Sealed and Ported, 11 to 15 Inch, 17 Builds

Stereo Integrity Subwoofer Boxes and Enclosures

Sealed and ported enclosures cut for the Stereo Integrity SQL-12, SQL-15 and BM-11, CNC-machined in Tullahoma, Tennessee.

Proline X subwoofer enclosures built for Stereo Integrity subwoofers.

Sealed and Ported, 11 to 15 Inch, 17 Builds

Seventeen enclosures for three Stereo Integrity drivers, and we stock the drivers too. Start with the SQL-12, SQL-15 or BM-11, choose sealed or ported, then pick the shape and driver count that fit the vehicle.

Where a driver comes as both a sealed standard box and a sealed wedge, the two hold the same airspace, so the shape is a fitment decision and the alignment does not change. The directory below lists every box with its net volume, tuning and outside dimensions.

17 Proline X enclosures for the Stereo Integrity SQL-12, SQL-15 and BM-11: 13 sealed and 4 ported, single through triple, in wedge, standard and down fire.

Langboard Elite MDF enclosures. Authorized Stereo Integrity dealer. Expert SQ-judge support. Built and shipped from Tullahoma, TN.

Driver parameters and fitment dimensions come from Stereo Integrity published data, with the BM-11 total Q cross-checked against loudspeakerdatabase and a ResoNix Klippel measurement. Audio Intensity is an authorized Stereo Integrity dealer, and the drivers themselves are on our Stereo Integrity page.

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Same Driver, Same Airspace, Different Shape

Two of these three drivers are offered as both a sealed standard box and a sealed wedge, or a sealed down fire and a sealed wedge, and both shapes hold the identical airspace. That means the alignment does not change: a Stereo Integrity SQL-12 in our sealed standard box and in our sealed wedge produce the same Qtc and the same F3. The shape decides where the cabinet fits in the vehicle, not how it sounds.

Seventeen cabinets, three chassis, three drivers. Current prices are on each listing.
ChassisGoes whereDrivers offeredOptions
WedgeTrunk or cargo area, leaning on the rear seat backSQL-12, SQL-15, BM-11Sealed single to triple, standard or wide; ported single
StandardTrunk, upright rectangular boxSQL-12Sealed single or dual; Professional Series ported dual at 29 Hz
Down FireUnder or behind a seat, fires at the floorBM-11Sealed single

The Three Drivers

Every cabinet is cut to one specific model. The sealed alignment below is computed from Stereo Integrity published Thiele-Small parameters at the single-driver volume. We stock all three drivers as an authorized Stereo Integrity dealer.

Sealed alignment per driver. All figures anechoic, before cabin gain.
DriverSealed net per driverQtcF3Offered as
SQL-121.00 cu ft0.76442.6 HzSealed standard or wedge, single or dual; sealed wide wedge, dual or triple; ported wedge, single; Professional ported dual
SQL-152.00 cu ft0.81641.8 HzSealed wedge, single or dual; sealed wide wedge, dual; ported wedge, single
BM-110.40 cu ft1.43241.5 HzSealed down fire, single; sealed wedge, single, dual or triple; ported wedge, single

Shared across the Performance Optimized cabinets: Langboard Elite MDF cut on ShopSabre routers in Tullahoma, Tennessee. A 1.5 inch double front baffle. Plush black carpet. A Proline X ABS and carbon fibre composite terminal cup with stainless hardware, pre-wired in 12-gauge OFC. Threaded inserts at every mounting location. Polyfill installed.

Stereo Integrity Subwoofer Box Directory by Model

We build sealed and ported enclosures for 3 Stereo Integrity subwoofer models, 11 to 15 inch, in standard, wedge and down-fire styles from single, dual and triple woofer cabinets. Open a model to see every box cut for it, with net volume, tuning and outside dimensions. Full specs and fitment notes are on each product page.

