It is 40 inches wide, 13 tall and 13.26 deep at the base, tapering to 8.53 at the top. Measure between the rear wheel wells, the floor depth with the seat upright, and the height under your cargo cover.The raked face goes against the seat back and the woofers fire toward the liftgate.

Proline X

Performance Optimized Wedge Wide Sealed Triple 8" Enclosure | DD Audio 2508g ESP

Q: Does this fit the DD Audio 2508g ESP, and its coil versions?

Yes. Each opening is cut to 8.000 in for the 8.95 in frame, and the 6.69 in deep motor clears the raked rear panel with 0.75 in to spare. Coil versions of the DD Audio 2508g ESP share the frame, cutout and mounting depth, so any of them drops in. The alignment on this page is computed on the 2508g ESP parameters.Run three matched drivers, same model and same coil, so every chamber sees the alignment on this page.

Q: Why 0.550 cubic feet per driver, and what alignment does it target?

On DD Audio's published Fs 42.0 Hz, Qts 0.560 and Vas 4.6 liters, 0.550 cubic feet per driver gives Qtc 0.638, system resonance 47.8 Hz and half power 53.6 Hz.The 6.69 in deep motor sets the shallowest the wedge can be, and that smallest box is still more air than flat wants, so it lands below 0.707: tighter and more damped, trading a little extension for control.

Q: What amplifier power should I run, and how should I wire it?

DD Audio rates the 2508g ESP at 1200 watts RMS per driver. Recommended amplifier: 840 to 1200 W RMS per driver, 2,520 to 3,600 W RMS for the full set of 3.Loads depend on the coil version you run. Three dual 4 ohm drivers, coils in series, all three in parallel: 2.67 ohms; coils in parallel, all three in series: 6 ohms. Dual 2 ohm: 1.33 ohms or 3 ohms the same two ways. Single 4 ohm: 1.33 ohms in parallel, 12 ohms in series. Use the lower load only on an amplifier rated stable there.

Q: Why are all three terminal cups on the back?

Each driver has its own sealed chamber, and the center chamber has no side wall to take a cup. Putting all three on the rear panel gives a matching set, one cup per chamber.Wire them at the amplifier end; there is no cross-chamber wiring inside the cabinet.

Q: What is the expected low-frequency extension?

Anechoic F3 is 53.6 Hz per driver with system resonance at 47.8 Hz.Those figures exclude cabin gain. An SUV cabin adds real output below about 50 Hz, so in-vehicle response runs deeper than the numbers above.

Q: Do I need to add polyfill or damping?

No. Polyfill is already installed as a light wall lining in every chamber, and the quantity is chosen so it does not change the acoustic volume.Do not add more. Packing a sealed box makes it behave as though it were larger, which moves the alignment away from 0.550 cubic feet per driver.

Q: Are the drivers included?

No. This is an enclosure only. You receive the cabinet finished in plush black carpet with the gloss black acrylic baffle insert, three pre-wired terminal cups on the rear panel, the polyfill lining in place, threaded inserts and stainless machine screws.Bring three matched DD Audio 2508g ESP drivers. The cabinet is cut direct fit to them, not a general purpose 8 inch box.

SKU: PO 8TW-S W 2508GESP BB

QUICK SPECS

Best For: Triple DD Audio 2508g ESP SUV Cargo-Floor Builds
Net Volume: 0.550 cu ft per Driver (1.65 cu ft Net Total)
Driver Match: Three DD Audio 2508g ESP (matched set), matched
Construction: 3 Chambers | 40" Wide Wedge | V-Groove/Dado | Double 1.5" Baffle | 3 Terminal Cups

Shipping Included No freight charges at checkout. What you see is what you pay.

Built in Tennessee CNC cut from 3/4" Langboard Elite MDF. V-groove and dado joinery.

Advanced Terminal Cup Built in-house. ABS/Carbon Fiber. Stainless steel hardware. Copper ring terminals.

$ 379.99

Acrylic Insert Color

In Stock and Ready to Ship

Financing available. Choose Shop Pay Installments at checkout.

