3 Dual 8 Inch Subwoofer Box Design Options in 2026

#1. Goldwood TR8D: a compact divided sealed box

Goldwood TR8D dual sealed enclosure

Our verdict:

Small sealed chambers

A compact option only when each driver's required airspace fits the stated chamber size.

Keep in mind: The worked CWR8 example needs more volume than this box states per chamber.

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• Two unloaded 8-inch positions
• 0.33 cubic feet stated per chamber
• 7.125-inch cutouts; 6.5-inch mounting depth

The TR8D maker page and current catalog describe two sealed positions with 0.33 cubic feet per chamber. This is a compact dual 8 inch subwoofer box design choice for drivers with small sealed-box needs. It is not a general fit for every pair of eights.

Goldwood gives 7.125-inch holes and 6.5 inches of mounting depth. The outside height is 10 inches, the length is 20 inches and the depth slopes from 7 inches at the top to 9.75 inches at the bottom. Check the rear wall where each magnet will sit. A maximum depth measured elsewhere in the box is not enough.

The small chambers are the main constraint. We rejected a second branded listing with the same dimensions and layout as an extra pick. Two listing names do not create two useful design choices.

#2. Skar SK2X8V: a larger vented route

Skar SK2X8V dual vented enclosure

Our verdict:

Larger vented option

Compare the complete two-driver plan with its volume and tuning before choosing it.

Keep in mind: Confirm whether the volume label is total and how the internal port and chambers are arranged.

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• Two unloaded 8-inch positions
• 2 cubic foot volume label; 39 Hz tuning
• 7.25-inch cutouts; 11.5-inch mounting depth

The Skar SK2X8V is an unloaded vented enclosure. The catalog states 2 cubic feet of internal volume and 39 Hz tuning. Its listed openings are 7.25 inches across, with 11.5 inches of mounting depth.

Do not divide the headline volume by two and call the result verified net airspace per driver. You need the volume definition, installed-part allowance and actual chamber arrangement. Those questions matter when you compare a driver's small-signal model with a finished prefab box.

This option is here for its larger vented layout. That does not establish greater low-frequency output than the sealed box. A valid response comparison needs the exact pair of drivers, their limits and the intended filter settings.

#3. Atrend Bbox dual-eight: divided and vented

Atrend Bbox dual-eight vented enclosure

Our verdict:

Divided vented layout

Its divided layout offers a different build path from the small sealed Goldwood box.

Keep in mind: The catalog gives tuning and fit sizes but no usable net-volume figure.

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• Two 8-inch positions; vented and divided
• Catalog lists 32 Hz tuning
• 7-inch cutout; 14-inch mounting depth listed

The Atrend listing identifies a vented, divided dual-eight box. It states 32 Hz tuning, a 7-inch cutout and 14-inch mounting depth. Its catalog outside dimensions are 24 inches wide, 10.5 inches high and 16.625 inches deep. These figures belong to this listing, not to the different Skar enclosure.

Its 7-inch opening is smaller than both other picks' listed openings. That can exclude a driver even when depth looks ample. Obtain the current Atrend drawing and net volume for the exact box before ordering. We leave the airspace as unknown rather than borrowing a figure from another Bbox product.

The divided layout makes this a separate design branch. We could not qualify a distinct shared-chamber sealed prefab from the initial candidates. A shared design remains a custom-planning option, not an invented fourth product or a relabelled TR8D.

Factors to consider when planning a dual 8 inch subwoofer box design

Work one CWR8 reference through

The 2021 KICKER CompR manual gives a sealed range of 0.4 to 1 cubic foot per CWR8 driver. Its convention includes woofer displacement. Two drivers therefore need a combined 0.8 to 2 cubic feet on that same basis, calculated by doubling the per-driver range. A divided build applies the range to each chamber.

The TR8D's 0.33 per-chamber label is below that manual's 0.4 minimum before resolving any further difference in volume convention. We therefore do not recommend that combination. The example shows how to reject a mismatch; it does not approve the two vented picks for a CWR8.

For another worked check, see the Rockford Fosgate design guide. Keep each driver's airspace and mounting requirements in its own record.

Keep divided and shared boxes distinct

For identical drivers sharing one cavity, combine their airspace needs on a consistent basis. For separate cavities, solve each one and include the divider as solid material in the shell plan. A divider changes the cut list and usable space. Two holes do not prove whether a divider exists.

Use the rectangular calculator with the real driver count and occupied parts. It does not turn a shared-cavity calculation into a complete divided layout. The finished drawing must show each chamber, its terminal and any port.

Check wiring independently

Driver count is not final impedance. Follow the exact voice-coil diagram for the two drivers and the amplifier's permitted load. A two-terminal box does not choose that wiring for you. Confirm polarity and isolate loose wire strands before closing the box.

How we picked the dual-eight enclosures

The linked maker sources support the Goldwood fit data and CWR8 example. Limits in the Atrend and Skar catalog data stay beside each pick.

We compared mounting holes and depth before considering the stated airspace. An unknown net volume remains a reason to pause the purchase. We did not build or hear these boxes.

Dual 8 inch subwoofer box design verdict

Choose a dual 8 inch subwoofer box design from the exact driver requirements. Use the TR8D only for a suitable small sealed pair. Consider the vented boxes after you resolve their volume and fit data. The general enclosure shortlist helps if your driver plan changes to a single or dual twelve.