Performance Optimized Series PO 12D-S W R2 speaker enclosure by Proline, designed for Alpine R2-W series. The product is a black dual-baffle woofer box with two circular openings, shown on a dark blue gradient background with technical specifications and dimensions.

Proline X PO 12D-S W R2 sealed wedge enclosure, interior through the baffle opening showing the 1.5 inch mounting baffle and pre-wired leads. Optimized for Alpine R2-W.

A Proline Performance Optimized Series woofer subwoofer shown as a wedge-shaped black cabinet with dimension labels 14 inches wide, 15 inches tall, and 8.5 inches top width, plus text listing features and compatibility with Alpine R2-W series.

Proline X

Performance Optimized Wedge Sealed Dual 12" Enclosure | Alpine R2-W12

Q: Will this enclosure fit both the R2-W12D2 and R2-W12D4?

Yes. Both mounting locations are direct-fit for either impedance option. Run matched impedance drivers only (both D2 or both D4).

Q: Why does this enclosure have two separate chambers instead of one shared chamber?

All Proline X dual-driver sealed enclosures use two fully separate chambers with a bonded full-height divider. Each R2-W12 gets its own dedicated air volume and polyfill damping.

Q: How is this enclosure wired, and how do I set my final impedance?

Two independent Proline X terminal cups, one per chamber. Alpine's push terminals with VC jumpers let you configure the dual coils in series or parallel at each driver first, then combine the two cups externally at the amp.

Q: What amplifier power should I run to this enclosure?

Each R2-W12 is rated 750W RMS continuous. For a matched pair target 1000-1500W RMS total (500-750 per driver) at the final wired impedance.

Q: How does a wedge enclosure improve the sound in a trunk installation?

The wedge geometry angles both drivers rear-firing into the trunk at approximately 23 degrees from vertical.

Q: Why is the front baffle double-layered on this enclosure?

Both driver positions get the full double-baffle treatment: two bonded 3/4 inch Langboard Elite MDF sheets with CNC-precision cutouts.

Q: Do I need to add any additional damping or polyfill to this enclosure?

No additional damping required. Each chamber ships with polyfill pre-installed to correct density.

Q: Are the Alpine R2-W12 subwoofers included with this enclosure?

No. Enclosure only. Bring your own matched pair of R2-W12D2 (DVC 2Ω) or R2-W12D4 (DVC 4Ω) drivers.

SKU: PO 12D-S W R2 BB

QUICK SPECS

Best For: Dual Alpine R2-W12 Trunk-Fit Builds
Net Volume: 0.75 cu ft per chamber (1.70 cu ft Gross Total)
Driver Match: Pair of Alpine R2-W12 (D2 or D4, matched)
Construction: Dual Chamber Wedge | V-Groove/Dado | Double 1.5" Baffle | 2 Terminal Cups

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.

$ 369.99

Acrylic Insert Color

In Stock and Ready to Ship

Financing available. Choose Shop Pay Installments at checkout.

Performance Optimized Wedge Sealed Dual 12" Enclosure | Alpine R2-W12

Enclosure Type Sealed

External Dimensions 29.5" W x 15" H x 14" D at base tapering to 8.57" D at top

Gross Volume 1.98 cu ft

Net Volume 0.75 per chamber (1.50 total) cu ft

Weight 43.5 lbs

Front Panel Thickness 1.5"

INSTALLER'S TAKE

This is the dual-12 wedge for people who want a pair of R2-W12s in a single trunk-loading cabinet. Two chambers, one wedge, +6 dB of headroom over a single-driver setup, and per-chamber alignment that matches the single-driver PO Wedge for the same driver.

The critical detail on this build is the separate-chamber architecture. Every dual-driver sealed enclosure I build gets a full-height bonded divider between the two chambers. Two drivers in a common sealed chamber will interact acoustically - one driver's compression phase becomes the other driver's cabin-pressure environment, which smears transient response and blurs the alignment character each driver would have on its own. Separate chambers eliminate that entirely. Each R2-W12 sees its own 0.75 net cubic feet and its own polyfill, and produces its own clean sealed alignment.

Per-chamber alignment matches Alpine's own recommended sealed volume. D2 coil lands at Qtc 0.68 - a near-Butterworth musical alignment. D4 coil lands at Qtc 0.81 - punchier and tighter. Fc lands at approximately 48 Hz across both coils. If you strongly favor the D2 target this is the right cabinet; the D4 coil in this volume is well-controlled but sits on the punchy side of Butterworth.

The double-baffle 1.5" front is not optional. Each R2-W12 exerts serious mechanical load into its mounting flange at high output, and a single 3/4" layer would telegraph flex back into the cone on both driver positions. Two bonded 3/4" layers with the CNC-precision cutouts stops that entirely.

