Calibrating the SPL reading gives REW an absolute SPL reference by entering
a reading from your SPL meter while a speaker or subwoofer calibration signal
is playing. Alternatively an SPL calibrator may be used.
- Select the Mic/Meter
tab of the Preferences panel
- If using an SPL meter set it to C weighting and tick the
C Weighted SPL Meter box in the Mic/Meter
Preferences. Set the meter range to suit the measurement level used in
the check levels process
(the 80dB range is recommended for the Radio Shack meter). If using
a mic and preamp leave the C Weighted SPL Meter
box unticked
- Open the REW SPL meter by clicking the SPL Meter button in the toolbar
then press the Calibrate button
- On the dialog which appears choose whether to calibrate the meter
reading using your subwoofer or a main speaker driven by a calibration
signal generated within REW, or to use an external test signal you provide,
making the appropriate selection in the drop-down box and clicking OK.
- Enter the reading from your SPL meter in the calibration panel and
press Finished when done
For more information about the SPL Meter see the SPL Meter help
- At the end of the calibration process a message is displayed showing the
maximum SPL that can be measured with the current input level settings. If
higher SPL needs to be measured the input sensitivity must be reduced by lowering
the soundcard input volume setting or, if using an external microphone preamp,
reducing the preamp gain.
- A warning is shown if measurements are attempted before
calibrating the SPL reading as the results of the measurement would
not reflect the actual SPL. The SPL reading is shown in red
until the SPL calibration procedure has been completed
- REW remembers the calibration setting for the next startup,
so it will usually not be necessary to repeat this process, but check the
REW SPL reading against your SPL meter or calibrator before starting a new set
of measurements
- If the input volume setting is changed or another soundcard input is
selected it will be necessary to repeat the calibration process
(selecting a different input or input device will cause REW to
treat the SPL reading as uncalibrated - the reading goes red).
REW is now ready to
make measurements.
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