Why do some bass-reflex speakers have a port on the rear panel while others have a port on the front baffle where the drivers are? And is the port location important?
Many smaller speakers use a rear port simply because there isn’t room on the front baffle. A designer might specify a woofer that’s comparatively large in relationship to the baffle dimensions. Other speakers use a tweeter with a large mounting plate for rigidity so even if the tweeter itself is small, the physical package it comes in isn’t. Still another reason for not having a front port may be bracing inside the enclosure that mounts exactly where the port would otherwise go.
A rear port solves these problems. There’s generally a lot more room to place the port as the only other element on most rear panels is the speaker wire terminals and they’re comparatively small.
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From a performance perspective, there’s virtually no difference whatsoever between a front port and a rear port.
The only thing you have to be careful about with a rear-ported speaker is placement. Don’t mount it flush against a wall or other solid surface. That will restrict the air flow in and out of the port and thus restrict bass response. (Without going into details, the woofer cone and port work together to bring you the bass you want.)
The solution is to leave enough room (about 6” will do nicely) between the rear panel of the speaker and the solid object behind it. That’ll allow free air movement through the port so you’ll get all the performance you’ve paid for.
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