Proline X

Proline X Performance Optimized Wedge Enclosure | Fits Kicker Solo X 15" Subwoofer

Q: Will my Kicker Solo X 15 fit this enclosure?

Yes. The baffle is CNC-cut to Kicker's published 13.75 inch cutout for the Solo X L7X 15, and the cabinet clears the required 11.5625 inch mounting depth with margin at every point of the stroke, including breathing room for the vented motor. Both the dual 1-ohm 49L7X151 and dual 2-ohm 49L7X152 fit identically.

Q: What is a Butterworth alignment and why does it matter?

Butterworth describes a sealed system with a total Q of 0.707, the point where the response stays maximally flat all the way to the knee with no peak and no early sag. Below 0.707 a box trades extension for even tighter damping; above it, response picks up a bump around resonance that reads as boom. This cabinet's airspace was solved from Kicker's factory Thiele/Small parameters to land the dual 1-ohm Solo X 15 at 0.707 exactly, so you get the flattest, best-controlled bass the driver can produce in a sealed box.

Q: Which coil version should I buy, dual 1-ohm or dual 2-ohm?

Choose by amplifier, not by the box. In this airspace the dual 1-ohm lands at Qtc 0.707 and the dual 2-ohm at 0.79; both are firmly in the accurate, musical zone and the audible difference in a vehicle is minimal. Buy the coil configuration that wires to the impedance your amplifier makes its rated power into: dual 1-ohm gives you a 0.5 or 2 ohm final, dual 2-ohm gives you 1 or 4 ohms.

Q: How much power should I run to the Solo X 15 in this box?

Kicker recommends 1000-2000 watts RMS for the Solo X 15, and this sealed alignment supports the full range. The sealed air spring keeps cone travel controlled as level rises, so the driver stays composed at power in a way ported boxes cannot match near tuning. Prioritize clean power with properly set gains over sheer wattage; an honest 1200-1500 watts will deliver everything most daily systems ask for.

Q: Where is the terminal cup and how is the enclosure wired?

A single Proline X ABS and carbon fiber composite terminal cup is mounted on the side of the cabinet, which keeps the connection accessible when the vertical rear panel is tight against the cab wall. It is pre-wired internally with 12 gauge OFC to the driver position. Your final impedance is set by how you wire the Solo X's dual voice coils at the driver.

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

It was drawn for exactly that spot. You need 26 inches of width, 18.25 inches of height, and 19.25 inches of floor depth; the top of the box needs only 12.625 inches because the baffle rakes back 20 degrees to follow the seat lean. The rear panel is fully vertical so it sits flat against the cab wall without wasting space. A 15 is a big driver, so measure your cab before ordering; in many mid-size and single-cab trucks this box belongs on the passenger side or centered with the seat forward one notch.

Q: Is the subwoofer included with this enclosure?

No, this listing is the enclosure only. It is built specifically for the Kicker Solo X L7X 15 in either coil configuration, and you install your own driver using the pressed 8/32 threaded inserts and included stainless mounting hardware. If you want help pairing a Solo X 15 or an amplifier with it, call or text us at 931-563-5151.

SKU: PO 15-S W Solo X

QUICK SPECS

Alignment: 2.76 cu ft net in a sealed wedge. Dual 1-ohm 49L7X151 lands at Qtc 0.707 (true Butterworth), Fc 45 Hz, F3 45 Hz; dual 2-ohm 49L7X152 runs Qtc 0.79, Fc 46 Hz, F3 41.7 Hz
Geometry: 20° front-firing wedge, vertical rear panel sits flat against the cab wall. 26 in W x 18.25 in H x 12.625 in top / 19.25 in bottom depth
Driver: Kicker Solo X L7X 15 (either coil version). Baffle CNC-cut to 13.75 in per Kicker spec, 11.5625 in mounting depth cleared with margin
Wiring: One side-mounted terminal cup, 12 gauge OFC pre-wired. Kicker recommends 1000-2000 watts RMS; set final impedance at the driver's coils
Cabinet: 3/4 in Langboard Elite MDF, 1.5 in double-layer baffle plus trim, dado-locked brace behind the woofer, 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 Kicker Solo X 15" Subwoofer

$ 549.99

Enclosure Type Sealed

External Dimensions 26" W x 18.25" H x 12.625" top / 19.25" bottom D (20° wedge)

Net Volume 2.76cu 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 Butterworth box of the Solo X wedge line. At 2.76 net cubic feet the dual 1-ohm 15 lands at Qtc 0.707 almost exactly, which is the alignment every sealed-box textbook is written around: flattest possible response with zero peaking and the best transient behavior a closed box can give. The dual 2-ohm runs 0.79 in the same air, a hair warmer through the 50-70 Hz octave. Nobody will pick the difference in a truck cab.

