Plugging speaker ports...any harm?

pearsall001 · « **on:** 9 Feb 2007, 07:28 pm »

Just a question out of curiousity. Some speaker designs are sealed & others are ported. Now granted, the designer had specific goals in mind for their performance by choising one of the two designs. What is the real difference between the two? Does a ported speaker provide more bass than a sealed speaker? Does one design perform better than the other, & if you were to stuff the port holes how would it effect the speakers performance? Could that possible harm the speaker? I think it's all about moving air inside the cabinet. In a sealed design where does the air go or maybe it doesn't. I guess either design has it's +/-. Any thoughts?

WEEZ · « **Reply #1 on:** 9 Feb 2007, 11:26 pm »

This is a question better answered by some of the speaker guys here at AC. But...

..generally, a sealed design will begin to roll off in the bass at a slightly higher frequency than a ported design, but at a more gradual slope. Usually, the cabinet is smaller with a sealed design. And usually, the bass will be percieved a 'tighter' with a sealed design. There is much more to it than that, however. There are great designs of both types.

You probably won't hurt anything by plugging the ports on your speakers, and it may help to improve the blending if you choose to use a subwoofer, but it might alter the voicing of the midrange. Hard to say. Many variables.

Rick Craig, Dave Ellis, or Jim Salk could explain it better than me

WEEZ

avahifi · « **Reply #2 on:** 10 Feb 2007, 01:12 am »

Actually plugging speaker ports can be a good thing.

In my old home in Burnsville we had mice. My two cats loved to catch them.

One day I noticed that my ported B&W 801s did not smell as nice as before. I investigated and found that the cats had discovered they could push their dead mice into the cabinet through the front panel port.

A complete disassembly and cleanout fixed the problem, phew! The cats were not happy because I had eliminated their mouse storeroom.

Regards,

Frank Van Alstine

WEEZ · « **Reply #3 on:** 10 Feb 2007, 01:33 am »

TheChairGuy · « **Reply #4 on:** 10 Feb 2007, 02:09 am »

I can't top Frank's reason for plugging ports....

I'll just add that distortion for any driver increases as it reaches ever lower in frequencies. Every driver acts differently for reasons others are more aware of than I....but all drivers do. Porting enclosures most often forces the mid/bass unit to work at frequencies it is ill-equipped to handle without a lot of distortion. As your system improves in resolution, you begin to hear this distortion more and more...and it becomes more and more aggravating

Plugging the ports will roll off the bass at higher frequencies....allowing the speaker to act more as satellite and increasing it's chance of integrating with a subwoofer more cleanly. If you plug the ports, and don't integrate a subwoofer...you'll lose ultimate bass extension (as WEEZ mentioned)

Yes, I'm sure one of the more capable DIY guys and or speaker builders will chime in with their expert opinions on the subject....but the more I merrily roll along in this hobby, and study what I like and dislike about speaker performance - cone distortion leads the list of no-no issues. The more you can do to eliminate them in your speaker, the more you will enjoy music daily.

So, plugging the port rolls off the bass from the mid/bass unit, while rolling out a lot of cone related distortion that drivers particularly exhibit at their (lowest) frequency limits. You get less bass, but less distorted bass, too....and it makes it all the easier to integrate with a subwoofer (that is properly designed to only handle the lowest couple of octaves with less distortion than most mid/bass drive units in your speaker enclosure).

I'm sure this an opinion not shared by everyone, but it has worked for me in every instance of a ported speaker in the past 15 years or so

Bill Baker · « **Reply #5 on:** 10 Feb 2007, 02:17 am »

Quote

One day I noticed that my ported B&W 801s did not smell as nice as before. I investigated and found that the cats had discovered they could push their dead mice into the cabinet through the front panel port.

Sorry Frank but that one deserves a chuckle.

EProvenzano · « **Reply #6 on:** 10 Feb 2007, 02:37 am »

Quote from: TheChairGuy on 10 Feb 2007, 02:09 am

So, plugging the port rolls off the bass from the mid/bass unit, while rolling out a lot of cone related distortion that drivers particularly exhibit at their (lowest) frequency limits. You get less bass, but less distorted bass, too....and it makes it all the easier to integrate with a subwoofer (that is properly designed to only handle the lowest couple of octaves with less distortion than most mid/bass drive units in your speaker enclosure).

I'm sure this an opinion not shared by everyone, but it has worked for me in every instance of a ported speaker in the past 15 years or so

Hmm.
My understanding is, well, different.
A ported woofer will move less as it reaches closer and closer to the port tuning frequency. The energy is instead seen as increased air flow through the port. However, below the port tuning frequency the driver will unload with huge x-max demands. In theory, up until the tuning frequency the ported woofer is working less.

I've read Dave Ellis' comments on this subject in various strings. He speaks very intelligently on the matter.... I'll see if I can dig up a thread...

Good question

EProvenzano · « **Reply #7 on:** 10 Feb 2007, 02:45 am »

Here is some good reading:

http://www.audiocircle.com/index.php?topic=7813.0

Rob Babcock · « **Reply #8 on:** 10 Feb 2007, 04:23 am »

Some manufacturers actually ship their speakers with port plugs, to use if needed (eg rear ported speakers placed very near a room boundry). I've used foam to plug ports in speakers with mixed results.