Proline X PO 12-P W S2 ported wedge enclosure, front baffle with gloss black acrylic insert and pre-wired leads, 30 by 16 inches. Optimized for Image Dynamics IDMAX.

Proline X

Performance Optimized Wedge Ported 12" Enclosure | Alpine S2-W12

Q: Why the 20 degree wedge, and why rear-firing?

The raked face is the seat side. A factory rear seat back leans about 20 degrees off vertical, so the cabinet sits flat against it and uses floor a square box wastes. The baffle stays vertical and fires rearward into the trunk, which acts as the acoustic extension into the cabin. This one is 13.52 inches deep at the base and 7.88 at the top, 30.00 wide and 16 tall.

Q: Do I need a subsonic filter?

Yes, at 28 Hz, 24 dB per octave. Below tuning a vented box stops loading the cone and excursion runs away toward DC. With the filter in place this cabinet puts the Alpine S2-W12 at 51 percent of its usable travel at full rated power; without it there is no meaningful number to quote.

Q: How much power can I run, and at what impedance?

Alpine rate the S2-W12 at 600 W RMS and that is the thermal ceiling. The Performance Graphs tab shows the mechanical limit, the power at which the cone reaches the end of its travel in this cabinet: here the cone sits at 51 percent of usable travel at the rating, so heat is what stops you, not travel. A D2 coil is 4 ohms in series or 1 ohm in parallel; run series unless the amplifier is rated for 1 ohm. A D4 is 8 series or 2 parallel.

Q: Would a sealed box be better for me?

Below about 22 Hz, yes. The sealed wedge we build for it is louder down there by up to 1.4 dB, because a sealed box rolls off gently where a vented one falls away steeply under tuning. Above that this alignment is the louder of the two for the same power. The Performance Graphs tab plots this cabinet against the 0.85 cu ft sealed wedge we build for this driver (PO 12-S W S2).

Q: How does the side port work?

It is a triangular slot in the bottom-rear corner: the floor and the raked back wall are two sides, one bevelled panel is the third. It runs across the cabinet, opens into the box through a 4.34 inch gap at the far end and exits through the side panel as the same triangle. Straight, no bend: 23.91 inches of path and 18.4 square inches of channel running at 22.1 metres per second, 54 percent of its turbulence limit. The three mouth edges are rounded over at 1/2 inch, so the opening at the face is 29.5 square inches and the air leaves it at 13.7 metres per second against the 17.0 threshold where a slot port starts to chuff; the panel's throat end is rounded at 3/8 inch for the same reason. The terminal cup is on the other side.

Q: Does this enclosure ship with polyfill?

No, and do not add any. Every sealed Proline X enclosure ships with polyfill; a ported one must not, because damping changes the effective volume the port is tuned against. The port here is cut to 23.91 inches for 35.0 Hz. Stuff it and you move the tuning without shortening the port.

Q: Is the S2-W12 included?

No. This is an enclosure only, cut for the Alpine S2-W12 specifically: the 10.750 inch cutout, the 4.880 inch mounting depth allowance and the 1.31 cubic foot alignment all come from Alpine's published parameters. It fits both coil versions; the alignment published here is the D4. Bring your own driver.

SKU: PO 12-P W S2 BB

QUICK SPECS

Alignment: 1.31 cu ft net vented at 35.0 Hz. F3 33.9 Hz anechoic, 1.52 dB passband ripple
Driver: Alpine S2-W12 D4, 600 W RMS, 15.0 mm Xmax, 28.80 Hz Fs
Build: Rear-firing wedge, 20 degree rear rake, V-groove and dado joinery, triangular side-exit slot port with a 1/2" rounded mouth, double 1.5" baffle, side-mounted terminal cup
Cabinet: 30.00" W x 15.50" H x 13.52" D at base tapering to 7.88" D at top, 18.4 sq in port, ships dry

Shipping Included No freight charges at checkout. What you see is what you pay.

Built in Tennessee CNC cut from 3/4" Langboard Elite MDF. V-groove and dado joinery.

Advanced Terminal Cup Built in-house. ABS/Carbon Fiber. Stainless steel hardware. Copper ring terminals.

$ 399.99

Acrylic Insert Color

In Stock and Ready to Ship

Financing available. Choose Shop Pay Installments at checkout.

