Performance Optimized Series PO 8D-S W XL speaker enclosure by Proline, featuring a black frame with two circular openings, shown on a dark blue background with dimensions labeled 32 inches wide and 11 inches deep.Proline X PO 8D-S W XL sealed wedge enclosure, interior through the baffle opening showing the 1.5 inch mounting baffle and pre-wired leads. Optimized for PowerBass XL.A Proline Power Bass XL wedge subwoofer enclosure shown on a dark blue promotional graphic with dimensions labeled 11 inches tall, 7.8 inches wide at the top, and 11.

Performance Optimized · Datasheet

Performance Optimized Wedge Sealed Dual 8" Enclosure | PowerBass XL-844 Dual 8" Sealed enclosure

Net volume
1.00 cu ft total, 0.50 per driver
Max mounting depth
4.4375 in required
Cutout
7.1250 in
External dimensions
32.00 in W × 11 in at the seat face H × 11.80 in at the base D
Front baffle
1.5 in, double baffle
Buy at Audio Intensity
  • Best For: Dual PowerBass XL-844 Trunk-Fit Builds
  • Net Volume: 0.50 cu ft per driver (0.55 cu ft Gross)
  • Alignment: Qtc 0.610, fc 50.5 Hz, F3 59.8 Hz
  • Driver Match: XL-844
  • Impedance: single 4 ohm coil
  • Construction: Dual Chamber | Rear-Firing Wedge | V-Groove/Dado | Double 1.5" Baffle | Threaded Inserts

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Wedge
Compatible DriverPowerBass XL-844, quantity 2. Direct fit
ConfigurationDual 8 inch, dual 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 Width32.00 in
External Height11 in at the seat face
External Depth11.80 in at the base, tapering to 7.80 in at the top
Internal Volume, Gross1.10 cu ft total, 0.55 per chamber
Internal Volume, Net Acoustic1.00 cu ft total, 0.50 per driver
AlignmentQtc 0.610, fc 50.5 Hz, F3 59.8 Hz anechoic
Driver Cutout7.1250 in
Driver Mounting Depth4.4375 in required
Power Handling400 watts RMS total across the pair
ImpedanceSingle 4 ohm voice coil
MaterialLangboard Elite MDF
ConstructionCNC cut, V-groove and dado joinery
Panel Thickness0.75 in
Front Baffle1.5 in, double baffle
Internal BracingFull chamber divider
Driver MountingThreaded inserts at every mounting location, stainless machine screws included
Terminal CupsOne Proline X ABS and carbon fiber composite, side mounted, pre wired 12 gauge OFC
DampingLight polyfill wall lining, does not alter acoustic volume
CarpetPlush black
Weight35.5 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Performance in this enclosure

Net airspace
0.50
cu ft per chamber
System Qtc
0.61
sealed
Half power
59.8
Hz · F3
Xmax at
30
W RMS · no filter
With 25 Hz subsonic
44
W RMS · +44%
Amplifier
200
W RMS recommended
This enclosure holds 0.50 cu ft net per chamber. In it the PowerBass XL-844 runs a system Qtc of 0.61 with half power at 59.8 Hz, and the cone reaches its 5.0 mm travel limit at 30 W, below the driver’s 200 W thermal rating, so travel is what stops you here, not heat. Run a subsonic filter at 25 Hz and that becomes 44 W — +13 W, or 44 percent more power for the same 5.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 75.2
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 XL-844 75.2
XL-844 · EBP 75.2
At 75.2 the XL-844 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

0.50 cu ft against a 6.4 L Vas.

