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Proline X PO 12-S DFW NB2 sealed down-fire wide enclosure for the Prodigy NB2-12, 41 inches wide by 8.25 inches tall, feet add 1.75 inches of height.
Proline X PO 12-S DFW NB2 sealed down-fire wide enclosure, end panel with side-mounted terminal cup, 8.25 inches tall by 14 inches deep.

Performance Optimized · Datasheet

Performance Optimized Down Fire Wide Sealed 12" Enclosure Prodigy NB2-12 · Single 12" Sealed enclosure

Net volume
1.532 cu ft after displacement and the brace
Max mounting depth
6.75 in
External dimensions
41 in W × 8.25 in in the down fire position H × 14 in D
Front baffle
1.5 in double baffle, outer layer machined as a flush recess
Buy at Audio IntensityFactory-direct, ships from Tullahoma
Prodigy NB2-12Buy at Audio Intensity
  • Alignment: 1.532 cu ft net. Qtc 0.690, Fc 42.8 Hz, F3 43.9 Hz
  • Down Fire Wide: 41"W x 14"D x 8.25"H in down fire position, excludes the 1.75" standoffs (installed height 10"). Stands lower than the standard 30 x 15 at 8.6875"
  • Height set by: motor clearance, 0.75" above the 6.75" deep motor; holds more air than the standard box's 1.25
  • Driver: Prodigy NB2-12D4 (DVC 4 ohm), 400W RMS / 800W peak, 14mm Xmax at 70% BL, 28.37 Hz Fs, 6.75" mounting depth
  • Build: Langboard Elite MDF, V-groove and dado, 1.5" double baffle with flush outer recess, windowed U-brace, 12g OFC side-mounted terminal cup

Spec of record

Technical specifications

SeriesProline X Performance Optimized Down Fire Wide
Compatible DriverProdigy NB2-12D4 (DVC 4 ohm), quantity 1. Direct fit
Enclosure TypeSealed, down fire, floor coupled
Intended FitmentLong, low spaces where height or depth is the limit and 41 in of run is available
Firing DirectionDown firing. Feet ship uninstalled, so front or up firing is also possible
Chamber ConfigurationSingle chamber, windowed U-brace, one side-mounted terminal cup
External Width41 in
External Depth14 in
External Height8.25 in in the down fire position, excludes standoffs
Installed Height10 in including the 1.75 in standoffs
Dimension ReferenceAll external dimensions measured in down fire position
Standard 30 x 15 Version8.6875 in tall, 1.25 cu ft net
Internal Volume, Gross1.671 cu ft
Internal Volume, Net1.532 cu ft after displacement and the brace
Height Set ByMotor clearance: 0.75 in above the motor, so the box holds more air than the standard version
AlignmentQtc 0.690, Fc 42.8 Hz, F3 43.9 Hz anechoic
Woofer Opening11.2 in
Mounting Depth Required6.75 in
Frame Outer Diameter12.5 in
Driver Displacement0.13 cu ft
Driver Fs28.37 Hz
Driver Qts0.457
Driver Qes / Qms0.522 / 3.662
Driver Vas55.392 Liters / 1.956 Cubic Feet
Driver Mms216.268 g
Driver BL21.268
Driver Re6.2 Ohm
Driver Xmax14mm (One-Way at 70% BL)
Driver Sensitivity85.4 dB
Driver Power Handling400 Watts RMS / 800 Watts Peak
Driver Voice Coil2.0 in | 4-Layer Copper
Driver CoolingVented Pole Piece + Radial Backplate Vents
Mounting Hardware8/32 Threaded Inserts | Stainless Steel Machine Screws Included
Voice Coil ConfigurationDual 4-Ohm | 2Ω Parallel or 8Ω Series At The Driver
Recommended Power300-400 Watts RMS (Prodigy Rated: 400W RMS)
MaterialLangboard Elite 3/4 in MDF
JoineryV-groove and dado, CNC cut on ShopSabre routers
Front Baffle1.5 in double baffle, outer layer machined as a flush recess
Internal BracingWindowed U-brace, dadoed to the shell
Corner ProfileSquare (Down Fire series standard)
Terminal CupOne Proline X ABS and carbon fiber composite, side mounted, pre-wired 12 gauge OFC
Standoffs1.75 in, included, shipped uninstalled
DampingPolyfill installed as a light wall lining
CarpetPlush black
Bundle OptionsEnclosure only (bring your own NB2-12D4)
Warranty1 year limited (enclosure)
Built InTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
1.532
cu ft per chamber
System Qtc
0.69
sealed
Half power
43.9
Hz · F3
Xmax at
360
W RMS · no filter
With 25 Hz subsonic
525
W RMS · +46%
Amplifier
400
W RMS recommended
This enclosure holds 1.532 cu ft net per chamber. In it the Prodigy Audio NB2-12 runs a system Qtc of 0.69 with half power at 43.9 Hz, and the cone reaches its 14.0 mm travel limit at 360 W, below the driver’s 400 W thermal rating, so travel is what stops you here, not heat. Run a subsonic filter at 25 Hz and that becomes 525 W — +165 W, or 46 percent more power for the same 14.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 54.3
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 D4 54.3
D4 · EBP 54.3
At 54.3 the NB2-12 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

1.532 cu ft against a 55.4 L Vas.

α = Vas ÷ Vb = 1.28  ·  Fc = Fs√(α+1) = 43 Hz  ·  Qtc = 0.69
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
D4 · Qtc 0.69, Fc 43 Hz, F3 43.9 Hz
The box lifts resonance from 28.4 Hz free-air to 43 Hz and half power lands at 43.9 Hz, anechoic, before any cabin gain.