Stereo Integrity BM-11 5 boxes
BoxSeriesNet volumeTuningOutside dimensions
Wedge Ported, SinglePerformance Optimized0.97 ft³36.5 Hz30.00" W x 14.50" H x 11.78" D, tapering to 6.50"
Down Fire Sealed, SinglePerformance Optimized0.40 ft³Sealed22.84" W x 15.00" D x 5.00" H
Wedge Sealed, SinglePerformance Optimized0.40 ft³Sealed16.74" W x 14" H x 9.81" D, tapering to 4.71"
Wedge Sealed, DualPerformance Optimized0.80 ft³Sealed31.18" W x 14" H x 9.81" D, tapering to 4.71"
Wedge Sealed, TriplePerformance Optimized1.20 ft³Sealed40.00" W x 14" H x 10.50" D, tapering to 5.41"
Stereo Integrity SQL-12 8 boxes
BoxSeriesNet volumeTuningOutside dimensions
Wedge Ported, SinglePerformance Optimized1.54 ft³37.5 Hz28.50" W x 15.50" H x 15.89" D, tapering to 10.25"
Standard Sealed, SinglePerformance Optimized1.0 ft³Sealed20"w x 15"h x 13.625"d
Wedge Sealed, SinglePerformance Optimized1.00 ft³Sealed20.70" W x 15" H x 13.90" D, tapering to 8.44"
Standard Ported, DualProfessional3.47 ft³29.0 Hz40.50" W x 16.00" H x 20.25" D
Standard Sealed, DualPerformance Optimized2.0 ft³Sealed31"w x 15"h x 13.625"d
Wedge Sealed, DualPerformance Optimized2.00 ft³Sealed32.00" W x 16" H x 15.45" D, tapering to 9.62"
Wedge Wide Sealed, DualPerformance Optimized2.28 ft³Sealed41" W x 16" H x 14.07" D, tapering to 8.25"
Wedge Wide Sealed, TriplePerformance Optimized3.00 ft³Sealed44" W x 17" H x 15.71" D, tapering to 9.52"
Stereo Integrity SQL-15 4 boxes
BoxSeriesNet volumeTuningOutside dimensions
Wedge Ported, SinglePerformance Optimized1.91 ft³34.5 Hz30.00" W x 18.50" H x 15.73" D, tapering to 9.00"
Wedge Sealed, SinglePerformance Optimized2.00 ft³Sealed29.16" W x 18" H x 14.81" D, tapering to 8.26"
Wedge Sealed, DualPerformance Optimized4.00 ft³Sealed37.50" W x 18" H x 19.74" D, tapering to 13.20"
Wedge Wide Sealed, DualPerformance Optimized4.00 ft³Sealed44" W x 18" H x 17.38" D, tapering to 10.83"

Shape Is a Fitment Decision, Not an Acoustic One

Where a driver is offered as both a sealed standard box and a sealed wedge, both hold the identical net volume. A SQL-12 in the standard box and a SQL-12 in the wedge both hold 1.00 cubic feet and run Qtc 0.764 with F3 at 42.6 Hz. The wedge leans on the seat back and keeps the trunk floor usable; the standard box is a simple upright rectangle. Neither sounds different.

The same is true of the BM-11: down fire at 0.40 cubic feet or wedge at 0.40, same Qtc 1.432 either way. Its shallow mounting depth is what makes both shapes possible.

Every Stereo Integrity Model We Build For

Three Stereo Integrity models, 17 cabinets. Ported tunings are the frequency each box is tuned to.

11 inch

BM-11: sealed wedge in single, dual and triple; sealed down-fire in single; ported wedge in single at 36.5 Hz.

12 inch

SQL-12: sealed wide wedge in dual and triple; sealed wedge in single and dual; sealed standard in single and dual; ported wedge in single at 37.5 Hz; Professional Series ported standard in dual at 29 Hz.

15 inch

SQL-15: sealed wide wedge in dual; sealed wedge in single and dual; ported wedge in single at 34.5 Hz.

How to Choose

Driver first

Unusually for one of our brand pages, the driver is the decision that matters and the shape is the easy one. SQL for a damped alignment and real excursion, BM-11 for an install with no room.

Then sealed or ported

Sealed gives the SQL the controlled alignment it was designed around, in the smallest cabinet. Each driver also has a ported wedge for more output near tuning, in a bigger box. The SQL-12 adds a Professional Series ported dual tuned to 29 Hz, the lowest tuning on this page.

