Sealed, Driver-Matched, 12 and 15 Inch

NVX Subwoofer Boxes and Enclosures

Sealed wedges cut for NVX VC-Series v3 subwoofers, CNC-machined in Tullahoma, Tennessee.

Proline X Performance Optimized Series sealed wedge enclosure, cut for the NVX VC-Series v3 subwoofer.

Sealed, Driver-Matched, 12 and 15 Inch

NVX publishes a recommended sealed volume for the VC-Series v3 and it is a sound number, so we built to it. The difference is that we build to it net. Half the boxes on the market quote a gross figure and hand the driver a smaller box than the label claims once displacement comes out.

A twelve and a fifteen, both rear firing wedges on the Performance Optimized standard. The choice on this page is driver diameter and the space you have, not build quality, because the standard does not change between them.

Sealed NVX wedge cabinets in twelve and fifteen inch, both Performance Optimized rear firing, both built to the net volume NVX publishes for the driver.

Cut, assembled and finished in Tullahoma, Tennessee, to the sealed volume NVX publishes for the VC-Series v3.

Driver parameters are taken from NVX published data. We build enclosures to those figures; we do not stock NVX drivers and make no claim to represent the brand.

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NVX Enclosures at a Glance

Both cabinets share the alignment, the orientation and the build standard, so this comes down to driver diameter and the space you have. Both are cut for the NVX VC-Series v3 in either coil version.

Every active NVX cabinet in stock, 30 August 2026.
12 inch15 inch
FitsVCW122v3, VCW124v3VCW152v3, VCW154v3
Net volume0.85 cu ft2.00 cu ft
AlignmentQtc 0.67, Fc 41.8 HzQtc 0.76
Cutout11.25 in14.25 in
Mounting depth needed7.02 in8.19 in
External size18.75 in W x 15 in H x 9 to 14.5 in D22.75 in W x 18 in H x 8.75 to 15.3 in D
Power target850 to 1200 W RMS1050 to 1500 W RMS
Shipping weight44 lb59 lb

Shared across both: Langboard Elite MDF, 1.5 inch double baffle, rear firing wedge, single driver, sealed with polyfill pre-installed, one terminal cup, Performance Optimized Series.

Built to the Net Volume, Not the Gross One

A sealed alignment is only as good as the volume the driver actually sees. The twelve is 0.85 cubic feet net after the driver's 0.15 cubic feet of displacement is subtracted, which lands system Qtc at 0.67 with resonance at 41.8 Hz. That is near-Butterworth: flat through the passband, no peak at the corner, no cabinet resonance propping up a driver that does not need it.

The fifteen is 2.0 cubic feet net out of 2.15 gross, which puts Qtc at 0.76. Slightly weightier than maximally flat and deliberately so, because a fifteen that measures like an oversized twelve has given up the reason you bought a fifteen. Build the same driver in a 2.0 gross box and it sees 1.85 net at a Q of 0.78, which is why the net figure is the one quoted here.

How to Choose

Pick the diameter your space allows

Both cabinets land at a properly damped sealed alignment, so this is not a quality ladder. The fifteen needs roughly four inches more width and three more inches of height than the twelve, and it weighs about fifteen pounds more. If the trunk takes it, the extra cone area is free output.

Let the amplifier decide the coil

The two coil versions of a given diameter are acoustically close enough that the deciding factor is what your amplifier is stable into, not what the driver measures. Work out the wired impedance first and buy the coil version that gets you there.

Do not add stuffing

Both cabinets ship with polyfill already installed and the net volume is a finished figure. Adding more makes the box read acoustically larger and walks Qtc below where the alignment was set. If you want to chase resonance, put the effort into the trunk sheet metal and the rear deck.

Then source the driver

We do not stock NVX drivers. Both cabinets are cut to the figures NVX publishes, for a subwoofer you already own or buy elsewhere.

Coil Version, Amplifier Load and Space

Either coil version drops in

NVX builds each VC-Series v3 in a dual 2 ohm and a dual 4 ohm. Within a diameter the two share the same frame, cone and motor, so cutout, bolt pattern, mounting depth and displacement are identical. The twelve takes an 11.25 inch cutout at 7.02 inches of depth. The fifteen takes 14.25 inches at 8.19 inches. The coil version changes the wiring, not the box.