Complete Your System

Arc Audio X2 1100.1 Monoblock Subwoofer Amplifier 1100W Class D - Arc Audio Amplifier for car audio systems

Arc Audio Arc Audio X2 1100.1 Monoblock Subwoofer Amplifier | 1100W | Class D $ 758.00

Performance Optimized Wedge Ported 12" Enclosure | Alpine S2-W12

Enclosure Type Ported

External Dimensions 30.00" W x 15.50" H x 13.52" D at base tapering to 7.88" D at top

Net Volume 1.31cu ft

Tuning Frequency 35.0 Hz

Port Area 18.4 Square Inches

Cutout Diameter Direct Fit

Front Panel Thickness 1.5"

INSTALLER'S TAKE

Alpine's S2-W12 is a shallow-motor twelve, 4.88 inches of mounting depth, and the wedge keeps it shallow: 7.88 inches at the top, 13.52 at the base. A 0.44 Qts with 51.5 litres of Vas is a proper ported driver, and 35 Hz gives an F3 of 33.9 Hz on 1.52 dB of ripple, 2.82 dB in the car. Alpine publish sealed volumes only for this line, so there is no factory vented figure to compare; the sealed S2 wedge we already build is 0.85 cubic feet, Alpine's recommended volume.

The D2 coil has a different Fs and Vas, 26.6 Hz and 55.1 litres, and it solves to this same cabinet at 34.5 Hz, so buy the coil your amplifier wants. Xmax is 15 mm with no basis stated, taken as printed, and the cone uses 7.6 of it at 600 watts with the subsonic filter set. The channel runs half a metre per second under its limit; run the filter.

Product Details

Proline X Performance Optimized Wedge 12" Ported

Alpine's S2-W12 vented at 35 Hz in a 13.5 inch deep wedge, 1.31 cubic feet and 1.52 dB of ripple

1.31 cu ft net Tuned 35.0 Hz F3 33.9 Hz Side slot port Cut for the Alpine S2-W12 Built in Tennessee

1.31cu ft net

35.0Hz tuning

33.9Hz F3 anechoic

18.4sq in port area

Why this driver is vented at 35.0 Hz

The S2-W12D4 is a 28.8 Hz motor with a 0.44 Qts, 51.5 litres of Vas and 600 watts, and the wedge gives it 1.31 cubic feet net vented at 35 Hz through an 18.4 square inch port. The cabinet is 30 inches wide, 15.5 tall, 7.88 inches at the top and 13.52 at the base, a shallow cabinet for a twelve.

A 0.44 Qts on 51.5 litres reaches below its resonance in a modest box: F3 33.9 Hz anechoic on 1.52 dB of ripple, and 2.82 dB of in-car spread across 25 to 60 Hz at 35 Hz tuning. The D2 coil, with its 26.6 Hz Fs and 55.1 litres, solves to the same cabinet at 34.5 Hz and reads 2.93 in the car, so one box serves both. The port takes 23.91 of the 25.43 inches available and runs at 22.1 metres per second in the channel against a 22.6 limit, 13.7 at the rounded mouth.

Trunk-load wedge, explained

The 20 degree face is the seat side

A factory rear seat back leans about 20 degrees off vertical. The wedge's raked rear panel matches that lean and tucks against it, so the cabinet uses the triangle of trunk floor a square box wastes.

The driver fires rearward

The baffle stays vertical and faces the trunk opening. The trunk acts as the acoustic extension into the cabin; nothing about the driver is angled.

13.52 inches at the base, 7.88 at the top

A 4.88 inch mounting depth is what makes this cabinet shallow. The port panel needs 7.08 inches of top depth to seat a 6.25 inch leg, against 6.22 for the magnet alone, and the base lands at 13.52, two inches under the 15.5 inch height. 4.27 inches of flat floor stay clear in front of the panel.

30.00 inches wide

Width is the wedge's free dimension and it buys two things at once here: airspace, and port length, because the port runs the full width of the box.

The port is the product

The port is a triangular slot in the bottom-rear corner. The floor and the raked back wall are two of its three sides; the third is a single panel bevelled to sit flush against both. It runs across the cabinet, opens into the box at the far end and exits through the side panel: a straight run with no bend, 23.91 inches of centreline path.

The channel is an isosceles triangle with 6.25 inch legs, 18.4 square inches, running at 22.1 metres per second at the tuning frequency. The mouth is that same triangle cut through the side panel with its three edges rounded over at 1/2 inch, so the opening at the face is 29.5 square inches and air leaves it at 13.7 metres per second, against the 17.0 metre per second threshold where a slot port starts to chuff. The panel's throat end carries a 3/8 inch roundover for the same reason.

This enclosure ships dry. Polyfill goes in every sealed Proline X cabinet we build. It does not go in this one. Damping material changes the effective volume the port is tuned against, which moves the tuning away from the 35.0 Hz the port was cut for.

Run a subsonic filter

Below tuning the port stops loading the cone and excursion climbs without limit toward DC, so a 28 Hz high-pass at 24 dB per octave is part of the specification. Set it and the same cabinet takes substantially more power for the same cone travel.

Every wattage on the Performance Graphs tab is a mechanical limit, the power at which the cone reaches the end of its linear travel in this box. What the voice coil can dissipate as heat is a separate ceiling set by Alpine.

