BRUEL & KJAER 2225 User Manual

Fig. 3. 3. Calibrating the instrument
6. Switch the Calibrator on and adjust the potentiometer with a small screwdriver as in
Fig.3.3 so that the LED at the 93 dB position just extinguishes but the 94 dB LED is
lit when "moving up" the scale, i.e . turning the sensitivity potentiometer screw
clockwise . This gives a calibration of 93,8 dB to correspond with the half-inch free-
field microphone sensitivity, with an accuracy of ±0, 1 dB :
This process is made easier with the Type 2226 if the DC Output plug is inserted to
override the "Max. hold" facility. This gives a display which is continuously adjus -
table both up and down instead of held at the max i mum value by the "Max. hold"
circuit, requiring continual resetting .
7.
Remove the Calibrator gently. It will turn off automatically .
8. Replace the dustcap or windscreen.
The Sound Level Meter is now calibrated and ready for use.
3.5. SOUND LEVEL MEASUREMENTS
3. 5.1. General
10
The accompanying booklet "Measuring Sound" should be read before proceeding with
measurements. Always use a Windscreen outdoors or in dusty environments and ensure
that the measuring position is suitable and that the background noise level is low
enough to make valid readings. In order to minimise the effect of reflections, the obser-
ver should hold the instrument at arms length or mount the microphone remotely on a
tripod using a connection cable.

BRUEL & KJAER 2225 Specifications

General

Brand	BRUEL & KJAER
Model	2225
Category	Measuring Instruments
Language	English