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Proline X PO 8Q-S W 508E sealed wedge enclosure, product photos pending. Placeholder graphic reading Photos Coming Soon.

Performance Optimized · Datasheet

Performance Optimized Wedge Wide Sealed Quad 8" Enclosure DD Audio 508e · Quad 8" Sealed enclosure

Net volume
1.156 cu ft per driver, 4.62 cu ft total, after the divider and DD Audio's published 0.040 cu ft displacement per driver
Max mounting depth
4.88 in required; 12.30 in clearance above the motor against the raked rear panel
External dimensions
44 in W × 13 in at the seat face H × 23.00 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
DD Audio 508eBuy at Audio Intensity
  • Best For: Quad DD Audio 508e SUV Cargo-Floor Builds
  • Net Volume: 1.156 cu ft per Driver (4.62 cu ft Net Total)
  • Driver Match: Four DD Audio 508e (matched set), matched
  • Construction: 2 Chambers | 44" Wide Wedge | V-Groove/Dado | Double 1.5" Baffle | 2 Terminal Cups

Spec of record

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Wedge Wide
Compatible DriverDD Audio 508e, quantity 4, matched. Direct fit
ConfigurationQuad 8 inch sealed wedge, 2 chambers, 2 drivers 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 Height13 in at the seat face
External Depth23.00 in at the base, tapering to 18.27 in at the top
Internal Volume, Gross4.87 cu ft total
Internal Volume, Net Acoustic1.156 cu ft per driver, 4.62 cu ft total, after the divider and DD Audio's published 0.040 cu ft displacement per driver
Driver Mounting Depth4.88 in required; 12.30 in clearance above the motor against the raked rear panel
Alignment Per Driver508e Qtc 0.754, fc 46.7 Hz, F3 44.0 Hz anechoic
Woofer Openings4 at 7.125 in
Woofer LayoutOne row across the face
Frame Outer Diameter8.25 in
Fs / Qts / Qes / Qms44.0 Hz / 0.710 / 0.820 / 5.010
Vas / Sd / Xmax4.2 L / 198 cm2 / 14 mm
Driver Power Handling500 W RMS per driver, 2000 W RMS for the set of 4 (thermal rating)
Recommended Amplifier330-470 W RMS per driver, 1,320-1,880 W RMS for the full set
Parameter SourceDD Audio 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 BracingOne full-height 3/4 in divider
Driver MountingThreaded inserts, stainless machine screws included
Terminal CupsTwo Proline X ABS and carbon fiber composite, side mounted, 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 Weight86 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
1.156
cu ft per driver
System Qtc
0.75
sealed
Half power
44.0
Hz · F3
Xmax at
374
W RMS per driver · no filter
With 25 Hz subsonic
472
W RMS per driver · +26%
Amplifier, per driver
330–470
W RMS recommended
This enclosure holds 1.156 cu ft net per driver. In it the DD Audio 508e runs a system Qtc of 0.75 with half power at 44.0 Hz, and the cone reaches its 14.0 mm travel limit at 374 W per driver, below the driver’s 500 W thermal rating, so travel is what stops you here, not heat. Run a subsonic filter at 25 Hz and that becomes 472 W per driver — +98 W, or 26 percent more power for the same 14.0 mm of travel.

00Sizing the amplifier

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

Per driver 330–470 W RMS  ×  4 drivers  =  full set 1,320–1,880 W RMS
Look for a mono amplifier rated 1,320–1,880 W RMS at the load your coil version wires to. Travel sets the top here, not heat: past 472 W per driver the cone runs beyond Xmax even with the subsonic set, under the driver’s 500 W thermal rating. The top of the range needs the 25 Hz subsonic filter set; without it, keep each driver under 374 W, where the cone reaches Xmax unfiltered. 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 = 53.7
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 508e 53.7
508e · EBP 53.7
At 53.7 the 508e 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

1.156 cu ft against a 4.2 L Vas.

