Proline X

Proline X Performance Optimized Wedge Enclosure | Fits Dual Kicker Solo X 12" Subwoofers

Q: Will my Kicker Solo X 12s fit this enclosure?

Yes. Each baffle opening is CNC-cut to Kicker's published 11-1/16 inch cutout for the Solo X L7X 12, and each chamber clears the required 10-1/8 inch mounting depth with margin, including breathing room for the vented motors. Both coil versions fit; just use a matched pair.

Q: Why two separate chambers instead of one shared volume?

Because two drivers sharing one volume stop behaving like the alignment says they should. Each cone's compression stroke becomes the other's pressure environment, which smears transients and blurs the Qtc both were designed to hit. The full-height 3/4 inch divider gives each Solo X 12 its own 1.13 cubic feet at the same tightly damped tune as our single 12, keeps the pair perfectly matched, and braces the widest span of the cabinet as a bonus.

Q: Do both subwoofers need to be the same coil version?

Yes. Run two dual 1-ohm drivers or two dual 2-ohm drivers, never one of each. Identical drivers wired identically off the shared cup share power evenly and move in lockstep; mixed coils create unequal branch impedances that unbalance the pair. A dual 1-ohm pair commonly wires to 1 or 4 ohms, a dual 2-ohm pair to 0.5 or 2 ohms; choose whichever lands on your amplifier's rated load.

Q: How does the dual 12 compare to the single 18 wedge?

The dual 12s bring more total cone area and about 3 dB more thermal capability, in a cabinet 3 inches shorter than the 18's. The 18 counters with reach: its Fc sits down near 40 Hz, the deepest sealed tune in the line, and one giant cone has a scale to its presentation that multiple smaller drivers never quite copy. Chasing maximum clean output behind a seat, take the dual 12s. Chasing the deepest, most effortless bottom octave, take the 18. Neither answer is wrong.

Q: Will this wedge fit behind the seat of my truck?

You need 31.75 inches of width, 15.25 inches of height, and 17.25 inches of depth at the floor; the top needs only 11.75 inches thanks to the 20 degree baffle rake, and the vertical rear panel sits flat against the cab wall. This is a crew-cab-class footprint. Measure the clear span behind your seat between belt towers and door trim, and check height against the seat back, before ordering.

Q: Are the subwoofers included with this enclosure?

No, this listing is the enclosure only. It is built for a matched pair of Kicker Solo X L7X 12s, which you install using the pressed 8/32 threaded inserts and the two sets of included stainless mounting hardware. If you want help sourcing a pair of Solo X 12s or matching an amplifier, call or text us at 931-563-5151.

SKU: PO 12D-S W Solo X

QUICK SPECS

Alignment: Two identical sealed chambers, 1.13 cu ft net each (2.26 total), tightly damped. Dual 1-ohm 49L7X121s run Qtc 0.61, F3 59.8 Hz; dual 2-ohm 49L7X122s run Qtc 0.64, F3 58.8 Hz per chamber
Chambers: Full-height 3/4 in dado-locked divider, one driver per chamber, doubles as bracing across the 31.75 in span
Drivers: Pair of Kicker Solo X L7X 12s, matched coil versions. Each opening CNC-cut to 11-1/16 in per Kicker spec, 10-1/8 in depth cleared
Wiring: One shared side-mounted terminal cup, 12 gauge OFC to both positions. Kicker recommends 1000-2000 watts RMS per driver, 2000-4000 system
Cabinet: 31.75 in W x 15.25 in H x 11.75/17.25 in D, 3/4 in Langboard Elite MDF, 1.5 in double baffle plus trim, plush black carpet with black acrylic insert

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.

$ 549.99

In Stock and Ready to Ship

Financing available. Choose Shop Pay Installments at checkout.

