Proline X

Proline X Performance Optimized Wedge Enclosure | Fits Triple Kicker Solo X 8" Subwoofers

Q: Will my Kicker Solo X 8s fit this enclosure?

Yes. Each of the three baffle openings is CNC-cut to Kicker's published 7-5/16 inch cutout for the Solo X L7X 8, and every chamber clears the required 7-15/16 inch mounting depth with margin, including breathing room for the vented motors. Both coil versions fit; use three matched drivers.

Q: Why is the triple 8 deeper than the single and dual 8 wedges?

Because chamber volume is non-negotiable. At 32 inches wide, the two internal dividers consume width that would otherwise be airspace, so the triple carries a slightly deeper profile, 11.75 inches at the top and 16 at the floor, to keep every chamber at the same 0.51 net cubic feet the single and dual use. Same Butterworth alignment per driver, just packaged to hold it three times over.

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

Yes, all three must match. The chambers are identical, so identical drivers wired identically share power evenly and stay in phase lockstep. Mixing coil versions off the single shared cup creates unequal branch impedances, splits power unevenly, and unbalances the set. Choose the coil version whose three-driver wiring lands at a load your amplifier is stable into: three dual 1-ohm drivers commonly net 0.67 or 6 ohms, three dual 2-ohm drivers net 1.33 ohms fully parallel.

Q: How do three 8s compare to a single 12 or 15?

Three 8s roughly match a 12 in cone area while spreading it across lighter, faster cones, and the cabinet stays 11.75 inches tall where our 12 wedge stands 15.25 and the 15 stands 18.25. The big singles still dig deeper anechoically with their lower F3s. The trio answers with transient speed, a wall-of-cone visual, and a height that works behind seats the big boxes cannot. If depth below 40 Hz is the priority, look at the 15 or 18; if speed, fit, and impact are, this is the one.

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

You need 32 inches of width, 11.75 inches of height, and 16 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. The height is friendly, the width is the thing to verify: measure the clear span behind your seat between belt towers and trim before ordering.

Q: Are the subwoofers included with this enclosure?

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

SKU: PO 8T-S W Solo X

QUICK SPECS

Alignment: Three identical sealed chambers, 0.51 cu ft net each (1.53 total). Dual 1-ohm 49L7X81s land at Qtc 0.707 (true Butterworth) per chamber, Fc 54 Hz, F3 54 Hz; dual 2-ohm 49L7X82s run Qtc 0.74, F3 52.2 Hz
Chambers: Two full-height 3/4 in dado-locked dividers, one driver per chamber, doubling as bracing across the 32 in span. Slightly deeper profile than the single and dual 8s to hold chamber volume
Drivers: Three matched Kicker Solo X L7X 8s. Each opening CNC-cut to 7-5/16 in per Kicker spec, 7-15/16 in depth cleared
Wiring: One shared side-mounted terminal cup, 12 gauge OFC to all three positions. Kicker recommends 400-800 watts RMS per driver, 1200-2400 system
Cabinet: 32 in W x 11.75 in H x 11.75/16 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.

$ 499.99

In Stock and Ready to Ship

Financing available. Choose Shop Pay Installments at checkout.

Proline X Performance Optimized Wedge Enclosure | Fits Triple Kicker Solo X 8" Subwoofers

$ 499.99

Enclosure Type Sealed

External Dimensions 32" W x 11.75" H x 11.75" top / 16" bottom D (20° wedge)

Net Volume 1.53 total / 0.51 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

Three Butterworth 8s across one baffle is 12-inch cone area with 8-inch physics: light cones, big combined motor force, and a cabinet that never grows past 11.75 inches tall. Each driver owns an identical 0.51 cubic foot chamber at Qtc 0.707, so the trio moves as one driver with triple the displacement. This is the show-off piece of the 8 family and the loudest small-driver wedge we make.

Notice the profile: the triple runs 11.75 inches of top depth and 16 at the floor, a step deeper than its single and dual siblings. That is deliberate. At 32 inches wide with two dividers eating internal width, depth is where we recovered the airspace to keep every chamber at the full 0.51 net. Nothing about the alignment was compromised to hit the width.

