Mc Squared System Design Group, Inc

Main Page > Useful Calculators > Q Calculator

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The Speaker Q Calculator

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This page will calculate the approximate Q of a loudspeaker from the rated coverage angles. To accurately calculate Q you really need to use a full 3D polar plot to identify the coverage variations compared to a true spherical coverage pattern.

Input loudspeaker coverage
Horizontal coverage
Default value
Enter new value
in degrees
Vertical coverage
Default value
Enter new value
in degrees

You can change the values and re-calculate.

Loudspeaker Q
calculated here
Directivity Index
calculated here
in Decibels

Note that the theoretical Q or Directivity index of a loudspeaker is very theoretical. Real live loudspeakers tend to vary significantly from theory, and one manufacturer's 90x40 loudspeaker is not often the same as another's. Loudspeakers also vary widely in directivity with frequency. Where a speaker may actually have a Q of 12.8 at 2kHz, it is likely that that the directivity value would drop to a Q of 4 at 500Hz, and as low as a Q of 1 at 125Hz. A thorough acoustical and sound system design would include the prediction of expected sound system behaviour across the entire audio bandwidth, taking into consideration the variations in loudspeaker coverage and variations in reverberation time. This is where computer modelling is very handy.

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Mc Squared System Design Group, Inc Mc Squared System Design Group, Inc
323 - 901 West 3rd Street
North Vancouver, BC V7P 3P9
Phone 604 - 986 - 8181