Proline X Performance Optimized Wedge Enclosure | Fits Dual Kicker Solo X 12" Subwoofers

$ 549.99

Enclosure Type Sealed

External Dimensions 31.75" W x 15.25" H x 11.75" top / 17.25" bottom D (20° wedge)

Net Volume 2.26 total / 1.13 per chambercu ft

Tuning Frequency N/A (Sealed)

Cutout Diameter Direct Fit

Front Panel Thickness 1.5"

Max Mounting Depth Direct Fit

INSTALLER'S TAKE

This is the output king of the sealed wedge line. Two Solo X 12s, each in its own 1.13 cubic foot chamber at the same tightly damped 0.61-0.64 Qtc as the single 12, deliver the most cone area and the most displacement of any box we build in this series. Same flat, controlled character as the single, roughly 6 dB more of it, and the authority to make sealed bass feel effortless at any volume.

The full-height divider earns its keep twice here. Sonically it keeps each 12 in its own air so neither modulates the other's alignment. Structurally it bisects a 31.75 inch cabinet at exactly the span where big cone area would otherwise start talking through the panels. Two drivers at up to 2000 watts each will find any weakness; this box does not offer one.

Matched coils, identical wiring, one shared cup. A dual 1-ohm pair lands at 1 or 4 ohms in the common configurations, a dual 2-ohm pair at 0.5 or 2 ohms; map your amplifier's rated load first, then order drivers. Feed the pair 2000-4000 clean watts and set gains properly; the sealed chambers keep both cones loaded and composed at full output.

Measure twice on this one. You need 31.75 inches of clear width, 15.25 of height, and 17.25 of floor depth. In most crew cabs it fits centered behind the seat; in anything smaller, confirm the span between belt towers. If it fits, nothing else in this line touches it for sheer capability.

Product Details

Performance Optimized Wedge | Dual Kicker Solo X 12

Dual 12" Sealed Wedge Enclosure | Behind-Seat Wedge Design for Two Kicker Solo X L7X 12s

2.66 ft³ Gross1.13 ft³ Net / ChamberTightly Damped31.75" × 15.25" × 11.75/17.25"V-Groove / DadoBuilt in Tennessee

Two Kicker Solo X 12s in a Purpose-Built Sealed Wedge

A matched pair of Solo X L7X 12s is a statement system: two triple-stacked ferrite motors and two 3-inch coils of thermal capacity behind the seat. Each chamber was computed directly from Kicker's factory Thiele/Small parameters, not adapted from a generic dual 12" box.

A 3/4" divider splits the box into two identical sealed chambers, 1.13 cu ft net each after driver displacement. That puts each dual 1-ohm Solo X 12 at a tightly damped Qtc of 0.61 and dual 2-ohm drivers at 0.64: firmly in the control-first zone below Butterworth, with no peaking anywhere in the passband.

Behind-Seat Wedge Design Explained

This is a front-firing wedge built for behind-seat and rear-wall installs. The rear panel is vertical and sits flat against the cab wall; both woofers mount on the baffle, raked back 20 degrees to follow the seat lean.

Vertical Rear Panel

Sits flush against the cab back wall or trunk bulkhead, so the full footprint of the box goes to airspace instead of wasted gaps.

20° Raked Baffle

Matches the lean of most factory seat backs and fires both Solo X drivers forward into the cabin instead of into the seat.

Chambered and Braced

The 3/4" dado-locked center divider isolates each driver in its own sealed chamber and doubles as a full-height brace, killing panel resonance across the 31.75-inch span.

Carpet-Wrap Ledge

A recessed perimeter ledge terminates the carpet cleanly at the baffle edge for a finished, factory look.

Engineered for the Kicker Solo X 12

Each chamber is built to 1.13 cubic feet net. Dual 1-ohm 49L7X121 drivers run a Qtc of 0.61 and dual 2-ohm 49L7X122 drivers run 0.64: alignments on the damped side of Butterworth, where the box and suspension keep the massive SoloX motors on a short leash. The payoff is bass with zero bloom, kick drums that hit and stop, and a gradual roll-off that in-vehicle cabin gain fills back in below the knee. Because the chambers are identical, both drivers stay perfectly matched.

