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

Performance Optimized · Datasheet

Performance Optimized Wedge Wide Sealed Triple 8" Enclosure Arc Audio ARC 8 · Triple 8" Sealed enclosure

Net volume
0.436 cu ft per driver, 1.31 cu ft total, after both dividers and Arc Audio's published 0.040 cu ft displacement per driver
Max mounting depth
4.75 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 × 11.32 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
Arc Audio ARC 8Buy at Audio Intensity
  • Best For: Triple Arc Audio ARC 8 SUV Cargo-Floor Builds
  • Net Volume: 0.436 cu ft per Driver (1.31 cu ft Net Total)
  • Driver Match: Three Arc Audio ARC 8 (Dual 2 Ohm), 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 DriverArc Audio ARC 8, 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 Depth11.32 in at the base, tapering to 6.59 in at the top
Internal Volume, Gross1.49 cu ft total
Internal Volume, Net Acoustic0.436 cu ft per driver, 1.31 cu ft total, after both dividers and Arc Audio's published 0.040 cu ft displacement per driver
Driver Mounting Depth4.75 in required; 0.75 in clearance above the motor against the raked rear panel
Alignment Per DriverARC 8 D2 Qtc 0.640, fc 50.3 Hz, F3 56.1 Hz anechoic
Woofer Openings3 at 7.125 in
Woofer LayoutOne row across the face
Frame Outer Diameter8.3125 in
Fs / Qts / Qes / Qms22.7 Hz / 0.289 / 0.317 / 3.331
Vas / Sd / Xmax48.1 L / 231 cm2 / 15 mm
Driver Power Handling150 W RMS per driver, 450 W RMS for the set of 3 (thermal rating)
Recommended Amplifier100-150 W RMS per driver, 300-450 W RMS for the full set, at 3 ohms
Parameter SourceArc 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 Weight55 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
0.436
cu ft per driver
System Qtc
0.64
sealed
Half power
56.1
Hz · F3
Xmax at
212
W RMS per driver · no filter
With 25 Hz subsonic
295
W RMS per driver · +39%
Amplifier, per driver
100–150
W RMS recommended
This enclosure holds 0.436 cu ft net per driver. In it the Arc Audio ARC 8 D2 runs a system Qtc of 0.64 with half power at 56.1 Hz, and the cone reaches its 15.0 mm travel limit at 212 W per driver, above the driver’s 150 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 295 W per driver — +83 W, or 39 percent more power for the same 15.0 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 100–150 W RMS  ×  3 drivers  =  full set 300–450 W RMS at 3 ohms
Look for a mono amplifier rated 300–450 W RMS at 3 ohms, the load the set wires to most easily. The top is the driver’s 150 W thermal rating; with the 25 Hz subsonic set the cone still has travel to spare there, reaching Xmax only at 295 W. 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 = 71.6
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 Dual 2 Ohm 71.6
Dual 2 Ohm · EBP 71.6
At 71.6 the ARC 8 D2 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

0.436 cu ft against a 48.1 L Vas.

α = Vas ÷ Vb = 3.90  ·  Fc = Fs√(α+1) = 50 Hz  ·  Qtc = 0.64
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
Dual 2 Ohm · Qtc 0.64, Fc 50 Hz, F3 56.1 Hz
The box lifts resonance from 22.7 Hz free-air to 50 Hz and half power lands at 56.1 Hz, anechoic, before any cabin gain. Figures are Arc Audio’s published parameters; Qes and Qms reproduce the printed Qts. This cabinet holds three drivers in three separate sealed chambers of 0.436 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 15.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

PXmax = 212 W per driver unfiltered  →  295 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 15.0 mm 212 W reaches Xmax here
Dual 2 Ohm · 212 W, no filterDual 2 Ohm · 295 W with subsonic at 25 Hz, 24 dB/octXmax 15.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 15.0 mm. Unfiltered that is 212 W per driver, reached first at 20 Hz. It sits above the 150 W the driver can take thermally, so the voice coil gives up before the suspension does. 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 15.0 mm. That is 39 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs22.70Hzfree-air resonance
Qts0.289Dual 2 Ohm
Vas48.14Lequivalent compliance
Sd231.0cm²effective piston area
Xmax15mmone-way linear travel
Pe150Wcontinuous RMS
SPL84.3dB1 W / 1 m, derived from T/S

Driver parameters as published by Arc Audio ARC 8 D2 published specifications. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

Start with the size. The maker's optimum sealed size is 0.41 per driver, but the 4.75 in deep motor sets the top of the wedge at 6.59 in, and the smallest box that clears it holds 0.436 per driver. 0.436 cubic feet per driver puts the ARC 8 at Qtc 0.640, resonance 50.3 Hz, half power 56.1 Hz anechoic: no peak, flat to the rolloff.

Measure the base depth, not the top. This cabinet is 11.32 in deep where it meets the floor, 6.59 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.

Impedance. ARC 8 D2: wire for 3 ohms (coils in parallel, the three in series), the load most monoblocks are built to deliver full power into; 1.33 ohms is the other clean option (coils in series, the three cups in parallel). Work the load out before you buy the amplifier, not after.

Power. Size the amplifier for the set, not one driver: 100 to 150 W RMS per driver is 300 to 450 W RMS across all 3 at 3 ohms.

Arc 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 0.64.

Before you order

Questions

Does this fit the Arc Audio ARC 8, and its coil versions?

Yes. Each opening is cut to 7.125 in for the 8.3125 in frame, and the 4.75 in deep motor clears the raked rear panel with 0.75 in to spare. Coil versions of the Arc Audio ARC 8 share the frame, cutout and mounting depth, so any of them drops in. The alignment on this page is computed on the ARC 8 D2 parameters.

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

Why 0.436 cubic feet per driver, and what alignment does it target?

On Arc Audio's published Fs 22.7 Hz, Qts 0.289 and Vas 48.1 liters, 0.436 cubic feet per driver gives Qtc 0.640, system resonance 50.3 Hz and half power 56.1 Hz.

The maker's optimum sealed size is 0.41 cubic feet per driver, but the 4.75 in deep motor sets the shallowest the wedge can be, so it comes down only to 0.436: no peak, flat to the rolloff.

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

Arc Audio rates the ARC 8 at 150 watts RMS per driver. Recommended amplifier: 100 to 150 W RMS per driver, 300 to 450 W RMS for the full set of 3.

Each ARC 8 D2 has two 2 ohm voice coils, 4 ohms in series or 1 ohm in parallel. With each driver's coils in series and the three cups in parallel, the three present 1.33 ohms to a mono amplifier. With each driver's coils in parallel and the three in series, they present 3 ohms. Three drivers do not reach the round loads a pair does, so check the result against your amplifier's minimum stable impedance before powering up.

Will it fit my SUV?

It is 40 inches wide, 13 tall and 11.32 deep at the base, tapering to 6.59 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 56.1 Hz per driver with system resonance at 50.3 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 0.436 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 Arc Audio ARC 8 drivers. The cabinet is cut direct fit to them, not a general purpose 8 inch box.

Same series, same size

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