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Calculating Vent Air Speed

 This calculator is intended to help you determine the speed of the air in a port. This will help you decide if a particular port is too small for your application, which will cause noise at high volume levels. This is not intended for use on bandpass designs. The answer is in percentage of the speed of sound. If you don't need to know the air speed in the vent, click here to automatically calculate a port that is the proper size for your speaker enclosure.

Speaker Reference Efficiency

A general rule regarding port air speed is to try to keep it 10 percent or less of the speed of sound.

Explanation of Terms
W is the acoustic power output of the speaker in Watts. You can calculate this by multiplying the reference efficiency times the power handling of the speaker.
Fb is the tuning frequency of the enclosure.
R is the radius of the port.
Mach is the speed of sound in air (344.8 m/sec or 1131.2 ft/sec).
 To use this form, enter the values for W, Fb, and port radius. Then click the "Calculate Values" button, and the answer will appear in the empty text box.
Enter W
Enter Fb Hz
Enter Radius  inches
 percentage of Mach

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