Proline X
Performance Optimized Down Fire Sealed Dual 10" Enclosure | JL Audio 10W3v3-4
SKU: PO 10D-S DF W3
- Alignment: 0.55 cu ft net per chamber, 1.10 cu ft net total. Qtc 0.849, Fc 55.1 Hz, F3 47.4 Hz per driver
- Chambers: Two fully separate sealed chambers, 3/4" MDF full divider, one shared side-mounted terminal cup
- Drivers: Pair of JL Audio 10W3v3-4 (SVC 4Ω), 500W RMS each, 1000W combined, 14.0mm Xmax, 5.93" mounting depth
- Wiring: Two 4 ohm drivers in parallel to one cup, 2 ohm final load, confirm amplifier stability
- Cabinet: 30"W x 15"D x 8"H measured in down fire position, square corners
Financing available — choose Shop Pay Installments at checkout.
Performance Optimized Down Fire Sealed Dual 10" Enclosure | JL Audio 10W3v3-4
The Performance Optimized Down Fire Sealed Dual 10" Enclosure for the JL Audio 10W3v3-4 is a two-chamber sealed cabinet built around a pair of JL's W3v3 10s. At 8 inches tall on a 30 by 15 inch footprint, it delivers roughly 6 dB more maximum output than a single driver in the same alignment.
Each JL Audio 10W3v3-4 is a 4-ohm single voice coil subwoofer rated 500 watts RMS with a recommended amplifier range of 150 to 500 watts. Across the pair that is 1000 watts RMS combined and 106.95 square inches of piston area. Mineral-filled polypropylene cones, rubber surrounds, 14.0mm of one-way linear excursion each. JL's Dynamic Motor Analysis system and Elevated Frame Cooling, which routes air through slots above the top plate directly to the voice coil, handle linearity and thermal management.
This enclosure follows the Proline X standing design rule for dual sealed builds: two fully separate chambers divided by a bonded full-height 3/4 inch MDF panel, giving each driver its own dedicated airspace. Two drivers sharing one sealed volume interact acoustically, with each driver's compression phase becoming the other's pressure environment, which smears transient response and blurs the alignment each would have on its own. Separate chambers eliminate that entirely.
Each chamber gives 0.55 cubic feet net per driver, producing Qtc 0.849, Fc 55.1 Hz, and a predicted F3 of 47.4 Hz per driver.
Worth understanding how this cabinet is sized. The 10W3v3-4 has a 5.93 inch mounting depth, and after the flush-recess outer baffle layer and the milled magnet relief the minimum internal height is 5.3125 inches. We build to 5.75 inches internal, which gives just under half an inch of additional clearance behind each motor beyond the minimum. Cabinet height on a dual is set by driver depth rather than by volume, since the chamber divider runs vertically and does not affect the depth requirement at all.
Note that the per-chamber volume lands closer to JL's own 0.625 sealed recommendation than the single-driver cabinet manages, since halving the width brings the forced volume back down toward their target. The single cabinet is pushed to 1.09 net and lands at Qtc 0.850; this dual sits at 0.849 per chamber. If a flatter alignment matters more than output, the single is the better choice. If you want the headroom, this is it.
Firing down into the floor, the sealed rolloff meets rising cabin gain below 60 Hz, and in-car response extends well below the anechoic figure.
Construction is the full Proline X Performance Optimized platform: ShopSabre CNC-cut Langboard Elite MDF with V-groove and dado joinery, perimeter cross-bracing, and double-layer 1.5 inch front baffles at both driver positions with the outer layer machined as a flush recess. A relief is milled behind each motor. Corners are square on Down Fire cabinets. Both drivers fire down into the floor, and one side-mounted Proline X ABS/carbon fiber composite terminal cup serves both chambers, fed in parallel to both driver positions with 12 gauge OFC.
Bring your own pair of JL Audio 10W3v3-4 subwoofers. Each is a single 4-ohm voice coil, so the pair presents 2 ohms through the cup.
