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Proline X PO 12T-S W XL1240T sealed wedge enclosure, product photos pending. Placeholder graphic reading Photos Coming Soon.

Performance Optimized · Datasheet

Performance Optimized Wedge Wide Sealed Triple 12" Enclosure PowerBass XL-1240T · Triple 12" Sealed enclosure

Net volume
0.466 cu ft per driver, 1.40 cu ft total, after both dividers and PowerBass's published 0.126 cu ft displacement per driver
Max mounting depth
3.80 in required; 0.75 in clearance above the motor against the raked rear panel
External dimensions
44 in W × 17 in at the seat face H × 11.04 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
PowerBass XL-1240TBuy at Audio Intensity
  • Best For: Triple PowerBass XL-1240T SUV Cargo-Floor Builds
  • Net Volume: 0.466 cu ft per Driver (1.40 cu ft Net Total)
  • Driver Match: Three PowerBass XL-1240T (SVC), matched
  • Construction: 3 Chambers | 44" Wide Wedge | V-Groove/Dado | Double 1.5" Baffle | 3 Terminal Cups

Spec of record

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Wedge Wide
Compatible DriverPowerBass XL-1240T, quantity 3, matched. Direct fit
ConfigurationTriple 12 inch sealed wedge, 3 chambers, 1 driver per chamber
Mounting PositionSUV cargo floor, raked face against the rear seat back
Firing DirectionRearward toward the liftgate. Not a down fire design
External Width44 in
External Height17 in at the seat face
External Depth11.04 in at the base, tapering to 4.85 in at the top
Internal Volume, Gross1.84 cu ft total
Internal Volume, Net Acoustic0.466 cu ft per driver, 1.40 cu ft total, after both dividers and PowerBass's published 0.126 cu ft displacement per driver
Driver Mounting Depth3.80 in required; 0.75 in clearance above the motor against the raked rear panel
Alignment Per DriverXL-1240T Qtc 1.080, fc 67.7 Hz, F3 51.6 Hz anechoic
Woofer Openings3 at 11.063 in
Woofer LayoutOne row across the face
Frame Outer Diameter12.244 in
Fs / Qts / Qes / Qms33.0 Hz / 0.526 / 0.597 / 4.458
Vas / Sd / Xmax42.4 L / 511 cm2 / 8 mm
Driver Power Handling400 W RMS per driver, 1200 W RMS for the set of 3 (thermal rating)
Recommended Amplifier250-360 W RMS per driver, 750-1,080 W RMS for the full set
Parameter SourcePowerBass published specifications
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 BracingTwo full-height 3/4 in dividers
Driver MountingThreaded inserts, stainless machine screws included
Terminal CupsThree Proline X ABS and carbon fiber composite, on the rear panel, one per chamber, pre wired 12 gauge OFC
Acrylic InsertGloss black acrylic baffle insert standard
DampingLight polyfill wall lining in every chamber, does not alter acoustic volume
CarpetPlush black
Shipping Weight64 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
0.466
cu ft per driver
System Qtc
1.08
sealed
Half power
51.6
Hz · F3
Xmax at
366
W RMS per driver · no filter
With 25 Hz subsonic
368
W RMS per driver · +0%
Amplifier, per driver
250–360
W RMS recommended
This enclosure holds 0.466 cu ft net per driver. In it the PowerBass XL-1240T runs a system Qtc of 1.08 with half power at 51.6 Hz, and the cone reaches its 7.5 mm travel limit at 366 W per driver, below the driver’s 400 W thermal rating, so travel is what stops you here, not heat. A 25 Hz subsonic filter adds little here: 368 W per driver against 366 W, 0 percent. The box already resonates at 68 Hz, so its own rolloff has removed most of what the filter would have stopped.

00Sizing the amplifier

Every wattage on this panel is per driver. This cabinet holds three, so the amplifier feeds all three at once.

Per driver 250–360 W RMS  ×  3 drivers  =  full set 750–1,080 W RMS
Look for a mono amplifier rated 750–1,080 W RMS at the load your coil version wires to. Travel sets the top here, not heat: past 368 W per driver the cone runs beyond Xmax even with the subsonic set, under the driver’s 400 W thermal rating. Below the bottom of the range it will play, just with less headroom; above the top you are buying power the drivers cannot use.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 55.3
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 SVC 55.3
SVC · EBP 55.3
At 55.3 the XL-1240T 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

0.466 cu ft against a 42.4 L Vas.

α = Vas ÷ Vb = 3.21  ·  Fc = Fs√(α+1) = 68 Hz  ·  Qtc = 1.08
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
SVC · Qtc 1.08, Fc 68 Hz, F3 51.6 Hz
The box lifts resonance from 33.0 Hz free-air to 68 Hz and half power lands at 51.6 Hz, anechoic, before any cabin gain. Figures are PowerBass’s published parameters; Qes and Qms reproduce the printed Qts. This cabinet holds three drivers in three separate sealed chambers of 0.466 cubic feet each, the volume plotted 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 7.5 mm, and in this alignment a subsonic filter barely moves it.

