Proline X
Performance Optimized Down Fire Wide Sealed 10" Shallow Sub Enclosure | Arc Audio A10
SKU: PO 10-S DFW A10
- Alignment: 0.848 cu ft gross, 0.801 net, on Arc's published gross optimum. Qtc 0.853 / F3 39.0 Hz (D4), Qtc 0.796 / F3 40.6 Hz (D2)
- Down Fire Wide: 41"W x 12"D x 5.875"H measured in down fire position, sized for under the rear seat of a truck or SUV
- Driver: Arc Audio A10D2 or A10D4, 250W RMS / 500W musical, 8mm Xmax, 26.995 Hz Fs, 3.77" mounting depth, 9.06" cutout
- Volume Convention: Arc publishes sealed recommendations as gross, not net; both figures are listed
- Build: V-groove and dado joinery, double layer 1.5" front baffle, windowed U-brace, side mounted 12 gauge OFC terminal cup, feet ship uninstalled (+1.75")
Financing available. Choose Shop Pay Installments at checkout.
Performance Optimized Down Fire Wide Sealed 10" Shallow Sub Enclosure | Arc Audio A10
More enclosures cut for Arc Audio subwoofers: Arc Audio Subwoofer Boxes
Proline X Performance Optimized Down Fire Wide 10" Sealed
Under rear seat fitment for trucks and SUVs. Cut and tuned for the Arc Audio A10
The Down Fire Wide Format
Down Fire Wide is the Performance Optimized answer to a specific problem: the space under the rear seat of a truck or SUV, or a narrow cargo floor, is long and shallow, and the standard 30 by 15 inch Down Fire cabinet will not go in it.
So the cabinet is turned sideways. This one runs 41 inches wide by 12 inches deep by 5.875 inches tall, measured in the down fire position. It is cut for the same Arc Audio A10 as our standard box, 3 inches shallower front to back and 11 inches longer. The airspace lost from the depth is recovered along the length, and the height is solved to the driver.
Measure the depth before anything else. Under seat spaces vary widely between cab configurations, and depth is almost always the limiting dimension. If you have 15 inches of depth, the standard 30 by 15 inch cabinet at 6.25 inches tall is the pick. If your space stops at 12 inches deep and you have 41 inches of run, this cabinet fits. The feet add 1.75 inches, so the installed height is 7.625 inches.
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. Down Fire Wide variants like this one run long and shallow for under seat fitment. | Compact per driver footprint. 21.5 by 14.5 inches on the 10 inch. |
| Front baffle | Single, 3/4 inch. | Double layer, outer layer machined as a flush recess. 1.5 inch. | 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 Arc Audio A10's own published numbers. A Performance box fits your subwoofer. A Performance Optimized box was built for it.
Built Around the Arc Audio A10
The baffle is bored to the A10's 9.06 inch cutout, and the 10.08 inch frame sits on the 12 inch deep baffle with material to spare fore and aft. The cabinet height is solved around its 3.77 inch mounting depth: the motor clears the top panel by 1.355 inches, so airspace set the height here, not clearance.
The number that sets this driver apart is its 26.995 Hz free-air resonance. That is low for a 10 inch subwoofer of any depth, and unusual for one that mounts in under four inches. Most 10s sit in the mid to high 30s, and shallow 10s are typically worse because a shortened motor and a stiffer suspension push resonance up. Arc got this one down near 27 Hz on both coil variants.
Arc pairs that low Fs with a moderate Qts, 0.477 on the A10D2 and 0.506 on the A10D4. That is the combination that lets the driver reach a properly damped sealed alignment instead of being forced into an underdamped one. Xmax is 8mm one way, sensitivity is 85.4 dB at 1W/1m, and both variants are rated 250 watts RMS with 500 watts musical.
Net Volume, Not Gross
The machined cavity measures 0.848 cubic feet gross, which lands on Arc Audio's own optimum sealed recommendation, published as a gross figure. After the driver's 0.04 cubic feet of displacement the working airspace is 0.801 cubic feet net.
Read that pair of numbers carefully, because Arc publishes their sealed recommendations as gross volume rather than net, which is unusual. Almost every other manufacturer states net, meaning the airspace left after the driver's own displacement is removed. We built to Arc's gross figure, so this is the enclosure Arc designed the driver around, in a 41 by 12 footprint. Both conventions are listed so you can compare against either one.
The two coil variants land in different places in this volume. The A10D2 reaches Qtc 0.796, Fc 45.0 Hz, F3 40.6 Hz, the more damped of the two, with tighter transient control. The A10D4 lands at Qtc 0.853, Fc 45.5 Hz, F3 39.0 Hz, a little less damped and a little lower. The D4 also runs more motor force, 18.090 T against the D2's 13.766. Both are 250 watts RMS with identical fitment, so choose on the load your amplifier is stable and efficient into.
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. The wide cabinet holds 0.801 net against the 0.80 our standard 30 by 15 A10 box was built to, so the alignment carries over unchanged.
Down Fire Wide 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.
The cabinet measures 41 inches wide by 12 inches deep by 5.875 inches tall, measured in the down fire position. Feet ship with the enclosure but are not installed; they add 1.75 inches, for an installed height of 7.625 inches.
1.5 Inch Double Baffle
Two 3/4 inch layers laminated to 1.5 inches, the outer layer machined as a flush recess so the driver bolts to the inner layer, with 8/32 threaded inserts at the driver position.
Windowed U-Brace
A windowed U-brace dadoed to the shell ties the front and rear walls together across the 41 inch span without walling off the airspace.
