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.

Performance Optimized · Datasheet

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

Net volume
1.76 Cubic Feet
Max mounting depth
9.75 Inches (Prodigy Spec)
Cutout
13.75 Inches (Prodigy Spec)
External dimensions
21.5 Inches W × 18 Inches H × 11 Inches / 16.55 Inches D
Front baffle
Vertical Trunk-Lid-Side Woofer Mounting Face
Buy at Audio Intensity
  • 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

Technical specifications

Enclosure TypeSealed | Wedge Geometry | Rear-Firing Trunk-Load
Driver-Specific FitmentProdigy 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 Displacement0.24 Cubic Feet (Published by Prodigy)
Baffle ConfigurationVertical Trunk-Lid-Side Woofer Mounting Face
MaterialLangboard Elite 3/4" MDF
Front Baffle ConstructionDouble-Layer 1.5" MDF (Two 3/4" Sheets Bonded)
JoineryV-Groove and Dado (CNC-Cut)
ConstructionShopSabre CNC / Angled Seat-Side Compound Cuts / Perimeter Cross-Brace
External Width21.5 Inches
External Height18 Inches
External Depth (Top)11 Inches
External Depth (Bottom)16.55 Inches
Baffle Angle~17° From Vertical (Seat-Side Face)
Mounting Hole Diameter13.75 Inches (Prodigy Spec)
Mounting Depth Required9.75 Inches (Prodigy Spec)
Mounting Hardware8/32 Threaded Inserts | Stainless Steel Machine Screws Included
Terminal CupProline X ABS/Carbon Fiber Composite | 12g OFC Pre-Wired
DampingPolyfill Pre-Installed
Recommended Power800-1200 Watts RMS (Prodigy Rated: 1200W RMS Continuous)
Carpet FinishDark Gray Trunkliner (Standard) or Plush Black
Acrylic InsertBlack, Blue, Red, White, or None
Bundle OptionsEnclosure Only (Bring Your Own NB5-15D2 or NB5-15D4)
Warranty1-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Performance in this enclosure

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
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 D2 66.7 D4 58.9
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
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
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.

PXmax = 4012–4067 W unfiltered  →  5041–5524 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 8 16 24 32 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 27.0 mm 4012 W reaches Xmax here
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.
ParamValueUnitNote
Fs35.60Hzfree-air resonance
Qts0.485 / 0.536D2 / D4
Vas43.55 / 47.20Lequivalent compliance
Sd863.1cm²effective piston area
Xmax27mmone-way linear travel
Pe1200Wcontinuous RMS
SPL87.5dB1 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.

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.

Questions

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

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

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).

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.

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.

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.

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.

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.

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.

Other Performance Optimized models