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Proline X PO 10-S DFW XLT sealed down-fire wide enclosure for the PowerBass XL-1040T, 41 inches wide by 4.9375 inches tall, feet add 1.75 inches of height.
Proline X PO 10-S DFW XLT sealed down-fire wide enclosure, end panel with side-mounted terminal cup, 4.9375 inches tall by 12 inches deep.

Performance Optimized · Datasheet

Performance Optimized Down Fire Wide Sealed 10" Enclosure PowerBass XL-1040T · Single 10" Sealed enclosure

Net volume
0.546 cu ft after the brace and 0.0771 displacement
Max mounting depth
3.4 in required, shallow mount
External dimensions
41 in W × 4.9375 in in the down fire position H × 12 in 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-1040TBuy at Audio Intensity
  • Alignment: 0.546 cu ft net. Qtc 0.748, Fc 53.8 Hz, F3 51.0 Hz
  • Down Fire Wide: 41"W x 12"D x 4.9375"H, 3" shallower than the standard 21.05 x 15 cabinet, for under rear seats
  • Driver: PowerBass XL-1040T, 350 W RMS, 7.5 mm Xmax, 3.4 in mounting depth, single 4 ohm
  • Rear Venting: Vented rear motor, pole vent may be fully obstructed
  • Standoffs: Included, 1.75 in, uninstalled. Installed height 6.6875 in

Spec of record

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Down Fire Wide
Compatible DriverPowerBass XL-1040T, quantity 1. Direct fit
ConfigurationSingle 10 inch shallow mount, sealed down fire wide
Mounting PositionUnder a rear seat or on a narrow cargo floor where depth is limited, baffle facing down on standoffs
Firing DirectionDownward. Feet ship uninstalled, so front or up firing is also possible
External Width41 in
External Depth12 in
External Height4.9375 in in the down fire position, excludes standoffs
Installed Height6.6875 in including the 1.75 in standoff
Internal Volume, Gross0.629 cu ft
Internal Volume, Net Acoustic0.546 cu ft after the brace and 0.0771 displacement
PowerBass Published Target0.30 cu ft optimum, 0.25 to 0.75 acceptable. Their figures are GROSS and include driver displacement
Height Set ByDriver clearance: 3.4 in mounting depth plus 0.75 in above the motor
AlignmentQtc 0.748, Fc 53.8 Hz, F3 51.0 Hz anechoic
Comparison, Standard Down Fire21.05 x 15 x 4.90 in, 0.30 cu ft net. The wide cabinet holds more air at its clearance-set height
Woofer Opening9.3125 in (237 mm) direct fit
Driver Mounting Depth3.4 in required, shallow mount
Driver MotorRear vented, pole vent may be fully obstructed. 0.79 in clearance above the motor
Driver Power Handling350 W RMS, 700 W peak
Driver Voice CoilSingle 4 ohm, 2 in
Wiring4 ohms, no wiring choice
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 U-brace, dadoed to the shell
Driver MountingThreaded inserts, 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
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
0.546
cu ft per chamber
System Qtc
0.75
sealed
Half power
51.0
Hz · F3
Xmax at
160
W RMS · no filter
With 25 Hz subsonic
188
W RMS · +18%
Amplifier
350
W RMS recommended
This enclosure holds 0.546 cu ft net per chamber. In it the PowerBass XL-1040T runs a system Qtc of 0.75 with half power at 51.0 Hz, and the cone reaches its 7.5 mm travel limit at 160 W, below the driver’s 350 W thermal rating, so travel is what stops you here, not heat. Run a subsonic filter at 25 Hz and that becomes 188 W — +28 W, or 18 percent more power for the same 7.5 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 60.7
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 XL-1040T 60.7
XL-1040T · EBP 60.7
At 60.7 the XL-1040T 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

0.546 cu ft against a 21.0 L Vas.

α = Vas ÷ Vb = 1.36  ·  Fc = Fs√(α+1) = 54 Hz  ·  Qtc = 0.75
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
XL-1040T · Qtc 0.75, Fc 54 Hz, F3 51.0 Hz
The box lifts resonance from 35.0 Hz free-air to 54 Hz and half power lands at 51.0 Hz, anechoic, before any cabin gain.

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 a bigger one once a subsonic filter stops it wasting travel below the passband.

