Front port vs Rear port

"The position too near the wall, so to speak, usually manifests itself in nearfield reflections, a larger problem imho than port constriction." - Lrsky

Well said - I agree 100%.

Regarding port location, note that if the speakers are designed for placement near room boundaries, the location of the port relative to those boundaries has already been taken into account. Audio Note, for instance, designs their rear-ported speakers for corner placement. Best to examine the specifics of a given speaker design rather than make decisions based on "rules of thumb" that have notable exceptions.

Even if a rear-ported speaker wasn't designed for placement near the room boundaries, in many cases it's possible to lower the tuning frequency by lengthening the port and/or reducing its cross-sectional area. This causes the speaker's inherent bass output to start rolling off higher up but not as steeply, so that it synergizes better with the additional room gain. This can of course also be done with a front port also, but it's more likely to be visually unacceptable.

One acoustic argument in favor of a rear port is that in most cases, with a bit of toe-in, your two bass sources (woofer & port) are now a different distance from room boundaries in all three dimensions. Thus their outputs will interact with the room modes a bit differently, in some cases smoothing the in-room bass significantly as compared with an equivalent front-ported speaker.

Finally, nearly all ports have a resonance in the midrange region (imagine talking through a cardboard tube), so all else being equal we'd like that unwanted midrange energy to start out facing away from us and to travel as long as path as possible before reaching the ears.

Duke
dealer/manufacturer

Weseixas, I believe that the fundamental resonance of an open-on-both-ends tube will occur at the frequency where the tube's length is equal to one-half wavelenth. For a port 6" long, that would be about 1.1 kHz.

In my opinion a nearfield or small-room setup would be where well thought-out rear porting is most likely to be superior to front porting, for reasons mentioned in my earlier post.

Duke

The audibility of coloration from a delayed signal gently peaks at about 2 milliseconds as I recall (based on an AES paper by by James M. Kates), corresponding to a path length difference of about 27 inches, but remember that the point of origin for the sound that emanates from the port is the back of the woofer cone, so that must be taken into account.

The significantly greater distance that must be travelled to reach the ears for the midrange output from a rear port in a nearfield setup (in comparison with the distance from a front port) means that it will probably be about 6 dB or so down in level compared to the output from a front port, and this will make a more significant difference than if the rear reflection distanace happens to correspond to 2 milliseconds. In addition, if the reflective surfaces around the rear port are not 100% reflective in the midrange, then that much less of its output will be reflected to the ears.

Uneven bass due to room modal behavior is generally worse in small rooms than in large ones, so the relative benefit from having the woofer and port interacting with the room modes differently (due to physical displacement in two or three dimensions) is theoretically greater in a small room.

Hence my position that well-though-out rear ports are likely to be superior in a nearfield or small-room setup.