A gray carpeted car audio subwoofer box with a large gray speaker cone, shown at a three-quarter angle on a white background.

Proline X

Proline X P12-S W | Single 12" Sealed Wedge Subwoofer Enclosure | Loaded with Arc Audio X2V2 12

Q: What comes in this system?

A Proline X P12-S W sealed wedge enclosure with the Arc Audio X2V2 12 already mounted, gasketed and sealed against the baffle, in your chosen D2 or D4 configuration. The driver is prewired with 12 gauge OFC to a recessed Proline X ABS and carbon fiber terminal cup, and polyfill is installed and matched to the volume. Choose dark gray trunkliner or plush black carpet above. An amplifier, power wire and RCA cables are not included.

Q: Can I choose the voice coil?

Yes. Select the D2 or D4 voice-coil option at checkout so the subwoofer matches your amplifier's target impedance and wiring.

Q: Do I need an amplifier, and how much power?

Yes. This is a passive enclosure with no amplification built in. Target 200 to 250 watts RMS at your final impedance from a Class D monoblock. The X2V2 12 is rated at 250 watts RMS continuous, so stay in that range rather than chasing the 500 watt peak figure. A clean 250 watt amplifier will outperform a clipping 500 watt amplifier on this driver every time. If you are keeping the factory head unit you will also need a line output converter or a DSP with speaker level inputs.

Q: Which way round does the wedge mount?

Shallow edge up, deep edge on the floor, leaning back into the seat back or bulkhead. Mounted that way the cabinet occupies space that was already awkward and leaves the flat cargo floor usable. Mounted the other way round it stands proud and you lose the advantage the shape exists to give you.

Q: Should I choose D2 or D4?

Whichever matches the load your amplifier is stable at. D2 wires to 1 ohm in parallel or 4 ohms in series. D4 wires to 2 ohms in parallel or 8 ohms in series. Most single subwoofer builds run a D4 in parallel at 2 ohms, or a D2 in parallel at 1 ohm if the amplifier supports it. Decide before ordering, because the driver is installed and the cabinet is sealed before it ships.

Q: Why sealed rather than ported?

Sealed gives a shallower rolloff and tighter transient control in a smaller cabinet. Ported would buy output near a tuning frequency at the cost of size and control below tuning. In a vehicle, where cabin gain already reinforces the bottom end, a sealed 12 at 1.0 cubic foot usually produces a more even in car response than a ported box of the same footprint.

Q: What is the warranty on this system?

The enclosure carries a 1 year limited warranty on craftsmanship and materials, which is the standard across the Performance and Performance Optimized lines. Micro Series and Professional Series enclosures carry 2 years. The Arc Audio X2V2 12 carries its own 1 year manufacturer warranty separately, handled through Arc Audio.

Q: How should the enclosure be secured in the vehicle?

Anchor it properly. A loaded 12 in a one cubic foot cabinet carries real mass, and a wedge sitting on a carpeted floor will move under hard braking if it is not tied down. Use factory anchor points or through bolt to the floor pan. A single strap over the top is not enough. This is a safety consideration in a hard stop rather than a rattle prevention measure, and it is worth doing properly at install time instead of after something shifts.

SKU: P12-S W ARC X2V2 D4 G

QUICK SPECS

Best For: Behind-seat and bulkhead installs where a square box wastes floor
Configuration: Single 12" Sealed Wedge: Performance Series
Volume: 1.0 ft³ Net
Tuning: N/A, Sealed
Sonic Character: Warm, punchy, midbass forward

Proline X Enclosure: Built in Tennessee CNC-cut Langboard Elite 3/4" MDF, V-groove + dado joinery, recessed ABS/Carbon Fiber terminal cup.

Driver + Enclosure: Matched and Pre-Wired Subwoofer pre-installed and wired to the correct impedance. Connect your amplifier and it's ready to run.

Shipping Included No freight charges at checkout on orders to the lower 48. Alaska, Hawaii, and international orders are quoted live rates at checkout.

$ 379.99

Impedance

In Stock and Ready to Ship

Financing available. Choose Shop Pay Installments at checkout.

What's Included

Proline X P12-S W sealed wedge enclosure, single 12 inch, 1.0 cubic foot net
Arc Audio X2V2 12 subwoofer pre-installed in your chosen D2 or D4 configuration
Pre-wired 12 gauge OFC speaker wire to the terminal cup
Recessed Proline X ABS and carbon fiber terminal cup with stainless hardware and copper ring terminals
Polyfill installed and acoustically matched to this volume
Your choice of dark gray trunkliner or plush black carpet

Amplifier, power wire and RCA cables are not included.

