Calibration Tutorial
Introduction
The monitor calibration system on the AWS 900 console enables the level of any loudspeaker connected to the
AWS 900 to be trimmed by ±10dB. This allows for quick and easy calibration without having to physically alter
settings on the individual loudspeakers. Calibration is important so that each loudspeaker will produce the
same level of sound, and for setting reference monitoring levels. Note that with the monitor gain at maximum a
trim level of +10dB corresponds to unity gain through the monitor section.
Note: Do not attempt to carry out loudspeaker calibration unless you have accurately calibrated test equipment.
Sound Level Meter Set up
Position your Sound Level Meter (SLM) on a microphone stand for maximum stability and for the least
interference from the operator. Set the level to 80dB, C Weighting with a slow response. When calibrating, a
recommended level of 85dB C is required for each loudspeaker.
Reference Level: A reference value of 85dB is the Dolby Reference level used in movie theatres and movie
presentations. This level was set by the SMPTE (Society of Motion Pictures and Television) organisation to
ensure and achieve repeatable results of a finished product for cinema post-production work. For more
information on Dolby and for speaker setups, please visit their website at:
http://www.dolby.com
.
C Weighting: Human hearing sensitivity varies with frequency, which can be shown with loudness curves –
please visit
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
and click on
Sound and Hearing>Sound
Level Measurement>Ear's Response Curves
for graphs and detailed descriptions. Sound Pressure Level
meters have different filter contours, or weightings, corresponding to the loudness curves of the ear. The
different contours are intended to match the ear at different sound intensities. C-Weighted curves are used for
high sound levels, and corresponds to the 100 phon loudness curve (see link above). This filter contour doesn't
filter out as much of the low or high end of the spectrum when compared to the other filter contours (A and B
weighting) – please visit
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
and click on
Sound and
Hearing>Sound Level Measurement>Filter Contours A, B, C
for graphs of the filters and detailed descriptions.
Figure 1 - Sound Level Meter
Place the SLM on its stand in the position where the sound engineer would sit at the console, at head height.
Point the SLM in the direction of the loudspeaker you are calibrating. See figure 2 for position.
AWS 900 Tutorials
1
AWS 900 Calibration Tutorial
