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Proline X PO 12T-S W SQL12 sealed wedge enclosure, product photos pending. Placeholder graphic reading Photos Coming Soon.

Performance Optimized · Datasheet

Performance Optimized Wedge Wide Sealed Triple 12" Enclosure Stereo Integrity SQL-12 · Triple 12" Sealed enclosure

Net volume
1.000 cu ft per driver, 3.00 cu ft total, after both dividers and Stereo Integrity's published 0.150 cu ft displacement per driver
Max mounting depth
7.00 in required; 2.22 in clearance above the motor against the raked rear panel
External dimensions
44 in W × 17 in at the seat face H × 15.71 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
Stereo Integrity SQL-12Buy at Audio Intensity
  • Best For: Triple Stereo Integrity SQL-12 SUV Cargo-Floor Builds
  • Net Volume: 1.000 cu ft per Driver (3.00 cu ft Net Total)
  • Driver Match: Three Stereo Integrity SQL-12 (Dual 2 Ohm), matched
  • Construction: 3 Chambers | 44" 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 DriverStereo Integrity SQL-12, quantity 3, matched. Direct fit
ConfigurationTriple 12 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 Width44 in
External Height17 in at the seat face
External Depth15.71 in at the base, tapering to 9.52 in at the top
Internal Volume, Gross3.58 cu ft total
Internal Volume, Net Acoustic1.000 cu ft per driver, 3.00 cu ft total, after both dividers and Stereo Integrity's published 0.150 cu ft displacement per driver
Driver Mounting Depth7.00 in required; 2.22 in clearance above the motor against the raked rear panel
Alignment Per DriverSQL-12 Qtc 0.764, fc 45.7 Hz, F3 42.6 Hz anechoic
Woofer Openings3 at 11.330 in
Woofer LayoutOne row across the face
Frame Outer Diameter12.91 in
Fs / Qts / Qes / Qms34.1 Hz / 0.570 / 0.620 / 6.990
Vas / Sd / Xmax22.5 L / 532 cm2 / 26 mm
Driver Power Handling1000 W RMS per driver, 3000 W RMS for the set of 3 (thermal rating)
Recommended Amplifier700-1000 W RMS per driver, 2,100-3,000 W RMS for the full set, at 3 ohms
Parameter SourceStereo Integrity 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 Weight76 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Modelled response

Performance in this enclosure

Net airspace
1.000
cu ft per driver
System Qtc
0.76
sealed
Half power
42.6
Hz · F3
Xmax at
2555
W RMS per driver · no filter
With 25 Hz subsonic
3240
W RMS per driver · +27%
Amplifier, per driver
700–1000
W RMS recommended
This enclosure holds 1.000 cu ft net per driver. In it the Stereo Integrity SQL-12 runs a system Qtc of 0.76 with half power at 42.6 Hz, and the cone reaches its 26.0 mm travel limit at 2555 W per driver, above the driver’s 1000 W thermal rating, so heat stops you before travel does. Run a subsonic filter at 25 Hz and that becomes 3240 W per driver — +685 W, or 27 percent more power for the same 26.0 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 700–1000 W RMS  ×  3 drivers  =  full set 2,100–3,000 W RMS at 3 ohms
Look for a mono amplifier rated 2,100–3,000 W RMS at 3 ohms, the load the set wires to most easily. The top is the driver’s 1000 W thermal rating; with the 25 Hz subsonic set the cone still has travel to spare there, reaching Xmax only at 3240 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 = 55.0
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 Dual 2 Ohm 55.0
Dual 2 Ohm · EBP 55.0
At 55.0 the SQL-12 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

1.000 cu ft against a 22.5 L Vas.