Proline X P12-S W | Single 12" Sealed Wedge Subwoofer Enclosure | Loaded with Arc Audio X2V2 12

Enclosure Type Sealed

External Dimensions 16" (W) x 14.5" (H) x 8.5" top / 13.75" bottom (D)

Net Volume 1.0 cu ft

Tuning Frequency N/A - Sealed

Cutout Diameter 11.13"

Front Panel Thickness 0.75" Single Baffle

Max Mounting Depth 6.75"

INSTALLER'S TAKE

The wedge only pays off if you mount it the right way round. The shallow edge goes up, the deep edge sits on the floor, and the whole cabinet leans back into the seat or bulkhead. Fitted the other way it stands proud, wastes the space you bought it to save, and puts the baffle back parallel with the glass. It sounds obvious until you are working in a dark cargo area at the end of a job.

Secure it properly. A loaded 12 in a one cubic foot cabinet has real mass, and a wedge sitting on a carpeted floor will walk under hard braking if it is not anchored. Tie it to a factory anchor point or through bolt to the floor pan, and do not rely on a single strap over the top. This is a safety item in a hard stop, not a rattle prevention measure.

On wiring, the driver arrives already connected to the terminal cup with 12 gauge OFC, so your only job is the run from the amplifier. Decide your final impedance before you order rather than after, because the coil configuration is a variant choice and not something we can change once the box is built and sealed.

Product Details

Proline X P12-S W Sealed Wedge, Loaded

Cut and tuned for the Arc Audio X2V2 12

V-Groove and Dado Langboard Elite MDF 1.00 cu ft Net Fits Arc Audio X2V2 12

1.00cu ft net

0.918system Qtc

41 HzF3 rolloff

6.75 inX2V2 12 mounting depth

Built Around the Arc Audio X2V2 12

Nothing about this box is generic. Every layer is cut to the X2V2 12's published sealed target, with the baffle bored to the X2V2 12's 11.11 in cutout, and clearance cut for its 6.75 in mounting depth.

The X2V2 12 carries a published Fs of 25.57 Hz, Qts of 0.471 and Vas of 79.36 litres, and an EBP of 49, which puts it in sealed enclosure territory. We ran the alignment math on that data and built the box to land where it belongs.

Net Volume, Not Gross

We build this cabinet at 1.00 cubic feet net, against a published recommendation of 0.9 to 1.55 cu ft (optimal 1.15). The volume quoted is true net internal airspace, measured after the walls, bracing and driver displacement are accounted for.

True net, not marketing net. Internal volume is calculated by summing each CNC cut layer's opening, not estimated from external dimensions minus wall thickness.

Proline X Performance Series Construction

This enclosure is cut with V-groove and dado joinery on our ShopSabre routers from Langboard Elite 3/4 inch MDF, a dense 48.5 lb/ft³ board with a 200 psi internal bond and 410,000 psi MOE. The panels are V-grooved and folded on the seam, then dadoed where the internal bracing lands, so every joint is a mechanical lock rather than a glue line under load.

Pre-Wired Terminal Cup

Proline X ABS and carbon fiber composite cup with stainless hardware and copper ring terminals, pre-wired internally with 12 gauge OFC. No CCA anywhere in the build.

Damped and Finished

Polyfill is pre-installed to smooth the in box response, and the shell is wrapped in plush black carpet. Built in Tullahoma, Tennessee.

Enclosure Only or Loaded

Order the enclosure bare and mount your own X2V2 12, or order it loaded and we mount the driver, dress the wiring and ship it ready to bolt in.

Sealed Enclosure Performance: Pre-Calculated

Using the published Thiele Small parameters for the Arc Audio X2V2 12, here is the predicted Qtc, system resonance (Fc) and F3 rolloff for this enclosure. Calculated with the same formulas as the Audio Intensity Sealed Box Calculator.

Arc Audio X2V2 12 D2 | Qts 0.471 | Fs 25.57 Hz | Vas 79.36 L

Enclosure Size	Qtc	Fc	F3
1.00 cu ft as built	0.918	49.9 Hz	40.9 Hz

Arc Audio X2V2 12 Frequency Response | Sealed, 1.00 cu ft

1.00 cu ft (Qtc 0.918) -3dB reference

Note on coil choice: The figures above are the D2 set. The D4 X2V2 12 carries Qts 0.543 and Vas 82.65 litres, which in this same 1.00 cubic foot volume lands at Qtc 1.075, Fc 50.6 Hz and F3 38.6 Hz. Worth accounting for if you are choosing between the two. Run your own numbers in the Sealed Box Calculator.