Performance Optimized Wedge Wide Sealed Triple 8" Enclosure | DD Audio 2508g ESP

More enclosures cut for Digital Designs subwoofers: Digital Designs Subwoofer Boxes

Enclosure Type Sealed

External Dimensions 40" W x 13" H x 13.26" D at base tapering to 8.53" D at top

Gross Volume 1.97 cu ft

Net Volume 1.65 cu ft

Shipping Weight 59 lbs

Front Panel Thickness 1.5"

INSTALLER'S TAKE

Start with the size. 0.550 cubic feet per driver puts the 2508g ESP at Qtc 0.638, resonance 47.8 Hz, half power 53.6 Hz anechoic. The 6.69 in deep motor sets the shallowest the wedge can be, and that smallest box is still more air than flat wants, so it lands below 0.707: tighter and more damped, trading a little extension for control.

Measure the base depth, not the top. This cabinet is 13.26 in deep where it meets the floor, 8.53 at the top, 40 wide and 13 tall. In an SUV the 40 has to clear between the rear wheel wells at floor height, the base depth is measured from the seat back with the seat upright and latched, and the 13 has to clear the cargo cover.

All three terminal cups are on the rear panel, and the rear panel is the face that goes against the seat back. Wire all three before the box goes in, with enough slack to slide it into place; once the raked face is against the seat you cannot reach them.

The load depends on which coil version you run, so settle the coil before you buy the amplifier; the wiring section lists the clean loads for each version.

Power. Size the amplifier for the set, not one driver: 840 to 1200 W RMS per driver is 2,520 to 3,600 W RMS across all 3. At 3,600 W the charging system is part of the install: alternator output, the big three, and a battery that holds voltage under load.

DD Audio's Qes and Qms reproduce the printed Qts within 3 percent, so the alignment rests on a self-consistent set.

Polyfill is in as a wall lining in every chamber. Do not add more: it makes the box act larger and walks Qtc off 0.64.

Product Details

Performance Optimized Wedge Wide | Triple DD Audio 2508g ESP

Triple 8" Sealed Wedge Enclosure | Built for SUV Cargo Floors

0.550 ft3 Net per Driver1.65 ft3 Net TotalQtc 0.643 Sealed Chambers40" x 13" x 8.53/13.26"Built in Tennessee

Three DD Audio 2508g ESP in a 40 Inch Sealed Wedge

The wide wedge is a fixed SUV platform: 40 inches across and 13 tall, built to span a cargo floor against the rear seat. Depth is the only dimension that moves, and it is solved for the driver. Here it runs 8.53 in at the top to 13.26 in at the base.

0.550 cubic feet net per driver on DD Audio's published Fs 42.0 Hz, Qts 0.560 and Vas 4.6 liters: Qtc 0.638, system resonance 47.8 Hz, half power 53.6 Hz. The 6.69 in deep motor sets the shallowest the wedge can be, and that smallest box is still more air than flat wants, so it lands below 0.707: tighter and more damped, trading a little extension for control.

Three Fully Separate Chambers

Two bonded full-height 3/4 inch MDF dividers split the cabinet into three sealed chambers of 0.550 cubic feet net, one driver each, so no driver loads another. Three pre-wired terminal cups on the rear panel, one per chamber. The center chamber has no side wall, so all three cups go on the back for a matching set.

Cargo-Floor Wedge Design

The woofers mount on the vertical face and fire rearward toward the liftgate. The raked face goes against the rear seat back.

Raked Face Matches the Seat

A 20 degree rear panel follows the lean of a rear seat back.

40 Inches Across

Built to span a cargo floor. Measure between the rear wheel wells.

13 Inches Tall

Check it against your cargo cover and rear glass before you order.

13.26 Inches Deep at the Base

Measure the cargo floor before you order.

Engineered for the DD Audio 2508g ESP

Half power lands at 53.6 Hz anechoic, before cabin gain. DD Audio publishes 0.080 cubic feet of driver displacement and it is taken out of the net figure for every driver.