Buy three identical drivers and wire all three the same off the shared cup. With three positions in play, wiring math matters more than usual: three dual 1-ohm drivers land at 0.67 or 6 ohms in the common configurations, while three dual 2-ohm drivers give you 1.33 ohms with everything in parallel. Map your amplifier's stable loads before choosing coils.

Plan 1200-2400 clean watts across the set, 400-800 per driver per Kicker. Fit check before ordering: 32 inches of width is real estate; measure between seat-belt towers and door trim, and confirm 16 inches of floor depth with the seat where you actually keep it, not slid full forward.

Product Details

Performance Optimized Wedge | Triple Kicker Solo X 8

Triple 8" Sealed Wedge Enclosure | Behind-Seat Wedge Design for Three Kicker Solo X L7X 8s

1.83 ft³ Gross0.51 ft³ Net / ChamberQtc 0.707 Butterworth32" × 11.75" × 11.75/16"V-Groove / DadoBuilt in Tennessee

Three Kicker Solo X 8s in a Purpose-Built Sealed Wedge

Three Solo X L7X 8s in matched sealed chambers put 12"-class cone area on the baffle with 8"-class speed and control. Each driver carries Kicker's square-cone SoloX architecture and a high-mass ferrite motor, and each chamber was computed directly from Kicker's factory Thiele/Small parameters. This is the widest 8 in the line, and it runs a slightly deeper profile than its single and dual siblings specifically to hold the chamber volumes identical at the 32-inch width.

Two 3/4" dividers split the box into three identical sealed chambers, 0.51 cu ft net each after driver displacement. That lands every dual 1-ohm Solo X 8 at a textbook Qtc of 0.707, the true Butterworth alignment, with dual 2-ohm drivers at 0.74 in the same chambers.

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; all three 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 all three Solo X drivers forward into the cabin instead of into the seat.

Chambered and Braced

Two 3/4" dado-locked dividers isolate each driver in its own sealed chamber and double as full-height braces, killing panel resonance across the 32-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 8

Each chamber is built to 0.51 cubic feet net, the airspace that puts the dual 1-ohm 49L7X81 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. Dual 2-ohm 49L7X82 drivers run 0.74 in the same chambers. Because all three chambers are identical, the trio stays perfectly matched.

Alignment Numbers (Per Driver)

Dual 1-Ohm: Qtc 0.707 · Fc 54 Hz · F3 54 Hz — Dual 2-Ohm: Qtc 0.74 · Fc 54 Hz · F3 52.2 Hz

Mounting Geometry

Each baffle opening is CNC-cut to 7-5/16" (Kicker spec). Mounting depth required is 7-15/16", 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 8 in its own 0.51 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 both dividers 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. Three Solo X 8s put serious mechanical load into the baffle; 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 trio of Solo X 8s.

Wiring Three Kicker Solo X 8s to Your Amplifier

Kicker recommends 400-800 watts RMS per Solo X 8, so plan 1200-2400 watts RMS of clean system power across the trio at your wired impedance. Match all three drivers to the same coil configuration so the set loads and wires symmetrically; 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.

Triple Kicker Solo X 8s: True Butterworth, Times Three

Three identical 0.51 cubic foot sealed chambers, solved from factory T/S to land every Solo X 8 at Qtc 0.707. Twelve-inch cone area with eight-inch speed, in a wedge that disappears behind the seat.

