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Proline X PO 12-S DF NSW sealed down fire enclosure, front panel on 1.75 inch feet, 30 by 10.3 inches.
Proline X PO 12-S DF NSW sealed down fire enclosure, end panel with recessed terminal cup, 15 by 10.3 inches.

Performance Optimized · Datasheet

Performance Optimized Down Fire Sealed 12" Enclosure NVX NSW12v3 · Single 12" Sealed enclosure

Net volume
1.63 cu ft after the brace and the 0.080 cu ft displacement NVX publishes
Max mounting depth
6.00 in required, 3.51 in clearance above the motor
External dimensions
30.00 in W × 10.26 in in the down fire position H × 15.00 in D
Front baffle
1.5 in double baffle, outer layer machined as a flush recess
Buy at Audio IntensityFactory-direct, ships from Tullahoma
NVX NSW12v3Buy at Audio Intensity
  • Alignment: 1.63 cu ft net, Qtc 0.659 (D2), F3 50.4 Hz
  • Driver: NVX NSW12v3 (NSW122v3 D2 or NSW124v3 D4), 500 W RMS, 12.5 mm Xmax, 6.00 in mounting depth
  • Standoffs: Included, 1.75 in, shipped uninstalled. Installed height near 12.01 in
  • Cabinet: 30.00"W x 15.00"D x 10.26"H in down fire position, excludes standoffs, square corners

Spec of record

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Down Fire
Compatible DriverNVX NSW12v3 (NSW122v3 D2 or NSW124v3 D4), quantity 1. Direct fit
ConfigurationSingle 12 inch, sealed down fire
Mounting PositionTrunk or cargo floor, baffle facing down on standoffs
Firing DirectionDownward. Feet ship uninstalled, so front or up firing is also possible
External Width30.00 in
External Depth15.00 in
External Height10.26 in in the down fire position, excludes standoffs
Installed Height12.01 in including the 1.75 in standoff
Internal Volume, Gross1.72 cu ft
Internal Volume, Net Acoustic1.63 cu ft after the brace and the 0.080 cu ft displacement NVX publishes
Height Set ByAirspace; clearance alone would allow a lower cabinet
Driver Mounting Depth6.00 in required, 3.51 in clearance above the motor
Floor Slot0.75 times the cone area at the 1.75 in standoff
Alignment, D2Qtc 0.659, fc 46.7 Hz, F3 50.4 Hz anechoic
Alignment, D4Qtc 0.755, fc 49.8 Hz, F3 46.8 Hz anechoic
Woofer Opening10.86 in, NVX's published cutout
Frame Outer Diameter12.46 in, NVX published
Bolt Circle11.73 in, NVX published; threaded inserts pre-installed
Driver Displacement0.080 cu ft, NVX published
NSW122v3 (D2) Fs / Qts / Qes / Qms / Vas34.67 Hz / 0.489 / 0.534 / 5.79 / 37.70 L
NSW124v3 (D4) Fs / Qts / Qes / Qms / Vas36.92 Hz / 0.560 / 0.620 / 5.75 / 37.83 L
Driver Sd511 cm2, published by NVX
Xmax12.5 mm, NVX spec; the manual does not state one-way or peak to peak
Driver Power Handling500 W RMS, NVX spec
Wiring OptionsThe NSW122v3 (D2) wires to 4 ohms with its coils in series or 1 ohm in parallel. The NSW124v3 (D4) wires to 8 ohms in series or 2 ohms in parallel. Anything under 1 ohm, and many amplifiers at 1 ohm, is outside what the amplifier is built for; series wiring is the safe default.
Parameter SourceNVX NSW122v3 / NSW124v3 owner's manual and nvx.com product pages
MaterialLangboard Elite MDF
ConstructionCNC cut, V-groove and dado joinery, square corners
Panel Thickness0.75 in
Front Baffle1.5 in double baffle, outer layer machined as a flush recess
Internal BracingWindowed brace, dadoed to the shell
Driver MountingThreaded inserts pre-installed on the published bolt circle, stainless machine screws included
Terminal CupsOne Proline X ABS and carbon fiber composite, side mounted, pre wired 12 gauge OFC
StandoffsIncluded, 1.75 in, shipped uninstalled
DampingLight polyfill wall lining, does not alter acoustic volume
CarpetPlush black
Shipping Weight44 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
1.63
cu ft
System Qtc
0.66–0.76
sealed
Half power
46.8–50.4
Hz · F3
Xmax at
323
W RMS · no filter
With 25 Hz subsonic
438
W RMS · +36%
Amplifier
500
W RMS recommended
This enclosure holds 1.63 cu ft net . In it the NVX NSW12v3 runs a system Qtc of 0.66–0.76 with half power at 46.8–50.4 Hz, and the cone reaches its 12.5 mm travel limit at 323 W, below the driver’s 500 W thermal rating, so travel is what stops you here, not heat. Run a subsonic filter at 25 Hz and that becomes 438 W — +115 W, or 36 percent more power for the same 12.5 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 59.5–64.9
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 dual 2 ohm 64.9 dual 4 ohm 59.5
dual 2 ohm · EBP 64.9dual 4 ohm · EBP 59.5
At 59.5–64.9 the NSW12v3 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

1.63 cu ft against a 37.7 L Vas.

α = Vas ÷ Vb = 0.82  ·  Fc = Fs√(α+1) = 47–50 Hz  ·  Qtc = 0.66–0.76
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
dual 2 ohm · Qtc 0.66, Fc 47 Hz, F3 50.4 Hzdual 4 ohm · Qtc 0.76, Fc 50 Hz, F3 46.8 Hz
The box lifts resonance from 34.7–36.9 Hz free-air to 47–50 Hz and half power lands at 46.8–50.4 Hz, anechoic, before any cabin gain. Figures are NVX’s published NSW12v3 parameters from its owner’s manual and product pages, displacement included (0.080 cubic feet). One cabinet serves both coils; both are plotted.

