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Proline X PO 15-S DF VCW sealed down fire enclosure, front panel on 1.75 inch feet, 30 by 12.2 inches.
Proline X PO 15-S DF VCW sealed down fire enclosure, end panel with recessed terminal cup, 15 by 12.2 inches.

Performance Optimized · Datasheet

Performance Optimized Down Fire Sealed 15" Enclosure NVX VCW15v3 · Single 15" Sealed enclosure

Net volume
2.00 cu ft after the brace and the 0.130 cu ft displacement NVX publishes
Max mounting depth
8.19 in required, 3.28 in clearance above the motor
External dimensions
30.00 in W × 12.22 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 VCW15v3Buy at Audio Intensity
  • Alignment: 2.00 cu ft net, Qtc 0.706 (D4), F3 49.2 Hz
  • Driver: NVX VCW15v3 (VCW154v3 D4), 1500 W RMS, 23 mm Xmax, 8.19 in mounting depth
  • Standoffs: Included, 1.75 in, shipped uninstalled. Installed height near 13.97 in
  • Cabinet: 30.00"W x 15.00"D x 12.22"H in down fire position, excludes standoffs, square corners

Spec of record

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Down Fire
Compatible DriverNVX VCW15v3 (VCW154v3 D4), quantity 1. Direct fit
ConfigurationSingle 15 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 Height12.22 in in the down fire position, excludes standoffs
Installed Height13.97 in including the 1.75 in standoff
Internal Volume, Gross2.14 cu ft
Internal Volume, Net Acoustic2.00 cu ft after the brace and the 0.130 cu ft displacement NVX publishes
Height Set ByAirspace; clearance alone would allow a lower cabinet
Driver Mounting Depth8.19 in required, 3.28 in clearance above the motor
Floor Slot0.62 times the cone area at the 1.75 in standoff
Alignment, D4Qtc 0.706, fc 49.1 Hz, F3 49.2 Hz anechoic
Woofer Opening14.12 in, NVX's published cutout
Frame Outer Diameter15.59 in, NVX published
Bolt Circle14.78 in, NVX published; threaded inserts pre-installed
Driver Displacement0.130 cu ft, NVX published
VCW154v3 (D4) Fs / Qts / Qes / Qms / Vas31.30 Hz / 0.450 / 0.620 / 1.68 / 82.90 L
Driver Sd804 cm2, published by NVX
Xmax23 mm one way, NVX spec
Driver Power Handling1500 W RMS, NVX spec
Wiring OptionsThe VCW154v3 (D4) wires to 8 ohms in series or 2 ohms in parallel.
Parameter SourceNVX VCW154v3 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 Weight45 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
2.00
cu ft
System Qtc
0.71
sealed
Half power
49.2
Hz · F3
Xmax at
2244
W RMS · no filter
With 25 Hz subsonic
2914
W RMS · +30%
Amplifier
1500
W RMS recommended
This enclosure holds 2.00 cu ft net . In it the NVX VCW15v3 runs a system Qtc of 0.71 with half power at 49.2 Hz, and the cone reaches its 23.0 mm travel limit at 2244 W, above the driver’s 1500 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 2914 W — +670 W, or 30 percent more power for the same 23.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 50.5
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 dual 4 ohm 50.5
dual 4 ohm · EBP 50.5
At 50.5 the VCW15v3 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

2.00 cu ft against a 82.9 L Vas.

α = Vas ÷ Vb = 1.46  ·  Fc = Fs√(α+1) = 49 Hz  ·  Qtc = 0.71
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
dual 4 ohm · Qtc 0.71, Fc 49 Hz, F3 49.2 Hz
The box lifts resonance from 31.3 Hz free-air to 49 Hz and half power lands at 49.2 Hz, anechoic, before any cabin gain. Figures are NVX’s published VCW15v3 parameters from its owner’s manual and product pages, displacement included (0.130 cubic feet). This box is for the VCW154v3 (D4). The VCW152v3 D2’s higher Qts reads Qtc 0.98 in the same 2.00 cubic feet, boomy rather than tight, so we do not recommend it here.

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

PXmax = 2244 W unfiltered  →  2914 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 8 16 24 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 23.0 mm 2244 W reaches Xmax here
dual 4 ohm · 2244 W, no filterdual 4 ohm · 2914 W with subsonic at 25 Hz, 24 dB/octXmax 23.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 23.0 mm. Unfiltered that is 2244 W, reached first at 20 Hz. It sits above the 1500 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 2914 W before hitting the same 23.0 mm. That is 30 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs31.30Hzfree-air resonance
Qts0.450dual 4 ohm
Vas82.90Lequivalent compliance
Sd804.2cm²effective piston area
Xmax23mmone-way linear travel
Pe1500Wcontinuous RMS
SPL88.0dB1 W / 1 m, derived from T/S

Driver parameters as published by NVX VCW15v3 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 12.22 tall on its own and the standoffs add 1.75, so plan around 13.97 inches of stack on the 30 by 15 footprint.

Airspace set the height here, 2.00 cubic feet; the motor clear the lid with 3.28 to spare.

Floor slot is 0.62 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 14.12, NVX's own figure, and the inserts are already pressed on their 14.78 bolt circle. It is sealed, so leave the polyfill as it is and run it at 1500 watts or under.

Before you order

Questions

Does this fit the NVX VCW15v3, and will any other 15 inch fit?

The VCW154v3 (D4), yes. The baffle is cut to 14.12 in, NVX's published cutout, under the 15.59 in frame. The 8.19 inch motor clears the cabinet with 3.28 inch to spare. This box is for the VCW154v3 (D4). The VCW152v3 D2's higher Qts reads Qtc 0.98 in the same 2.00 cubic feet, boomy rather than tight, so we do not recommend it here.

Any other 15, no. The airspace is worked out from the VCW15v3'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 2.00 cubic feet, and what alignment does it target?

2.00 cubic feet is the Butterworth volume on the D4 figures (Fs 31.3 Hz, Qts 0.45, Vas 82.9 liters): Qtc 0.706, half power at 49.2 Hz. This box is for the VCW154v3 (D4). The VCW152v3 D2's higher Qts reads Qtc 0.98 in the same 2.00 cubic feet, boomy rather than tight, so we do not recommend it here.

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 VCW15v3 at 1500 watts RMS, so target 1050 to 1500 watts RMS at the final load.

The VCW154v3 (D4) wires to 8 ohms in series or 2 ohms in parallel. Confirm your amplifier's minimum stable impedance first.

How tall is this once the standoffs are on?

The cabinet is 12.22 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 13.97 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 15 inch woofer puts on it at 1500 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 15.59 inch frame, so the driver bolts to the inner layer.

What is the expected low-frequency extension?

Anechoic F3 is 49.2 Hz on the D4, with system resonance at 49.1 Hz. At Qtc 0.71 the response is maximally flat into the rolloff, so F3 and fc coincide.

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 2.00 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 14.78 inch bolt circle with stainless machine screws.

The NVX VCW15v3 is purchased separately, and the cabinet is cut direct fit to it, not a general purpose 15 inch box.

Same series, same size

Other Performance Optimized models