Settle the load before the amplifier

On the dual 4 ohm versions, parallel gives 2 ohms, which is where most monoblocks make rated power. On the dual 2 ohm versions, parallel gives 1 ohm, and plenty of amplifiers rated for that on paper do not enjoy it in a hot trunk. Run those coils in series for 4 ohms unless your amplifier is genuinely 1 ohm stable. More coils come off the bench burnt from unstable 1 ohm loads than from anything else.

Then measure the trunk floor

These are wedges, so they want a seat back to lean against rather than uniform floor clearance. Measure at the deepest point, which is the larger of the two depth figures on each listing. External dimensions are published on every product page.

Net Volume, Not Gross

NVX specifies 0.85 cubic feet for the twelve and 2 cubic feet for the fifteen. Both cabinets deliver that figure net, after driver displacement is subtracted, not gross before it. On the fifteen that is the difference between 2.0 net at Qtc 0.76 and 1.85 net at 0.78. It is a small number on paper and an audible one in the car.

We Cut the Box, You Source the Driver

We do not stock NVX drivers. Both cabinets are built to the figures NVX publishes for the VC-Series v3, for a subwoofer you already own or buy elsewhere. Nothing about the fit depends on where the driver came from.

Twelve or Fifteen, Both Sealed Wedges

The twelve suits a trunk build where the subwoofer has to disappear into the space and still keep up with a front stage. The fifteen is for the build that wants the extra cone area and has the cargo depth to give it, and it stays a sealed alignment rather than trading damping for output.

Both are rear firing wedges. The tall face sits against the rear seat back and the taper runs out toward the trunk lid, so the cabinet uses the length of the trunk instead of standing up in the middle of it. Both run a 1.5 inch double baffle, because a 1200 or 1500 watt motor moving over 20 mm one way will flex a single three quarter inch panel, and flex is lost output.

Every cabinet on this page is Performance Optimized Series. Each product page states its own net volume, the alignment it lands at, and the cutout it is machined for.

NVX Subwoofer Box Questions

Which NVX subwoofers do these boxes fit?

Both cabinets are cut for the NVX VC-Series v3. The 12 inch takes the VCW122v3 or VCW124v3 and the 15 inch takes the VCW152v3 or VCW154v3. Within a diameter the dual 2 ohm and dual 4 ohm share the same frame, cone and motor, so either coil version drops into the same cabinet. Match the model rather than the diameter alone.

Do you sell NVX subwoofers?

No. We build the enclosure and you source the driver. Both cabinets are cut to the figures NVX publishes for the VC-Series v3, so they suit a subwoofer you already own or buy elsewhere.

Why do you quote net volume instead of gross?

Because net is what the driver actually sees. NVX specifies 0.85 cubic feet for the twelve and 2 cubic feet for the fifteen, and both cabinets deliver that after driver displacement is subtracted. A box built to 2.0 gross hands a fifteen 1.85 net and a different alignment than the one on the label.

What alignment do these cabinets land at?

The twelve sits at a system Qtc of 0.67 with resonance at 41.8 Hz, which is near-Butterworth: flat through the passband with no peak at the corner. The fifteen sits at 0.76, slightly weightier than maximally flat, which keeps a fifteen sounding like a fifteen rather than an oversized twelve.

How should I wire the coils?

On the dual 4 ohm versions, parallel gives a 2 ohm load and that is where most monoblocks make rated power. On the dual 2 ohm versions, parallel gives 1 ohm, so run those coils in series for 4 ohms unless your amplifier is genuinely rated 1 ohm stable. An unstable amplifier into 1 ohm clips into the coil and kills drivers.

Do these ship with polyfill?

Yes. Both cabinets ship with polyfill already installed. Do not add more and do not remove it. The net volume is a finished figure and stuffing the box further makes it read acoustically larger, which walks Qtc below where the alignment was set.

How low will they play in a car?

The anechoic F3 works out around 44 Hz on the twelve and between 46 and 50 Hz on the fifteen depending on coil version. Those are anechoic figures and not what you will hear. In a sealed trunk-load install, cabin gain typically adds usable output an octave below the anechoic corner, so expect solid, articulate output into the low 30s in most sedans.

Drivers Built to Match

Subwoofers Spec'd for These Enclosures

The drivers below are matched to the enclosures above by Thiele-Small parameters. Buying together guarantees the alignment, port tuning, and damping work the way the engineering intended.

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Amplifiers for the System

Power for Your Subwoofer System

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Last updated August 30, 2026