Proline X
Performance Optimized Down Fire Sealed 13" Enclosure | JL Audio 13TW5v2
SKU: PO 13-S DF TW5
- Alignment: 0.80 cu ft net. Qtc 1.014 (13TW5v2-4) / 0.939 (13TW5v2-2), F3 41.2 to 41.3 Hz
- Driver: JL Audio 13TW5v2, 600 W RMS, 11 mm Xmax, 2.638 in mounting depth, the shallowest in the program
- Mounting: WOOD SCREWS into the 1.5 in baffle. No threaded inserts, the flange is only 0.236 in per side
- Standoffs: Included, 1.75 in, shipped uninstalled. Installed height near 8.00 in
- Cabinet: 30"W x 15"D x 6.25"H in down fire position, excludes standoffs, square corners
Financing available. Choose Shop Pay Installments at checkout.
Performance Optimized Down Fire Sealed 13" Enclosure | JL Audio 13TW5v2
Proline X Performance Optimized Down Fire 13" Sealed
Cut and tuned for the JL Audio 13TW5v2
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. | A shared 30 by 15 inch platform, with cabinet height as the variable. This build uses it at 6.25 inches tall. | Compact per driver footprint. |
| 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. | Normally threaded inserts with machine screws. Not on this build. The TW5v2's flange is too narrow for inserts, so it mounts with wood screws direct into the 1.5 inch baffle. | 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.
Built Around the JL Audio 13TW5v2
The baffle is bored to the TW5v2's 318 mm cutout and the airspace is built to 0.80 cubic feet net, which is the figure JL publishes for this driver. Not a range. JL lists 0.80 as both the minimum and the maximum sealed volume, and does not recommend a ported enclosure for it at all, so there is no larger box on offer and no alternative alignment to choose between.
The TW5v2 is a thin-line 13 inch built for shallow installs. Its 2.638 inch mounting depth is the shallowest of any driver in this program, which is why the cabinet is sized by airspace rather than by motor clearance: the driver needs 4.14 inches of internal height and the volume needs 6.25.
Mounting: Wood Screws, Not Inserts
This build does not use threaded inserts, and that is a deliberate departure from the rest of the Performance Optimized range. The TW5v2 measures 12.992 inches across the frame against a 12.52 inch cutout, which leaves 0.236 inches of flange per side. There is not enough material there to land an insert. The driver mounts with wood screws direct into the 1.5 inch baffle instead.
The double baffle is what makes that work. A wood screw into a single 3/4 inch panel is a weak joint on a subwoofer; into 1.5 inches of bonded MDF it has real thread engagement. Pilot the holes and do not overdrive them, and treat repeated removal with more care than you would an insert, because wood screws do not tolerate being cycled the way machine screws into metal do.
Net Volume, Not Gross
We build this cabinet at 0.80 cubic feet net. The volume quoted is true net internal airspace after panel thickness, bracing and the driver's own 0.052 cubic feet of displacement are accounted for. Gross is 0.8603.
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.
What the Alignment Actually Is
Both coil versions are covered by this cabinet and they land close together in it. These are high Q results, and that follows directly from JL fixing the volume at 0.80 rather than from anything about the enclosure.
| Coil | System Qtc | fc | F3 |
|---|---|---|---|
| 13TW5v2-4, 4 ohm | Qtc 1.014 | 52.8 Hz | 41.3 Hz |
| 13TW5v2-2, 2 ohm | Qtc 0.939 | 50.9 Hz | 41.2 Hz |
There is no larger box to move to. JL publishes 0.80 as both the minimum and the maximum sealed volume for the TW5v2 and does not recommend ported. A bigger sealed cabinet would lower Qtc but would be outside what the driver is specified for. This is the alignment the driver is sold with.
Down Fire Construction
Cut with V-groove and dado joinery on our ShopSabre routers from Langboard Elite 3/4 inch MDF. 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.
The cabinet measures 30.00 inches wide by 15.00 inches deep by 6.25 inches tall, measured in the down fire position and excluding standoffs. Plan around the installed height: the standoffs hold 1.75 inches under the baffle, so the finished stack sits near 8.00 inches.
Double Baffle, Flush Recess
The front baffle is 1.5 inches, two bonded 3/4 inch sheets. On this build it is also what the mounting screws bite into, so the second layer is structural rather than just stiffening.
