Proline X PO 15-S W SQL15 sealed wedge, front baffle with gloss black insert and pre-wired leads, 29.16 by 18 inches.Proline X PO 15-S W SQL15 sealed wedge, side profile with recessed terminal cup, 14.81 inch base, 18 inches tall.

Performance Optimized · Datasheet

Performance Optimized Wedge Sealed 15" Enclosure | Stereo Integrity SQL-15 Single 15" Sealed enclosure

Net volume
2.00 cu ft
Max mounting depth
7.400 in required
Cutout
14.17 in
External dimensions
29.16 in W × 18 in at the seat face H × 14.81 in at the base D
Front baffle
1.5 in, double baffle
Buy at Audio Intensity
  • Best For: Stereo Integrity SQL-15 Trunk-Fit Builds
  • Net Volume: 2.00 cu ft (2.17 cu ft Gross)
  • Alignment: Qtc 0.816, fc 47.2 Hz, F3 41.8 Hz
  • Driver Match: SQL-15
  • Impedance: dual 2 ohm or dual 4 ohm
  • Construction: Rear-Firing Wedge | V-Groove/Dado | Double 1.5" Baffle | Threaded Inserts

Technical specifications

SpecificationValue
SeriesProline X Performance Optimized Wedge
Compatible DriverStereo Integrity SQL-15, quantity 1. Direct fit
ConfigurationSingle 15 inch, single 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 Width29.16 in
External Height18 in at the seat face
External Depth14.81 in at the base, tapering to 8.26 in at the top
Internal Volume, Gross2.17 cu ft
Internal Volume, Net Acoustic2.00 cu ft
AlignmentQtc 0.816, fc 47.2 Hz, F3 41.8 Hz anechoic
Driver Cutout14.17 in
Driver Mounting Depth7.400 in required
Power Handling1000 watts RMS
ImpedanceDual 2 ohm or dual 4 ohm
MaterialLangboard Elite MDF
ConstructionCNC cut, V-groove and dado joinery
Panel Thickness0.75 in
Front Baffle1.5 in, double baffle
Internal BracingWindowed C brace
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
Weight47.8 lb
Warranty1 Year Limited
Built InTullahoma, Tennessee

Performance in this enclosure

Net airspace
2.00
cu ft per chamber
System Qtc
0.82
sealed
Half power
41.8
Hz · F3
Xmax at
2744
W RMS · no filter
With 25 Hz subsonic
3208
W RMS · +17%
Amplifier
1000
W RMS recommended
This enclosure holds 2.00 cu ft net per chamber. In it the Stereo Integrity SQL-15 runs a system Qtc of 0.82 with half power at 41.8 Hz, and the cone reaches its 26.0 mm travel limit at 2744 W, 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 3208 W — +464 W, or 17 percent more power for the same 26.0 mm of travel.

01Is it a sealed driver?

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

EBP = Fs ÷ Qes = 54.1
SEALED 0–50 TRANSITION 50–100 PORTED 100–150 0 50 100 150 SQL-15 54.1
SQL-15 · EBP 54.1
At 54.1 the SQL-15 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

2.00 cu ft against a 59.4 L Vas.

α = Vas ÷ Vb = 1.05  ·  Fc = Fs√(α+1) = 47 Hz  ·  Qtc = 0.82
20 30 50 70 100 150 200 +6 +0 -6 -12 -18 -24 FREQUENCY · Hz LEVEL · dB −3 dB
SQL-15 · Qtc 0.82, Fc 47 Hz, F3 41.8 Hz
The box lifts resonance from 33.0 Hz free-air to 47 Hz and half power lands at 41.8 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 26.0 mm — and a bigger one once a subsonic filter stops it wasting travel below the passband.

PXmax = 2744 W unfiltered  →  3208 W 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 2744 W reaches Xmax here
SQL-15 · 2744 W, no filterSQL-15 · 3208 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 2744 W, reached first at 23 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 3208 W before hitting the same 26.0 mm. That is 17 percent more amplifier for the price of one filter setting.
ParamValueUnitNote
Fs33.00Hzfree-air resonance
Qts0.570SQL-15
Vas59.40Lequivalent compliance
Sd823.2cm²effective piston area
Xmax26mmone-way linear travel
Pe1000Wcontinuous RMS
SPL87.3dB1 W / 1 m, derived from T/S

Driver parameters as published by stereointegrity.com. Curves computed against this enclosure’s actual net airspace.

Installer's take

Read the alignment first. 2.00 cubic feet net puts the SQL-15 at Qtc 0.816 with resonance at 47.2 Hz and half power at 41.8 Hz anechoic.

That is a properly damped sealed alignment and it needs no qualification. The SQL-15 has the excursion to use the power, 26 mm one way, so give it real amplifier.

On impedance: The SQL-15 comes as a dual 2 ohm or a dual 4 ohm. A D2 gives 4 ohms in series or 1 ohm in parallel; a D4 gives 8 ohms or 2 ohms.

Measure the base depth. This cabinet is 14.81 inches deep at the trunk floor, 8.26 at the top, and 29.16 wide.

Questions

Will this enclosure fit the SQL-15 exactly?

Yes. The baffle is CNC cut to 14.17 in for the SQL-15's cutout and the cabinet clears its 7.400 in mounting depth. Threaded inserts are pressed in at every mounting location.

Why 2.00 cubic feet net?

It puts the SQL-15 at Qtc 0.816 with fc 47.2 Hz and F3 41.8 Hz anechoic. That is a well damped sealed alignment, the target for this driver.

What amplifier power should I run, and what impedance?

The SQL-15 is rated 1000 watts RMS, so 1000 across the driver. The SQL-15 comes as a dual 2 ohm or a dual 4 ohm. A D2 gives 4 ohms in series or 1 ohm in parallel; a D4 gives 8 ohms or 2 ohms. Aim for roughly 700 to 1000 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.

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.

What is the expected low-frequency extension?

Anechoic F3 is 41.8 Hz at Qtc 0.816. The rolloff is clean rather than peaked. These figures 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 and the quantity is chosen so it does not change the acoustic volume. Do not add more.

Is the driver included?

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

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