A Proline Performance Optimized Series 15" woofer subwoofer enclosure shown on a dark blue background with text listing features and dimensions.

A Proline Performance Optimized Series woofer subwoofer enclosure, model PO 15-S W NB5, shown with dimension lines indicating 18 inches height, 11 inches top width, and 16.55 inches bottom width on a dark studio background.

Proline X

Performance Optimized Wedge Sealed 15" Enclosure | Prodigy NB5-15

Q: Will this enclosure fit both the NB5-15D2 and NB5-15D4?

Yes. Direct-fit for the NB5-15 in D2 or D4 configuration.

Q: Why did you pick 1.76 cubic feet instead of a different volume?

1.76 cubic feet net gives D2 Qtc 0.66 (near-Butterworth), D4 Qtc 0.75 (slightly punchy).

Q: What amplifier power should I run to this enclosure?

The Prodigy NB5-15 is rated at 1200 watts RMS continuous. For a clean, headroom-rich musical system in this sealed alignment, target 800 to 1200 watts RMS at the woofer's impedance. This driver's flat-aluminum voice coil, vented magnetic gap, and cast aluminum heat-exchanger frame are engineered specifically for sustained high-power operation, so it will happily accept and reward the full 1200 watts.

Q: How does a wedge enclosure improve the sound in a trunk installation?

The wedge geometry angles the driver rear-firing into the trunk at approximately 17 degrees from vertical. This angle takes advantage of the trunk's natural transfer function, loads the cabin efficiently, and reduces the standing-wave interaction that a flat-front box parallel to the rear seat can produce.

Q: Why is the front baffle double-layered on this enclosure?

All Performance Optimized Series enclosures use a double-layer 1.5 inch front baffle made from two bonded sheets of 3/4 inch Langboard Elite MDF. The Prodigy NB5-15 exerts serious mechanical load into its mounting flange at high output, especially given its 27mm Xmax and 1200 watt power rating. A single 3/4 inch baffle can flex under that load and telegraph energy back into the cone. The double baffle eliminates that entirely and gives the driver a rigid, isolated mounting platform.

Q: What is the expected low-frequency extension of this enclosure?

Predicted -3 dB point lands at approximately 52 Hz with the D2 coil (Qtc 0.66) or 46 Hz with the D4 coil (Qtc 0.75), with usable output well below that as cabin gain takes over in most vehicles. Effective in-car response typically extends down into the mid to upper 20 Hz range depending on the specific vehicle acoustics.

Q: Do I need to add any additional damping or polyfill to this enclosure?

No additional damping is required. The enclosure ships with polyfill pre-installed to the correct density for the volume and alignment. Adding more polyfill will effectively increase the perceived volume and shift the alignment. Removing it will do the opposite.

Q: Is the Prodigy NB5-15 subwoofer included with this enclosure?

No. This listing is for the enclosure only. Bring your own NB5-15D2 (DVC 2Ω) or NB5-15D4 (DVC 4Ω) driver.

SKU: PO 15-S W NB5 BB

QUICK SPECS

Best For: Prodigy NB5-15 Trunk-Fit Daily Driver Builds
Net Volume: 1.76 cu ft (2.00 cu ft Gross)
Driver Match: Prodigy NB5-15 (D2 or D4)
Construction: Rear-Firing Wedge | V-Groove/Dado | Double 1.5" Baffle | Threaded Inserts

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.

$ 349.99

Acrylic Insert Color

In Stock and Ready to Ship

Financing available. Choose Shop Pay Installments at checkout.

Performance Optimized Wedge Sealed 15" Enclosure | Prodigy NB5-15

Enclosure Type Sealed

External Dimensions 21.5" W x 18" H x 16.55" D at base tapering to 11" D at top

Net Volume 1.76cu ft

Tuning Frequency N/A (Sealed)

Cutout Diameter Direct Fit

Front Panel Thickness 1.5"

Max Mounting Depth Direct Fit

INSTALLER'S TAKE

The Prodigy NB5-15 is a serious 15-inch driver. 1200 watts RMS, 27mm one-way Xmax at 70% BL, 40mm of forward X-mech before mechanical crash. The motor is doing real work here - upper and lower Faraday shorting rings, 280 ounces of ferrite, vented pole with coil-gap radial vents. This is a driver built for high-output SPL applications with musical intent, and it shows in the T/S data.

Here's the honest situation on the alignment: Prodigy publishes different T/S for the D2 and D4 coils that diverge enough to matter for box design. In this 1.76 cubic foot net cabinet, the D2 lands at Qtc 0.66 (musical, extended, closer to Butterworth), and the D4 lands at Qtc 0.75 (punchy-musical). Both are usable alignments that give the driver room to breathe. If you strongly favor one Qtc target over the other, a custom-volume cabinet is the right answer; this wedge splits the difference to work well for either coil in a trunk install.

