Pioneer VSX-9040TXH, VSX-21TXH How to Interpret the Graphs, How to interpret reverb graphs Reverb

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 display can be switched between the reverb characteristics graphs before and after calibration. For details, see About the display of the reverb characteristics graphs before and after calibration (page 23).

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.

Note

•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 ADJ” calibration settings in the receiver’s “Auto MCACC” function. (For details, see page 78 of the receiver’s Operating Instructions.)

•It is usually not possible to calculate the equalization values employed by the receiver’s Acoustic Cal EQ function simply by viewing the graphs displayed on your PC. (This is because the automatic adjustments made by Acoustic Cal EQ 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.

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