Performance Optimized · Datasheet

Performance Optimized Wedge Ported 12" Enclosure | Stereo Integrity SQL-12 Single 12" Ported enclosure

Net volume
1.54 Cubic Feet
Tuning
37.5 Hz
Max mounting depth
7.000 Inches (Stereo Integrity Spec)
Cutout
11.330 Inches (Stereo Integrity Spec)
External dimensions
28.50 Inches W × 15.50 Inches H × 10.25 Inches / 15.89 Inches D
Front baffle
Vertical Baffle - Driver Fires Rearward Into The Trunk
Buy at Audio Intensity
  • Alignment: 1.54 cu ft net vented at 37.5 Hz. F3 30.9 Hz anechoic, 4.13 dB passband ripple
  • Driver: Stereo Integrity SQL-12, 1000 W RMS, 26.0 mm Xmax, 34.10 Hz Fs
  • Build: Rear-firing wedge, 20 degree rear rake, V-groove and dado joinery, triangular side-exit slot port with a 1/2" rounded mouth, double 1.5" baffle, side-mounted terminal cup
  • Cabinet: 28.50" W x 15.50" H x 15.89" D at base tapering to 10.25" D at top, 24.7 sq in port, ships dry

Technical specifications

SeriesProline X Performance Optimized Wedge
Driver-Specific FitmentStereo Integrity SQL-12 (Dual 2 Ohm)
Enclosure TypePorted | Rear-Firing Trunk Wedge
Baffle ConfigurationVertical Baffle - Driver Fires Rearward Into The Trunk
Wedge Angle20 Degrees On The Rear (Seat-Side) Panel
External Width28.50 Inches
External Height15.50 Inches
Top Depth10.25 Inches
Base Depth15.89 Inches
Internal Volume (Gross)2.12 Cubic Feet
Internal Volume (Net After Displacement)1.54 Cubic Feet
Port TypeTriangular Slot | Bottom-Rear Corner | Straight, No Bend | Side Exit
Port GeometryIsosceles, 7.25 Inch Legs, 24.7 Square Inches, 23.39 Inches Long, Side Mouth
Port Tuning (Fb)37.5 Hz
Port MouthTriangle Through Side A, 1/2 In Roundover On All Three Edges, 37.4 Square Inches At The Face
Port ThroatOpen Far End, 3.36 In Gap To Side B, 3/8 In Roundover On The Panel End
Port Air Velocity27.0 m/s In The Channel, 17.8 m/s At The Flared Mouth (17.0 m/s Chuff Threshold)
Predicted F330.9 Hz (Anechoic)
Passband Ripple4.13 dB (Anechoic)
Subsonic Filter30 Hz High-Pass, 24 dB/Octave - REQUIRED On A Vented Enclosure
Driver Fs34.10 Hz
Driver Qts0.570
Driver Qes / Qms0.620 / 6.990
Driver Vas22.500 Liters / 0.795 Cubic Feet
Driver Sd532.3 Square Centimeters
Driver Mms387.90 g
Driver BL21.00
Driver Re3.3 Ohm
Driver Xmax26mm (One-Way at 70% BL)
Excursion Design BasisDerated To 22.1mm For Alignment - Stereo Integrity Publishes At 70% BL
Driver Displacement0.15 Cubic Feet (Published by Stereo Integrity)
Driver Sensitivity83.1 dB
Driver Power Handling1000 Watts RMS
Driver Overall Diameter12.910 Inches (Stereo Integrity Spec)
Mounting Depth Required7.000 Inches (Stereo Integrity Spec)
Cutout Diameter11.330 Inches (Stereo Integrity Spec)
MaterialLangboard Elite 3/4" MDF
ConstructionShopSabre CNC / Two Windowed C Braces At The Third Points, Seated On The Port Panel
JoineryV-Groove and Dado (CNC-Cut)
Front Baffle ConstructionDouble-Layer 1.5" MDF | Cosmetic Front Layer Routed For The Acrylic Insert
Mounting HardwareThreaded Inserts At Every Mounting Location | Stainless Steel Machine Screws Included
Voice Coil ConfigurationDual 2 Ohm
Terminal CupProline X ABS/Carbon Fiber Composite | Side Mounted, Opposite The Port | 12g OFC Pre-Wired
DampingNone - Ships Dry. Polyfill Detunes A Ported Enclosure
Recommended Power700-1000 Watts RMS (Stereo Integrity Rated: 1000W RMS)
Carpet FinishPlush Black
Weight50 lb
Bundle OptionsEnclosure Only (Bring Your Own Stereo Integrity SQL-12)
Warranty1-Year Limited (Enclosure)
ManufacturedTullahoma, Tennessee, USA

Performance in this enclosure

Net airspace
1.54
cu ft
Tuning
37.5
Hz · Fb
Half power
30.9
Hz · F3, anechoic
Xmax at
11027
W RMS · 30 Hz subsonic
With NO filter
2055
W RMS · unfiltered
Port
17.8
m/s at the mouth

01Is this driver right for a ported box?