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.
Standoffs Included
JL publishes no front clearance figure for the TW5v2, so this cabinet uses the Proline X standard 1.75 inch standoff, shipped uninstalled so you can place them to suit your floor.
Motor Clearance and Orientation
The motor rises off the baffle into the cavity, so on a down fire cabinet the clearance that matters runs to the top panel. At 4.00 inches of internal height against a 2.638 inch mounting depth there is well over the 0.75 inch minimum, because this cabinet is sized by airspace and the TW5v2 is unusually shallow.
JL does not publish a position on down firing this driver, and this cabinet makes no claim on their behalf. The feet ship uninstalled, so front firing or up firing remains available to you at install time without changing anything about the enclosure.
Power and Warranty
JL rates the TW5v2 at 600 watts RMS. The 13TW5v2-4 is a single 4 ohm coil and the 13TW5v2-2 a single 2 ohm, so a single driver presents whichever impedance you bought.
The enclosure carries a 1 year limited warranty. Bring your own TW5v2; the driver is purchased separately.
Cut for the Driver, Not the Catalog
Built one at a time in Tullahoma, Tennessee, with standoffs and a 1 year limited warranty. Questions on fitment or amplifier matching, call or text 931-563-5151.
| Specification | Value |
|---|---|
| Series | Proline X Performance Optimized Down Fire |
| Compatible Driver | JL Audio 13TW5v2, quantity 1. Direct fit, either coil |
| Configuration | Single 13 inch, sealed down fire |
| Mounting Position | Trunk or cargo floor, baffle facing down on standoffs |
| Firing Direction | Downward. Feet ship uninstalled, so front or up firing is also possible |
| External Width | 30 in |
| External Depth | 15 in |
| External Height | 6.25 in in the down fire position, excludes standoffs |
| Installed Height | 8.00 in including the 1.75 in standoff |
| Internal Volume, Gross | 0.8603 cu ft |
| Internal Volume, Net Acoustic | 0.80 cu ft after 0.052 displacement |
| JL Published Target | 0.80 cu ft, stated as both minimum and maximum. Ported not recommended |
| Alignment, 13TW5v2-4 | Qtc 1.014, fc 52.8 Hz, F3 41.3 Hz anechoic |
| Alignment, 13TW5v2-2 | Qtc 0.939, fc 50.9 Hz, F3 41.2 Hz anechoic |
| Woofer Opening | 12.52 in (318 mm) direct fit |
| Driver Mounting Depth | 2.638 in required |
| Driver Mounting | Wood screws direct into the 1.5 in baffle. No threaded inserts: the 12.992 in frame against a 12.52 in cutout leaves only 0.236 in of flange per side |
| Driver Power Handling | 600 W RMS |
| Material | Langboard Elite MDF |
| Construction | CNC cut, V-groove and dado joinery, square corners |
| Panel Thickness | 0.75 in |
| Front Baffle | 1.5 in double baffle, also the mounting substrate |
| Internal Bracing | Windowed U-brace, dadoed to front, top and back |
| Terminal Cups | One Proline X ABS and carbon fiber composite, side mounted, pre wired 12 gauge OFC |
| Standoffs | Included, 1.75 in, shipped uninstalled |
| Damping | Light polyfill wall lining, does not alter acoustic volume |
| Carpet | Plush black |
| Weight | 32 lb |
| Warranty | 1 Year Limited |
| Built In | Tullahoma, Tennessee |
01Is it a sealed driver?
Efficiency bandwidth product places the motor before anything else is decided.
02What the box does to it
0.80 cu ft against a 64.0 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 11.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.
| Param | Value | Unit | Note |
|---|---|---|---|
| Fs | 26.00 / 27.60 | Hz | free-air resonance |
| Qts | 0.480 / 0.530 | 13TW5v2-2 / 13TW5v2-4 | |
| Vas | 64.00 / 60.30 | L | equivalent compliance |
| Sd | 634.0 | cm² | effective piston area |
| Xmax | 11 | mm | one-way linear travel |
| Pe | 600 | W | continuous RMS |
| SPL | 85.3 | dB | 1 W / 1 m, derived from T/S |
Driver parameters as published by loudspeakerdatabase.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.
Shop By Series