Cut for the Driver, Not the Catalog

Select your configuration above. This enclosure ships free to the lower 48 with a 1 year limited warranty, built one at a time in Tullahoma, Tennessee. Ordered loaded, the X2V2 12 carries its own 1 year manufacturer warranty through authorized dealers.

Enclosure Specifications

Enclosure	Proline X P12-S W, Performance Series sealed wedge
Driver	Arc Audio X2V2 12, pre-installed
Voice Coil	Dual, available D2 or D4
Material	Langboard Elite MDF, 3/4" (18mm)
Enclosure Type	Sealed
Net Internal Volume	1.0 ft³ Net
Tuning Frequency	N/A: Sealed
External Width	16"
External Height	14.5"
External Depth (Top)	8.5": shallow end
External Depth (Bottom)	13.75": deep end
Wedge Angle	~20° taper
Subwoofer Cutout	11.13"
Max Mounting Depth	8.5"
Front Panel Thickness	0.75" Single Baffle
Finish	Dark Gray Trunkliner or Plush Black
Terminal Cup	Proline X ABS/Carbon Fiber, recessed mount, stainless hardware, copper ring terminals
Wiring	Pre-wired 12g OFC speaker wire
Polyfill	Installed
Built	Tullahoma, Tennessee
Warranty	1-Year Limited on the enclosure

Performance Graphs

Woofer Details

The Arc Audio X2V2 12 is the workhorse of the Arc subwoofer range: 250 watts RMS continuous, 500 watts peak, and 15.1mm of one-way linear excursion from a 2 inch copper-coated aluminum voice coil on a Kapton former. Arc rates it conservatively. Their testing philosophy is to double test power after each successful round until something actually fails, so the 250 watt figure reflects sustained thermal capacity rather than a marketing number. The four-spoke stamped steel basket carries eight integrated motor cooling vents plus a T-yoke center vent, and the motor uses double-stacked magnets for efficiency. Construction is built for daily use rather than show: a moisture-coated reinforced pulp cone, a large-diameter rubber surround instead of foam, and a high-roll Conex spider with the tinsel leads woven directly into it, which removes the bare-lead designs that cause cone slap and shorts over time. It is available in dual 2 ohm and dual 4 ohm, and the Thiele Small parameters differ between the two, which changes the sealed alignment. Pick the coil that suits your amplifier first.

Brand + Model	Arc Audio X2V2 12
Size	12"
RMS Power	250W
Peak Power	500W
Recommended Amp Power	5–500W
Voice Coil Config	Dual 2 ohm or Dual 4 ohm
Voice Coil Diameter	2"
Xmax	15.1mm one-way linear
Fs	25.57 Hz
Qts	0.471 (D2) / 0.543 (D4)
Vas	79.36 L (D2) / 82.65 L (D4)
Sensitivity	85.95 dB
Frequency Response	25–500 Hz
Cone Area (Sd)	514 cm²
Mms	176.4 g
Mounting Depth	6.75"
Cutout Diameter	11.11"
Displacement	0.07 ft³
Driver Warranty	1-Year through Arc Audio

Why This Combo Works

Arc Audio X2V2 12 in a Proline X 1.0 Cubic Foot Sealed Wedge

The X2V2 12 has an Fs of 25.57 Hz and a Qts of 0.471 on the D2 or 0.543 on the D4, which puts it firmly in sealed territory. Arc Audio publishes a sealed range of 0.9 to 1.55 cubic feet with 1.15 listed as their optimum. This cabinet is 1.0 cubic foot net, deliberately at the tighter end of that range.

That choice raises system Qtc above what the Arc optimum would give you, which produces more midbass punch and a tighter, more controlled character rather than the flattest possible response. It is the right trade for a cabinet that has to fit behind a seat. If you want the flatter, more extended alignment, you want more box than a wedge this size can provide, and we would rather tell you that now than after it ships.

The wedge shape is what makes it liveable. A square 1.0 cubic foot 12 inch cabinet eats a large rectangle of cargo floor. This one leans against the seat back, occupies space that was already awkward, and leaves the flat floor usable.