Cut for this driver, not for a catalogue

Mounting

Cut to Alpine's published 10.750 inch cutout through a double-layer 1.5 inch baffle, with a cosmetic front layer routed for the acrylic insert. Threaded inserts at every mounting location.

Clearance

Alpine publish 15 mm of linear excursion without stating the basis, so it is taken as printed; the cone uses 7.6 of it at 600 watts with the subsonic filter set. The channel runs 0.5 metres per second under its limit. Alpine publish a sealed range only for the S2 (0.61 to 1.06 cubic feet) and no vented box; we also build this driver as a 0.85 cubic foot sealed wedge, Alpine's recommended volume, and the graphs tab compares the two.

Braced

Two windowed C braces run the cabinet profile at the third points of the width and seat on the port panel; the windows keep the cavity one chamber.

Joinery

V-groove and dado throughout, 0.75 inch Langboard Elite MDF, the shell folded from one strip with the sides dropped into dados and the port panel seated in dados of its own.

Power, wiring and warranty

Alpine rate the S2-W12 at 600 W RMS. Terminal cup is side mounted on the side opposite the port mouth. A dual 2 ohm driver wired parallel presents 1 ohm, which many amplifiers are not stable into; series at 4 ohm is the safe default unless yours is rated for it.

Performance Optimized carries a 1-year warranty. Built to order in Tullahoma, Tennessee. The driver is not included.

Cut, folded and finished for the Alpine S2-W12. The alignment, the port geometry and the power figures all come from Alpine's published parameters run through our own solver.

Specifications

Series	Proline X Performance Optimized Wedge
Driver-Specific Fitment	Alpine S2-W12 D4 (Dual 4 Ohm)
Enclosure Type	Ported \| Rear-Firing Trunk Wedge
Baffle Configuration	Vertical Baffle - Driver Fires Rearward Into The Trunk
Wedge Angle	20 Degrees On The Rear (Seat-Side) Panel
External Width	30.00 Inches
External Height	15.50 Inches
Top Depth	7.88 Inches
Base Depth	13.52 Inches
Internal Volume (Gross)	1.71 Cubic Feet
Internal Volume (Net After Displacement)	1.31 Cubic Feet
Port Type	Triangular Slot \| Bottom-Rear Corner \| Straight, No Bend \| Side Exit
Port Geometry	Isosceles, 6.25 Inch Legs, 18.4 Square Inches, 23.91 Inches Long, Side Mouth
Port Tuning (Fb)	35.0 Hz
Port Mouth	Triangle Through Side A, 1/2 In Roundover On All Three Edges, 29.5 Square Inches At The Face
Port Throat	Open Far End, 4.34 In Gap To Side B, 3/8 In Roundover On The Panel End
Port Air Velocity	22.1 m/s In The Channel, 13.7 m/s At The Flared Mouth (17.0 m/s Chuff Threshold)
Predicted F3	33.9 Hz (Anechoic)
Passband Ripple	1.52 dB (Anechoic)
Subsonic Filter	28 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs	28.80 Hz
Driver Qts	0.440
Driver Qes / Qms	0.470 / 5.900
Driver Vas	51.500 Liters / 1.819 Cubic Feet
Driver Sd	472.0 Square Centimeters
Driver Mms	187.00 g
Driver BL	22.80
Driver Re	7.2 Ohm
Driver Xmax	15mm (One-Way at None)
Excursion Design Basis	Derated To 15.0mm For Alignment - Alpine Publishes At None
Driver Displacement	0.06 Cubic Feet (Published by Alpine)
Driver Sensitivity	86.2 dB
Driver Power Handling	600 Watts RMS
Driver Overall Diameter	12.680 Inches (Alpine Spec)
Mounting Depth Required	4.880 Inches (Alpine Spec)
Cutout Diameter	10.750 Inches (Alpine Spec)
Material	Langboard Elite 3/4" MDF
Construction	ShopSabre CNC / Two Windowed C Braces At The Third Points, Seated On The Port Panel
Joinery	V-Groove and Dado (CNC-Cut)
Front Baffle Construction	Double-Layer 1.5" MDF \| Cosmetic Front Layer Routed For The Acrylic Insert
Mounting Hardware	Threaded Inserts At Every Mounting Location \| Stainless Steel Machine Screws Included
Voice Coil Configuration	Dual 4 Ohm
Terminal Cup	Proline X ABS/Carbon Fiber Composite \| Side Mounted, Opposite The Port \| 12g OFC Pre-Wired
Damping	None - Ships Dry. Polyfill Detunes A Ported Enclosure
Recommended Power	420-600 Watts RMS (Alpine Rated: 600W RMS)
Carpet Finish	Plush Black
Weight	49 lb
Bundle Options	Enclosure Only (Bring Your Own Alpine S2-W12)
Warranty	1-Year Limited (Enclosure)
Manufactured	Tullahoma, Tennessee, USA

Performance Graphs

Net airspace

1.31

cu ft

Tuning

35.0

Hz · Fb

Half power

33.9

Hz · F3, anechoic

Xmax at

2348

W RMS · 28 Hz subsonic

With NO filter

318

W RMS · unfiltered

Port

13.7

m/s at the mouth

01Is this driver right for a ported box?

