Forward firing port vs rear firing port ?

[dis]

<font color='#000000'>I've notice that some speaker manufacturers like chose to place their ports in the front while others chose to use the back.

My bookshelfs have their ports in the back and I've notice that the port emits lower freq signals than the actual driver. According to my ear I see this as a good thing.

The only potential problem I foresee is port noise if the speaker is driven really hard. So does anybody know why some chose the back and others the front

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[Rob Babcock]

<font color='#000000'>Performance-wise it shouldn't matter much which way the port faces. &nbsp;The bass isn't directional.

The main advantage of rear ports is that higher frequency components that may &quot;leak&quot; thru the port tends to be less audible, as it's far off axis. &nbsp;Any chuffing or port noise is also less noticeable on rear ports.

The principal advantage of front porting is that if you're forced to place the speakers closer to the wall than is optimal, front ports will perform better.</font>

 

[Ultra Nexus]

<font color='#000000'>I guess front ported bookshelf speakers are good for rear channel since it can be fixed easily to a wall... in which case a rear ported speakers aren`t, but thats just my opinion

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[PaulF]

<font color='#000000'>Its also a question of internal baffle design. The sound emitting from the port needs to be in phase with the driver.</font>

 

[Khellandros66]

<font color='#000000'>Also Bass reflects off the wall in a room (why there are bass traps) &nbsp;so a rear firing port will bounce the bass of the wall, this can cause acoustical naunces, and maybe harder to place.</font>

 

[toquemon]

question: Would a front ported speaker still have a bass enphasys if placed near a wall?. Is the effect(bass emphasys) greater in a rear ported than in a front ported?.
My listening room is very solid (bricks and cement) and I don´t know what kind of speakers would work best (for minimizing interactions with the walls or wall-coupling or wherever distortion)

 

[cam]

question: Would a front ported speaker still have a bass enphasys if placed near a wall?. Is the effect(bass emphasys) greater in a rear ported than in a front ported?.
My listening room is very solid (bricks and cement) and I don´t know what kind of speakers would work best (for minimizing interactions with the walls or wall-coupling or wherever distortion)

To me, a front ported speaker is better due to the fact you will not have positioning problems. A front ported speaker will have no effect placed against a wall. Rear ported will sound boomy and interfere with your over all sound especially when you are incorporating a sub, so it is important to give rear ported speakers room. In your situation I would opt for front ported unless you find a speaker that sounds awesome (to your ears) and is at a price that you just can't give up. So in other words, if you buy some speakers that you are happy with, rear or front ported, as long as you like them, then it doesn't matter.

 

[annunaki]

<font color='#000000'>Performance-wise it shouldn't matter much which way the port faces. &nbsp;The bass isn't directional.

The main advantage of rear ports is that higher frequency components that may &quot;leak&quot; thru the port tends to be less audible, as it's far off axis. &nbsp;Any chuffing or port noise is also less noticeable on rear ports.

The principal advantage of front porting is that if you're forced to place the speakers closer to the wall than is optimal, front ports will perform better.</font>

Actuallly Rob, bass only tends to be non-directional around 60hz or so (from my experiences) when using 18-24 db/oct. filters. Up to 1st order harmonic information can bleed through making bass localized as we (unfortunately) do not have brick wall type filters. Using crossover points such as 80hz-100hz can yield bass that is quite directional. Especially if a crossover slope of less than 18db/oct. is used.

However, in this case you are pretty much right as the bass is coming from the same general location (whether it be front or rear placement). My vote is for front ports as placement (within the room) is much more flexible. One cannot really be considered better than the other. What really matters is how the drivers and enclosure interact and function together as a system.

Sorry to be a stickler Rob

 

[JoeE SP9]

I also believe that a front firing port is better, however a rear firing port allows one to do some tweaking of the bass response by varying the distance from the front wall.

 

[markw]

Front, rear or no port...

...Bass is enhanced when a speaker is in close proximity to any room boundary. The more, the merrier.

 

[Ken]

Some port observations

In my main speaker design I chose to place the port in the rear simply for aesthetic reasons. I have read in my speaker design books that a rear port will raise the overall low end response by a couple of hertz. The port is most active at the frequency of the box at which point the reaction of the woofer with the box causes the woofer not to move at all. So all of the sound at that frequency is emanating from the port. I have experimented with this with a sine wave generator, it is a really cool phenomenon. Like some of the other responses have said, I'm sure it causes different responses with the room and in hind sight I would put the port in the front.