The woofer cabinet is the enclosure loading the bass driver, and it shapes how a speaker rolls off, how it behaves near a wall, and how large it has to be for the bass it produces. It appears in the spec table for the 46 passive speakers and 14 powered speakers here that publish it, of which 39 and 12 respectively use some form of port.
Ported designs dominate because a port buys extra output in the bass for very little cost. What it costs instead is placement flexibility and a steeper roll-off below tuning.
Sealed
A closed box with no port and no radiator. The driver works against the trapped air inside, which acts as a spring.
Sealed cabinets roll off gently, at about 12 dB per octave below their tuning point. That gentle slope is why they often measure flatter in a real room, where room gain rises as the speaker’s own output falls and the two partly cancel out. They also tend to have tighter transient behaviour, and they are the least fussy about placement because there is no port to choke.
The trade is efficiency and extension. For the same cabinet size and driver, a sealed design gives up meaningful output in the bottom octave compared with a ported one. Only 3 passive speakers and 1 powered speakers here use a sealed woofer cabinet, which reflects how strongly the market favours the extra output a port provides.
Ported, Also Called Bass Reflex
A box with a tuned port. The air in the port resonates near the driver’s low-frequency cutoff and adds roughly 3 to 6 dB of output in that range, which is a large gain for the cost of a hole and a tube.
Two things come with it. The roll-off below the tuning point steepens to about 24 dB per octave, so output disappears faster once you get below where the port works. And the port itself needs air, which makes where the port fires a real placement constraint rather than a detail:
- Front ported. The most flexible. The cabinet can sit close to the wall behind it without choking the port. ELAC DBR62, JBL 4367 and Revel F208 are front ported.
- Rear ported. Needs genuine clearance behind the cabinet, typically six inches or more, or the port chuffs and the tuning shifts. The worst choice for a speaker pushed against a wall. KEF Blade Two Meta, Wharfedale Linton 85 and Klipsch RP-500M II are rear ported.
- Unspecified. Many records list only “ported” without a position. Where that matters for your placement, the manufacturer’s own page linked from the speaker’s card is usually the fastest way to check.
The practical rule is to match the port position to where the speaker is actually going. A rear ported speaker bought for a spot tight against a wall will underperform its own measurements no matter how good the drivers are.
Passive Radiator
A variant of the sealed box where a second undriven cone, with no voice coil and no magnet, replaces the port. Pressure inside the cabinet moves it the way a port’s air column would move, adding output in a similar range without the chuffing a port can produce at high excursion.
The trade is cost and complexity, because a passive radiator is a real driver-sized component rather than a hole. 3 passive and 1 powered speakers here use one in the woofer cabinet. It is far more common on portable speakers, where cabinet volume is scarce and a port would be impractically small.
A passive radiator is not counted as a driver, for the reasons set out in speaker drivers explained.
Open Baffle
No enclosure at all in the conventional sense. The driver is mounted on a flat panel, leaving the rear wave free to radiate into the room out of phase with the front.
This produces a distinctive dipole radiation pattern that interacts with the room very differently from a box, and it removes cabinet resonance as a variable entirely. What it demands in return is space, because an open baffle speaker needs real distance from the wall behind it to work, and it gives up low bass output unless the baffle is very large. The GR-Research NX-Treme is the example here.
How This Differs From The Subwoofer Enclosure Spec
Subwoofers carry their own Enclosure spec covering the same physics with a wider set of designs, including horn loaded and in-wall types that do not appear on full-range speakers. If you are reading about a subwoofer rather than a bookshelf or floorstanding speaker, subwoofer enclosure types explained is the more detailed page, including the full sealed versus ported argument and every port position in that data.
Where To Look Next
Cabinet design sets what the bass can do, so it reads alongside bass extension explained and frequency response explained. For the drivers the cabinet loads, see speaker drivers explained. For how the room finishes the job the cabinet starts, see how room acoustics affects speakers.
Every speaker’s woofer cabinet is in its spec table, across large bookshelf speakers, medium bookshelf speakers and large floorstanding speakers.
Frequently Asked Questions
Is a sealed or ported speaker better? Neither is better outright. A sealed cabinet rolls off gently at about 12 dB per octave, often measures flatter in a real room, and is the least sensitive to placement. A ported cabinet adds roughly 3 to 6 dB of output near its tuning point, at the cost of a steeper 24 dB per octave roll-off below that point and a port that needs clearance. Ported designs are far more common because that extra output is cheap to obtain.
Does port position matter? Yes, and it is a placement constraint rather than a detail. A front ported speaker can sit close to the wall behind it. A rear ported speaker needs real clearance, usually six inches or more, or the port chuffs and the tuning shifts. Matching port position to where the speaker will actually stand matters more than the difference between two well designed cabinets.
What is a passive radiator? A passive radiator is a second cone with no voice coil and no magnet that replaces a port in a sealed-style cabinet. Cabinet pressure moves it the way a port’s air column would, adding output in a similar range without a port’s chuffing at high excursion. It costs more than a port because it is a real driver-sized part.
Why do so few speakers use sealed cabinets? Because a port adds meaningful bass output for almost no manufacturing cost, and buyers reward deeper bass from smaller boxes. Sealed designs give up output in the bottom octave for the same cabinet size, so they tend to appear where flat in-room response and placement flexibility are the priority rather than maximum extension.