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

PXmax = 360 W unfiltered  →  525 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 12 16 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 14.0 mm 360 W reaches Xmax here
D4 · 360 W, no filterD4 · 525 W with subsonic at 25 Hz, 24 dB/octXmax 14.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 14.0 mm. Unfiltered that is 360 W, reached first at 20 Hz. It sits under the 400 W the driver can take thermally, so the enclosure sets the ceiling, not the voice coil. 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 525 W before hitting the same 14.0 mm. That is 46 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs28.37Hzfree-air resonance
Qts0.457D4
Vas55.39Lequivalent compliance
Sd525.5cm²effective piston area
Xmax14mmone-way linear travel
Pe400Wcontinuous RMS
SPL85.7dB1 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.

From the shop floor

Installer's take

A 28.37 Hz free-air resonance on a 400 watt entry-level 12 is not what you expect to find, and with 55.392 liters of Vas this driver has real low-end capability. The wide box gives it the same treatment as the standard one, spread over 41 inches instead of 30.

Height on this one is set by the motor, not the air. 6.75 inches of mounting depth plus 0.75 of clearance above the motor puts the cabinet at 8.25 tall, and on 41 by 14 that holds 1.532 net, more than the 1.25 in the standard box. More air, lower Qtc. That is the safe direction.

Qts of 0.457 is low enough to reach a properly damped sealed alignment. In this cabinet it lands at Qtc 0.690 with F3 at 43.9 Hz, just under maximally flat, with tight control.

The 216 gram moving mass tells you what this driver is for: weight and impact rather than speed. Dual 4 ohm coils, 2 ohms parallel or 8 ohms series at the driver. Target 300 to 400 watts RMS.

Measure installed height, not cabinet height: 8.25 on its own, 10 with the 1.75 inch feet on. The standard 30 by 15 is still the pick if you do not have 41 inches of run.

Before you order

Questions

Why is this cabinet 41 inches wide instead of 30?

Because it trades length for depth and height. The standard Performance Optimized Down Fire platform is 30 wide by 15 deep; this one is 14 deep, 1 inch shallower, and 41 long. Spreading the airspace along 11 more inches lets the cabinet stand 8.25 inches tall instead of 8.6875.

Here the height is set by the 6.75 inch mounting depth of the NB2-12, which needs 0.75 inch of air above the motor, so the wide box ends up holding 1.532 cubic feet net, more than the standard box. Fourteen inches of depth is the practical minimum, since a 12 inch frame needs about 13 inches of baffle.

How does this compare to the standard 30 x 15 NB2-12 enclosure?

Same driver, different shape. The standard cabinet is 30 by 15 by 8.6875 inches and holds 1.25 cubic feet net. This cabinet is 41 by 14 by 8.25 inches and holds 1.532 cubic feet net.

The wide box holds more air because its height is set by motor clearance rather than airspace, which lowers Qtc a little. Choose the standard box when length is limited; choose this one when height or depth is the limit and you have 41 inches of run.

What alignment does this cabinet produce with the NB2-12?

At 1.532 cubic feet net the NB2-12D4 lands at Qtc 0.690 with Fc at 42.8 Hz and a predicted anechoic F3 of 43.9 Hz, computed from Prodigy's published Fs 28.37 Hz, Qts 0.457 and Vas 55.392 liters.

That is just under the 0.707 maximally flat reference, a well damped alignment with tight control. The extra air over Prodigy's 1.25 recommendation comes from the motor setting the cabinet height, and it moves Qtc in the safe direction. In a vehicle, cabin gain adds output below the anechoic figure.

How do I wire this enclosure and set my impedance?

The enclosure has one side-mounted Proline X terminal cup pre-wired in 12 gauge OFC. The NB2-12D4 is dual 4-ohm, so you set the final load at the driver: coils in parallel for 2 ohms, or in series for 8 ohms. Most single-driver builds run 2 ohms.

Prodigy rates this driver at 400 watts RMS. Confirm your amplifier is stable at your chosen load and set gains for 300 to 400 watts.

Where is the terminal cup located on a down fire enclosure?

Side mounted. Every Proline X Performance Optimized enclosure uses a side mounted terminal cup, whether standard, wedge or down fire, which keeps the connection accessible with the baffle facing the floor. The cup is our Proline X ABS and carbon fiber composite unit, recessed, with stainless hardware, copper ring terminals and pre-wired 12 gauge OFC.

Why are the corners square instead of radiused?

Down Fire cabinets are built with square corners as a series standard. The 3 inch top down corner radius used on other Proline X alignments does not apply here. A down fire box is a low, long platform that sits flat against a floor or cargo deck, and square corners maximize usable internal volume for a given footprint while keeping the cabinet stable on its mounting surface.

How is this enclosure built?

V-groove and dado joinery, CNC cut on ShopSabre routers from Langboard Elite MDF. Every panel joint is a machined interlocking groove that locks the panels before adhesive is applied, which keeps the cabinet airtight under sustained pressure cycling. The front baffle is a 1.5 inch double layer, the outer layer machined as a flush recess around the 11.2 inch cutout.

A windowed U-brace stiffens the long panels, and polyfill is installed as a light wall lining. Do not add more fill; packing a sealed box makes it act larger and moves the alignment off the 1.532 cubic feet it was built to. Assembled and inspected in Tullahoma, Tennessee.

Is the Prodigy NB2-12 subwoofer included with this enclosure?

No. This listing is for the enclosure only. Bring your own Prodigy NB2-12D4. The cutout and mounting depth are cut specifically for this driver.

Same series, same size

Other Performance Optimized models