted (LCFP)
2.3.4 Overload
Testing is done in the Basic SLM mode, as the overload feature uses the same elec-
tronics and hardware under both Basic and Enhanced SLM configurations.
Action:
● Press , select Application, then Basic SLM. Press , select Weightings.
Use to set Detector 1’s Freq. Wgt. to C, and Detector 2’s Weighting to
Peak/C. Use to select OK, then select General. Set range to 50 - 130 dB.
Use to select OK, then to Close.
● Set generator output to 2.0V (126dBµV), 20Hz.
Result:
● No overload indicated. Display reads » 123.8dB (RMS).
Action:
● Increase Generator output by 1.5dB.
Result:
● An overload is indicated in the display window with .
● Display reads »125.2dB (RMS).
2.3.5 Measuring Range–Attenuator Accuracy
Action:
● Set the 2238 Detector 1 to RMS, BB/F and C weighting. Set the range (you can do
this anytime directly by pressing ) to 50.0 - 130.0 dB. Press to OK. Set
the generator output to 1kHz, and adjust the generator amplitude until the dis-
Generator Freq.
Hz
dB SPL value
on the Display
Actual
Reading
Ref 1000 128.0 128.0
10 113.7+1.0/–3.0
31.6
125.0
± 0.5
3981
127.2
± 0.4
19950 116.8+1.0/–3.0
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