Then the shape, on fitment alone

A sealed standard box and a sealed wedge for the same driver hold the same airspace, so there is no acoustic penalty either way. Choose on where it goes.

Count changes output and load

A dual or triple adds output, cabinet size and amplifier load. Check the per-driver volume in the directory above: most multiples match the single, and the SQL-12 dual wide wedge holds a little more at 2.28 cubic feet for two.

Buy the driver here too

We are an authorized Stereo Integrity dealer and stock the SQL 12 Series 2, SQL 15 Series 2 and BM-11. Order the driver with the box and both ship from Tullahoma. See the Stereo Integrity lineup.

Measuring for One

Wedge: measure the trunk floor

A wedge is deepest at its base and that base dimension has to clear on the trunk floor. Widths run from 16.74 inches on the single BM-11 wedge to 44 inches on the SQL-12 triple and SQL-15 dual wide wedges.

Down fire: measure height

The BM-11 down-fire cabinet stands on a 1.75 inch standoff and wants a hard flat floor beneath it. Installed height, not cabinet height, is the number to check.

Standard: measure everything

The sealed standard SQL-12 boxes are upright rectangles, 20 inches wide for the single and 31 for the dual, both 15 inches tall and 13.625 deep. The Professional Series ported dual is 40.5 inches wide, 16 tall and 20.25 deep.

The Shape Does Not Change the Sound

Where a driver is offered as both a sealed standard box and a sealed wedge, both hold the same net airspace, so both produce the same Qtc and the same F3. Choose the shape on where it fits in the vehicle. The acoustics are already settled by the volume.

The BM-11 Q Is Disputed, and We Say So

Stereo Integrity publish a total Q of 0.73 for the BM-11, loudspeakerdatabase carries 0.83, and a ResoNix Klippel measurement gives 0.85. Our figures use 0.83. At 0.40 cubic feet those give a system Qtc of 1.26, 1.43 and 1.47, so the cabinet is under-damped on every reading. We would rather print which number we used than pick the flattering one.

SQL or BM

The SQL cabinets are the damped ones. SQL-12 at Qtc 0.764 and SQL-15 at 0.816, both with 26 mm of one-way travel and a 1000 watt rating behind them. If you want a flat sealed alignment with real excursion, that is the pair.

The BM-11 is a different proposition. An 11 inch cone on a 3.071 inch mounting depth, so it fits where nothing else does, and it reaches 41.5 Hz doing it. The trade is the alignment: Qtc 1.432 is peaked, not flat, and no small sealed cabinet changes that.

Most builds

Sealed cabinets

13 builds

Thirteen sealed wedge, standard and down-fire cabinets across the SQL-12, SQL-15 and BM-11. The controlled alignment the SQL was designed around, in the smallest box.

Performance Optimized

More output

Ported wedge

3 builds

One ported wedge per driver: the BM-11 at 36.5 Hz, the SQL-12 at 37.5 Hz and the SQL-15 at 34.5 Hz. More output near tuning in a bigger cabinet.

Performance Optimized

Lowest tuning

Professional Series dual SQL-12

29 Hz

A ported dual SQL-12 at 3.47 cubic feet tuned to 29 Hz, the deepest tuning on this page and the only Professional Series cabinet here.

2 year warranty

Sixteen cabinets are Performance Optimized with a 1 year limited warranty. The ported dual SQL-12 is Professional Series with 2 years.

Categories

Keep Reading

Supporting guides to help you design, build, and tune your system.

Stereo Integrity Subwoofer Box Questions

Which Stereo Integrity subwoofers do these boxes fit?

Three models: the SQL-12, the SQL-15 and the BM-11. Each product title names the exact model it is cut for, and the directory above lists every box by driver with net volume, tuning and outside dimensions.

Do you sell the Stereo Integrity drivers too?

Yes. Audio Intensity is an authorized Stereo Integrity dealer and stocks the SQL 12 Series 2, SQL 15 Series 2 and BM-11. Order the driver with the enclosure and both ship from Tullahoma, Tennessee.

Should I run sealed or ported?