On wiring: this cabinet uses one side-mounted terminal cup that feeds both driver positions in parallel. You set your final impedance at the drivers themselves. The R2's 8AWG push terminals with VC configuration jumpers make that straightforward - set the voice coil wiring on each driver and that determines the load the amp sees through the cup. Wire both drivers identically. Target 500-750 watts RMS per driver at whatever load you land on.

Product Details

Performance Optimized Wedge | Alpine R2-W12 Dual

Dual 12" Sealed Wedge | Two Separate Chambers | Rear-Firing Trunk-Load

1.70 ft³ Gross0.75 ft³ Net/ChDual Chamber29.5" × 15" × 8.57/14"V-Groove / DadoBuilt in Tennessee

The Alpine R2-W12 in a Dual-Driver Sealed Wedge

Two R2-W12s in a single trunk-loading wedge with fully independent sealed chambers. 750W RMS per driver, +6dB headroom over single.

1.70 cu ft total gross, split into 0.85 cu ft per-chamber gross, 0.75 cu ft per-chamber net. Same per-chamber alignment as the single-driver PO Wedge for R2-W12.

Two Fully Separate Chambers

Full-height, full-depth 3/4" MDF divider. Each driver sees its own dedicated air volume and terminal cup.

All Proline X dual-driver sealed enclosures use this architecture. Each driver produces its own clean sealed alignment.

Trunk-Load Wedge Design Explained

Both R2-W12s mount on the vertical trunk-lid-side face and fire rearward into the trunk cavity.

Seat-Side Face Matches Seat Lean

Angled face matches ~20 degree factory seat lean.

Trunk-Lid-Side Face Fires the Woofers

Both drivers on vertical face, firing rearward.

Trunk Cavity Loading

Trunk acts as acoustic extension.

Preserves Trunk Cargo Space

Wedge tucks against seat back.

Engineered for the Alpine R2-W12

Per-chamber 0.75 cubic feet net gives D2 Qtc 0.68 (near-Butterworth), D4 Qtc 0.81 (punchy). Matches Alpine's own recommended sealed volume per driver.

Alignment Numbers (Per Chamber)

D2 Qtc: 0.68 · D4 Qtc: 0.81 · Fc: ~48 Hz · F3: 43-50 Hz

Performance Series Construction, Driver-Specific Tuning

Langboard Elite MDF

Premium 3/4" MDF panels + 3/4" chamber divider.

V-Groove and Dado Joinery

CNC-cut V-grooves at every panel intersection.

Double-Layer 1.5" Front Baffle

Two bonded 3/4" MDF sheets at both driver positions.

Two Pre-Wired Terminal Cups

One per chamber, 12g OFC pre-wired.

Customize Your Build

Carpet Finish

Charcoal gray trunk liner standard; plush black +$10.

Acrylic Insert Color

Black, Blue, Red, White, or none (-$40).

Box-Only or Loaded

Box-only: bring your own pair of matched R2-W12 drivers.

Wiring the R2-W12 Pair to Your Amplifier

Two independent terminal cups let you wire in series or parallel externally at the amp. Run matched impedance drivers only.

Built in Tennessee, Backed by Audio Intensity

Manufactured in Tullahoma, Tennessee. 1-year limited warranty. Call 931-563-5151.

Alpine R2-W12 Dual, Alpine's Own Sealed Spec, Doubled

0.75 cubic feet net per chamber, Alpine's published sealed volume, doubled up for +6dB of headroom.

