CR:270 Series User Manual
Page 7
CR:270 Controls
Weighting
This is the lowest position slide switch, Marked OFF
dB(C) dB(A). The CR:274 and CR:273 instruments
feature dB(Lin) in the place of dB(C).
The left hand position OFF disconnects all power
from the instrument and empties the Leq store.
Thus if the unit is turned off, all the accumulated
Leq data is lost. Therefore, always read the meter's
Leq value before turning the CR:27x to 'OFF'.
Similarly the PEAK(C) data is also lost. Normally for
industrial measurements the switch should be in
the 'A' position where the CR:27x will measure in
dB(A).
Under NO CIRCUMSTANCES should this switch or
the range switch be moved during an
Leqmeasurement as the Leq will be reset by the
instrument to prevent nonsensical results due to
mixtures of levels or weightings.
The centre position, marked dB(C) permits use as a
normal sound level meter with the 'C' Weighting
filter in circuit.
The right hand position dB(A) permits use as a
normal sound level meter with the 'A' filter in
circuit.
Range
This is the three position slide switch which selects
the operating range of the meter.
In the left hand position, marked <75 the
instrument measures levels on average below 75dB
although it will function accurately up to 80dB. For
Leqmeasurements averaging over 75dB you are
recommended to switch to the centre or right slide
position.
In the centre position, marked 50 - 100 the instrument measures levels in the range 50
to 100dB although it will function accurately up to 110dB. For Leq measurements
averaging over 100dB you are recommended to switch to the right slide position.