Side-Mounted Terminal Cup
Proline X ABS and carbon fiber composite cup with stainless hardware and copper ring terminals, side mounted and pre-wired in 12 gauge OFC.
Polyfill Installed
Polyfill is installed as a light wall lining. It controls internal reflections and is not packed to change the acoustic volume.
Power and Wiring
Arc rates the A10 at 250 watts RMS continuous with 500 watts musical. Their documentation is direct about what happens above that: sustained operation beyond the RMS rating will burn the voice coil, and that damage is treated as abuse rather than a warranty claim. Arc also notes that underpowering carries no risk, but a small amplifier driven into clipping does. Feed it clean, unclipped power in the 200 to 250 watt range.
Both variants are dual voice coil, so final impedance is set at the driver. The single side mounted cup is pre-wired in 12 gauge OFC to the driver position. Drivers mount to 8/32 threaded inserts with stainless machine screws, included.
Bring your own A10D2 or A10D4; the driver is purchased separately. The enclosure carries a 1 year limited warranty.
Cut for the Driver, Not the Catalog
One driver, one volume, one set of machine files, in a footprint built for the space under a rear bench. Cut, assembled and inspected one at a time in Tullahoma, Tennessee.
| Series | Proline X Performance Optimized Down Fire Wide |
| Compatible Driver | Arc Audio A10D2 (DVC 2Ω) or A10D4 (DVC 4Ω) |
| Enclosure Type | Sealed | Down Fire Geometry | Floor-Coupled |
| Intended Fitment | Under the rear seat of trucks and SUVs, or narrow cargo floors, where depth is the limiting dimension |
| Firing Direction | Down Firing, Driver Fires Toward Floor |
| External Width | 41 Inches |
| External Depth | 12 Inches |
| External Height | 5.875 Inches |
| Installed Height | 7.625 Inches With The 1.75 Inch Feet |
| Dimension Reference | All External Dimensions Measured In Down Fire Position, Excluding Feet |
| Internal Volume (Gross) | 0.848 Cubic Feet, On Arc's Published Gross Optimum |
| Internal Volume (Net) | 0.801 Cubic Feet |
| Arc Published Sealed Range | 0.65 Min / 0.85 Optimum / 1.1 Max (All Gross) |
| System Qtc / Fc / F3 (A10D2) | 0.796 / 45.0 Hz / 40.6 Hz |
| System Qtc / Fc / F3 (A10D4) | 0.853 / 45.5 Hz / 39.0 Hz |
| Comparison, Standard 30x15 A10 | 30 x 15 x 6.25 In, 0.80 Cubic Feet Net. Same airspace, different shape |
| Driver Fs | 26.995 Hz (Both Variants) |
| Driver Qts | 0.477 (D2) / 0.506 (D4) |
| Driver Qes / Qms | 0.511 / 7.155 (D2) | 0.547 / 6.744 (D4) |
| Driver Vas | 40.41 Liters (D2) / 41.82 Liters (D4) |
| Driver BL | 13.766 T (D2) / 18.090 T (D4) |
| Driver Mms | 146.54 g (D2) / 141.59 g (D4) |
| Driver Re | 3.9 Ohms (D2) / 7.466 Ohms (D4) |
| Driver Sd | 346.4 cm² |
| Driver Xmax (One-Way) | 8mm (Arc Spec) |
| Driver Sensitivity | 85.4 dB (1W/1m) |
| Driver Power Handling | 250 Watts RMS / 500 Watts Musical |
| Driver Displacement | 0.04 Cubic Feet |
| Mounting Depth Required | 3.77 Inches (Arc Spec), 1.355 Inches Clear Above The Motor |
| Woofer Opening | 9.06 Inches (Arc Spec) |
| Driver Frame Diameter | 10.08 Inches, Sits On The 12 Inch Deep Baffle |
| Feet | 1.75 Inch, Included, Shipped Uninstalled |
| Material | Langboard Elite 3/4" MDF |
| Joinery | V-Groove and Dado (CNC-Cut) |
| Construction | ShopSabre CNC / Windowed U-Brace |
| Panel Thickness | 3/4 Inch |
| Front Baffle Construction | Double-Layer 1.5" MDF (Two 3/4" Sheets Bonded), Outer Layer Flush Recess |
| Corner Profile | Square (Down Fire Series Standard) |
| Driver Mounting | 8/32 Threaded Inserts | Stainless Steel Machine Screws Included |
| Voice Coil Configuration | Dual Voice Coil, Final Impedance Set At The Driver |
| Terminal Cup | Proline X ABS/Carbon Fiber Composite | Side Mounted | 12g OFC Pre-Wired |
| Damping | Polyfill Installed, Light Wall Lining |
| Carpet Finish | Plush Black |
| Bundle Options | Enclosure Only (Bring Your Own A10D2 or A10D4) |
| Warranty | 1-Year Limited (Enclosure) |
| Built In | 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
0.801 cu ft against a 40.4 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 8.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.
| Param | Value | Unit | Note |
|---|---|---|---|
| Fs | 27.00 | Hz | free-air resonance |
| Qts | 0.477 / 0.506 | D2 / D4 | |
| Vas | 40.41 / 41.82 | L | equivalent compliance |
| Sd | 346.4 | cm² | effective piston area |
| Xmax | 8 | mm | one-way linear travel |
| Pe | 250 | W | continuous RMS |
| SPL | 83.8 | dB | 1 W / 1 m, derived from T/S |
Driver parameters as published by Arc Audio A-Series spec sheet. 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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