Specifications

Enclosure Type	Sealed \| Dual Driver \| Wedge Geometry \| Rear-Firing Trunk-Load
Chamber Configuration	Two Fully Separate Chambers \| Full-Height Divider \| Single Shared Side-Mounted Terminal Cup
Driver-Specific Fitment	Alpine R2-W12 - R2-W12D2 (DVC 2Ω) or R2-W12D4 (DVC 4Ω) \| Pair Required
Total Internal Gross Volume	1.70 Cubic Feet
Per-Chamber Gross Volume	0.85 Cubic Feet
Per-Chamber Net Volume (After Displacement)	0.75 Cubic Feet
Per-Chamber Target Qtc (D2)	0.68 (Near-Butterworth Musical \| Based on Published T/S)
Per-Chamber Target Qtc (D4)	0.81 (Punchy \| Based on Published T/S)
Predicted F3 Per Driver	~43-50 Hz (Depending on Coil)
Predicted Fc Per Driver	~48 Hz
Driver Displacement (Each)	0.10 Cubic Feet (Published by Alpine)
Baffle Configuration	Vertical Trunk-Lid-Side Woofer Mounting Face \| Both Drivers
Material	Langboard Elite 3/4" MDF
Front Baffle Construction	Double-Layer 1.5" MDF (Two 3/4" Sheets Bonded) at Both Driver Positions
Chamber Divider	3/4" MDF Full-Height Bonded Panel
Joinery	V-Groove and Dado (CNC-Cut)
Construction	ShopSabre CNC / Angled Seat-Side Compound Cuts / Perimeter Cross-Brace
External Width	29.5 Inches
External Height	15 Inches
External Depth (Top)	8.57 Inches
External Depth (Bottom)	14 Inches
Baffle Angle	~20° From Vertical (Seat-Side Face)
Mounting Hole Diameter (Each)	10.79 Inches (Alpine Spec)
Mounting Depth Required (Each)	7.45 Inches (Alpine Spec)
Mounting Hardware	8/32 Threaded Inserts \| Stainless Steel Machine Screws Included \| 2 Sets
Terminal Cup	One Proline X ABS/Carbon Fiber Composite \| Side Mounted \| 12g OFC Pre-Wired to Both Driver Positions
Damping	Polyfill Pre-Installed Per Chamber
Recommended Power Per Driver	500-750 Watts RMS (Alpine Rated: 750W RMS Continuous)
Carpet Finish	Dark Gray Trunkliner (Standard) or Plush Black (+$10)
Acrylic Insert	Black, Blue, Red, White, or None (-$40)
Bundle Options	Enclosure Only (Bring Your Own Pair of R2-W12D2 or R2-W12D4)
Warranty	1-Year Limited (Enclosure)
Manufactured	Tullahoma, Tennessee, USA

Performance Graphs

Net airspace

0.75

cu ft per chamber

System Qtc

0.68–0.81

sealed

Half power

42.4–50.1

Hz · F3

Xmax at

1132

W RMS · no filter

With 25 Hz subsonic

1467

W RMS · +30%

Amplifier

750

W RMS recommended

This enclosure holds 0.75 cu ft net per chamber. In it the Alpine R2-W12D2 runs a system Qtc of 0.68–0.81 with half power at 42.4–50.1 Hz, and the cone reaches its 20.0 mm travel limit at 1132 W, above the driver’s 750 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 1467 W — +335 W, or 30 percent more power for the same 20.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 54.5–65.9

D2 · EBP 65.9D4 · EBP 54.5

At 54.5–65.9 the R2-W12D2 sits in the transition band, not the sealed band. That is not a mismatch: a transition motor works in either alignment, and sealed buys a smaller box and a gentler roll-off at the cost of some low-end output. Stage 02 shows what this airspace actually does with it.

02What the box does to it

0.75 cu ft against a 36.9 L Vas.

α = Vas ÷ Vb = 1.74 · Fc = Fs√(α+1) = 48–48 Hz · Qtc = 0.68–0.81

D2 · Qtc 0.68, Fc 48 Hz, F3 50.1 HzD4 · Qtc 0.81, Fc 48 Hz, F3 42.4 Hz

The box lifts resonance from 29.0 Hz free-air to 48–48 Hz and half power lands at 42.4–50.1 Hz, anechoic, before any cabin gain. This enclosure ships without a driver, so both coil variants the maker offers are plotted. They do not load the same box the same way.

03The 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 20.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

P_Xmax = 1132–1261 W unfiltered → 1467–1545 W with a 25 Hz subsonic

D2 · 1132 W, no filterD4 · 1261 W, no filterD2 · 1545 W with subsonic at 25 Hz, 24 dB/octD4 · 1467 W with subsonic at 25 Hz, 24 dB/octXmax 20.0 mm one-way

Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 20.0 mm. Unfiltered that is 1132 W, reached first at 20 Hz. It sits above the 750 W the driver can take thermally, so the voice coil gives up before the suspension does. The dashed traces are the same driver behind a subsonic filter at 25 Hz, 24 dB/oct: stopping the cone wasting travel below the passband lets it take 1467 W before hitting the same 20.0 mm. That is 30 percent more amplifier for the price of one filter setting.

Param	Value	Unit	Note
Fs	29.00	Hz	free-air resonance
Qts	0.410 / 0.510		D2 / D4
Vas	36.90 / 32.80	L	equivalent compliance
Sd	479.0	cm²	effective piston area
Xmax	20	mm	one-way linear travel
Pe	750	W	continuous RMS
SPL	85.0	dB	1 W / 1 m, derived from T/S

Driver parameters as published by Alpine R2-W Thiele-Small sheet CN_TS_R2-W (2022). Curves computed against this enclosure’s actual net airspace.

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.