Alignment Numbers (Per Driver)

Dual 1-Ohm: Qtc 0.61 · Fc 50 Hz · F3 59.8 Hz — Dual 2-Ohm: Qtc 0.64 · Fc 52 Hz · F3 58.8 Hz

Mounting Geometry

Each baffle opening is CNC-cut to 11-1/16" (Kicker spec). Mounting depth required is 10-1/8", cleared with margin at every point of the stroke, including breathing room for the vented motor. 8/32 threaded inserts pressed into the baffle backside.

Sealed Alignment Response

Predicted anechoic response of each Solo X 12 in its own 1.13 cu ft sealed chamber, computed from Kicker factory T/S parameters. This enclosure ships without drivers, so both coil variants are plotted; they do not load the same chamber identically.

The dashed line marks the half-power point. Roll-off below F3 is the gentle 12 dB/octave slope characteristic of sealed alignments, which cabin gain in a real vehicle substantially fills in. Run the numbers yourself with our sealed box calculator.

Performance Series Construction, Driver-Specific Tuning

Langboard Elite MDF

Premium 3/4" MDF panels milled to documented spec.

V-Groove and Dado Joinery

CNC-cut V-grooves at every panel intersection. Dado joints lock the raked baffle, vertical rear panel, and center divider into the side walls.

Double-Layer 1.5" Front Baffle

Two bonded 3/4" MDF sheets plus a trim layer at the driver mounting face. Two Solo X 12s put serious mechanical load into the baffle at 4000 combined watts; it does not flex.

Pre-Wired Terminal Cup

Proline X ABS/carbon-fiber composite terminal cup, side-mounted, with 12 gauge OFC pre-wired.

Finish and Trim

Plush Black Carpet

Every enclosure ships wrapped in plush black automotive carpet, the standard finish for the PO Wedge line.

Black Acrylic Insert

The signature Proline X acrylic insert comes in black.

Box-Only

This listing is box-only. Bring your own pair of Solo X 12s.

Wiring Two Kicker Solo X 12s to Your Amplifier

Kicker recommends 1000-2000 watts RMS per Solo X 12, so plan 2000-4000 watts RMS of clean system power across the pair at your wired impedance. Match both drivers to the same coil configuration so the pair loads and wires symmetrically; the tight damping keeps cone travel controlled through the passband.

Built in Tennessee, Backed by Audio Intensity

Manufactured in Tullahoma, Tennessee on our ShopSabre CNC equipment. 1-year limited warranty. Call or text 931-563-5151.

Dual Kicker Solo X 12s: Tight, Controlled Power, Twice Over

Two identical 1.13 cubic foot sealed chambers, solved from factory T/S for a tightly damped alignment. Double the cone area, zero bloom, in a wedge that disappears behind the seat.