Specifications

Series	Proline X Performance Optimized Wedge
Compatible Driver	Kicker Solo X L7X 8 (49L7X81 / 49L7X82) \| Three Required
Enclosure Type	Sealed \| Triple Driver \| Front-Firing Wedge
Chamber Configuration	Three Identical Sealed Chambers \| Two Full 3/4" Dividers \| Single Shared Side-Mounted Terminal Cup
Wedge Angle	20 Degrees, Vertical Rear Panel
External Width	32 Inches
External Height	11.75 Inches
External Depth (Top)	11.75 Inches
External Depth (Bottom)	16 Inches
Total Internal Gross Volume	1.83 Cubic Feet
Per-Chamber Net Volume	0.51 Cubic Feet
Total Net Volume	1.53 Cubic Feet
System Qtc Per Chamber (Dual 1-Ohm)	0.707 Butterworth
System Qtc Per Chamber (Dual 2-Ohm)	0.74
Predicted Fc Per Driver	54 Hz (D1) / 54 Hz (D2)
Predicted F3 Per Driver (Anechoic)	54 Hz (D1) / 52.2 Hz (D2)
Driver Fs (D1 / D2)	48.0 Hz / 47.95 Hz (Kicker Factory)
Driver Qts (D1 / D2)	0.630 / 0.651 (Kicker Factory)
Driver Vas (D1 / D2)	3.75 L / 4.13 L (Kicker Factory)
Woofer Cutout (Each)	7-5/16 Inches (Kicker Spec)
Mounting Depth Required (Each)	7-15/16 Inches, Cleared With Margin
Recommended Power Per Driver	400-800 Watts RMS (Kicker Recommendation)
Recommended System Power	1200-2400 Watts RMS Across The Trio
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 Dividers	Two 3/4" MDF Full-Height, Dado-Locked, Double As Braces
Driver Mounting	8/32 Threaded Inserts \| Stainless Machine Screws Included \| 3 Sets
Terminal Cup	One Proline X ABS/Carbon Fiber Composite \| Side Mounted \| Serves All Three Chambers
Internal Wiring	12 Gauge OFC, Pre-Wired To All Three Driver Positions
Finish	Plush Black Carpet \| Black Acrylic Insert
Bundle Options	Enclosure Only (Bring Your Own Trio of Solo X 8s)
Warranty	1-Year Limited (Enclosure)
Built In	Tullahoma, Tennessee, USA

Performance Graphs

Net airspace

0.51

cu ft per chamber

System Qtc

0.71–0.74

sealed

Half power

52.2–53.8

Hz · F3

Xmax at

2371

W RMS · no filter

With 25 Hz subsonic

2804

W RMS · +18%

Amplifier

400–800

W RMS recommended

This enclosure holds 0.51 cu ft net per chamber. In it the Kicker SoloX L7X 8 (49L7X81) runs a system Qtc of 0.71–0.74 with half power at 52.2–53.8 Hz, and the cone reaches its 24.0 mm travel limit at 2371 W, above the driver’s 800 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 2804 W — +433 W, or 18 percent more power for the same 24.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 62.3–65.3

D1 · EBP 65.3D2 · EBP 62.3

At 62.3–65.3 the SoloX L7X 8 (49L7X81) 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

0.51 cu ft against a 3.8 L Vas.

α = Vas ÷ Vb = 0.26 · Fc = Fs√(α+1) = 54 Hz · Qtc = 0.71–0.74

D1 · Qtc 0.71, Fc 54 Hz, F3 53.8 HzD2 · Qtc 0.74, Fc 54 Hz, F3 52.2 Hz

The box lifts resonance from 48.0 Hz free-air to 54 Hz and half power lands at 52.2–53.8 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 24.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

P_Xmax = 2371–2450 W unfiltered → 2804–3018 W with a 25 Hz subsonic

D1 · 2450 W, no filterD2 · 2371 W, no filterD1 · 3018 W with subsonic at 25 Hz, 24 dB/octD2 · 2804 W with subsonic at 25 Hz, 24 dB/octXmax 24.0 mm one-way

Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 24.0 mm. Unfiltered that is 2371 W, reached first at 20 Hz. It sits above the 800 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 2804 W before hitting the same 24.0 mm. That is 18 percent more amplifier for the price of one filter setting.

Param	Value	Unit	Note
Fs	48.00 / 47.95	Hz	free-air resonance
Qts	0.631 / 0.651		D1 / D2
Vas	3.75 / 4.13	L	equivalent compliance
Sd	249.6	cm²	effective piston area
Xmax	24	mm	one-way linear travel
Pe	800	W	continuous RMS
SPL	79.4	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.