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Performance Optimized · Datasheet

Performance Optimized Wedge Sealed 12" Enclosure Skar Audio VD-12 · Single 12" Sealed enclosure

Net volume
1.00 cu ft after the brace and an estimated 0.085 cu ft displacement
Max mounting depth
4.95 in required; 0.75 in clearance above the motor against the raked rear panel
External dimensions
25.41 in W × 15 in at the seat face H × 11.85 in at the base D
Front baffle
1.5 in double baffle, outer layer machined as a flush recess
Buy at Audio IntensityFactory-direct, ships from Tullahoma
Skar Audio VD-12Buy at Audio Intensity
  • Best For: Skar Audio VD-12 Trunk-Fit Builds
  • Net Volume: 1.00 cu ft (1.10 cu ft Gross)
  • Driver Match: Skar Audio VD-12 (D2)
  • Construction: Rear-Firing Wedge | V-Groove/Dado | Double 1.5" Baffle | Threaded Insert Kit

Spec of record

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Wedge
Compatible DriverSkar Audio VD-12 D2, quantity 1. Direct fit
ConfigurationSingle 12 inch, single chamber sealed wedge
Mounting PositionTrunk or cargo area, tall face against the rear seat back
Firing DirectionRearward into the trunk. Not a down fire design, no feet included
External Width25.41 in
External Height15 in at the seat face
External Depth11.85 in at the base, tapering to 6.39 in at the top
Internal Volume, Gross1.10 cu ft
Internal Volume, Net Acoustic1.00 cu ft after the brace and an estimated 0.085 cu ft displacement
Driver Mounting Depth4.95 in required; 0.75 in clearance above the motor against the raked rear panel
Alignment, D2Qtc 0.876, fc 56.2 Hz, F3 47.4 Hz anechoic
Skar Recommended Sealed1 cu ft, net of driver, bracing and port (Qtc 0.88 D2)
Woofer Opening11.28 in, Skar's published cutout
Frame Outer Diameter12.60 in
Bolt CircleNot printed by Skar; threaded insert kit included
Driver Displacement0.085 cu ft, estimated; Skar publishes none
D2 Fs / Qts / Qes / Qms / Vas35.3 Hz / 0.55 / 0.62 / 4.42 / 43.5 L
Driver Sd505 cm2, derived from Vas and Cms; Skar leaves it blank
Xmax11 mm one way, Skar spec
Driver Power Handling500 W RMS, Skar spec
Wiring OptionsThe VD-12 D2 wires to 4 ohms with its coils in series or 1 ohm 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 Sourceskaraudio.com VD-12 product page, T/S Parameters and Subwoofer Measurements
MaterialLangboard Elite MDF
ConstructionCNC cut, V-groove and dado joinery
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 insert kit included, NOT pre-installed: Skar prints no bolt circle
Terminal CupsOne Proline X ABS and carbon fiber composite, side mounted, pre wired 12 gauge OFC
Acrylic InsertGloss black acrylic baffle insert standard
DampingLight polyfill wall lining, does not alter acoustic volume
CarpetPlush black
Shipping Weight40 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
1.00
cu ft
System Qtc
0.88
sealed
Half power
47.4
Hz · F3
Xmax at
394
W RMS · no filter
With 25 Hz subsonic
414
W RMS · +5%
Amplifier
500
W RMS recommended
This enclosure holds 1.00 cu ft net . In it the Skar Audio VD-12 runs a system Qtc of 0.88 with half power at 47.4 Hz, and the cone reaches its 11.0 mm travel limit at 394 W, below the driver’s 500 W thermal rating, so travel is what stops you here, not heat. A 25 Hz subsonic filter adds little here: 414 W against 394 W, 5 percent. The box already resonates at 56 Hz, so its own rolloff has removed most of what the filter would have stopped.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 56.9
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 dual 2 ohm 56.9
dual 2 ohm · EBP 56.9
At 56.9 the VD-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

1.00 cu ft against a 43.5 L Vas.

α = Vas ÷ Vb = 1.54  ·  Fc = Fs√(α+1) = 56 Hz  ·  Qtc = 0.88
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
dual 2 ohm · Qtc 0.88, Fc 56 Hz, F3 47.4 Hz
The box lifts resonance from 35.3 Hz free-air to 56 Hz and half power lands at 47.4 Hz, anechoic, before any cabin gain. Figures are Skar Audio’s published VD-12 parameters from its product page. Driver displacement is not published; 0.085 cubic feet is an estimate. Worth knowing: Skar leaves cone area blank on the VD, so the 505 square centimetres here is derived from their Vas and compliance. This box is for the VD-12 D2. The D4’s higher Qts reads Qtc 0.96 in the same 1.00 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 11.0 mm, and in this alignment a subsonic filter barely moves it.

