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Proline X PO 8TW-S W SL608 sealed wedge enclosure, product photos pending. Placeholder graphic reading Photos Coming Soon.

Performance Optimized · Datasheet

Performance Optimized Wedge Wide Sealed Triple 8" Enclosure DD Audio SL608 · Triple 8" Sealed enclosure

Net volume
0.336 cu ft per driver, 1.01 cu ft total, after both dividers and DD Audio's published 0.040 cu ft displacement per driver
Max mounting depth
3.50 in required; 0.75 in clearance above the motor against the raked rear panel
External dimensions
40 in W × 13 in at the seat face H × 10.07 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 SL608Buy at Audio Intensity
  • Best For: Triple DD Audio SL608 SUV Cargo-Floor Builds
  • Net Volume: 0.336 cu ft per Driver (1.01 cu ft Net Total)
  • Driver Match: Three DD Audio SL608 (matched set), matched
  • Construction: 3 Chambers | 40" 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 DriverDD Audio SL608, quantity 3, matched. Direct fit
ConfigurationTriple 8 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 Width40 in
External Height13 in at the seat face
External Depth10.07 in at the base, tapering to 5.34 in at the top
Internal Volume, Gross1.17 cu ft total
Internal Volume, Net Acoustic0.336 cu ft per driver, 1.01 cu ft total, after both dividers and DD Audio's published 0.040 cu ft displacement per driver
Driver Mounting Depth3.50 in required; 0.75 in clearance above the motor against the raked rear panel
Alignment Per DriverSL608 Qtc 0.614, fc 52.4 Hz, F3 61.6 Hz anechoic
Woofer Openings3 at 7.370 in
Woofer LayoutOne row across the face
Frame Outer Diameter8.31 in
Fs / Qts / Qes / Qms34.0 Hz / 0.398 / 0.432 / 5.139
Vas / Sd / Xmax13.1 L / 214 cm2 / 12 mm
Driver Power Handling300 W RMS per driver, 900 W RMS for the set of 3 (thermal rating)
Recommended Amplifier200-290 W RMS per driver, 600-870 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 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 Weight52 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
0.336
cu ft per driver
System Qtc
0.61
sealed
Half power
61.6
Hz · F3
Xmax at
210
W RMS per driver · no filter
With 25 Hz subsonic
295
W RMS per driver · +41%
Amplifier, per driver
200–290
W RMS recommended
This enclosure holds 0.336 cu ft net per driver. In it the DD Audio SL608 runs a system Qtc of 0.61 with half power at 61.6 Hz, and the cone reaches its 12.0 mm travel limit at 210 W per driver, below the driver’s 300 W thermal rating, so travel is what stops you here, not heat. Run a subsonic filter at 25 Hz and that becomes 295 W per driver — +85 W, or 41 percent more power for the same 12.0 mm of travel.

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 200–290 W RMS  ×  3 drivers  =  full set 600–870 W RMS
Look for a mono amplifier rated 600–870 W RMS at the load your coil version wires to. Travel sets the top here, not heat: past 295 W per driver the cone runs beyond Xmax even with the subsonic set, under the driver’s 300 W thermal rating. The top of the range needs the 25 Hz subsonic filter set; without it, keep each driver under 210 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 = 78.7
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 SL608 78.7
SL608 · EBP 78.7
At 78.7 the SL608 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

0.336 cu ft against a 13.1 L Vas.

α = Vas ÷ Vb = 1.38  ·  Fc = Fs√(α+1) = 52 Hz  ·  Qtc = 0.61
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
SL608 · Qtc 0.61, Fc 52 Hz, F3 61.6 Hz
The box lifts resonance from 34.0 Hz free-air to 52 Hz and half power lands at 61.6 Hz, anechoic, before any cabin gain. Figures are DD Audio’s published parameters; Qes and Qms reproduce the printed Qts. This cabinet holds three drivers in three separate sealed chambers of 0.336 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 12.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

PXmax = 210 W per driver unfiltered  →  295 W per driver with a 25 Hz subsonic
20 30 50 70 100 150 200 0 4 8 12 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 12.0 mm 210 W reaches Xmax here
SL608 · 210 W, no filterSL608 · 295 W with subsonic at 25 Hz, 24 dB/octXmax 12.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 12.0 mm. Unfiltered that is 210 W per driver, reached first at 20 Hz. It sits under the 300 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 295 W per driver before hitting the same 12.0 mm. That is 41 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs34.00Hzfree-air resonance
Qts0.398SL608
Vas13.11Lequivalent compliance
Sd214.1cm²effective piston area
Xmax12mmone-way linear travel
Pe300Wcontinuous RMS
SPL82.6dB1 W / 1 m, derived from T/S

Driver parameters as published by DD Audio SL608 published specifications. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

Start with the size. 0.336 cubic feet per driver puts the SL608 at Qtc 0.614, resonance 52.4 Hz, half power 61.6 Hz anechoic. The 3.50 in deep motor sets the shallowest the wedge can be, and that smallest box is still more air than flat wants, so it lands below 0.707: tighter and more damped, trading a little extension for control.

Measure the base depth, not the top. This cabinet is 10.07 in deep where it meets the floor, 5.34 at the top, 40 wide and 13 tall. In an SUV the 40 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.

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: 200 to 290 W RMS per driver is 600 to 870 W RMS across all 3. On this driver travel sets the top, not heat: Xmax arrives at 295 W per driver with a 25 Hz subsonic, under the 300 W rating. Set the 25 Hz subsonic to use the top of that range; without it keep each driver under 210 W.

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 0.61.

Before you order

Questions

Does this fit the DD Audio SL608, and its coil versions?

Yes. Each opening is cut to 7.370 in for the 8.31 in frame, and the 3.50 in deep motor clears the raked rear panel with 0.75 in to spare. Coil versions of the DD Audio SL608 share the frame, cutout and mounting depth, so any of them drops in. The alignment on this page is computed on the SL608 parameters.

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

Why 0.336 cubic feet per driver, and what alignment does it target?

On DD Audio's published Fs 34.0 Hz, Qts 0.398 and Vas 13.1 liters, 0.336 cubic feet per driver gives Qtc 0.614, system resonance 52.4 Hz and half power 61.6 Hz.

The 3.50 in deep motor sets the shallowest the wedge can be, and that smallest box is still more air than flat wants, so it lands below 0.707: tighter and more damped, trading a little extension for control.

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

DD Audio rates the SL608 at 300 watts RMS per driver. Recommended amplifier: 200 to 290 W RMS per driver, 600 to 870 W RMS for the full set of 3. Travel, not heat, sets the top: the cone reaches Xmax at 295 W per driver with a 25 Hz subsonic set, under the 300 W rating. The top of that range needs the 25 Hz subsonic; without it keep each driver under 210 W.

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 40 inches wide, 13 tall and 10.07 deep at the base, tapering to 5.34 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 61.6 Hz per driver with system resonance at 52.4 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 0.336 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 DD Audio SL608 drivers. The cabinet is cut direct fit to them, not a general purpose 8 inch box.

Same series, same size

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