Ported, Sealed or Transmission Line


What are the pros and cons of ported, sealed and transmission line speaker cabinets?

Is one inherently better than the other?

Some Proac speakers use what looks like a bunch of straws in the port. Is this an attempt to create graduated friction similar to a transimission line to increase base from a smaller speaker?
cdc2
The straws? cuts down on port noise I've read. Ported speakers are designed to increase bass response of small speakers...a way of outputing the rear wave as energy to combine with the direct sound. I'm not a big fan but do own some of these type speakers...they work as long as you don't over-drive. I'm a planer man myself...which is another set of problems!

Dave
Check your local library and they'll usually have a few books on the topic. Weems' (David) might be better for what you need to know: just to get some general insight. The tone of the book is still quite contemporary despite looking 10years outdated. A two week checkout should be enough. Dickason's book isn't bad and more technical in every way that Weems'. Its a good book to have too, but get some momentum through something simpler. The answer to your question is kind of hard to answer in a condensed straightforward manner.
Is one inherently better than the other?

That question's answer is (IMHO) no. But, they do have real differences and performance tradeoffs, and other tradeoffs.
Again I sum it up..."Ported speakers make excellent bird houses".
Tobias writes:
Sealed box designs need more amplifier power, on the whole, because the cones have to work against the very stiff spring of the air trapped inside the box.
Although stiffness is provided by the air in the sealed box, the spider on a driver designed for acoustic suspension is less stiff, and compensates.

When Vilchur designed the acoustic suspension speaker he modified the driver spider to provide less spring restoring force on cone excursion because he knew the air in his sealed box would provide some restoring force.

The main reason the acoustic suspension speaker needs more amplifier power is the energy of the back wave is totally absorbed by the stuffing (converted to heat). In a reflex design, the out-of-phase back wave energy hits the port and is inverted 180 degrees, and is now in phase with the sound coming off the front of the driver. This extends the bass response, although the eventual rolloff when it does occur is much steeper (typically 12dB per octave as opposed to 6 dB per octave).

There are many good speakers using the bass reflex system.

Regards,