Proline X
JL Audio 10TW1 Dual Box: Sealed 10" Down Fire Enclosure
SKU: PO 10D-S DF TW1
- Alignment: 0.34 cu ft net per chamber (0.69 total). 10TW1-2: Qtc 0.932, Fc 59.5 Hz, F3 48.4 Hz. 10TW1-4: Qtc 0.900, Fc 57.2 Hz, F3 47.4 Hz.
- Fitment: Cut for two JL Audio 10TW1 thin-lines, 9.055" cutout, 4.37" mounting depth.
- Footprint: 30" W x 15" D x 6" H in the down fire position.
- Construction: 2 Separate Chambers | V-Groove/Dado | Double 1.5" Baffle, Flush Recess | Milled Magnet Reliefs | Side Terminal Cup
Financing available. Choose Shop Pay Installments at checkout.
JL Audio 10TW1 Dual Box: Sealed 10" Down Fire Enclosure
More enclosures cut for JL Audio subwoofers: JL Audio Subwoofer Boxes
Proline X Performance Optimized Down Fire Dual 10" Sealed
Cut and tuned for a pair of JL Audio 10TW1 thin-line subwoofers
Performance, Performance Optimized, and Micro
Proline X builds three tiers of Down Fire enclosure. The difference is not finish or materials, it is whether the cabinet was designed for a category or for a driver, and how much of the fitting work is already done for you.
| Performance | Performance Optimized | Micro Series | |
|---|---|---|---|
| Fitment | Universal. Accepts any subwoofer that clears the published cutout and mounting depth. | Woofer specific. Cut for one named subwoofer, with cutout, mounting depth, magnet clearance and displacement drawn in CAD from that driver. | Woofer specific. Cut for one named subwoofer. |
| Footprint | Sized to the driver diameter. 24.5 by 13.5 inches on the 10 inch. | Shared 30 by 15 inch platform on most builds, with cabinet height as the variable. A few drivers need a wider or deeper platform. | Compact per driver footprint. 21.5 by 14.5 inches on the 10 inch. |
| Front baffle | Single, 3/4 inch. | Double, 1.5 inch, outer layer machined as a flush recess. | Double, 1.5 inch. |
| Driver mounting | Solid flange. You drill your own mounting holes. | 8/32 threaded inserts, stainless machine screws included. | 8/32 threaded inserts, stainless machine screws included. |
| Joinery | V-groove and dado, CNC cut. | V-groove and dado, CNC cut, perimeter cross brace. | Stack fab, dowel reinforced. |
| Published alignment | Modeled Qtc profiles across a range of drivers. No single response curve. | A real predicted Qtc and F3 for that exact driver, calculated from its own Thiele-Small parameters. | Target alignment described in the listing. |
| Carpet | Gray standard, black optional. | Plush black. | Plush black. |
| Warranty | 1 year limited. | 1 year limited. | 2 years. |
Feet ship with every tier, uninstalled on purpose. Mount them where your floor wants them for a down fire install, or leave them off and run the cabinet front firing or up firing. The orientation is yours to choose.
This page is a Performance Optimized enclosure. The airspace, the cutouts and the cabinet height all come from the JL Audio 10TW1's own published numbers. A Performance box fits your subwoofers. A Performance Optimized box was built for them.
Built Around the 10TW1
Nothing about this cabinet is generic. Both baffle positions are bored to the 10TW1's 9.055 inch cutout, 230mm, and the cabinet height is set by the driver's 4.37 inch mounting depth, 111mm. The 10TW1 is JL's thin-line ten, so a pair of them fits in a cabinet just 6 inches tall.
Each 10TW1 is a single voice coil subwoofer, offered as the 2 ohm 10TW1-2 and the 4 ohm 10TW1-4, rated 300 watts RMS. Across the pair that is 600 watts RMS combined and twice the cone area, roughly 6 dB more maximum output than one driver in the same alignment.