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

PXmax = 323–361 W unfiltered  →  438–459 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 12.5 mm 323 W reaches Xmax here
dual 2 ohm · 323 W, no filterdual 4 ohm · 361 W, no filterdual 2 ohm · 459 W with subsonic at 25 Hz, 24 dB/octdual 4 ohm · 438 W with subsonic at 25 Hz, 24 dB/octXmax 12.5 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 12.5 mm. Unfiltered that is 323 W, reached first at 20 Hz. It sits under the 500 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 438 W before hitting the same 12.5 mm. That is 36 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs34.67 / 36.92Hzfree-air resonance
Qts0.489 / 0.560dual 2 ohm / dual 4 ohm
Vas37.70 / 37.83Lequivalent compliance
Sd510.6cm²effective piston area
Xmax12.5mmone-way linear travel
Pe500Wcontinuous RMS
SPL86.5dB1 W / 1 m, derived from T/S

Driver parameters as published by NVX NSW12v3 owner’s manual. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

Measure the installed height, not the cabinet height. The box is 10.26 tall on its own and the standoffs add 1.75, so plan around 12.01 inches of stack on the 30 by 15 footprint.

Airspace set the height here, 1.63 cubic feet; the motor clear the lid with 3.51 to spare.

Floor slot is 0.75 times the cone area at the 1.75 standoff, under the 1.0 I like. Taller feet fix it if the floor allows.

Cut is 10.86, NVX's own figure, and the inserts are already pressed on their 11.73 bolt circle. It is sealed, so leave the polyfill as it is and run it at 500 watts or under.

Before you order

Questions

Does this fit the NVX NSW12v3, and will any other 12 inch fit?

The NSW12v3, yes, in either coil (NSW122v3 or NSW124v3). The baffle is cut to 10.86 in, NVX's published cutout, under the 12.46 in frame. The 6.00 inch motor clears the cabinet with 3.51 inch to spare. One cabinet serves both coils: the NSW122v3 (D2) reads Qtc 0.659 with half power at 50.4 Hz, and the NSW124v3 (D4) reads Qtc 0.755 at 46.8 Hz.

Any other 12, no. The airspace is worked out from the NSW12v3's own Qts and Vas, and a different woofer that happened to drop into the hole would not see the alignment printed on this page.

Why 1.63 cubic feet, and what alignment does it target?

1.63 cubic feet is split between the coils' Butterworth volumes (1.22 for the D2, 2.25 for the D4) on the D2 figures (Fs 34.7 Hz, Qts 0.49, Vas 37.7 liters): Qtc 0.659, half power at 50.4 Hz. One cabinet serves both coils: the NSW122v3 (D2) reads Qtc 0.659 with half power at 50.4 Hz, and the NSW124v3 (D4) reads Qtc 0.755 at 46.8 Hz.

NVX's manual and product pages are the only published source for this driver, so treat the Qtc as good to a few hundredths.

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

NVX rates the NSW12v3 at 500 watts RMS, so target 350 to 500 watts RMS at the final load.

The NSW122v3 (D2) wires to 4 ohms with its coils in series or 1 ohm in parallel. The NSW124v3 (D4) wires to 8 ohms in series or 2 ohms in parallel. Anything under 1 ohm, and many amplifiers at 1 ohm, is outside what the amplifier is built for; series wiring is the safe default. Confirm your amplifier's minimum stable impedance first.

How tall is this once the standoffs are on?

The cabinet is 10.26 inches tall measured in the down fire position, and that figure excludes the standoffs. The standoffs hold 1.75 inches under the baffle, so plan your space around a finished stack of roughly 12.01 inches.

The footprint is the standard Performance Optimized down fire platform, 30.00 inches wide by 15.00 deep. Height is the only dimension solved to the driver.

Why is the front baffle double-layered?

The baffle is two bonded 3/4 inch sheets, 1.5 inches through. A single 3/4 inch panel flexes under the pressure a 12 inch woofer puts on it at 500 watts, which smears output and works the driver loose over time; the second layer stiffens the face and gives the mounting hardware twice the material to bite.

The outer layer is machined as a flush recess to the 12.46 inch frame, so the driver bolts to the inner layer.

What is the expected low-frequency extension?

Anechoic F3 is 50.4 Hz on the D2, with system resonance at 46.7 Hz. Below Qtc 0.707 the rolloff is gentle and F3 sits above fc, which is what a damped sealed box does.

Those figures exclude cabin gain. In a car the cabin's transfer function adds real output below 50 Hz, so in-vehicle response runs deeper than the numbers above.

Do I need to add polyfill or damping?

No. Polyfill is already installed as a light wall lining to control internal reflections, and the quantity is chosen so it does not change the acoustic volume.

Do not add more. Packing a sealed box with fill makes it behave as though it were larger, which walks the alignment away from the 1.63 cubic feet this cabinet was built to.

Is the driver included, and are the threaded inserts installed?

No driver. This is an enclosure only. You receive the cabinet finished in plush black carpet, one side-mounted pre-wired terminal cup, the polyfill lining already in place, the standoffs, and threaded inserts pressed on NVX's published 11.73 inch bolt circle with stainless machine screws.

The NVX NSW12v3 is purchased separately, and the cabinet is cut direct fit to it, not a general purpose 12 inch box.

Same series, same size

Other Performance Optimized models