α = Vas ÷ Vb = 0.45  ·  Fc = Fs√(α+1) = 51 Hz  ·  Qtc = 0.61
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
XL-844 · Qtc 0.61, Fc 51 Hz, F3 59.8 Hz
The box lifts resonance from 41.9 Hz free-air to 51 Hz and half power lands at 59.8 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 5.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

PXmax = 30 W unfiltered  →  44 W with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 5.0 mm 30 W reaches Xmax here
XL-844 · 30 W, no filterXL-844 · 44 W with subsonic at 25 Hz, 24 dB/octXmax 5.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 5.0 mm. Unfiltered that is 30 W, reached first at 20 Hz. It sits under the 200 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 44 W before hitting the same 5.0 mm. That is 44 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs41.90Hzfree-air resonance
Qts0.506XL-844
Vas6.44Lequivalent compliance
Sd176.7cm²effective piston area
Xmax5mmone-way linear travel
Pe200Wcontinuous RMS
SPL81.1dB1 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

This one is straightforward. 0.50 cubic feet net is PowerBass's own published sealed airspace for the XL-844 and we cut to it exactly, which lands at Qtc 0.610. PowerBass publishes 0.650 at the same volume, so there is no argument to have about the alignment.

F3 lands at 59.8 Hz anechoic. That is high for a 8 inch, and it is the driver rather than the cabinet: at a Qts of 0.506 the XL-844 is past the knee for sealed loading, so no sealed box gets it much below 61 Hz. Adding volume makes it worse, not better. If you want the deepest sealed 8 inch in this range, the XL-1244 reaches 46.2 Hz.

On impedance: Each driver is a single 4 ohm voice coil. A pair is 2 ohms in parallel or 8 ohms in series. Two ohms is the usual choice and almost every monoblock is stable there.

Measure the base depth. This cabinet is 11.80 inches deep at the trunk floor, 7.80 at the top, and 32.00 wide. The floor dimension is what decides whether it goes in.

Questions

Will this enclosure fit the XL-844 exactly?

Yes. The baffle is CNC cut to 7.1250 in for the XL-844's published cutout and the cabinet clears its 4.4375 in mounting depth. Threaded inserts are pressed in at every mounting location so the driver bolts to metal, not to MDF.

Why 0.50 cubic feet net per driver?

It is PowerBass's published sealed recommendation for the XL-844. In it the driver runs Qtc 0.610 with fc at 50.5 Hz and F3 at 59.8 Hz. PowerBass publishes Qtc 0.650 and F3 52 Hz for the same airspace, so our numbers and theirs agree.

What amplifier power should I run, and what impedance?

The XL-844 is rated 200 watts RMS each, so 400 across the pair. Each driver is a single 4 ohm voice coil. A pair is 2 ohms in parallel or 8 ohms in series. Two ohms is the usual choice and almost every monoblock is stable there. Aim for roughly 280 to 400 watts at the final wired impedance.

How does a wedge enclosure improve the sound in a trunk installation?

The angled seat-side face matches the roughly 20 degree lean of a factory rear seat, so the cabinet sits flat against it instead of leaving a wasted triangle. The vertical trunk-lid-side face carries the driver, firing rearward into the trunk cavity, which acts as an acoustic extension into the cabin.

Why is the front baffle double-layered?

The baffle is two bonded 3/4 inch sheets, 1.5 inches through. A subwoofer pushes as hard against its mounting surface as it does against the air, and a single 3/4 inch panel flexes under that load. With 5 mm of one-way travel and 400 watts on tap that matters.

What is the expected low-frequency extension?

F3 lands at 59.8 Hz anechoic. That is high for a 8 inch, and it is the driver rather than the cabinet: at a Qts of 0.506 the XL-844 is past the knee for sealed loading, so no sealed box gets it much below 61 Hz. Adding volume makes it worse, not better. If you want the deepest sealed 8 inch in this range, the XL-1244 reaches 46.2 Hz. Qtc is 0.610, so the rolloff is clean rather than peaked. These figures are anechoic and exclude cabin gain, which in most vehicles adds real output below 40 Hz.

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 this driver moves Qtc down and F3 up.

Are the drivers included?

No. This is an enclosure only. You receive the cabinet finished in plush black carpet, with threaded inserts at both driver positions, stainless machine screws, one side-mounted pre-wired terminal cup and the polyfill lining already installed.

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