Efficiency Bandwidth Product (EBP) EBP = Fs / Qes 50 or less = best used in a sealed enclosure. 50 - 90 = flexible enclosure options. 90 or greater = best used in ported enclosure. -OR- Qts < 0.30 - ported Qts = 0.30 - 0.50, use ported or sealed. Qts > 0.50 sealed
Woofers with Qts of less than .35 are more effective in ported enclosures.
Woofers with Qts of greater than .40 are more effective in sealed enclosures.
Woofers with Qts between 35-40 are borderline, and may be used in either or... The result will be almost identical. These woofers are "Ideal".
You may choose to run your woofer in any enclosure you like, but it will cost you efficiency. I sometimes use a woofer in a lesser efficient enclosure just so I can ballance out my system. I do it for allignment/speed/frequency response purposes, not volume.
you're just using more narrow guidelines than I did.. that's all. Most people are pretty decided on the type of box they like before they start though, so it's more a matter of choosing the right sub for your application than choosing the right box for your chosen sub if it's done right.
