CR:270 Series User Manual
Page 11
Turning off Octave filters
To turn off the octave filters press on the OCTAVE FILTER button for 5 seconds. When
the octave filters are turned off the red LED's in the upper most label will all be
extinguished.
Filters and Weighting
The active filter red LED will flash if A weighting is selected for the instrument. The
FLAT position is the same as having the octave filters switched off but the latter saves
power if you are not using the filters.
Peak is always C weighted and so is not affected by the filter sets or Weighting switch
but both SPL and Leq are filtered as selected.
Display and Indicators
The LCD display of the CR:27x is scaled in decibels.
Annunciators
Full (Centre colon)
This indicates that one of the registers inside the CR:27x is full and that no further
Leqacquisition can take place. However, the readings when this colon is lit are correct
and the accuracy is not affected; it is simply that data acquisition stops. The CR:27x
will still function on SPL and PEAK(C). If this colon lights then read the Leq, note it
along with the peak, if required, and reset the instrument.
Overload (+)
The + sign at the left of the dB reading indicates that an overload of one of the
amplifiers has occurred. This can be an overload before weighting or an overload of the
rms signal. If the instrument is displaying SPL the + sign will flash momentarily when
the signal overloads the internal circuitry. There are however separate stores for Leq
and Peak which will latch the moment this overload occurs to indicate that the current
Leq or Peak measurement contains an overload. This latch can be seen by switching the
display to Leq. If the overload sore has latched the + sign will be permanently lit. The
latch is reset when Leq or Peak is reset thus starting a new reading.
Battery low
When this indicator comes on the batteries are discharged and the unit should not be
used because erroneous results may occur. The batteries must be replaced. Remove
discharged batteries immediately from the CR:27x to prevent possible leakage and
damage.