Pick your coil version by your amplifier, not by the box. Both versions load this cabinet correctly, so buy the coils that let your amp see its happiest load: dual 1-ohm for a 1-ohm-stable monoblock wired parallel, dual 2-ohm if you want a 1-ohm or 4-ohm final. The alignment takes care of itself.

Placement is what the wedge shape is for. The rear panel is dead vertical, so it sits flush against the back wall of the cab, and the baffle rakes forward 20 degrees to clear a leaned seat back while firing the cone into the cabin. Measure before you order: you need 26 inches of width, 18.25 of height, and 19.25 of depth at the floor. The top of the box only needs 12.625.

On power, Kicker's recommendation is 1000-2000 watts RMS and the sealed loading is what makes the top of that range usable. The air spring rises fast below Fc, so the cone stays controlled where a ported box would let it unload. Clean power matters more than big power; set gains with a scope or DMM and the 15 will take everything a real 2000-watt amp makes.

Know what you are buying. A ported Solo X build will out-SPL this box, no argument. What this wedge does is play flat, stop on a dime, and disappear behind a seat, and cabin gain hands back most of the bottom octave the anechoic chart gives up. If the goal is musical, accurate low end from the flagship square sub, this is the alignment that does it.

Product Details

Performance Optimized Wedge | Kicker Solo X 15

15" Sealed Wedge Enclosure | Behind-Seat Wedge Design for the Kicker Solo X L7X 15

3.00 ft³ Gross2.76 ft³ NetQtc 0.707 Butterworth26" × 18.25" × 12.6/19.25"V-Groove / DadoBuilt in Tennessee

The Kicker Solo X 15 in a Purpose-Built Sealed Wedge

The Solo X L7X 15 is Kicker's flagship square-cone driver, built around a massive triple-stack motor with SPL-lane pedigree. That same motor authority makes it a devastating sealed-box driver when the airspace is solved for it, and this wedge was: the internal volume was computed directly from Kicker's factory Thiele/Small parameters, not adapted from a generic 15" box.

3.00 cu ft gross internal volume produces 2.76 cu ft net after driver displacement. That lands the dual 1-ohm Solo X 15 at a textbook Qtc of 0.707, the true Butterworth alignment, with the dual 2-ohm at 0.79 in the same cabinet.

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; the woofer mounts 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 the Solo X forward into the cabin instead of into the seat.

Dado-Locked Internal Brace

A 3/4" brace directly behind the woofer halves the largest panel span. Its depth matches the baffle stack, so driver clearance is engineered in, not left to luck.

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 15

Built to 2.76 cubic feet net, the airspace that puts the dual 1-ohm 49L7X151 exactly on the Butterworth alignment. Qtc 0.707 delivers the flattest response and tightest transient control a sealed enclosure can produce: no peaking, no overhang, bass that starts and stops with the recording. The dual 2-ohm 49L7X152 runs 0.79 in the same box, still squarely inside the accurate, musical zone.

Alignment Numbers

Dual 1-Ohm: Qtc 0.707 · Fc 45 Hz · F3 45 Hz — Dual 2-Ohm: Qtc 0.79 · Fc 46 Hz · F3 41.7 Hz

Mounting Geometry

The baffle is CNC-cut to 13.75" (Kicker spec). Mounting depth required is 11.5625", 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 the Solo X 15 in this enclosure's 2.76 cu ft net airspace, computed from Kicker factory T/S parameters. This enclosure ships without a driver, so both coil variants are plotted; they do not load the same box 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 internal brace 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. The Solo X 15 puts serious mechanical load into its flange at 2000 watts; this baffle 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 Solo X 15.

