Sealed vs. Ported Subwoofer Enclosures in Pro Audio

Art Welter

Jan 11, 2011
Re: Sealed vs. Ported Subwoofer Enclosures in Pro Audio

Pardon the comparison, but Keystones remind me (visually) of Karlson's. (Showing my age, aren't I)?
Relatively aged ;^), grew up listening to 8" Karlsons my dad built in the 1960s, the first cabinet I built in high school shop was a 15" Karlson, around 1972.Sold it ASAP. The Karlson exit looks more like a Christmas tree, internally it is a bass reflex. The Keystone has around a 10 foot folded horn path terminating at the floor. One of the dozens of exit shapes tried was more similar to the Karlson, but the keystone shape worked the best compromise between low end extension and a smoother upper end.

Fred Campbell

Dec 1, 2013
Re: Sealed vs. Ported Subwoofer Enclosures in Pro Audio

Per and David, thanks for your responses.

David, given the nature of the forum I think the assumption is that the output levels will be closer to maximum than minimum.

Unfortunately I operate at a level where budget is a major concern, so the ability to optimise less than perfect components is a plus.
Oct 25, 2018
Bideford, Devon. UK
Ported subs offer virtually free improvement to low end output/efficiency depending on your preferred viewpoint. This relates very closely to profit for the manufacturers. To match the output using sealed enclosures requires larger or better drivers, or both due to the early onset rolloff. This is not a good selling point.
In my view, the overwhelming weakness of ported subs is the huge increased in stored energy with relatively low damping in the system, rendering good step/transient response impossible, since the energy is dissipated over a relatively long time period after the exciting force (provided by the driver) has been removed. One has only to look at the step response of sealed against ported enclosures, which shows the massive increase in settling time of the latter. I believe that any ported speaker offers lower fidelity of reproduction in relation to a comparable sealed one.