PXmax = 160 W unfiltered  →  188 W 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 160 W reaches Xmax here
XL-1040T · 160 W, no filterXL-1040T · 188 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 160 W, reached first at 20 Hz. It sits under the 350 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 188 W before hitting the same 7.5 mm. That is 18 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs35.00Hzfree-air resonance
Qts0.487XL-1040T
Vas21.02Lequivalent compliance
Sd346.4cm²effective piston area
Xmax7.5mmone-way linear travel
Pe350Wcontinuous RMS
SPL83.8dB1 W / 1 m, derived from T/S

Driver parameters as published by powerbassusa.com. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

This one is not the same air as the standard box, and that is worth knowing before the sale. The standard XL-1040T cabinet is 21.05 by 15 and holds 0.30 net. Stretch it to 41 by 12 and the height still has to clear a 3.4 inch driver with 0.75 above the motor, so the cabinet lands at 4.9375 tall and holds 0.546 net.

More air lowers Qtc, which is the safe direction. Qtc 0.748, Fc 53.8 Hz, F3 51.0 Hz, against a tight box at 0.30. It stays inside the 0.25 to 0.75 range PowerBass lists as acceptable.

Watch the volume convention on this brand. PowerBass quotes 0.30 as GROSS, displacement included. We publish net everywhere.

Measure the installed height, not the cabinet height. 4.9375 tall plus 1.75 of standoff puts you at 6.6875 inches of stack. Footprint is 41 by 12, for 12 inches of depth under a rear bench.

Rear vented motor, so the pole vent can be blocked. Single 4 ohm coil. One driver is simply 4 ohms. Nothing to get wrong.

Before you order

Questions

Why is this cabinet 41 inches wide instead of 21.05?

Because it is only 12 inches deep. Our standard Performance Optimized Down Fire cabinet for this driver is 21.05 wide by 15 deep, and this one is built for spaces three inches shallower than that, typically under the rear seat of a truck or SUV or on a narrow cargo floor.

Airspace has to come from somewhere. Losing depth means recovering it along the length, so the cabinet runs 41 inches long and stands 4.9375 inches tall, and the driver still gets a properly sized chamber. If your space is wide and shallow rather than deep, this is the shape that works.

How does this compare to the standard 21.05 x 15 PowerBass XL-1040T enclosure?

Same driver, different shape. The standard cabinet is 21.05 by 15 by 4.9 inches and holds 0.30 cubic feet net. This cabinet is 41 by 12 by 4.9375 inches and holds 0.546 cubic feet net.

The wide cabinet holds more air because its height is set by the driver's mounting depth rather than by a volume target, and a larger sealed box runs a slightly lower Qtc, which is the safe direction. Choose on the space: with 15 inches of depth the standard cabinet is the pick; if depth stops at 12 inches and you have 41 inches of run, this one fits.

Will this enclosure fit any 10 inch subwoofer?

No. The baffle is cut direct fit at 237 mm for the PowerBass XL-1040T and the airspace is built to that driver; a conventional 10 needs both a deeper cabinet and more air.

Even where another driver dropped into the hole, it would be loading into an airspace engineered around a Qts of 0.487, and the alignment printed on this page would no longer describe what you own.

PowerBass says 0.30 cubic feet. How does this cabinet compare?

PowerBass quotes 0.30 as internal airspace that INCLUDES the driver's displacement, so their figure is gross; we publish net everywhere. This cabinet holds 0.546 cubic feet net, well above their optimum, because its height is set by the driver's 3.4 inch mounting depth plus 0.75 inch above the motor.

That is still inside the 0.25 to 0.75 range PowerBass lists as acceptable, and the extra air lowers Qtc, the safe direction: Qtc 0.748, Fc 53.8 Hz, F3 51.0 Hz anechoic.

What amplifier power and impedance?

The XL-1040T is rated 350 watts RMS and 700 peak, with a single 4 ohm voice coil. A single driver simply presents 4 ohms, so there is no low impedance trap to fall into on this driver.

Target 350 watts RMS and set gains properly rather than to a number.

Does the pole vent need clearance under the cabinet?

No. The XL-T uses a vented rear motor, so the pole vent can be obstructed without harming the driver, and this cabinet still clears 0.79 inches above the motor.

The standoffs are there to give the cone room to breathe in front of the baffle, which faces the floor, not to relieve the pole vent. Installed on the 1.75 inch standoffs the finished stack is 6.6875 inches.

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 0.546 cubic feet this cabinet was built to. PowerBass also warns against letting fill reach the vented pole piece.

Are the PowerBass XL-1040T included?

No. This is an enclosure only: you receive the cabinet finished in plush black carpet, with threaded inserts, stainless machine screws, one side-mounted pre-wired terminal cup, the standoffs and the polyfill lining already in place.

The driver is purchased separately. We do not stock PowerBass drivers.

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