Calculate (Fs / Qes). If above 85 and the Qts value is 0.6 or less, then the driver is likely suitable for a vented enclosure.

The only information needed to use the calculator is the nominal driver size. Width, height, depth values shown in the calculator results are the interior dimensions.

The back and sides of the enclosure interior should be lined with damping material. A small enclosure can be lined with a few layers of craft felt. Consider rounding off the backside of the cutout hole to allow air to escape from the backside of the driver.

Source reference:

• Weems David B. & Koonce G.R. (1990, 2000) Great Sound Stereo Speaker Manual, The McGraw Hill Companies Inc.