Specifications

Series	Proline X Performance Optimized Wedge
Compatible Driver	Kicker Solo X L7X 12 (49L7X121 / 49L7X122) \| Pair Required
Enclosure Type	Sealed \| Dual Driver \| Front-Firing Wedge
Chamber Configuration	Two Identical Sealed Chambers \| Full 3/4" Divider \| Single Shared Side-Mounted Terminal Cup
Wedge Angle	20 Degrees, Vertical Rear Panel
External Width	31.75 Inches
External Height	15.25 Inches
External Depth (Top)	11.75 Inches
External Depth (Bottom)	17.25 Inches
Total Internal Gross Volume	2.66 Cubic Feet
Per-Chamber Net Volume	1.13 Cubic Feet
Total Net Volume	2.26 Cubic Feet
System Qtc Per Chamber (Dual 1-Ohm)	0.61 Tightly Damped
System Qtc Per Chamber (Dual 2-Ohm)	0.64 Tightly Damped
Predicted Fc Per Driver	50 Hz (D1) / 52 Hz (D2)
Predicted F3 Per Driver (Anechoic)	59.8 Hz (D1) / 58.8 Hz (D2)
Driver Fs (D1 / D2)	40.3 Hz / 41.6 Hz (Kicker Factory)
Driver Qts (D1 / D2)	0.487 / 0.506 (Kicker Factory)
Driver Vas (D1 / D2)	18.05 L / 18.36 L (Kicker Factory)
Woofer Cutout (Each)	11-1/16 Inches (Kicker Spec)
Mounting Depth Required (Each)	10-1/8 Inches, Cleared With Margin
Recommended Power Per Driver	1000-2000 Watts RMS (Kicker Recommendation)
Recommended System Power	2000-4000 Watts RMS Across The Pair
Material	Langboard Elite 3/4" MDF
Construction	ShopSabre CNC \| V-Groove and Dado Joinery
Panel Thickness	3/4 Inch
Front Baffle	Double-Layer 1.5" MDF Plus Trim Layer
Chamber Divider	3/4" MDF Full-Height, Dado-Locked, Doubles As Brace
Driver Mounting	8/32 Threaded Inserts \| Stainless Machine Screws Included \| 2 Sets
Terminal Cup	One Proline X ABS/Carbon Fiber Composite \| Side Mounted \| Serves Both Chambers
Internal Wiring	12 Gauge OFC, Pre-Wired To Both Driver Positions
Finish	Plush Black Carpet \| Black Acrylic Insert
Bundle Options	Enclosure Only (Bring Your Own Pair of Solo X 12s)
Warranty	1-Year Limited (Enclosure)
Built In	Tullahoma, Tennessee, USA

Performance Graphs

Net airspace

1.13

cu ft per chamber

System Qtc

0.61–0.63

sealed

Half power

58.8–59.8

Hz · F3

Xmax at

4802

W RMS · no filter

With 25 Hz subsonic

6874

W RMS · +43%

Amplifier

1000–2000

W RMS recommended

This enclosure holds 1.13 cu ft net per chamber. In it the Kicker SoloX L7X 12 (49L7X121) runs a system Qtc of 0.61–0.63 with half power at 58.8–59.8 Hz, and the cone reaches its 31.25 mm travel limit at 4802 W, above the driver’s 2000 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 6874 W — +2072 W, or 43 percent more power for the same 31.25 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 76.5–78.2

D1 · EBP 78.2D2 · EBP 76.5

At 76.5–78.2 the SoloX L7X 12 (49L7X121) 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

1.13 cu ft against a 18.0 L Vas.

α = Vas ÷ Vb = 0.56 · Fc = Fs√(α+1) = 50–52 Hz · Qtc = 0.61–0.63

D1 · Qtc 0.61, Fc 50 Hz, F3 59.8 HzD2 · Qtc 0.63, Fc 52 Hz, F3 58.8 Hz

The box lifts resonance from 40.3–41.6 Hz free-air to 50–52 Hz and half power lands at 58.8–59.8 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 31.25 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

P_Xmax = 4802–5009 W unfiltered → 6874–6949 W with a 25 Hz subsonic

D1 · 4802 W, no filterD2 · 5009 W, no filterD1 · 6949 W with subsonic at 25 Hz, 24 dB/octD2 · 6874 W with subsonic at 25 Hz, 24 dB/octXmax 31.25 mm one-way

Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 31.25 mm. Unfiltered that is 4802 W, reached first at 20 Hz. It sits above the 2000 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 6874 W before hitting the same 31.25 mm. That is 43 percent more amplifier for the price of one filter setting.

Param	Value	Unit	Note
Fs	40.30 / 41.60	Hz	free-air resonance
Qts	0.487 / 0.506		D1 / D2
Vas	18.05 / 18.36	L	equivalent compliance
Sd	585.6	cm²	effective piston area
Xmax	31.25	mm	one-way linear travel
Pe	2000	W	continuous RMS
SPL	85.5	dB	1 W / 1 m, derived from T/S

Driver parameters as published by Kicker published Klippel T/S sheet. 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.