Alignment Numbers (Per Driver)

Driver	System Qtc	fc	F3
2508g ESP	Qtc 0.638	47.8 Hz	53.6 Hz

Mounting Geometry

Each opening is cut to 8.000 in for the 8.95 in frame. The rear panel rakes 20 degrees, so the cavity deepens from 8.53 in at the top to 13.26 in at the base, and the 6.69 in deep motor clears it with 0.75 in to spare. Three woofers across the 40 inch face, one centered on each chamber.

What the Numbers Rest On

Langboard Elite MDF

Premium 3/4 in MDF throughout.

V-Groove and Dado Joinery

CNC cut V-grooves at every fold, sides and dividers seated in dados.

Double-Layer 1.5" Front Baffle

Two bonded 3/4 in MDF sheets at the driver face, the outer layer machined as a flush recess.

DD Audio's Own Parameters

Fs 42.0 Hz, Qts 0.560, Qes 0.620, Qms 5.880, Vas 4.6 L, Sd 266 cm2, Xmax 20 mm.

Wiring Three DD Audio 2508g ESP to Your Amplifier

Loads depend on the coil version you run. Three dual 4 ohm drivers, coils in series, all three in parallel: 2.67 ohms; coils in parallel, all three in series: 6 ohms. Dual 2 ohm: 1.33 ohms or 3 ohms the same two ways. Single 4 ohm: 1.33 ohms in parallel, 12 ohms in series. Use the lower load only on an amplifier rated stable there.

DD Audio rates the driver at 1200 watts RMS each, 3600 across all three. Recommended amplifier: 840 to 1200 W RMS per driver, 2,520 to 3,600 W RMS for the full set of 3.

Built in Tennessee, Backed by Audio Intensity

Cut and assembled in Tullahoma, Tennessee on our own CNC equipment. Finished in plush black carpet with the gloss black acrylic baffle insert, three pre-wired terminal cups on the rear panel, 12 gauge OFC. Polyfill wall lining installed in every chamber. Threaded inserts at every mounting location, stainless machine screws in the box. 1 year limited warranty. Enclosure only, the drivers are purchased separately. Call or text 931-563-5151.

Triple DD Audio 2508g ESP: 40 Inch SUV Sealed Wedge

0.550 cubic feet net per driver at Qtc 0.638, F3 53.6 Hz, cut direct fit and built to order in Tennessee.

Specifications

Specification	Value
Series	Proline X Performance Optimized Wedge Wide
Compatible Driver	DD Audio 2508g ESP, quantity 3, matched. Direct fit
Configuration	Triple 8 inch sealed wedge, 3 chambers, 1 driver per chamber
Mounting Position	SUV cargo floor, raked face against the rear seat back
Firing Direction	Rearward toward the liftgate. Not a down fire design
External Width	40 in
External Height	13 in at the seat face
External Depth	13.26 in at the base, tapering to 8.53 in at the top
Internal Volume, Gross	1.97 cu ft total
Internal Volume, Net Acoustic	0.550 cu ft per driver, 1.65 cu ft total, after both dividers and DD Audio's published 0.080 cu ft displacement per driver
Driver Mounting Depth	6.69 in required; 0.75 in clearance above the motor against the raked rear panel
Alignment Per Driver	2508g ESP Qtc 0.638, fc 47.8 Hz, F3 53.6 Hz anechoic
Woofer Openings	3 at 8.000 in
Woofer Layout	One row across the face
Frame Outer Diameter	8.95 in
Fs / Qts / Qes / Qms	42.0 Hz / 0.560 / 0.620 / 5.880
Vas / Sd / Xmax	4.6 L / 266 cm2 / 20 mm
Driver Power Handling	1200 W RMS per driver, 3600 W RMS for the set of 3 (thermal rating)
Recommended Amplifier	840-1200 W RMS per driver, 2,520-3,600 W RMS for the full set
Parameter Source	DD Audio published specifications
Material	Langboard Elite MDF
Construction	CNC cut, V-groove and dado joinery
Panel Thickness	0.75 in
Front Baffle	1.5 in double baffle, outer layer machined as a flush recess
Internal Bracing	Two full-height 3/4 in dividers
Driver Mounting	Threaded inserts, stainless machine screws included
Terminal Cups	Three Proline X ABS and carbon fiber composite, on the rear panel, one per chamber, pre wired 12 gauge OFC
Acrylic Insert	Gloss black acrylic baffle insert standard; None variant minus $20
Damping	Light polyfill wall lining in every chamber, does not alter acoustic volume
Carpet	Plush black
Shipping Weight	59 lb
Warranty	1 Year Limited
Built In	Tullahoma, Tennessee

