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Proline X PO 12-S DFW NSW sealed down-fire wide enclosure for the NVX NSW12v3, 41 inches wide by 8.4375 inches tall, feet add 1.75 inches of height.
Proline X PO 12-S DFW NSW sealed down-fire wide enclosure, end panel with side-mounted terminal cup, 8.4375 inches tall by 14 inches deep.

Performance Optimized · Datasheet

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

Net volume
1.634 cu ft after displacement and the brace
Max mounting depth
6 in
External dimensions
41 in W × 8.4375 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
NVX NSW12v3Buy at Audio Intensity
  • Alignment: 1.634 cu ft net. NSW122v3, dual 2 ohm: Qtc 0.659, Fc 46.7 Hz, F3 50.4 Hz; NSW124v3, dual 4 ohm: Qtc 0.755, Fc 49.8 Hz, F3 46.8 Hz
  • Down Fire Wide: 41"W x 14"D x 8.4375"H in down fire position, excludes the 1.75" standoffs (installed height 10.1875"). Stands lower than the standard 30 x 15 at 10.26"
  • Height set by: airspace; 1.69" of clearance above the motor
  • Driver: NVX NSW12v3 (NSW122v3 D2 or NSW124v3 D4), 500 W RMS, 12.5 mm Xmax, 6 in 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

SpecificationValue
SeriesProline X Performance Optimized Down Fire Wide
Compatible DriverNVX NSW12v3 (NSW122v3 D2 or NSW124v3 D4), 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 Height8.4375 in in the down fire position, excludes standoffs
Installed Height10.1875 in including the 1.75 in standoffs
Dimension ReferenceAll external dimensions measured in down fire position
Standard 30 x 15 Version10.26 in tall, 1.63 cu ft net
Internal Volume, Gross1.723 cu ft
Internal Volume, Net1.634 cu ft after displacement and the brace
Height Set ByAirspace; 1.69 in clearance above the motor
Alignment, NSW122v3, dual 2 ohmQtc 0.659, Fc 46.7 Hz, F3 50.4 Hz anechoic
Alignment, NSW124v3, dual 4 ohmQtc 0.755, Fc 49.8 Hz, F3 46.8 Hz anechoic
Woofer Opening10.86 in
Mounting Depth Required6 in
Frame Outer Diameter12.46 in
Driver Displacement0.08 cu ft
Bolt Circle11.73 in, NVX published; threaded inserts pre-installed
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
Driver MountingThreaded inserts pre-installed on the published bolt circle, stainless machine screws included
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 NSW12v3)
Warranty1 year limited (enclosure)
Built InTullahoma, Tennessee, USA

Modelled response

Performance in this enclosure

Net airspace
1.634
cu ft
System Qtc
0.66–0.75
sealed
Half power
46.8–50.4
Hz · F3
Xmax at
322
W RMS · no filter
With 25 Hz subsonic
438
W RMS · +36%
Amplifier
500
W RMS recommended
This enclosure holds 1.634 cu ft net . In it the NVX NSW12v3 runs a system Qtc of 0.66–0.75 with half power at 46.8–50.4 Hz, and the cone reaches its 12.5 mm travel limit at 322 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 D2 64.9 D4 59.5
D2 · EBP 64.9D4 · 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

1.634 cu ft against a 37.7 L Vas.

α = Vas ÷ Vb = 0.81  ·  Fc = Fs√(α+1) = 47–50 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 47 Hz, F3 50.4 HzD4 · Qtc 0.75, 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 = 322–361 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 322 W reaches Xmax here
D2 · 322 W, no filterD4 · 361 W, no filterD2 · 459 W with subsonic at 25 Hz, 24 dB/octD4 · 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 322 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 / 0.560D2 / D4
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 8.4375 tall on its own and the feet add 1.75, so plan around 10.1875 inches on the 41 by 14 footprint.

Height was solved to the airspace: 8.4375 tall holds 1.634 net, against 1.63 in the standard box, and the motor clears the lid with 1.69 inches to spare. Same air, lower box.

One cabinet, both coils: D2 at Qtc 0.659 with F3 50.4 Hz, D4 at Qtc 0.755 with F3 46.8 Hz.

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.

Measure installed height, not cabinet height: 8.4375 on its own, 10.1875 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 8.4375 inches tall instead of 10.26.

Fourteen inches of depth is the practical minimum, since a 12 inch frame needs about 13 inches of baffle. If your space is long and low rather than deep or tall, this is the shape that fits.

How does this compare to the standard 30 x 15 NSW12v3 enclosure?

Same driver, different shape. The standard cabinet is 30 by 15 by 10.26 inches and holds 1.63 cubic feet net. This cabinet is 41 by 14 by 8.4375 inches and holds 1.634 cubic feet net.

The airspace is effectively the same, so the driver behaves the same way in either. 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 each coil?

At 1.634 cubic feet net the NSW122v3 (D2) lands at Qtc 0.659, Fc 46.7 Hz and F3 50.4 Hz. The NSW124v3 (D4) lands at Qtc 0.755, Fc 49.8 Hz and F3 46.8 Hz. Both are computed from NVX's published parameters for each coil.

Those figures are anechoic. In a car the cabin adds real output below about 50 Hz, so in-vehicle response runs deeper.

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 in series or 1 ohm in parallel. The NSW124v3 (D4) wires to 8 ohms in series or 2 ohms in parallel. Series wiring is the safe default; confirm your amplifier's minimum stable impedance first.

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 10.86 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 1.634 cubic feet it was built to. Assembled and inspected in Tullahoma, Tennessee.

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 in place, the 1.75 inch feet, and threaded inserts pressed on NVX's published 11.73 inch bolt circle with stainless machine screws. The NVX NSW12v3 is purchased separately.

Same series, same size

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