Efficiency bandwidth product places the motor before anything else is decided.

EBP = Fs ÷ Qes = 61.3

Alpine S2-W12D4 · EBP 61.3

Between 50 and 100 a driver takes either load, and the choice becomes one of priorities rather than of physics. The Alpine S2-W12D4 reads 61.3. Ported buys output and low-end reach around tuning; sealed buys a shallower rolloff below it. This cabinet takes the first trade.

02What the box does to it

1.31 cu ft net against a 51.5 L Vas, vented at 35.0 Hz.

Fb = 35.0 Hz · F3 = 33.9 Hz · passband ripple 1.52 dB

Alpine S2-W12D4 · Fb 35.0 Hz, F3 33.9 Hz

Anechoic, before any cabin gain, with the 28 Hz subsonic filter already applied. The vent takes over below 35 Hz and the cone stops doing the work there, which is what holds travel down at the bottom of the passband.

03Perceived Ported vs Sealed

This cabinet, 1.31 cu ft net vented at 35.0 Hz, against the 0.85 cu ft sealed wedge we build for this driver (PO 12-S W S2).

Ported Fb 35.0 Hz · the 0.85 cu ft sealed box runs Qtc 0.78, Fc 51 Hz

Ported · this cabinet, 1.31 cu ft, Fb 35.0 HzSealed wedge we build, 0.85 cu ft, Qtc 0.78

Shaded blue is where the ported alignment is louder for the same power, orange where the sealed one is. The sealed curve is the 0.85 cu ft sealed wedge we build for this driver (PO 12-S W S2), not this cabinet with the port blocked: two different boxes, because that is the choice a buyer actually has. Across 25 to 60 Hz the vent is worth 5.0 dB at its widest and 3.8 dB on average. This is the anechoic picture, which is not what you hear in a car.

04Real World Ported vs Sealed

The same two boxes with cabin gain applied, 45 Hz corner, 18 dB ceiling.

Flatness across 25–60 Hz: ported 2.9 dB spread, the 0.85 cu ft sealed box 2.3 dB

Ported, in-car · 2.9 dB spreadSealed wedge we build, 0.85 cu ft, in-car · 2.3 dB spread

Cabin gain lifts both boxes by the same amount, so the gap between them does not change: what changes is the shape each one ends up with. A car pressurises below roughly 45 Hz, which fills in the sealed box's shallower rolloff and over-drives it where the ported box is already flat. Across 25 to 60 Hz, the band kick and bass fundamentals occupy, this alignment holds 2.9 dB of spread against 2.3 dB for the 0.85 cu ft sealed wedge we build for this driver (PO 12-S W S2). The sealed curve is flatter on paper; the ported one trades that for output. Note where the curves cross. Below about 22 Hz the sealed alignment becomes the louder of the two and stays louder all the way down, by up to 1.4 dB: a sealed box rolls off gently into the subsonic region where a vented one falls away steeply once it is below tuning and the vent stops contributing. If the content you are chasing lives below 22 Hz, a sealed alignment reaches further down than this one does. Cabin gain here is a house assumption, not a measurement of your vehicle.

05The watts that reach Xmax (in this enclosure)

Travel scales with the square root of power, so there is one wattage that puts the cone exactly on Alpine's published 15.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

P_Xmax = 2348 W with a 28 Hz subsonic · 318 W with none → the filter is worth 7.4×

2348 W · subsonic at 28 Hz, 24 dB/oct318 W · no subsonic filterXmax 15.0 mm one-way, published

Each trace touches the limit and no further, because each is drawn at the exact power that puts the cone on 15.0 mm. With a 28 Hz subsonic that takes 2348 W, reached first at 50 Hz. Take the filter away and the same cabinet reaches 15.0 mm on 318 W — the filter is worth 7.4× the safe power. A vent unloads the cone below tuning, so there is nothing holding it once the box stops loading: on a sealed build a subsonic filter is an improvement, here it is required equipment. The unfiltered trace is still rising where this chart stops at 20 Hz, so treat 318 W as a bound rather than a floor. Every wattage on this page is a MECHANICAL limit, not an electrical one. It is the power at which the cone runs out of linear travel in this cabinet, and nothing more. What the voice coil can dissipate as heat is a separate ceiling set by the driver, not by the box — Alpine rate this one at 600 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 600 W as the ceiling and the travel figures above as headroom. Final wired impedance, amplifier output and how long you hold the level are all electrical questions this graph does not answer.

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.