4. With the Measuring Amplifier set to "Ext. Filter" calibrate it for sound, vibration or
voltage measurements as described in its Instruction Manual.
5. Turn the INPUT and OUTPUT SECTION ATTENUATOR knobs of the Measuring Ampli-
fier to their extreme clockwise position and disconnect the reference source.
6. Set Filter Set controls:
SELECTIVITY "Bandwidth" and "Record Step" as required
RANGE "2 Hz — 20 kHz — A — Lin"
FILTER CONTROL MODE "Manual" — "Stop"
MANUAL FILTER CONTROL Required octave, third octave, A weighting or Lin.
frequency band in which measurements are to be
taken.
7. Apply the signal to be measured to the appropriate INPUT socket on the Measuring
Amplifier and step the INPUT SECTION ATTENUATOR knob anti-clockwise to obtain
a suitable meter deflection without the INPUT OVERLOAD lamp flashing on the Mea-
suring Amplifier and Filter Set.
If the deflection is insufficient even when the INPUT SECTION ATTENUATOR is in its
extreme anticlockwise position, then step the OUTPUT SECTION ATTENUATOR knob
until a suitable deflection is obtained without overload.
8. The signal level within the selected frequency band can be read from the meter
where 0 dB or full scale corresponds to the value indicated by the range indicator
lamps and/or the INPUT and OUTPUT ATTENUATOR knob settings of the Instru-
ment. See Instruction Manual for appropriate Measuring Amplifier.
When reporting measured levels it should be stated which octave, third octave,
weighting or linear frequency band has been used.
9. Use the MANUAL FILTER SELECTOR to select other frequency bands for measure-
ments in the same way.
3.3. USE WITH SOUND LEVEL AND VIBRATION METERS
In
To Ext.-140!
Filter V
Precision Sound
Level Meters
2203, 2209
2210, 2218
AO 0007/AO 0116
Vibration Me er
2511 To Ext.
In Filter
Band Pass Filter
1618
0087/AO 0064
790200
Fig.3.2. Use of the 1618 Band Pass Filter with B & K Sound Level
and Vibration Meters
As indicated in Fig.3.2 the 1618 Band Pass Filter may be used for octave and third oc-
tave measurements with a portable Sound Level Meter or Vibration Meter. Operation is
14
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