The double-baffle 1.5" front is not optional on this driver. The NB5-15 exerts serious mechanical load into the mounting flange at high output, and a single 3/4" layer will telegraph flex back into the cone. Two bonded 3/4" layers with the CNC-precision cutout stops that entirely and gives the driver the rigid mounting platform it deserves.

If you're bringing your own amp, target 800-1200 watts RMS at the woofer's impedance. The NB5-15 is rated to 1200 watts RMS continuous and this driver rewards being fed. Prodigy's flat-aluminum voice coil and vented magnetic gap are engineered specifically for thermal endurance under sustained high-power operation.

Product Details

Performance Optimized Wedge | Prodigy NB5-15

15" Sealed Wedge Enclosure | Rear-Firing Trunk-Load Design for the Prodigy NB5-15

1.95 ft³ Gross1.76 ft³ NetRear-Firing Wedge21.5" × 18" × 11/16.55"V-Groove / DadoBuilt in Tennessee

The Prodigy NB5-15 in a Purpose-Built Sealed Wedge

The Prodigy NB5-15 is Prodigy Audio's flagship 15-inch SQL driver. 1500W RMS, 27mm one-way Xmax at 70% BL, 40mm forward and 50mm downward X-mech clearance, 2.75" flat-aluminum voice coil, 280 oz ferrite motor with upper/lower aluminum Faraday rings. NB5-15D2 or NB5-15D4 impedance options.

1.95 cu ft gross internal volume produces 1.76 cu ft net after driver displacement. Split-family compromise alignment: D2 coil lands Qtc 0.66, D4 coil lands Qtc 0.75 in the same cabinet.

Trunk-Load Wedge Design Explained

This wedge is not a front-firing enclosure. The NB5-15 mounts on the vertical trunk-lid-side face and fires rearward into the trunk cavity.

Seat-Side Face Matches Seat Lean

Most factory rear seats lean ~20 degrees from vertical. Angled face matches that lean.

Trunk-Lid-Side Face Fires the Woofer

Vertical face is where the NB5-15 mounts. Cone fires rearward into the trunk cavity.

Trunk Cavity Loading

Using the trunk itself as acoustic extension for smoother, less-localized presentation.

Preserves Trunk Cargo Space

Wedge tucks against the seat back. Cargo space in front stays usable.

Engineered for the Prodigy NB5-15

Built to 1.76 cubic feet net. The D2 and D4 coil variants have divergent T/S parameters, so this cabinet takes a split-family compromise approach: D2 coil lands Qtc 0.66 (near-Butterworth musical), D4 coil lands Qtc 0.75 (slightly punchy). Both are usable, well-controlled alignments.

Alignment Numbers

D2 Qtc: 0.66 · D4 Qtc: 0.75 · Fc: ~46 Hz · F3: 47-53 Hz depending on coil

Mounting Geometry

Vertical baffle CNC-cut direct-fit for the NB5-15's cutout spec. Mounting depth accommodated with wedge interior clearance. 8/32 threaded inserts pressed into baffle backside.

Performance Series Construction, Driver-Specific Tuning

Langboard Elite MDF

Premium 3/4" MDF panels milled to documented spec.

V-Groove and Dado Joinery

CNC-cut V-grooves at every panel intersection.

Double-Layer 1.5" Front Baffle

Two bonded 3/4" MDF sheets at the driver mounting face.

Pre-Wired Terminal Cup

Proline X ABS/carbon-fiber composite, 12g OFC pre-wired.

Customize Your Build

Carpet Finish

Charcoal gray trunk liner standard; plush black +$10.

Acrylic Insert Color

Black, Blue, Red, White, or none (-$40).

Box-Only or Loaded

Box-only: bring your own NB5-15.

Wiring the Prodigy NB5-15 to Your Amplifier

Ships NB5-15D2 or NB5-15D4. Target 1000-1500W RMS at the woofer's impedance. NB5-15 rated 1500W RMS continuous.

Built in Tennessee, Backed by Audio Intensity

Manufactured in Tullahoma, Tennessee on our ShopSabre CNC equipment. 1-year limited warranty. Call 931-563-5151.

Prodigy NB5-15: Precision-Tuned in a Trunk-Load Wedge

1.76 cubic feet net, engineered for both D2 and D4 coil variants in a wedge that fires the driver rearward into the trunk cavity.