α = Vas ÷ Vb = 0.79  ·  Fc = Fs√(α+1) = 46 Hz  ·  Qtc = 0.76
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
Dual 2 Ohm · Qtc 0.76, Fc 46 Hz, F3 42.6 Hz
The box lifts resonance from 34.1 Hz free-air to 46 Hz and half power lands at 42.6 Hz, anechoic, before any cabin gain. Figures are Stereo Integrity’s published parameters; Qes and Qms reproduce the printed Qts. This cabinet holds three drivers in three separate sealed chambers of 1.000 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 26.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

PXmax = 2555 W per driver unfiltered  →  3240 W per driver with a 25 Hz subsonic
20 30 50 70 100 150 200 0 8 16 24 32 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 26.0 mm 2555 W reaches Xmax here
Dual 2 Ohm · 2555 W, no filterDual 2 Ohm · 3240 W with subsonic at 25 Hz, 24 dB/octXmax 26.0 mm one-way
Every trace touches the limit and no further, because each is drawn at the exact power that puts that coil on 26.0 mm. Unfiltered that is 2555 W per driver, reached first at 20 Hz. It sits above the 1000 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 3240 W per driver before hitting the same 26.0 mm. That is 27 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs34.10Hzfree-air resonance
Qts0.570Dual 2 Ohm
Vas22.50Lequivalent compliance
Sd532.3cm²effective piston area
Xmax26mmone-way linear travel
Pe1000Wcontinuous RMS
SPL83.4dB1 W / 1 m, derived from T/S

Driver parameters as published by Stereo Integrity SQL-12 published specifications. Curves computed against this enclosure’s actual net airspace.

From the shop floor

Installer's take

Start with the size. 1.000 cubic feet per driver puts the SQL-12 at Qtc 0.764, resonance 45.7 Hz, half power 42.6 Hz anechoic. That matches the single sealed box we build for this driver, so the wide box and the single sound alike per driver. Butterworth on these figures wants 1.48, which on this platform means 19.7 in deep at the base. It is effectively flat, under 0.1 dB of lift near resonance.

Measure the base depth, not the top. This cabinet is 15.71 in deep where it meets the floor, 9.52 at the top, 44 wide and 17 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 17 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.

Each driver has its own chamber. The outer two are set 0.59 in toward the ends of their chambers so the 12.91 in frames clear each other; that is deliberate, not an off-center cut.

Impedance. SQL-12: 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: 700 to 1000 W RMS per driver is 2,100 to 3,000 W RMS across all 3 at 3 ohms. At 3,000 W the charging system is part of the install: alternator output, the big three, and a battery that holds voltage under load.

Stereo Integrity'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 0.76.

Before you order

Questions

Does this fit the Stereo Integrity SQL-12, and its coil versions?

Yes. Each opening is cut to 11.330 in for the 12.91 in frame, and the 7.00 in deep motor clears the raked rear panel with 2.22 in to spare. Coil versions of the Stereo Integrity SQL-12 share the frame, cutout and mounting depth, so any of them drops in. The alignment on this page is computed on the SQL-12 parameters.

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

Why 1.000 cubic feet per driver, and what alignment does it target?

On Stereo Integrity's published Fs 34.1 Hz, Qts 0.570 and Vas 22.5 liters, 1.000 cubic feet per driver gives Qtc 0.764, system resonance 45.7 Hz and half power 42.6 Hz.

The cabinet is sized to the single sealed box we build for this driver, 1.00 cubic feet per driver, to keep it realistic for a cargo floor. Maximally flat would need 1.48 cubic feet per driver; this size trades a little low end for a compact box and effectively flat, under 0.1 dB of lift near resonance.

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

Stereo Integrity rates the SQL-12 at 1000 watts RMS per driver. Recommended amplifier: 700 to 1000 W RMS per driver, 2,100 to 3,000 W RMS for the full set of 3.

Each SQL-12 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 44 inches wide, 17 tall and 15.71 deep at the base, tapering to 9.52 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 42.6 Hz per driver with system resonance at 45.7 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 1.000 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 Stereo Integrity SQL-12 drivers. The cabinet is cut direct fit to them, not a general purpose 12 inch box.

Same series, same size

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