Example:

Guy has a IB (infinite baffle, take Vas, multiply by 4, ideally 10, and that is the size of your box) setup in his attic.

Thought he should try LLT (large low tuned ported box) so he ran two 10" ports per bank of drivers and still had issues with turbulance as in, he could hear the air moving and it detracted from the sound quality.

Usually 27 m/s is your absolute max port velocity.

ideally lower...