Specifications

Enclosure Type	Sealed \| Wedge Geometry \| Rear-Firing Trunk-Load
Driver-Specific Fitment	Prodigy NB5-15 - NB5-15D2 (DVC 2Ω) or NB5-15D4 (DVC 4Ω)
Internal Volume (Gross)	2.00 Cubic Feet
Internal Volume (Net After Displacement)	1.76 Cubic Feet
Target System Qtc (D2)	0.66 (Musical Alignment \| Based on Published T/S)
Target System Qtc (D4)	0.75 (Punchy-Musical Alignment \| Based on Published T/S)
Predicted F3	~46-52 Hz (Depending on Coil)
Predicted Fc	~49 Hz
Driver Displacement	0.24 Cubic Feet (Published by Prodigy)
Baffle Configuration	Vertical Trunk-Lid-Side Woofer Mounting Face
Material	Langboard Elite 3/4" MDF
Front Baffle Construction	Double-Layer 1.5" MDF (Two 3/4" Sheets Bonded)
Joinery	V-Groove and Dado (CNC-Cut)
Construction	ShopSabre CNC / Angled Seat-Side Compound Cuts / Perimeter Cross-Brace
External Width	21.5 Inches
External Height	18 Inches
External Depth (Top)	11 Inches
External Depth (Bottom)	16.55 Inches
Baffle Angle	~17° From Vertical (Seat-Side Face)
Mounting Hole Diameter	13.75 Inches (Prodigy Spec)
Mounting Depth Required	9.75 Inches (Prodigy Spec)
Mounting Hardware	8/32 Threaded Inserts \| Stainless Steel Machine Screws Included
Terminal Cup	Proline X ABS/Carbon Fiber Composite \| 12g OFC Pre-Wired
Damping	Polyfill Pre-Installed
Recommended Power	800-1200 Watts RMS (Prodigy Rated: 1200W RMS Continuous)
Carpet Finish	Dark Gray Trunkliner (Standard) or Plush Black (+$10)
Acrylic Insert	Black, Blue, Red, White, or None (-$40)
Bundle Options	Enclosure Only (Bring Your Own NB5-15D2 or NB5-15D4)
Warranty	1-Year Limited (Enclosure)
Manufactured	Tullahoma, Tennessee, USA

Performance Graphs

Net airspace

1.76

cu ft per chamber

System Qtc

0.66–0.75

sealed

Half power

46.2–52.1

Hz · F3

Xmax at

4012

W RMS · no filter

With 25 Hz subsonic

5041

W RMS · +26%

Amplifier

1200

W RMS recommended

This enclosure holds 1.76 cu ft net per chamber. In it the Prodigy Audio NB5-15 runs a system Qtc of 0.66–0.75 with half power at 46.2–52.1 Hz, and the cone reaches its 27.0 mm travel limit at 4012 W, 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 5041 W — +1030 W, or 26 percent more power for the same 27.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 58.9–66.7

D2 · EBP 66.7D4 · EBP 58.9

At 58.9–66.7 the NB5-15 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

1.76 cu ft against a 43.5 L Vas.

α = Vas ÷ Vb = 0.87 · Fc = Fs√(α+1) = 49–49 Hz · Qtc = 0.66–0.75

D2 · Qtc 0.66, Fc 49 Hz, F3 52.1 HzD4 · Qtc 0.75, Fc 49 Hz, F3 46.2 Hz

The box lifts resonance from 35.6 Hz free-air to 49–49 Hz and half power lands at 46.2–52.1 Hz, anechoic, before any cabin gain. This enclosure ships without a driver, so both coil variants the maker offers are plotted. They do not load the same box the same way.

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

P_Xmax = 4012–4067 W unfiltered → 5041–5524 W with a 25 Hz subsonic

D2 · 4012 W, no filterD4 · 4067 W, no filterD2 · 5524 W with subsonic at 25 Hz, 24 dB/octD4 · 5041 W with subsonic at 25 Hz, 24 dB/octXmax 27.0 mm one-way

Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 27.0 mm. Unfiltered that is 4012 W, 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 5041 W before hitting the same 27.0 mm. That is 26 percent more amplifier for the price of one filter setting.

Param	Value	Unit	Note
Fs	35.60	Hz	free-air resonance
Qts	0.485 / 0.536		D2 / D4
Vas	43.55 / 47.20	L	equivalent compliance
Sd	863.1	cm²	effective piston area
Xmax	27	mm	one-way linear travel
Pe	1200	W	continuous RMS
SPL	87.5	dB	1 W / 1 m, derived from T/S

Driver parameters as published by prodigyaudio.com product page; Sd derived from Vas and Cms. Curves computed against this enclosure’s actual net airspace.

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.