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Rear vs Front Ported

post #1 of 7
8/5/04 at 3:17pm
Thread Starter 
Hey
What are the differences between these two designs? Does one offer better efficiency/sound? Ive done a search on this whole forum and havent found anything useful.
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post #2 of 7
8/5/04 at 4:34pm
I am assuming that you are talking about speakers right? If so, then I think the difference would have to do with the placement of the speakers. Front ported designs are made more for or at least have the ability to be mounted close to the rear wall or jammed to the wall on a bookshelf for example. Hencs most small speakers that would benifit from wall reinforcment may be front ported. If the port were on the back, one could not jam the speaker against the wall as it would block the output from the port. Also if a rear ported design is placed to close to a wall then the bass may become tubby, over-emphasised or bloated. I think that most speakers designed to benifit from wall reinforement (speakers with small drivers or lack of low bass output) are front ported, and speakers that have a full range sound that dont need the wall reinforcement have rear mounted ports for free wall mounting.

This is just my uneducated opinion and from what little bits and pieces I have picked up from reading a few mags.

I also think that it may have some aesthetic value as well!!

D
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post #3 of 7
8/5/04 at 7:32pm
...essentially what he said...

but, a front-ported design will allow you to hear directly the "other" stuff that comes out of the port besides bass (which is what it's for). You'll get midrange and all of that nastiness. Hence, rear-porting is what you want unless it's absolutely necessary to be front-ported.
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post #4 of 7
8/5/04 at 8:58pm
As some people I have arbitrarily decided to trust say, go rear ported unless you're putting your speakers REALLY close to the back wall, like less than a foot. The bass that you want coming from the port is nondirectional unless you're talking about some dinky satellite tuned to 150hz or something. In which case, geez, who cares what you do with that satellite
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post #5 of 7
8/5/04 at 9:27pm
I think whether a speaker is front-ported or rear-ported comes down to the actual design of the speaker. dudlew is right about placing a rear-ported speaker too close to the wall and having it sound tubby or bloated, which was what happened when I had Paradigm Mini-Monitor V.1's. A ported speaker will produce chuffing noises there when pushed hard, which is why you see all kinds of designs on ports....check out B&W's dippled designs, or Polk Audio's Power Port, or any other specialized port designs. I have Energy C-3 monitors, which are front-ported, and they allow me to put them closer to the wall since I have a small room.
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post #6 of 7
8/5/04 at 10:32pm
Rear porting has the advantage of slightly better coupling to the room front wall/corner. The disadvantages are lost output due to absorbtion by the rear wall (drywall acts like a membrane bass trap) as well as potential interference if the speaker is closer than one diameter.

Front porting has the advantage of being in better phase relationship to the driver, and less smearing thanks to the direct radiation.

Sound differences indoors are minor, and somewhat room dependant. The less reflective the room, or the farther away the front wall from the speaker, the better the front port works. Outdoors the difference is extreme (bass becomes rather directional without a room around the system/listener).

I always front port. I have even gone so far as to recut ports to move from the back to the front.


gerG
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post #7 of 7
8/5/04 at 11:09pm
Moving the speaker closer to a boundary generally affects the baffle loading, not interference with the port. By nominally increasing the width of the baffle by placing it close to the wall, the frequency where the baffle step begins to rise is lowered, which will amplify the lower frequencies. Speakers can be baffle step compensated, so if the xover has already been designed to lower output relative to the baffle step, it would be bad to place the speaker too close to the wall.

Gerg, depending on the cabinet depth, can't the rear port be every bit as in phase as the front port? As for the drywall acting as a bass trap, wouldn't that be in effect no matter which direction the port fired? I guess it may be exacerbated if it fired straight at the drywall. I certainly haven't run any tests on this myself.
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