Manufactured in Tullahoma, Tennessee. 1-year enclosure warranty.
| Enclosure Type | Sealed | Dual Driver | Down Fire Geometry | Floor-Coupled |
| Chamber Configuration | Two Fully Separate Chambers | Full Divider | Single Shared Side-Mounted Terminal Cup |
| Driver-Specific Fitment | JL Audio 10W3v3-4 (SVC 4Ω) | Pair Required |
| Total Internal Gross Volume | 1.20 Cubic Feet |
| Per-Chamber Net Volume | 0.55 Cubic Feet |
| Total Net Volume | 1.10 Cubic Feet |
| Target Qtc Per Chamber | 0.849 |
| Predicted Fc Per Driver | 55.1 Hz |
| Predicted F3 Per Driver | 47.4 Hz |
| JL Audio Recommended Sealed Volume | 0.625 Cubic Feet Per Driver |
| Driver Fs | 31.49 Hz |
| Driver Qts | 0.485 |
| Driver Vas | 1.138 Cubic Feet / 32.23 Liters Each |
| Driver Xmax (One-Way Linear) | 14.0mm / 0.550 in |
| Driver Displacement | 0.049 Cubic Feet Each (Published by JL Audio) |
| Cone Area | 53.475 sq in Each / 106.95 sq in Total |
| Power Handling | 500 Watts RMS Each / 1000 Watts RMS Combined |
| Recommended Amplifier Power | 150 to 500 Watts RMS Per Driver (JL Audio Spec) |
| Driver Cone | Mineral-Filled Polypropylene | Rubber Surround |
| Driver Technology | Dynamic Motor Analysis (DMA) | Elevated Frame Cooling |
| Mounting Depth Required | 5.93 Inches / 151mm (JL Audio Spec) |
| Cutout Diameter (Each) | 9.0625 Inches / 230mm (JL Audio Spec) |
| Baffle Configuration | Down Firing - Both Drivers Fire Toward Floor |
| Material | Langboard Elite 3/4" MDF |
| Front Baffle Construction | Double-Layer 1.5" MDF at Both Driver Positions | Outer Layer Flush Recess |
| Magnet Relief | 3/8" Deep Milled Relief Behind Each Motor |
| Motor Clearance | 0.945 Inch Behind Each Magnet |
| Chamber Divider | 3/4" MDF Full Bonded Panel |
| Joinery | V-Groove and Dado (CNC-Cut) |
| Corner Profile | Square (Down Fire Series Standard) |
| Construction | ShopSabre CNC / Perimeter Cross-Brace |
| External Width | 30 Inches |
| External Depth | 15 Inches |
| External Height | 8 Inches |
| Dimension Reference | All External Dimensions Measured In Down Fire Position |
| Voice Coil Configuration | Single Voice Coil Per Driver | 4 Ohm Each | 2 Ohm Final Load Through The Cup |
| 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 |
| Carpet Finish | Dark Gray Trunkliner (Standard) or Plush Black |
| Bundle Options | Enclosure Only (Bring Your Own Pair of JL Audio 10W3v3-4) |
| Warranty | 1-Year Limited (Enclosure) |
| Manufactured | Tullahoma, Tennessee, USA |
01Is it a sealed driver?
Efficiency bandwidth product places the motor before anything else is decided.
02What the box does to it
0.55 cu ft against a 32.2 L Vas.
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 14.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.
| Param | Value | Unit | Note |
|---|---|---|---|
| Fs | 31.49 | Hz | free-air resonance |
| Qts | 0.485 | 4 | |
| Vas | 32.23 | L | equivalent compliance |
| Sd | 345.0 | cm² | effective piston area |
| Xmax | 14 | mm | one-way linear travel |
| Pe | 500 | W | continuous RMS |
| SPL | 84.7 | dB | 1 W / 1 m, derived from T/S |
Driver parameters as published by jlaudio.com. Curves computed against this enclosure’s actual net airspace.
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.
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 |
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.
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.
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.
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.
Handcrafted in USA
Hand-assembled at our facility in Tullahoma, TN. Every enclosure is inspected before it ships.
Tuned to the Build
Internal volume and port geometry are calculated to spec and CNC-cut to exact dimensions. The box performs the same way every time.
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