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How to Interpret the Graphs
As indicated in
Things you can accomplish with this application
(page 3), the reverb characteristics graph
can be used as reference when determining the calibration time position with the receiver’s “Advanced EQ
Setup” function. It is also a valuable means for checking the effect of measures taken to improve the
acoustics of the room.
The group delay characteristics graph can be used to check the group delay characteristics (before
calibration) of the speakers being used and the effect of calibration with the Full Band Phase Control
function. For details, refer to
Reading the group delay characteristics graph (Group Delay)
on page 25.
How to interpret reverb graphs (Reverb)
The graphs show changes in microphone input level along a time axis, beginning from a state of quiet at
time 0, when test tones begin to be output, and continuing while a constant level of sound is output from the
speakers.
• If there is absolutely no reverberation in your room, the graph will look like figure A below.
• If there is reverberation, the graph will show a gradual accumulation of acoustic power, as shown in figure
B.
• Due to an effect known as “group delay”, lower frequencies may take longer to be generated than higher
frequencies (this is most obvious when comparing the frequencies around 0 ms).
• If a graph extends beyond the display range, or almost fills it, you can change the display by using the Z
(Zoom) control on the graph adjustment bar, adjusting the display range of the Level [dB] scale so that the
whole graph is visible.
• Since channel level and speaker distance settings are displayed in the graphical output, it is best to make
sure these settings (made in the Auto MCACC “ALL” or “Channel Level” setup) are adjusted properly
before reverb measurement.
• Even in cases where there is a great difference in the output levels of different frequencies (the frequency
characteristics of the room are poor), the frequency characteristics of individual channels can be set
closer to flat using the “SYMMETRY” or “ALL CH ADJUST” calibration settings in the receiver’s “Auto
MCACC” function. (For details, see page 44 in the receiver’s Operating Instructions.)
• It is usually not possible to calculate the equalization values employed by the receiver’s Advanced EQ
Setup function simply by viewing the graphs displayed on your PC. (This is because the automatic
adjustments made by Advanced EQ Setup function take account of factors such as equalization band
interference and analytical filter characteristics, to achieve the optimum characteristic profile.)
• There may be differences on the reverb characteristics graphs after measurements with the Full Auto
MCACC function as compared to after measurements with the Reverb Measurement function (Manual
MCACC “EQ Professional”) due to the standing wave control setting. With Full Auto MCACC, the
reverberations are measured with standing wave controlled, so the reverb characteristics graph does not
reflect the influence of the standing waves. By contrast, with Reverb Measurement, the reverberations are
measured without standing wave control, so you can check the reverb characteristics including the
influence of the standing waves. If you want to check the acoustics of the room (with the standing waves),
we recommend using Reverb Measurement.
Note
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