Downfire Subwoofer Box and Enclosures

Best for Shallow Builds

A promotional product graphic for the Proline PO 12-S DF thinPRO speaker, showing a dark gray rectangular speaker with dimension callouts of 30 inches wide and 5.25 inches high.

Proline X

Performance Optimized Down Fire Sealed 12" Enclosure | Wavtech thinPRO12

Cut for a slim-profile 12 where floor-to-seat clearance is the constraint.

$ 269.99

Best for SQ

Proline X

Performance Optimized Down Fire Sealed 12" Enclosure | Morel Ultimo SCX122

Internal volume cut to the SCX122's published parameters for a sealed alignment.

$ 269.99

Best High-Output

A Proline Performance Optimized Series PO 10D-S DF TW3 double speaker enclosure box, shown with dimensions of 30 inches by 15 inches and a black front panel with two circular speaker cutouts.

Proline X

Performance Optimized Down Fire Sealed Dual 12" Enclosure | JL Audio 12TW3

Two 12s in isolated chambers, each cut to the TW3's published parameters.

$ 299.99

Best for Cargo Bays

A black Proline ResoNix PO 12-S DF GUS woofers subwoofer enclosure box shown on a dark brown gradient background with product specifications and branding.

Proline X

Performance Optimized Down Fire Sealed 15" Enclosure | ResoNix GUS-15

Performance Optimized 15 inch cut to the GUS-15's published sealed alignment at 1.41 cubic feet. The most displacement in the range for a cargo bay that has the floor space.

$ 329.99

Best Direct Fit

Proline X

Proline X Bronco Edition Dual 12" Down-Firing Sealed Subwoofer Enclosure

Stack-fab vehicle-specific cabinet cut to the Bronco cargo floor.

$ 499.99

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Down-Fire Series Comparison

Down fire is how a cabinet is mounted, not how it is built, so this page spans four Proline X series. Baffle thickness and construction differ because the cabinets are made differently, not because one is a better version of another.

All 81 enclosures in stock on 28 August 2026. Every one is sealed; ported down-fire is in development.
Series	In stock	Front baffle	Construction	Threaded inserts	Warranty
Performance Optimized	61	1.5 in double	Cut to one driver's published sealed alignment	Where the bolt pattern is on hand	1 year limited
Micro Series	17	1.5 in	Stack-fab with dowel reinforcement	8/32 on the baffle backside	2 year limited
Performance	2	0.75 in single	V-groove and dado joinery	Where the bolt pattern is on hand	1 year limited
Vehicle Specific	1	0.75 in	Stack-fab with dowel reinforcement	8/32 on the baffle backside	2 year limited

Shared across all four: Langboard Elite MDF at 48.5 lbs per cubic foot, 200 psi internal bond and 410,000 psi MOE, cut on ShopSabre routers in Tullahoma. Plush black carpet. A Proline X ABS and carbon fibre composite terminal cup with stainless hardware and copper ring terminals, pre-wired in 12-gauge OFC. Polyfill pre-installed, because every cabinet here is sealed.

Four Series, One Orientation

Down fire is how a cabinet is mounted, not how it is built, so this page spans four Proline X series. Performance Optimized is the bulk of it at 61 cabinets, on a 1.5 inch double baffle. Micro Series is 17 shallow-mount builds on a 1.5 inch baffle that ship with feet and work down-firing or upright. Performance is two universal-cutout cabinets on a single 3/4 inch baffle. Vehicle Specific is the Bronco cabinet, cut to the cargo floor.

Every enclosure here is sealed, and every sealed cabinet we build ships with polyfill already installed. Ported down-fire is in development and not yet available to order.

The bulk of the line

Performance Optimized, 1.5 inch double baffle

61 of 81

Sixty-one cabinets, each cut to one driver's published sealed alignment on a double 1.5 inch front baffle. This is where most of the down-fire line sits and where the widest driver choice is.

1 year limited warranty

When depth is the problem

Micro Series, shallow-mount, works either way

17 of 81

Seventeen stack-fab cabinets with dowel reinforcement and 8/32 threaded inserts on the baffle backside. All ship with feet, so they are down-fire capable without being cut exclusively for it.

2 year limited warranty

Lowest entry point

Performance, universal cutout

2 of 81

Two cabinets on a single 3/4 inch baffle with V-groove and dado joinery and a universal cutout, so no driver-specific tooling is involved. The cheapest way into a properly built down-fire cabinet.

1 year limited warranty

Cut to the vehicle

Vehicle Specific, built to the cargo floor

1 of 81

Stack-fab with dowel reinforcement, cut to a specific vehicle's cargo floor rather than to a generic footprint. Currently the Bronco dual 12.

2 year limited warranty

Counts are shelf counts from our own inventory, not a supplier feed. Series assignment follows the cabinet build, not the orientation: down fire is how a box is mounted, not how it is made.

Open SUV cargo bay at sunrise with a drill, coiled OFC wire and cargo tie-down straps on the carpet.

Down-Firing vs Front-Firing

Which orientation suits your vehicle, and what each one costs you.

Low angle close-up of automotive trunk carpet pile with a defined band of shadow across it.

Down-Fire Box Floor Clearance

How much floor gap you need, and why carpet changes the answer.

ShopSabre CNC router cutting a circular baffle from MDF sheet stock, with two finished cutout discs alongside.

Application

Which Subwoofers Work in a Down-Fire Box

Every driver we cut a down-fire cabinet for, with volumes per build.

Hands using dial calipers to measure the thickness of a sheet of MDF on a workbench.

Decision

Down-Fire Box Sizing

Single or dual, 10 or 12 inch, and how to decide.

The Proline X Enclosure Series, Explained (and How to Pick One) - Audio Intensity

Proline X Series Explained

What separates Performance, Performance Optimized, Micro and Vehicle Specific.

Polyfill in a Sealed Subwoofer Box: What It Does and How Much - Audio Intensity

Polyfill in a Sealed Box

What it does, why every sealed cabinet we build ships with it.