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 EBP 55.0
Stereo Integrity SQL-12 · EBP 55.0
Between 50 and 100 a driver takes either load, and the choice becomes one of priorities rather than of physics. The Stereo Integrity SQL-12 reads 55.0. Ported buys output and low-end reach around tuning; sealed buys a shallower rolloff below it. This cabinet takes the first trade.

02What the box does to it

1.54 cu ft net against a 22.5 L Vas, vented at 37.5 Hz.

Fb = 37.5 Hz  ·  F3 = 30.9 Hz  ·  passband ripple 4.13 dB
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB −3 dB Fb 37.5
Stereo Integrity SQL-12 · Fb 37.5 Hz, F3 30.9 Hz
Anechoic, before any cabin gain, with the 30 Hz subsonic filter already applied. The vent takes over below 38 Hz and the cone stops doing the work there, which is what holds travel down at the bottom of the passband.

03Perceived Ported vs Sealed

This cabinet, 1.54 cu ft net vented at 37.5 Hz, against the 1.00 cu ft sealed wedge we build for this driver (PO 12-S W SQL12).

Ported Fb 37.5 Hz  ·  the 1.00 cu ft sealed box runs Qtc 0.76, Fc 46 Hz
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB +7.5 dB at 40 Hz
Ported · this cabinet, 1.54 cu ft, Fb 37.5 HzSealed wedge we build, 1.00 cu ft, Qtc 0.76
Shaded blue is where the ported alignment is louder for the same power, orange where the sealed one is. The sealed curve is the 1.00 cu ft sealed wedge we build for this driver (PO 12-S W SQL12), not this cabinet with the port blocked: two different boxes, because that is the choice a buyer actually has. Across 25 to 60 Hz the vent is worth 7.5 dB at its widest and 4.8 dB on average. This is the anechoic picture, which is not what you hear in a car.

04Real World Ported vs Sealed

The same two boxes with cabin gain applied, 45 Hz corner, 18 dB ceiling.

Flatness across 25–60 Hz: ported 6.5 dB spread, the 1.00 cu ft sealed box 2.1 dB
20 30 50 70 100 150 200 +6 +0 −6 −12 −18 −24 FREQUENCY · Hz LEVEL · dB +7.5 dB at 40 Hz
Ported, in-car · 6.5 dB spreadSealed wedge we build, 1.00 cu ft, in-car · 2.1 dB spread
Cabin gain lifts both boxes by the same amount, so the gap between them does not change: what changes is the shape each one ends up with. A car pressurises below roughly 45 Hz, which fills in the sealed box's shallower rolloff and over-drives it where the ported box is already flat. Across 25 to 60 Hz, the band kick and bass fundamentals occupy, this alignment holds 6.5 dB of spread against 2.1 dB for the 1.00 cu ft sealed wedge we build for this driver (PO 12-S W SQL12). The sealed curve is flatter on paper; the ported one trades that for output. Note where the curves cross. Below about 25 Hz the sealed alignment becomes the louder of the two and stays louder all the way down, by up to 4.9 dB: a sealed box rolls off gently into the subsonic region where a vented one falls away steeply once it is below tuning and the vent stops contributing. If the content you are chasing lives below 25 Hz, a sealed alignment reaches further down than this one does. Cabin gain here is a house assumption, not a measurement of your vehicle.

05The 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 Stereo Integrity's published 26.0 mm. The two traces are the same cabinet with the subsonic filter switched on and switched off.

PXmax = 11027 W with a 30 Hz subsonic  ·  2055 W with none  →  the filter is worth 5.4×
20 30 50 70 100 150 200 0 8 16 24 32 FREQUENCY · Hz CONE TRAVEL · mm PAST LINEAR TRAVEL · Xmax 26.0 mm design limit 22.1 mm · 70% BL derated 11027 W reaches Xmax here
11027 W · subsonic at 30 Hz, 24 dB/oct2055 W · no subsonic filterXmax 26.0 mm one-way, published
Each trace touches the limit and no further, because each is drawn at the exact power that puts the cone on 26.0 mm. With a 30 Hz subsonic that takes 11027 W, reached first at 29 Hz. Take the filter away and the same cabinet reaches 26.0 mm on 2055 W — the filter is worth 5.4× the safe power. A vent unloads the cone below tuning, so there is nothing holding it once the box stops loading: on a sealed build a subsonic filter is an improvement, here it is required equipment. The unfiltered trace is still rising where this chart stops at 20 Hz, so treat 2055 W as a bound rather than a floor. Every wattage on this page is a MECHANICAL limit, not an electrical one. It is the power at which the cone runs out of linear travel in this cabinet, and nothing more. What the voice coil can dissipate as heat is a separate ceiling set by the driver, not by the box — Stereo Integrity rate this one at 1000 W RMS, and that is the number that binds first here: heat stops you before travel does, so treat 1000 W as the ceiling and the travel figures above as headroom. Final wired impedance, amplifier output and how long you hold the level are all electrical questions this graph does not answer. The dashed line at 22.1 mm is the figure the cabinet was actually designed against: Stereo Integrity publish this Xmax on a 70% BL basis, and we derate it before sizing the port so the alignment carries margin against an optimistic spec rather than sitting right on it.