Published Thiele-Small parameters for the 10TW1-2 are Fs 41.5 Hz, Qts 0.65, and Vas of 10.31 liters, 0.364 cubic feet, per driver, with 0.047 cubic feet of displacement each. The 4 ohm 10TW1-4 is listed at Fs 38.1 Hz, Qts 0.60, Vas 12.2 liters. One set does not cover both coils, so both alignments are published below.
Net Volume, Not Gross
The cabinet measures 0.78 cubic feet gross and 0.69 cubic feet net total, which is 0.34 cubic feet net per driver. Net is what each driver actually sees, after panel thickness, the chamber divider, bracing and the driver's own 0.047 cubic feet of displacement are subtracted.
True net, not marketing net. Internal volume is calculated from the machined cavity dimensions and the driver's published displacement, not estimated from external dimensions minus wall thickness.
At 0.34 net per chamber, each driver sits right on the 0.35 cubic feet JL Audio recommends for the 10TW1. A 10TW1-2 lands at Qtc 0.932 with Fc 59.5 Hz and a predicted F3 of 48.4 Hz; a pair of 10TW1-4 lands at Qtc 0.900, Fc 57.2 Hz, F3 47.4 Hz. That is above the 0.707 maximally flat reference, so there is more lift near the corner than the single cabinet shows at Qtc 0.791. Be straight about the tradeoff: the single is the better aligned product and this one is the output product. Firing down into the floor, the sealed rolloff meets rising cabin gain below 60 Hz either way.
Two Chambers, Not One
This enclosure follows the Proline X standing design rule for dual sealed builds: two fully separate chambers split by a bonded full-height 3/4 inch MDF divider, so each driver gets its own dedicated airspace and its own polyfill. Two drivers sharing one sealed volume interact acoustically, with each driver's compression phase becoming the pressure environment the other works against, which smears transient response and blurs the alignment each would have on its own. A full divider removes the interaction completely.
The divider runs vertically, so splitting the cabinet does not change the depth requirement at all. Minimum internal height after the flush recess baffle layer and the milled magnet relief is 3.75 inches, a 6 inch external cabinet, with the half inch minimum clearance maintained behind each motor. Every external dimension is stated as measured in the down fire position.
Down Fire Construction
Cut with V-groove and dado joinery on our ShopSabre routers from Langboard Elite 3/4 inch MDF, a dense 48.5 lb/ft³ board with a 200 psi internal bond and 410,000 psi MOE. Every panel joint is a machined interlocking groove that mechanically locks before adhesive is applied, which keeps both chambers airtight under sustained pressure cycling. Corners are square on Down Fire cabinets.
Perimeter cross-bracing carries the panels and polyfill is pre-installed in each chamber. Both drivers land on 8/32 threaded inserts, and two sets of stainless steel machine screws are included.
Double Baffle, Flush Recess
The front baffle is 1.5 inches at both driver positions, two bonded 3/4 inch sheets, with the outer layer machined as a flush recess so each driver bolts to the inner layer. That recovers 3/4 inch of internal clearance against a 4.37 inch mounting depth, and a 3/8 inch relief is milled behind each motor for the rest.
Side-Mounted Terminal Cup
One shared Proline X ABS and carbon fiber composite cup with stainless hardware and copper ring terminals, pre-wired in 12 gauge OFC to both driver positions in parallel. Side mounted so it stays accessible with the baffles facing the floor.
Separate Chambers
A full-height bonded 3/4 inch MDF divider gives each 10TW1 its own 0.34 cubic feet net and its own polyfill, so neither driver is working against the other's compression stroke.
Power and Warranty
JL Audio rates each 10TW1 at 300 watts RMS continuous, 600 watts RMS combined across the pair. Set gain carefully; a thin-line motor has less excursion in reserve than a W-series driver.