α = Vas ÷ Vb = 0.13  ·  Fc = Fs√(α+1) = 47 Hz  ·  Qtc = 0.75
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
508e · Qtc 0.75, Fc 47 Hz, F3 44.0 Hz
The box lifts resonance from 44.0 Hz free-air to 47 Hz and half power lands at 44.0 Hz, anechoic, before any cabin gain. Figures are DD Audio’s published parameters; Qes and Qms reproduce the printed Qts. This cabinet holds four drivers in two sealed chambers of 2.311 cubic feet, two drivers to a chamber, so each driver works into 1.156 cubic feet and that is 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 14.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

PXmax = 374 W per driver unfiltered  →  472 W per driver with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 12 16 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 14.0 mm 374 W reaches Xmax here
508e · 374 W, no filter508e · 472 W with subsonic at 25 Hz, 24 dB/octXmax 14.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 14.0 mm. Unfiltered that is 374 W per driver, reached first at 20 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: stopping the cone wasting travel below the passband lets it take 472 W per driver before hitting the same 14.0 mm. That is 26 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs44.00Hzfree-air resonance
Qts0.710508e
Vas4.19Lequivalent compliance
Sd197.9cm²effective piston area
Xmax14mmone-way linear travel
Pe500Wcontinuous RMS
SPL78.2dB1 W / 1 m, derived from T/S

Driver parameters as published by DD Audio 508e published specifications. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

Start with the size. 1.156 cubic feet per driver puts the 508e at Qtc 0.754, resonance 46.7 Hz, half power 44.0 Hz anechoic. The wide platform stops at 23 inches deep, so this box lands a little above flat: a small lift near resonance and firm midbass.

Measure the base depth, not the top. This cabinet is 23.00 in deep where it meets the floor, 18.27 at the top, 44 wide and 13 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 13 has to clear the cargo cover.

The two terminal cups are on the side panels, one per chamber, so they sit close to the wheel wells. Land the speaker wire on both before the box slides into its final spot, with slack to pull it forward again.

Two drivers share each chamber, so they have to match: same model, same coil, wired in phase. One driver reversed in a shared chamber pushes against its partner and the pair cancels instead of adding. Check polarity at each cup with a battery tap before the box goes in.

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: 330 to 470 W RMS per driver is 1,320 to 1,880 W RMS across all 4. On this driver travel sets the top, not heat: Xmax arrives at 472 W per driver with a 25 Hz subsonic, under the 500 W rating. Set the 25 Hz subsonic to use the top of that range; without it keep each driver under 374 W. At 1,880 W the charging system is part of the install: alternator output, the big three, and a battery that holds voltage under load.

DD Audio'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 0.75.

Before you order

Questions

Does this fit the DD Audio 508e, and its coil versions?

Yes. Each opening is cut to 7.125 in for the 8.25 in frame, and the 4.88 in deep motor clears the raked rear panel with 12.30 in to spare. Coil versions of the DD Audio 508e share the frame, cutout and mounting depth, so any of them drops in. The alignment on this page is computed on the 508e parameters.

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

Why 1.156 cubic feet per driver, and what alignment does it target?

On DD Audio's published Fs 44.0 Hz, Qts 0.710 and Vas 4.2 liters, 1.156 cubic feet per driver gives Qtc 0.754, system resonance 46.7 Hz and half power 44.0 Hz.

The wide platform stops at 23 inches deep, so this box lands a little above flat: a small lift near resonance and firm midbass.

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

DD Audio rates the 508e at 500 watts RMS per driver. Recommended amplifier: 330 to 470 W RMS per driver, 1,320 to 1,880 W RMS for the full set of 4. Travel, not heat, sets the top: the cone reaches Xmax at 472 W per driver with a 25 Hz subsonic set, under the 500 W rating. The top of that range needs the 25 Hz subsonic; without it keep each driver under 374 W.

Loads depend on the coil version you run. Dual 4 ohm drivers, coils in series: 2 ohms with each chamber's pair in parallel, 8 ohms with each pair in series. Dual 2 ohm, coils in series: 1 ohm or 4 ohms the same two ways. Single 4 ohm: 1 ohm or 4 ohms. Use the lower load only on an amplifier rated stable there.

Will it fit my SUV?

It is 44 inches wide, 13 tall and 23.00 deep at the base, tapering to 18.27 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 two drivers per chamber instead of four chambers?

Four chambers would need three dividers, and on a 44 inch face that space is needed for the woofers. Two matched drivers in one sealed chamber move together and see the same pressure, so each behaves as if it had half the chamber to itself: 1.156 cubic feet per driver here.

It also gives two terminal cups, one per pair, which keeps the wiring to the amplifier simple.

What is the expected low-frequency extension?

Anechoic F3 is 44.0 Hz per driver with system resonance at 46.7 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 1.156 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, two side-mounted pre-wired terminal cups, the polyfill lining in place, threaded inserts and stainless machine screws.

Bring four matched DD Audio 508e drivers. The cabinet is cut direct fit to them, not a general purpose 8 inch box.

Same series, same size

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