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How to Interpret the Graphs (Continued)
Deciding the time period for Advanced EQ Setup calibration
In standard Acoustic Cal EQ calibration, the input data from the microphone is analyzed at fixed time
periods from 80 to 160 msec (the red area in Figure 1). Advanced EQ Setup allows you to choice a point
(20 msec width) in the range from 0 to 80 msec (the blue area in Figure 1).
Note
The time period setting is that made on the receiver using “Advanced EQ Setup” of the “Acoustic Cal EQ
Professional” function. This setting is not required when you use “Auto Pro.” and the standard Acoustic Cal
EQ. (For details, see page 88 in the Operating Instructions.)
Figure 1 Comparison of microphone data acquisition time periods
To decide the time period for Advanced EQ Setup calibration, view the graphs of the measured reverb
characteristics, and refer to the following three patterns.
Pattern 1: Different reverb characteristics for high and low frequencies
In rooms with reverb characteristics like those shown in Figure 2, lower frequencies often seem overly
reverberant compared to higher frequencies (i.e. the room sounds ‘boomy’). If you calibrate the receiver
using ALL CH ADJUST of the standard Acoustic Cal EQ, data will be acquired in the 80 to 160 msec range
(the red area of Figure 2). The analysis concludes that low frequencies are too loud and high frequencies
are too soft, so it adjusts the equalization curve to strengthen high frequencies. In fact, however, the high
frequencies may already be loud enough if measured within 40 msec, which is the time it takes for sounds
coming directly from the speakers to reach your ears. Therefore, the standard Acoustic Cal EQ may result
in a room where high frequencies sound shrill. In cases like this, setting the time period for Advanced
EQ Setup to 20 to 40 msec (the blue area in Figure 2) to adjust for sounds coming directly from the
speakers can flatten the frequency response for direct sounds (including initial reflections) and give a
better-balanced sound field.
Figure 2
Level
(dB)
Acoustic Cal
EQ Professional
calibration range
(selectable points)
Standard Acoustic Cal
EQ calibration range
(fixed)
Time (in ms)
Level
(dB)
Time period
point to be
selected
Low frequencies
Time (in ms)
High frequencies