Proline X PO 10-S DF XLT single sealed down fire enclosure, product photos pending. Placeholder graphic reading Photos Coming Soon.

Performance Optimized · Datasheet

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

Net volume
0.30 cu ft after 0.0771 displacement
Max mounting depth
3.4 in required, shallow mount
External dimensions
21.05 in W × 4.90 in in the down fire position H × 15 in D
Front baffle
1.5 in double baffle, outer layer machined as a flush recess
Buy at Audio Intensity
  • Alignment: 0.30 cu ft net. Qtc 0.908, fc 65.2 Hz, F3 53.8 Hz
  • 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 near 6.65 in
  • Cabinet: 21.05"W x 15"D x 4.90"H in down fire position, excludes standoffs

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Down Fire
Compatible DriverPowerBass XL-1040T, quantity 1. Direct fit
ConfigurationSingle 10 inch shallow mount, 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 Width21.05 in
External Depth15 in
External Height4.90 in in the down fire position, excludes standoffs
Installed Height6.65 in including the 1.75 in standoff
Internal Volume, Gross0.3771 cu ft
Internal Volume, Net Acoustic0.30 cu ft after 0.0771 displacement
PowerBass Published Target0.30 cu ft optimum, 0.25 to 0.75 acceptable. Their figures are GROSS and include driver displacement
AlignmentQtc 0.908, fc 65.2 Hz, F3 53.8 Hz anechoic
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
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 front, top and back
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
Weight22 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Performance in this enclosure

Net airspace
0.30
cu ft per chamber
System Qtc
0.91
sealed
Half power
53.8
Hz · F3
Xmax at
297
W RMS · no filter
With 25 Hz subsonic
301
W RMS · +2%
Amplifier
350
W RMS recommended
This enclosure holds 0.30 cu ft net per chamber. In it the PowerBass XL-1040T runs a system Qtc of 0.91 with half power at 53.8 Hz, and the cone reaches its 7.5 mm travel limit at 297 W, below the driver’s 350 W thermal rating, so travel is what stops you here, not heat. A 25 Hz subsonic filter adds little here: 301 W against 297 W, 2 percent. The box already resonates at 65 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 = 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

0.30 cu ft against a 21.0 L Vas.

α = Vas ÷ Vb = 2.47  ·  Fc = Fs√(α+1) = 65 Hz  ·  Qtc = 0.91
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
XL-1040T · Qtc 0.91, Fc 65 Hz, F3 53.8 Hz
The box lifts resonance from 35.0 Hz free-air to 65 Hz and half power lands at 53.8 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 in this alignment a subsonic filter barely moves it.

PXmax = 297 W unfiltered  →  301 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 297 W reaches Xmax here
XL-1040T · 297 W, no filterXL-1040T · 301 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 297 W, reached first at 41 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, and they sit almost on top of the solid ones: 301 W against 297 W. At 65 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
Fs35.00Hzfree-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.

Installer's take

Watch the volume convention on this brand. PowerBass quotes 0.30 cu ft and that is GROSS, displacement included. This cabinet is 0.30 NET, which is 0.3771 gross. If a customer says the box looks big against the sheet, that is why, and it is inside their 0.25 to 0.75 acceptable range.

Measure the installed height, not the cabinet height. 4.90 tall plus 1.75 of standoff puts you at 6.65 inches of stack. Footprint is 21.05 by 15.

Rear vented motor, so the pole vent can be blocked. That is why this cabinet has no rear clearance allowance and why it comes out as short as it does.

Single 4 ohm coil. One driver is simply 4 ohms. Nothing to get wrong.

Qtc 0.908 at 0.30 net. This is a shallow driver in a small box and it reads that way: tight rather than deep. Set the expectation before the sale.

Questions

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. The XL-T is a shallow mount driver with a 3.4 inch mounting depth, and 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. Is this cabinet the same size?

Almost, and the difference is worth understanding. PowerBass quotes 0.30 cubic feet as internal airspace that INCLUDES the driver's displacement, so their figure is gross. We publish net everywhere, meaning the air the cone actually loads against after the driver's 0.0771 cubic feet is taken out.

This cabinet is 0.30 net, which is 0.3771 gross. That puts it slightly on the larger side of their optimum and comfortably inside the 0.25 to 0.75 cubic foot range they list as acceptable.

What amplifier power and impedance?

The XL-1040T is rated 350 watts RMS and 700 peak. It is 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.

How tall is this once the standoffs are on?

The cabinet is 4.90 inches tall measured in the down fire position, excluding standoffs. They hold 1.75 inches under the baffle, so plan around a finished stack of roughly 6.65 inches.

The footprint is 21.05 inches wide by 15 deep. That is narrower than the standard 30 inch down fire platform, because this driver needs so little air that the full width would overshoot the target.

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. That is what allows this cabinet to be built without the rear clearance allowance most drivers require, and it is a large part of why a shallow driver suits a down fire cabinet at all.

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.

What is the expected low-frequency extension?

Anechoic F3 lands at 53.8 Hz with system Qtc 0.908 and fc 65.2 Hz, calculated from PowerBass's published parameters at the 0.30 cubic feet net this cabinet holds.

Those figures are anechoic and exclude cabin gain. In a car the transfer function of the cabin adds real output below 50 Hz, so in-vehicle response runs deeper. A shallow mount driver in a small sealed box is a packaging decision, and the alignment reflects that honestly rather than promising otherwise.

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 on a cabinet this small would move the alignment noticeably. PowerBass also warns against letting fill reach the vented pole piece.

Is 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, a 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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