Proline X
Proline X M12-S ARC SW | Single 12" Sealed Subwoofer Enclosure | Built for Arc Audio SW12
SKU: M12-S ARC SW
- Fits: Arc Audio SW12 | 2.4" Shallow-Mount | Motor Outside Sealed Volume
- Net Volume: 0.65 / 0.8 / 1.0 cu ft | Shared 26" x 14.75" Footprint
- Orientation: Down-Fire Primary, Front-Fire Secondary | 4-Foot Kit Included
- Build: Stack-Fab Langboard Elite MDF | 3" Radiused Corners | Pre-Wired 12g OFC
Financing available. Choose Shop Pay Installments at checkout.
What's Included
Proline X M12-S ARC SW | Single 12" Sealed Subwoofer Enclosure | Built for Arc Audio SW12
Proline X Micro Series 12" Sealed Enclosure
Cut and tuned for the Arc Audio SW12
Built Around the Arc Audio SW12
Nothing about this box is generic. Every layer is cut to the SW12's published sealed target, with clearance cut for its 2.625 in mounting depth.
The SW12 carries a published Fs of 33 Hz, Qts of 0.616 and Vas of 33.73 litres, and an EBP of 46, which puts it in sealed enclosure territory. We ran the alignment math on that data and built the box to land where it belongs.
Net Volume, Not Gross
We build this cabinet at 0.80 cubic feet net, against a published recommendation of 0.8 cu ft. The volume quoted is true net internal airspace, measured after the walls, bracing and driver displacement are accounted for.
True net, not marketing net. Internal volume is calculated by summing each CNC cut layer's opening, not estimated from external dimensions minus wall thickness.
Proline X Micro Series Construction
This enclosure is stack fabricated 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 layer is a precision cut ring and the stacked layers do the joining themselves, so there is no butt joint or dado to flex or leak. Dowel reinforcement runs between layers as tension hardware only.
Threaded Inserts, Not Wood Screws
8/32 threaded inserts are set on the backside of the baffle so the driver mounts on machine screws. Pull it a dozen times and the threads are still there.
Pre-Wired Terminal Cup
Proline X ABS and carbon fiber composite cup with stainless hardware and copper ring terminals, pre-wired internally with 12 gauge OFC. No CCA anywhere in the build.
Damped and Finished
Polyfill is pre-installed to smooth the in box response, and the shell is wrapped in plush black carpet. Built in Tullahoma, Tennessee.
Enclosure Only or Loaded
Order the enclosure bare and mount your own SW12, or order it loaded and we mount the driver, dress the wiring and ship it ready to bolt in. Loaded builds are available in Dual 2-Ohm (D2) or Dual 4-Ohm (D4), selectable by variant.
Sealed Enclosure Performance: Pre-Calculated
Using the published Thiele Small parameters for the Arc Audio SW12, here is the predicted Qtc, system resonance (Fc) and F3 rolloff for this enclosure. Calculated with the same formulas as the Audio Intensity Sealed Box Calculator.
| Enclosure Size | Qtc | Fc | F3 |
|---|---|---|---|
| 0.80 cu ft as built | 0.972 | 52.1 Hz | 41.5 Hz |
Arc Audio SW12 Frequency Response | Sealed, 0.80 cu ft
Note on coil choice: This alignment is calculated from the published T/S for the SW12 in the D2 parallel set. The D4 variant carries slightly different Qts and Vas figures and will land a marginally different sealed alignment. Run your own numbers in the Sealed Box Calculator.
Cut for the Driver, Not the Catalog
Select your configuration above. This enclosure ships free to the lower 48 with a 2 year limited warranty, built one at a time in Tullahoma, Tennessee. Ordered loaded, the SW12 carries its own 1 year manufacturer warranty through authorized dealers.
| Proline X Micro Series 12" Sealed Enclosure Specifications | |
|---|---|
| Series | Proline X Micro Series |
| Enclosure Type | Sealed |
| Firing Orientation | Down-fire primary, front-fire secondary |
| Included Hardware | 4-foot down-fire kit (installed as needed) |
| Driver Fitment | Arc Audio SW12 (D2 or D4) |
| Baffle Cutout | 11 in, bored for the Arc Audio SW12 |
| Net Internal Volume | 0.65 / 0.8 / 1.0 cu ft (true net, selectable by size) |
| External Dimensions | 26 x 14.75 x 5.25 in (0.65) / 26 x 14.75 x 6.75 in (0.8) / 26 x 14.75 x 8.25 in (1.0) |
| Mounting Footprint | 26 x 14.75 in (shared across all three sizes) |
| Material | Langboard Elite 3/4 in MDF (48.5 lb/ft³, 200 psi internal bond, 410,000 psi MOE) |
| Construction | Stack-fabricated on ShopSabre CNC, dowel tension reinforcement |
| Corner Radius | 3 in, all four corners (viewed top-down) |
| Driver Mounting | 8/32 threaded inserts on baffle back face, machine screws included |
| Terminal Cup | Proline X ABS / carbon-fiber composite, stainless hardware, copper ring terminals, pre-wired 12-gauge OFC |
| Damping | Polyfill pre-installed |
| Finish | Plush black carpet |
| Configurations | Enclosure only / Loaded SW12 D2 / Loaded SW12 D4 |
| Build Location | Tullahoma, Tennessee |
| Warranty | 2-year limited |
| Shipping | Included to the lower 48 |
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 33.7 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 15.5 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.
| Param | Value | Unit | Note |
|---|---|---|---|
| Fs | 33.00 | Hz | free-air resonance |
| Qts | 0.616 / 0.624 | parallel / series | |
| Vas | 33.73 / 33.44 | L | equivalent compliance |
| Sd | 533.0 | cm² | effective piston area |
| Xmax | 15.5 | mm | one-way linear travel |
| Pe | 400 | W | continuous RMS |
| SPL | 84.1 | dB | 1 W / 1 m, derived from T/S |
Driver parameters as published by arcaudio.com SW10 published specification table. Curves computed against this enclosure’s actual net airspace.
| Brand + Model | Arc Audio SW12 |
| Voice Coil Config | Dual 2-Ohm (D2) or Dual 4-Ohm (D4) |
| Voice Coil Diameter | 3 in |
| Xmax | 15.5 mm |
| Cone Area (Sd) | 532.97 cm2 |
| Sensitivity | 85.29 dB |
| Mounting Depth | 2.625 in |
| Cone Material | Reinforced Cellulose Fiber |
| Surround | Low-Shore Butyl Rubber |
| Motor | Front-Mounted N42UH Neodymium |
| Manufacturer Sealed Recommendation | 0.8 cu ft |
| Fs | 33 Hz |
| Qts | 0.616 |
| Vas | 33.73 L |
| Driver Warranty | 1 Year (Authorized Dealers) |
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