Installer's take

Stereo Integrity's own vented box for the SQL-12 is 1.7 cubic feet at 27 Hz through a 22 inch port. A wedge holds a straight triangular port no longer than about 23.5 inches at this width, so it cannot tune that low; this cabinet is the nearest thing the wedge can do, 1.54 cubic feet at 37.5 Hz with a 30.9 Hz F3 on 4.13 dB of ripple. It reads 6.52 dB in the car, which is more spread than the rest of the line carries, and I am telling you that up front.

The port is the other thing to know. At the full 1000 watts it runs 27.0 metres per second in the channel and 17.8 at the mouth, both past the limits I hold the rest of the line to, and I chose to build it anyway because at the 300 to 500 watts most installs actually deliver those figures fall well inside. If you run a clean kilowatt into it on sustained low notes, you will hear the port. Xmax is quoted at 70 percent BL, derated from 26 to 22.1 mm, and the cone uses 7.8 of that at rated power with the subsonic filter set. The sealed SQL-12 wedge we build is the calmer alternative.

Questions

Why is this enclosure tuned to 37.5 Hz?

Stereo Integrity's own vented box is 1.7 cubic feet at 27 Hz with a 22 inch port, and a straight triangular port in a wedge cannot reach that length, so this cabinet tunes higher: F3 30.9 Hz anechoic on 4.13 dB of ripple and 6.52 dB of in-car spread across 25 to 60 Hz. The port takes 23.39 of the 23.48 inches the width allows and runs at 27.0 metres per second in the channel at the full 1000 watts, over the 24.7 limit this line normally holds, with 17.8 at the rounded mouth against a 17 target. Both figures were reviewed and accepted for this cabinet; at the power most installs run, they fall well inside. Tuning is chosen for in-car response rather than an anechoic curve: a vehicle adds roughly 12 dB per octave below about 45 Hz. In this cabinet that lands at 6.5 dB of in-car spread across 25 to 60 Hz.

Why the 20 degree wedge, and why rear-firing?

The raked face is the seat side. A factory rear seat back leans about 20 degrees off vertical, so the cabinet sits flat against it and uses floor a square box wastes. The baffle stays vertical and fires rearward into the trunk, which acts as the acoustic extension into the cabin. This one is 15.89 inches deep at the base and 10.25 at the top, 28.50 wide and 16 tall.

Do I need a subsonic filter?

Yes, at 30 Hz, 24 dB per octave. Below tuning a vented box stops loading the cone and excursion runs away toward DC. With the filter in place this cabinet puts the Stereo Integrity SQL-12 at 35 percent of its usable travel at full rated power; without it there is no meaningful number to quote.

How much power can I run, and at what impedance?

Stereo Integrity rate the SQL-12 at 1000 W RMS and that is the thermal ceiling. The Performance Graphs tab shows the mechanical limit, the power at which the cone reaches the end of its travel in this cabinet: here the cone sits at 35 percent of usable travel at the rating, so heat is what stops you, not travel. A D2 coil is 4 ohms in series or 1 ohm in parallel; run series unless the amplifier is rated for 1 ohm. A D4 is 8 series or 2 parallel.

Would a sealed box be better for me?

Below about 25 Hz, yes. The sealed wedge we build for it is louder down there by up to 4.9 dB, because a sealed box rolls off gently where a vented one falls away steeply under tuning. Above that this alignment is the louder of the two for the same power. The Performance Graphs tab plots this cabinet against the 1.00 cu ft sealed wedge we build for this driver (PO 12-S W SQL12).

How does the side port work?

It is a triangular slot in the bottom-rear corner: the floor and the raked back wall are two sides, one bevelled panel is the third. It runs across the cabinet, opens into the box through a 3.36 inch gap at the far end and exits through the side panel as the same triangle. Straight, no bend: 23.39 inches of path and 24.7 square inches of channel running at 27.0 metres per second, 60 percent of its turbulence limit. The three mouth edges are rounded over at 1/2 inch, so the opening at the face is 37.4 square inches and the air leaves it at 17.8 metres per second against the 17.0 threshold where a slot port starts to chuff; the panel's throat end is rounded at 3/8 inch for the same reason. The terminal cup is on the other side.

Does this enclosure ship with polyfill?

No, and do not add any. Every sealed Proline X enclosure ships with polyfill; a ported one must not, because damping changes the effective volume the port is tuned against. The port here is cut to 23.39 inches for 37.5 Hz. Stuff it and you move the tuning without shortening the port.

Is the SQL-12 included?

No. This is an enclosure only, cut for the Stereo Integrity SQL-12 specifically: the 11.330 inch cutout, the 7.000 inch mounting depth allowance and the 1.54 cubic foot alignment all come from Stereo Integrity's published parameters. It fits both coil versions; the alignment published here is the . Bring your own driver.

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