User manual

PRELIMINARY AND SUBJECT TO CHANGE
miniDSP Ltd, Hong Kong / www.minidsp.com / Features and specifications subject to change without prior notice 25
While the locations indicated are recommended, you can use a different set of locations if necessary. The
important thing is to ensure that the measurement locations are spread over the whole listening area and that
the microphone is moved a sufficient distance vertically as well as horizontally.
In some cases, such as when the listening area is very close to the loudspeakers, the size and in particular the
height of the measurement area can be reduced, to avoid discrepancies caused by varying output response from
the speakers themselves.
3.5.2 Executing measurements
With the microphone in place at the central location and pointed vertically (that is, towards the ceiling or floor),
click on the Start button. The DDRC-88A HDMI audio processor will generate a test signal, audible as a frequency
sweep through the left speaker, then the right, and so on through all channels, including the subwoofer. Finally,
the frequency sweep plays through the left speaker again.
While the measurement proceeds, the time-domain response graph of the captured audio signal is displayed at
the bottom of the measurement tab. (This graph is related to the magnitude response but is not the same
display. Its purpose is to verify that the recorded signal level is in a suitable range.)
At the completion of the measurement, the status bar will update with a progress indicator as the program
performs calculations on the measurement. If the measurement was successfully captured, the red arrow
marker will advance to the next location to be measured.
If the program indicates that the measurement was not successful, you will need to take corrective action. The
most common error is related to signal level:
 The measurement signal is too low to ensure a clean capture.
 The measurement signal is too high and the audio signal has exceeded the maximum level (clipping). This is
shown in red on the signal graph.
In either of the above cases, go back to the Output & Levels tab and adjust the output volume or microphone
input gain. Then re-run the measurement. (You do not need to redo the measurements you have already
successfully completed, even if you change volume or gain.)