PXmax = 394 W unfiltered  →  414 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 12 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 11.0 mm 394 W reaches Xmax here
dual 2 ohm · 394 W, no filterdual 2 ohm · 414 W with subsonic at 25 Hz, 24 dB/octXmax 11.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 11.0 mm. Unfiltered that is 394 W, reached first at 33 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, and they sit almost on top of the solid ones: 414 W against 394 W. At 56 Hz the filter sits well below resonance, where the sealed alignment has already rolled the cone off at 12 dB/oct, so there is little wasted travel left for it to recover. Set it anyway to keep road rumble out of the cone, but do not size the amplifier around it.
ParamValueUnitNote
Fs35.30Hzfree-air resonance
Qts0.550dual 2 ohm
Vas43.50Lequivalent compliance
Sd505.3cm²effective piston area
Xmax11mmone-way linear travel
Pe500Wcontinuous RMS
SPL86.7dB1 W / 1 m, derived from T/S

Driver parameters as published by Skar Audio VD-12 product page. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

1.00 cubic feet, Qtc 0.876 on the D2. This box is for the VD-12 D2. The D4's higher Qts reads Qtc 0.96 in the same 1.00 cubic feet, boomy rather than tight, so we do not recommend it here.

The 4.95 inch motor clears the raked back with 0.75 to spare; the volume, not the motor, sets the rest of the cabinet.

Cut is 11.28, Skar's own figure. Inserts ship in the kit, not pressed: Skar prints no bolt circle. Mark from the driver, drill, press. 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 Skar VD-12, and will any other 12 inch fit?

The VD-12 D2, yes. The baffle is cut to 11.28 in, Skar's published cutout, under the 12.60 in frame. The 4.95 inch motor clears the cabinet with 0.75 inch to spare. This box is for the VD-12 D2. The D4's higher Qts reads Qtc 0.96 in the same 1.00 cubic feet, boomy rather than tight, so we do not recommend it here.

Any other 12, no. The airspace is worked out from the VD-12'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 1.00 cubic feet, and what alignment does it target?

1.00 cubic feet is the volume this cabinet is built to on the D2 figures (Fs 35.3 Hz, Qts 0.55, Vas 43.5 liters): Qtc 0.876, half power at 47.4 Hz. This box is for the VD-12 D2. The D4's higher Qts reads Qtc 0.96 in the same 1.00 cubic feet, boomy rather than tight, so we do not recommend it here.

That is Skar's own recommended sealed volume for the VD-12. It reads Qtc 0.88 on the D2, above the 0.707 of a maximally flat alignment, so expect a mild lift near 56 Hz rather than a flat rolloff. Skar's numbers 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?

Skar rates the VD-12 at 500 watts RMS, so target 350 to 500 watts RMS at the final load.

The VD-12 D2 wires to 4 ohms with its coils in series or 1 ohm 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.

Why the wedge angle, and why rear-firing into the trunk?

The seat-side face carries a 20 degree rake that matches the lean of a factory rear seat back, so the cabinet sits flush against it and the cargo space in front stays usable. The baffle is the vertical trunk-lid-side face, so the driver fires rearward into the trunk cavity.

The trunk acts as an acoustic extension for the sealed box, and the cabin adds real output below 50 Hz, so in-vehicle response runs deeper than the anechoic 47.4 Hz on this page.

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 12.60 inch frame, so the driver bolts to the inner layer and sits flush with the gloss black acrylic insert.

What is the expected low-frequency extension?

Anechoic F3 is 47.4 Hz on the D2, with system resonance at 56.2 Hz. Above Qtc 0.707 the response carries a small bump before the rolloff and F3 sits below fc.

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 1.00 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 with the gloss black acrylic baffle insert, one side-mounted pre-wired terminal cup, the polyfill lining already in place, and a threaded insert kit with stainless machine screws.

The inserts ship loose on purpose: Skar prints no bolt circle for the VD-12, so you set the driver in the recess, mark its holes, drill and press the inserts. The Skar VD-12 is purchased separately, and the cabinet is cut direct fit to it, not a general purpose 12 inch box.

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