Both drivers are single voice coils, so there is no coil configuration decision at the driver. Wired in parallel through the one shared cup, a pair of 10TW1-4 presents a 2 ohm load and a pair of 10TW1-2 presents 1 ohm. Many amplifiers are not stable at 1 ohm, so confirm yours before powering the system.
The enclosure carries a 1 year limited warranty. Bring your own pair of JL Audio 10TW1 subwoofers; the drivers are purchased separately.
Cut for the Driver, Not the Catalog
Two cutouts, two chambers, two milled magnet reliefs, every dimension set by the JL Audio 10TW1 and nothing else. Machined on ShopSabre CNC routers and built one at a time in Tullahoma, Tennessee.
| Series | Proline X Performance Optimized Down Fire |
| Enclosure Type | Sealed | Dual Chamber | Down Fire Geometry | Floor-Coupled |
| Driver-Specific Fitment | Two JL Audio 10TW1-2 (SVC 2Ω) / 10TW1-4 (SVC 4Ω) |
| Internal Volume (Gross) | 0.78 Cubic Feet |
| Internal Volume (Net After Displacement) | 0.69 Cubic Feet Total / 0.34 Per Chamber |
| JL Audio Recommended Sealed Volume | 0.35 Cubic Feet Per Driver |
| Target System Qtc | 0.932 (-2) / 0.900 (-4) |
| Predicted Fc | 59.5 Hz (-2) / 57.2 Hz (-4) |
| Predicted F3 | 48.4 Hz (-2) / 47.4 Hz (-4) |
| Driver Fs | 41.5 Hz (-2) / 38.1 Hz (-4) |
| Driver Qts | 0.65 (-2) / 0.60 (-4) |
| Driver Vas | 0.364 Cubic Feet / 10.31 Liters (-2); 0.431 Cubic Feet / 12.2 Liters (-4) |
| Driver Displacement | 0.047 Cubic Feet / 1.33 L |
| Driver Power Handling | 300 Watts RMS Continuous |
| Driver Type | JL Audio TW1 Thin-Line | Single Voice Coil |
| Mounting Depth Required | 4.37 Inches / 111mm |
| Cutout Diameter | 9.055 Inches / 230mm |
| Baffle Configuration | Down Firing - Driver Fires Toward Floor |
| Material | Langboard Elite 3/4" MDF |
| Front Baffle Construction | Double-Layer 1.5" MDF | Outer Layer Flush Recess, Driver Mounts To Inner Layer |
| Magnet Relief | 3/8" Deep Milled Relief In Opposite Panel For Motor Clearance |
| Motor Clearance | 0.5 Inch Minimum Behind Magnet |
| Joinery | V-Groove and Dado (CNC-Cut) |
| Corner Profile | Square (Down Fire Series Standard) |
| Construction | ShopSabre CNC / Perimeter Cross-Brace |
| Chamber Divider | Full-Height Bonded 3/4" MDF | Two Fully Separate Chambers |
| External Width | 30 Inches |
| External Depth | 15 Inches |
| External Height | 6 Inches |
| Dimension Reference | All External Dimensions Measured In Down Fire Position |
| Voice Coil Configuration | Single Voice Coil Each | Parallel Through One Cup: 1 Ohm (-2 Pair) or 2 Ohm (-4 Pair) |
| Combined Power Handling | 600 Watts RMS (Pair) |
| Mounting Hardware | 8/32 Threaded Inserts | Two Sets Stainless Steel Machine Screws Included |
| Terminal Cup | One Shared Proline X ABS/Carbon Fiber Composite | Side Mounted | 12g OFC Pre-Wired |
| Damping | Polyfill Pre-Installed In Each Chamber |
| Carpet Finish | Plush Black |
| Bundle Options | Enclosure Only (Bring Your Own Pair Of JL Audio 10TW1) |
| Warranty | 1-Year Limited (Enclosure) |
| Manufactured | Tullahoma, Tennessee, USA |
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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