Choose your coil to suit the amplifier you already own. D2 wires to 1 ohm in parallel or 4 ohms in series. D4 wires to 2 ohms in parallel or 8 ohms in series. Match power to the 250 watt RMS rating rather than the 500 watt peak, and confirm your amplifier is stable at the load you intend to run.

Materials

Material

Built From a Spec Sheet, Not a Sales Sheet

Every Proline X Performance Series enclosure is CNC-cut from Langboard Elite MDF, 3/4" (18mm) panels produced to published mill specifications. Most enclosure manufacturers source generic MDF without published data. We can tell you the internal bond rating, the modulus of elasticity, the modulus of rupture, and the face and edge screw holding strength for every panel in this enclosure, because we chose the material based on those numbers, not on price or availability.

Langboard Elite is produced in the United States. The specifications below are pulled directly from Langboard's published mill data and are verifiable. This is the same panel stock used in our full Proline X lineup.

Specifications

Langboard Elite MDF: Published Mill Data

Property	Value	Why It Matters
Panel Stock	Langboard Elite MDF	Named, verifiable panel source, not generic "high-density MDF"
Thickness	3/4" (18mm)	Industry standard for subwoofer enclosures; panels below this flex under pressure
Density	48.5 lbs/ft³	Higher density = less porosity, better screw retention, reduced resonance
Internal Bond	200 psi	Measures resistance to delamination under sustained internal pressure. The most enclosure-relevant spec on this sheet
Modulus of Rupture (MOR)	4,200 psi	Bending strength before the panel breaks, relevant for larger unsupported baffle spans
Modulus of Elasticity (MOE)	410,000 psi	Stiffness under load; higher MOE means less panel flex under bass pressure, less resonance
Face Screw Holding	325 lbs	How firmly the panel surface holds a screw; critical for baffle joint integrity over time
Edge Screw Holding	250 lbs	Panel edge retention, relevant for every joint that isn't face-to-face

Internal Bond

200 psi: The Number That Actually Matters for Enclosures

The internal bond rating measures how well the MDF panel resists delamination under sustained pressure applied perpendicular to the face. In a subwoofer enclosure, every bass transient generates a pressure pulse that pushes outward on every panel simultaneously. A panel that begins to delaminate internally loses stiffness gradually. The symptoms are slow: a box that starts to sound softer, less defined, less punchy over months of use. 200 psi internal bond is the spec that determines how long this enclosure holds its acoustic integrity under daily use at real power levels.

Stiffness

410,000 psi MOE: Less Flex, Less Resonance

The modulus of elasticity measures panel stiffness, its resistance to bending under load. A stiffer panel flexes less under the pressure generated by a high-excursion driver at volume. Panel flex is a source of acoustic coloration: the panel itself begins to radiate sound at its own resonant frequency, adding distortion to the output. 410,000 psi stiffness combined with V-groove and dado joinery means the panels stay rigid and the bracing controls resonance at the structure level, not the panel level. The bass you hear comes from the driver, not the box.

Screw Holding

325 lb Face / 250 lb Edge: Joints That Stay Locked

Screw holding strength determines how firmly the panel grips a fastener at the face and at the edge. This matters most at the baffle joint, where the front panel meets the side panels and where the driver is mounted. A panel with low screw holding strength allows fasteners to loosen over time under vibration, leading to air gaps at the joint and loss of acoustic seal. 325 lb face screw holding strength means the baffle hardware stays put. Combined with dado joinery and adhesive, the front panel on a Proline X Performance Series enclosure is not going anywhere.

Sourcing

Named Panel Stock: Not "Premium MDF"

The phrase "premium MDF" or "high-density MDF" appears on marketing copy for enclosures across every price point, from $40 to $400. It is not a specification. It is a description with no defined standard. Langboard Elite is a named, sourced, mill-documented product with published data. We name it in our copy because naming it holds us accountable to the spec. You can look up Langboard Elite independently, verify the numbers on this page, and confirm you are getting what we say you are getting. That is the point.

Why Proline X?

Most enclosures are built to a price point. Proline X is built to a spec. Every box starts with published-data MDF, gets CNC-cut to exact internal volume, and is assembled by hand in our Tennessee facility. The difference shows up in the measurements, and in how the box holds up two years into daily use.

CNC-Cut to Spec

Panels are machine-cut on ShopSabre CNC routers and joined with V-groove and dado joinery. Consistent geometry, no hand-cut variance, no gaps at the joints.