Wiring the Kicker Solo X 15 to Your Amplifier

The Solo X 15 is rated at 2000 watts RMS continuous. In this sealed alignment, target 1200-2000 watts RMS at the woofer's wired impedance for a headroom-rich system; the driver does not need the full spec to sound its best, and sealed loading 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.

Kicker Solo X 15: True Butterworth in a Behind-Seat Wedge

2.76 cubic feet net, solved from factory T/S to land the Solo X 15 at Qtc 0.707. The flattest, tightest sealed alignment the driver can give, in a wedge that disappears behind the seat.

Specifications

Series	Proline X Performance Optimized Wedge
Compatible Driver	Kicker Solo X L7X 15 (49L7X151 Dual 1-Ohm / 49L7X152 Dual 2-Ohm)
Enclosure Type	Sealed \| Single Driver \| Front-Firing Wedge
Wedge Angle	20 Degrees, Vertical Rear Panel
External Width	26 Inches
External Height	18.25 Inches
External Depth (Top)	12.625 Inches
External Depth (Bottom)	19.25 Inches
Internal Gross Volume	3.00 Cubic Feet
Net Volume (After Driver Displacement)	2.76 Cubic Feet
System Qtc (Dual 1-Ohm)	0.707 Butterworth (Computed from Kicker Factory T/S)
System Qtc (Dual 2-Ohm)	0.79 (Computed from Kicker Factory T/S)
Predicted Fc	45 Hz (D1) / 46 Hz (D2)
Predicted F3 (Anechoic)	45 Hz (D1) / 41.7 Hz (D2)
Woofer Cutout	13.75 Inches (Kicker Spec)
Mounting Depth Required	11.5625 Inches, Cleared With Margin
Recommended Power	1000-2000 Watts RMS (Kicker Recommendation)
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
Internal Bracing	3/4" Dado-Locked Brace Behind Woofer
Driver Mounting	8/32 Threaded Inserts \| Stainless Machine Screws Included
Terminal Cup	One Proline X ABS/Carbon Fiber Composite \| Side Mounted
Internal Wiring	12 Gauge OFC, Pre-Wired
Finish	Plush Black Carpet \| Black Acrylic Insert
Bundle Options	Enclosure Only (Bring Your Own Solo X 15)
Warranty	1-Year Limited (Enclosure)
Built In	Tullahoma, Tennessee, USA

Performance Graphs

Net airspace

2.76

cu ft per chamber

System Qtc

0.71–0.79

sealed

Half power

41.3–45.0

Hz · F3

Xmax at

5263

W RMS · no filter

With 25 Hz subsonic

6600

W RMS · +25%

Amplifier

1000–2000

W RMS recommended

This enclosure holds 2.76 cu ft net per chamber. In it the Kicker SoloX L7X 15 (49L7X151) runs a system Qtc of 0.71–0.79 with half power at 41.3–45.0 Hz, and the cone reaches its 31.25 mm travel limit at 5263 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 6600 W — +1337 W, or 25 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 = 52.8–59.2

D1 · EBP 59.2D2 · EBP 52.8

At 52.8–59.2 the SoloX L7X 15 (49L7X151) 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

2.76 cu ft against a 42.1 L Vas.

α = Vas ÷ Vb = 0.54 · Fc = Fs√(α+1) = 45–46 Hz · Qtc = 0.71–0.79

D1 · Qtc 0.71, Fc 45 Hz, F3 45.0 HzD2 · Qtc 0.79, Fc 46 Hz, F3 41.3 Hz

The box lifts resonance from 36.3–36.4 Hz free-air to 45–46 Hz and half power lands at 41.3–45.0 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 = 5263–5385 W unfiltered → 6600–7231 W with a 25 Hz subsonic

D1 · 5263 W, no filterD2 · 5385 W, no filterD1 · 7231 W with subsonic at 25 Hz, 24 dB/octD2 · 6600 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 5263 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 6600 W before hitting the same 31.25 mm. That is 25 percent more amplifier for the price of one filter setting.

Param	Value	Unit	Note
Fs	36.30 / 36.40	Hz	free-air resonance
Qts	0.570 / 0.631		D1 / D2
Vas	42.10 / 44.80	L	equivalent compliance
Sd	961.0	cm²	effective piston area
Xmax	31.25	mm	one-way linear travel
Pe	2000	W	continuous RMS
SPL	87.0	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.