Performance Graphs

Net airspace

0.550

cu ft per driver

System Qtc

0.64

sealed

Half power

53.6

Hz · F3

Xmax at

1336

W RMS per driver · no filter

With 25 Hz subsonic

1924

W RMS per driver · +44%

Amplifier, per driver

840–1200

W RMS recommended

This enclosure holds 0.550 cu ft net per driver. In it the DD Audio 2508g ESP runs a system Qtc of 0.64 with half power at 53.6 Hz, and the cone reaches its 20.0 mm travel limit at 1336 W per driver, above the driver’s 1200 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 1924 W per driver — +588 W, or 44 percent more power for the same 20.0 mm of travel.

00Sizing the amplifier

Every wattage on this panel is per driver. This cabinet holds three, so the amplifier feeds all three at once.

Per driver 840–1200 W RMS × 3 drivers = full set 2,520–3,600 W RMS

Look for a mono amplifier rated 2,520–3,600 W RMS at the load your coil version wires to. The top is the driver’s 1200 W thermal rating; with the 25 Hz subsonic set the cone still has travel to spare there, reaching Xmax only at 1924 W. Below the bottom of the range it will play, just with less headroom; above the top you are buying power the drivers cannot use.

01Is it a sealed driver?

Efficiency bandwidth product places the motor before anything else is decided.

EBP = Fs ÷ Qes = 67.7

2508g ESP · EBP 67.7

At 67.7 the 2508g ESP sits in the transition band, not the sealed band. That is not a mismatch: a transition motor works in either alignment, and sealed buys a smaller box and a gentler roll-off at the cost of some low-end output. Stage 02 shows what this airspace actually does with it.

02What the box does to it

0.550 cu ft against a 4.6 L Vas.

α = Vas ÷ Vb = 0.30 · Fc = Fs√(α+1) = 48 Hz · Qtc = 0.64

2508g ESP · Qtc 0.64, Fc 48 Hz, F3 53.6 Hz

The box lifts resonance from 42.0 Hz free-air to 48 Hz and half power lands at 53.6 Hz, anechoic, before any cabin gain. Figures are DD Audio’s published parameters; Qes and Qms reproduce the printed Qts. This cabinet holds three drivers in three separate sealed chambers of 0.550 cubic feet each, the volume plotted here.

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 20.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

P_Xmax = 1336 W per driver unfiltered → 1924 W per driver with a 25 Hz subsonic

2508g ESP · 1336 W, no filter2508g ESP · 1924 W with subsonic at 25 Hz, 24 dB/octXmax 20.0 mm one-way

Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 20.0 mm. Unfiltered that is 1336 W per driver, reached first at 20 Hz. It sits above the 1200 W the driver can take thermally, so the voice coil gives up before the suspension does. The dashed traces are the same driver behind a subsonic filter at 25 Hz, 24 dB/oct: stopping the cone wasting travel below the passband lets it take 1924 W per driver before hitting the same 20.0 mm. That is 44 percent more amplifier for the price of one filter setting.

Param	Value	Unit	Note
Fs	42.00	Hz	free-air resonance
Qts	0.560		2508g ESP
Vas	4.64	L	equivalent compliance
Sd	266.3	cm²	effective piston area
Xmax	20	mm	one-way linear travel
Pe	1200	W	continuous RMS
SPL	79.3	dB	1 W / 1 m, derived from T/S

Driver parameters as published by DD Audio 2508g ESP published specifications. Curves computed against this enclosure’s actual net airspace.

Customer Installs

Materials

Material

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.

Specifications

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

Internal Bond

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.

Stiffness

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.

Screw Holding

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.

Sourcing

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.