rear port plugging

[croseiv]

My RC-70s come with port plugs. So I guess it was designed either way. What floats your boat.

So that would mean your speakers were designed to be plugged or not. Do you notice a decrease in output when plugged? I would imagine the speakers output capabilty drops somewhat when the ports are plugged.

 

[Exit]

Plugging up the ports not only cuts out the bass comming out of the ports, but it alters the base speaker from being bass reflex to acoustic suspension and the woofer is not designed to play against the increased air pressure in the box. At the port frequencies it is low in the bass spectrum and will flow out in one or two inches of space. The port base iproduces non-directional bass which flow out into the room and combines with the bass coming out the front of the speaker..

 

[TLS Guy]

Plugging up the ports not only cuts out the bass comming out of the ports, but it alters the base speaker from being bass reflex to acoustic suspension and the woofer is not designed to play against the increased air pressure in the box. At the port frequencies it is low in the bass spectrum and will flow out in one or two inches of space. The port base iproduces non-directional bass which flow out into the room and combines with the bass coming out the front of the speaker..

Actually the pressure in the box is usually highest ported, that is why the cone just about stops still at resonance and then quickly decouples below resonance.

If you plug the port, the F3 will go up by at least half an octave or more, but will roll off 12 db per octave instead of 24db per octave. The biggest problem is damping. A ported enclosure requires light damping, with only a little fill, or the Fb is killed. A sealed enclosure requires heavy fill to work correctly.

 

[Djizasse]

I'm going to have this problem on my speakers.

If I understand correctly, with the speaker's port so close to the wall, the sound waves will reflect at the wall and alter the frequency response, resulting in a muddy sound.

Can I put a deflector (a small rectangle made of metal or wood, or even a pyramid) to redirect the sound waves to the sides? Or would I just be trading one problem for another?

 

[Exit]

I think the port will function ok as long as it is not plugged or the speaker is flush against the wall so it is plugged. An inch or two clearance should be fine.

 

[TLS Guy]

I think the port will function ok as long as it is not plugged or the speaker is flush against the wall so it is plugged. An inch or two clearance should be fine.

I absolutely agree with that. We are not talking reflection here, the wavelengths are too long. If you did reflect, you would reflect what you don't want, which is mid range escaping from the port.

You just need to leave enough clearance for the air to escape without trouble. Play a test disc at the frequency where you can feel the most air pulsating from the port. Now put it where you plan, if the air feels as if it is speeding up, when you feel the air escaping from the back of the speaker, or the resonant frequency changes, then you are too close to the wall, and are adding air load to the port. The issue is not reflection, but adding air mass to the port. If you don't add mass, you will be fine.

 

[thisonekidmongo]

I realize this is for a slightly different reason, but -- Iplug the ports (using bundles of cut-up drinking straws, currently) on my Rocket RSC200 center, because otherwise it sounds way too boomy, echoey and muddled sitting in its cabinet under my TV. If I leave the ports free, dialogue sounds like it's being shouted from a box into another box. But is plugging up the ports drastically altering the speaker design or even harming it, as others have suggested? I don't believe the ports are used that much on the RSC200 anyway, except for the lowest frequencies (and I have the crossover set to 80, though it's capable down to 50).

 

[TLS Guy]

I realize this is for a slightly different reason, but -- Iplug the ports (using bundles of cut-up drinking straws, currently) on my Rocket RSC200 center, because otherwise it sounds way too boomy, echoey and muddled sitting in its cabinet under my TV. If I leave the ports free, dialogue sounds like it's being shouted from a box into another box. But is plugging up the ports drastically altering the speaker design or even harming it, as others have suggested? I don't believe the ports are used that much on the RSC200 anyway, except for the lowest frequencies (and I have the crossover set to 80, though it's capable down to 50).

You have changed the tuning of the speaker drastically. If you want to use it like that, plug the port and fill the speaker with polyfill. Fill heavy but do not compress.

You won't damage the speaker.

 

[Sheep]

The Energy C-C3 (dual 6.5inch woofer center channel, set up from mine) has rear firing ports, and they included port plugs for cabinet and close rear wall installations.

I would try it out and see if the difference is noticeable/desirable. If not, go back to the previous setup.

SheepStar