PXmax = 366 W per driver unfiltered  →  368 W per driver with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 7.5 mm 366 W reaches Xmax here
SVC · 366 W, no filterSVC · 368 W with subsonic at 25 Hz, 24 dB/octXmax 7.5 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 7.5 mm. Unfiltered that is 366 W per driver, reached first at 51 Hz. It sits under the 400 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: 368 W per driver against 366 W. At 68 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
Fs33.00Hzfree-air resonance
Qts0.526SVC
Vas42.37Lequivalent compliance
Sd510.7cm²effective piston area
Xmax7.5mmone-way linear travel
Pe400Wcontinuous RMS
SPL85.9dB1 W / 1 m, derived from T/S

Driver parameters as published by PowerBass XL-1240T published specifications. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

Start with the size. The maker's recommended sealed size is 0.27 per driver, but the 3.80 in deep motor sets the top of the wedge at 4.85 in, and the smallest box that clears it holds 0.466 per driver. 0.466 cubic feet per driver puts the XL-1240T at Qtc 1.080, resonance 67.7 Hz, half power 51.6 Hz anechoic: a pronounced lift near resonance, 1.7 dB above flat.

Measure the base depth, not the top. This cabinet is 11.04 in deep where it meets the floor, 4.85 at the top, 44 wide and 17 tall. In an SUV the 44 has to clear between the rear wheel wells at floor height, the base depth is measured from the seat back with the seat upright and latched, and the 17 has to clear the cargo cover.

All three terminal cups are on the rear panel, and the rear panel is the face that goes against the seat back. Wire all three before the box goes in, with enough slack to slide it into place; once the raked face is against the seat you cannot reach them.

The load depends on which coil version you run, so settle the coil before you buy the amplifier; the wiring section lists the clean loads for each version.

Power. Size the amplifier for the set, not one driver: 250 to 360 W RMS per driver is 750 to 1,080 W RMS across all 3. On this driver travel sets the top, not heat: Xmax arrives at 368 W per driver with a 25 Hz subsonic, under the 400 W rating.

PowerBass's Qes and Qms reproduce the printed Qts within 3 percent, so the alignment rests on a self-consistent set.

Polyfill is in as a wall lining in every chamber. Do not add more: it makes the box act larger and walks Qtc off 1.08.

Before you order

Questions

Does this fit the PowerBass XL-1240T, and its coil versions?

Yes. Each opening is cut to 11.063 in for the 12.244 in frame, and the 3.80 in deep motor clears the raked rear panel with 0.75 in to spare. Coil versions of the PowerBass XL-1240T share the frame, cutout and mounting depth, so any of them drops in. The alignment on this page is computed on the XL-1240T parameters.

Run three matched drivers, same model and same coil, so every chamber sees the alignment on this page.

Why 0.466 cubic feet per driver, and what alignment does it target?

On PowerBass's published Fs 33.0 Hz, Qts 0.526 and Vas 42.4 liters, 0.466 cubic feet per driver gives Qtc 1.080, system resonance 67.7 Hz and half power 51.6 Hz.

The maker's recommended sealed size is 0.27 cubic feet per driver, but the 3.80 in deep motor sets the shallowest the wedge can be, so it comes down only to 0.466: a pronounced lift near resonance, 1.7 dB above flat.

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

PowerBass rates the XL-1240T at 400 watts RMS per driver. Recommended amplifier: 250 to 360 W RMS per driver, 750 to 1,080 W RMS for the full set of 3. Travel, not heat, sets the top: the cone reaches Xmax at 368 W per driver with a 25 Hz subsonic set, under the 400 W rating.

Loads depend on the coil version you run. Three dual 4 ohm drivers, coils in series, all three in parallel: 2.67 ohms; coils in parallel, all three in series: 6 ohms. Dual 2 ohm: 1.33 ohms or 3 ohms the same two ways. Single 4 ohm: 1.33 ohms in parallel, 12 ohms in series. Use the lower load only on an amplifier rated stable there.

Will it fit my SUV?

It is 44 inches wide, 17 tall and 11.04 deep at the base, tapering to 4.85 at the top. Measure between the rear wheel wells, the floor depth with the seat upright, and the height under your cargo cover.

The raked face goes against the seat back and the woofers fire toward the liftgate.

Why are all three terminal cups on the back?

Each driver has its own sealed chamber, and the center chamber has no side wall to take a cup. Putting all three on the rear panel gives a matching set, one cup per chamber.

Wire them at the amplifier end; there is no cross-chamber wiring inside the cabinet.

What is the expected low-frequency extension?

Anechoic F3 is 51.6 Hz per driver with system resonance at 67.7 Hz.

Those figures exclude cabin gain. An SUV cabin adds real output below about 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 in every chamber, and the quantity is chosen so it does not change the acoustic volume.

Do not add more. Packing a sealed box makes it behave as though it were larger, which moves the alignment away from 0.466 cubic feet per driver.

Are the drivers included?

No. This is an enclosure only. You receive the cabinet finished in plush black carpet with the gloss black acrylic baffle insert, three pre-wired terminal cups on the rear panel, the polyfill lining in place, threaded inserts and stainless machine screws.

Bring three matched PowerBass XL-1240T drivers. The cabinet is cut direct fit to them, not a general purpose 12 inch box.

Same series, same size

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