Proline X
JL Audio 10TW1 Box: Sealed 10" Down Fire Enclosure
SKU: PO 10-S DF TW1
- Alignment: 0.35 cu ft net, JL Audio's recommended sealed volume. 10TW1-2: Qtc 0.927, Fc 59.2 Hz, F3 48.3 Hz. 10TW1-4: Qtc 0.895, Fc 56.8 Hz, F3 47.3 Hz.
- Fitment: Cut for the JL Audio 10TW1 thin-line, 9.055" cutout, 4.37" mounting depth.
- Footprint: 15.625" W x 15" D x 6" H in the down fire position.
- Construction: V-Groove/Dado | Double 1.5" Baffle, Flush Recess | Milled Magnet Relief | Side Terminal Cup
Financing available. Choose Shop Pay Installments at checkout.
JL Audio 10TW1 Box: Sealed 10" Down Fire Enclosure
More enclosures cut for JL Audio subwoofers: JL Audio Subwoofer Boxes
Proline X Performance Optimized Down Fire 10" Sealed
Cut and tuned for the JL Audio 10TW1 thin-line
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 cutout and the cabinet height all come from the JL Audio 10TW1's own published numbers. A Performance box fits your subwoofer. A Performance Optimized box was built for it.
Built Around the 10TW1
Nothing about this cabinet is generic. The baffle is bored to the 10TW1's 9.055 inch cutout, 230mm, and the internal height is set by the driver's 4.37 inch mounting depth, 111mm. The 10TW1 is JL's thin-line ten, built for installs that will not take a W-series motor, and it puts this cabinet at just 6 inches tall.
It is a single voice coil subwoofer, offered as the 2 ohm 10TW1-2 and the 4 ohm 10TW1-4, rated 300 watts RMS. JL describes its sealed enclosure requirement as extremely small, and the driver displaces just 0.047 cubic feet of the box it sits in.
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. 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 0.40 cubic feet gross and 0.35 cubic feet net after the driver's 0.047 cubic feet of displacement, panel thickness and bracing are subtracted. That is the 0.35 cubic feet JL Audio recommends for the 10TW1 in a sealed enclosure.
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.
Here is the chain. The driver needs 4.37 inches. The outer 3/4 inch baffle layer is machined as a flush recess and the driver bolts to the inner layer, which recovers 0.75 inch. A 3/8 inch relief milled into the opposite panel behind the magnet recovers a little more. Add the 0.5 inch minimum clearance required behind the motor and the minimum internal height lands at 3.75 inches, a 6 inch cabinet. With the height fixed by the driver, width is the dimension we solved: 15.625 inches across the 15 inch depth lands the cabinet on JL's 0.35 net. It is one of the few Performance Optimized builds that leaves our shared 30 inch platform, and it fits where a full-width box never would.
The alignment, stated plainly. At 0.35 net a 10TW1-2 sits at Qtc 0.927 with Fc 59.2 Hz and a predicted F3 of 48.3 Hz, and a 10TW1-4 at Qtc 0.895, Fc 56.8 Hz, F3 47.3 Hz. That is above the 0.707 maximally flat reference, so the response carries a little lift ahead of the rolloff: punchy and tight rather than flat, which is what JL tuned this driver to do in a small sealed box. Firing down into the floor, the 12 dB per octave rolloff meets rising cabin gain below 60 Hz.
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 the cabinet airtight under sustained pressure cycling. Corners are square on Down Fire cabinets.
Perimeter cross-bracing carries the panels and polyfill is pre-installed. The driver lands on 8/32 threaded inserts with stainless steel machine screws included, and every external dimension is stated as measured in the down fire position.
Double Baffle, Flush Recess
The front baffle is 1.5 inches, two bonded 3/4 inch sheets, with the outer layer machined as a flush recess so the driver bolts to the inner layer. That recovers 3/4 inch of internal clearance, which is the first half of fitting a 4.37 inch driver into a 6 inch cabinet.
Side-Mounted Terminal Cup
Proline X ABS and carbon fiber composite cup with stainless hardware and copper ring terminals, pre-wired in 12 gauge OFC. Side mounted so it stays accessible with the baffle facing the floor.
Milled Magnet Relief
A 3/8 inch deep relief is milled into the panel opposite the baffle so the motor clears, with 0.5 inch minimum maintained behind the magnet. That is the second half, and it is why this cabinet stands only 6 inches tall.
Power and Warranty
JL Audio rates the 10TW1 at 300 watts RMS continuous. Run an amplifier matched to that rating and set gain carefully; a thin-line motor has less excursion in reserve than a W-series driver.
Wiring is straightforward: a single voice coil, so there is no series or parallel decision at the driver. The amplifier sees 2 ohms through the cup with the 10TW1-2, or 4 ohms with the 10TW1-4. Confirm your amplifier is comfortable at that load before setting gain.
The enclosure carries a 1 year limited warranty. Bring your own JL Audio 10TW1; the driver is purchased separately.
Cut for the Driver, Not the Catalog
One cutout, one mounting depth, one milled relief, all of it 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 | Down Fire Geometry | Floor-Coupled |
| Driver-Specific Fitment | JL Audio 10TW1-2 (SVC 2Ω) / 10TW1-4 (SVC 4Ω) |
| Internal Volume (Gross) | 0.40 Cubic Feet |
| Internal Volume (Net After Displacement) | 0.35 Cubic Feet |
| JL Audio Recommended Sealed Volume | 0.35 Cubic Feet (Matched) |
| Target System Qtc | 0.927 (-2) / 0.895 (-4) |
| Predicted Fc | 59.2 Hz (-2) / 56.8 Hz (-4) |
| Predicted F3 | 48.3 Hz (-2) / 47.3 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 |
| External Width | 15.625 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 | 2 Ohm (-2) or 4 Ohm (-4) Nominal |
| Mounting Hardware | 8/32 Threaded Inserts | Stainless Steel Machine Screws Included |
| Terminal Cup | Proline X ABS/Carbon Fiber Composite | Side Mounted | 12g OFC Pre-Wired |
| Damping | Polyfill Pre-Installed |
| Carpet Finish | Plush Black |
| Bundle Options | Enclosure Only (Bring Your Own 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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