Sealed for most SQL builds. It gives the controlled alignment the SQL was designed around, at Qtc 0.764 for the SQL-12 and 0.816 for the SQL-15, in the smallest cabinet. Each driver also has a ported wedge for more output near tuning: 37.5 Hz for the SQL-12, 34.5 Hz for the SQL-15 and 36.5 Hz for the BM-11. The SQL-12 Professional Series ported dual tunes lower, to 29 Hz.

Does the cabinet shape change how it sounds?

Not between a sealed standard box and a sealed wedge for the same driver. Both hold the same airspace, so the alignment is identical. The SQL-12 runs Qtc 0.764 and F3 42.6 Hz in either one. Choose the shape that fits your vehicle.

Why is the BM-11 alignment so high?

Because of the driver, not the cabinet. Its total Q is high enough that no small sealed box brings the system below about 1.2. Sources also disagree on the exact figure: Stereo Integrity publish 0.73, loudspeakerdatabase carries 0.83 and a ResoNix Klippel measurement gives 0.85. We compute from 0.83 and say so on the listing. The alignment is under-damped on all three readings, so the disagreement changes the decimal and not the character. What you get in return is 41.5 Hz from a cabinet under five inches deep at the front.

Can I run three BM-11s?

Yes. The triple sealed wedge is 40 inches wide and holds 1.20 cubic feet, 0.40 per driver. Work out the impedance first: three dual 2 ohm drivers is six coils, and the two clean answers are 1.33 ohms or 3 ohms.

What is the warranty?

Performance Optimized enclosures carry a 1 year limited warranty on craftsmanship and materials, and the Professional Series ported dual carries 2 years. The Stereo Integrity driver carries its own manufacturer warranty.

Subwoofer Boxes by Brand

Every box is cut to one driver's published specs. Pick the brand your subwoofer comes from.

Drivers built to match

Stereo Integrity Drivers We Stock

We are an authorized Stereo Integrity dealer: the SQL 12 Series 2, SQL 15 Series 2 and BM-11 these boxes are cut for, plus SI midbass, midrange and tweeters for the front stage.

Stereo Integrity M350 Carbon 3.5 inch midrange, angled view of the open basket and motor

Stereo Integrity

Stereo Integrity M350 Carbon | 3.5 Inch Midrange - Pair

$ 359.99
Stereo Integrity SQL 12 Series 2 subwoofer, front view of the paper cone and logo dust cap

Stereo Integrity

Stereo Integrity SQL 12 Series 2 | 12 Inch Subwoofer

$ 439.99
Stereo Integrity TM65 mkIV 6.5 inch midbass, front view of the cone and dust cap

Stereo Integrity

Stereo Integrity TM65 mkIV | 6.5 Inch Midbass - Pair

$ 469.99
Stereo Integrity SQL 15 Series 2 subwoofer, front view of the paper cone and logo dust cap

Stereo Integrity

Stereo Integrity SQL 15 Series 2 | 15 Inch Subwoofer

$ 475.99

View all stereo integrity subwoofers and speakers | Need a custom build? Contact us

Amplifiers for the system

Monoblock Power for the SQL and BM-11

The SQL 12 and SQL 15 are rated 1000 W RMS and the BM-11 500 W RMS. Match the amplifier to that rating and to the final load your wiring presents.

Prodigy Audio 1200 Watt Mono Block Amplifier NBM1200.1 - Prodigy Amplifier for car audio systems

Prodigy Audio

Prodigy Audio 1200 Watt Mono Block Amplifier | NBM1200.1

$ 272.99 $ 326.99
Wavtech Link5001Mini

Wavtech

Wavtech Link5001Mini

$ 299.99
US Acoustics Mike 1500w Monoblock Amplifier US Acoustics

US Acoustics

US Acoustics Mike 1500w Monoblock Amplifier

$ 329.99
Image Dynamics SQ600.1D 600W Mono Block Amplifier

Image Dynamics

Image Dynamics SQ600.1D 600W Mono Block Amplifier

$ 399.99

View all monoblock amplifier | Need a custom build? Contact us

Last updated October 25, 2026