Proline X PO12-S SI | Single 12" Sealed Subwoofer Enclosure | Built for Stereo Integrity SQL
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Drop it in a generic box and you'll get loud bass. Drop it in a cabinet engineered around SI's published Thiele-Small parameters, with construction sized for the power level the SQL 12 delivers, and you'll hear what Nick Sowa's team built this driver to do. The Performance Optimized Sealed 12 for Stereo Integrity SQL 12 is that cabinet. Internal volume, baffle thickness, mounting hardware, and construction methods are all chosen to extract the SQL 12's full mechanical and acoustic potential — and to hold together as a rigid structure at the power levels this driver is capable of. This enclosure is engineered specifically around the Stereo Integrity SQL 12 Series 2. The 1.0 cubic foot net volume matches the maximum sealed volume SI specifies for the SQL 12 — where the driver's deep low-end extension fully develops with F3 points in single-digit territory. Why Performance Optimized Sits Where It Does The Performance Optimized line is the bridge between our standard Performance Series and our top-tier Professional Series. Same Performance-tier construction quality — Langboard Elite MDF, V-groove and dado joinery, ShopSabre CNC routing — but the geometry of every panel is cut around one specific driver instead of a class of drivers. For the SQL 12 specifically, that also means doubled baffle stock at the mounting position to handle the driver's power capability. vs Performance Series Standard Performance Series boxes (P6 through P15) are built for universal driver fitment within a size class. Great if you want flexibility across multiple driver options. Performance Optimized takes the same construction foundation and locks the airspace and hardware to one specific driver. vs Professional Series Professional Series uses extensive multi-layer baffles, triple-stacked construction, and a 2-year warranty for the most demanding builds. Performance Optimized delivers driver-specific engineering with double baffle construction at a more accessible price point with a 1-year warranty. Engineered Around the SQL 12's Parameters Stereo Integrity specifies the SQL 12 Series 2 for sealed enclosures between 0.65 and 1.0 cubic feet. The Performance Optimized Sealed 12 delivers 1.0 cubic feet net — the maximum of SI's specified range, where the SQL's deep low-end extension characteristics fully develop. In this cabinet, the SQL 12 plays down to F3 points in single-digit territory, delivering the low-frequency response that makes SI's SQL Series unmatched at its price point. Volume Selection 1.0 cubic foot net is the maximum of SI's recommended sealed volume range. Smaller volumes tighten Qtc and lose some low-end extension. Larger volumes fall outside SI's specification and compromise transient control. 1.0 cubic foot is where the SQL 12 delivers on its full low-end capability while staying inside the driver's engineered operating window. Mounting Geometry The baffle is cut to the SQL 12's exact 11.33" cutout specification and doubled to 1.5" total thickness at the mounting position. The SQL 12's 7" mounting depth leaves comfortable internal clearance inside the 13.625" deep cabinet. 8/32 threaded inserts are pressed into the doubled baffle stock for full-depth thread engagement and secure retention at high excursion levels. Performance Series Construction, Sized for Real Power Double Baffle Mounting Face The mounting face uses a doubled 1.5" total baffle thickness — two layers of 3/4" Langboard Elite MDF bonded together at the driver mounting position. Doubled baffle stock resists baffle flex and mounting screw pullout at the 1000-watt RMS power levels the SQL 12 delivers. 8/32 Threaded Inserts Into Double Baffle The baffle uses 8/32 threaded inserts pressed into the doubled 1.5" MDF backside, providing full-depth thread engagement for the supplied stainless steel mounting screws. No stripped pilot holes, no MDF damage from drywall screws, and secure retention at high excursion levels. V-Groove and Dado Joinery CNC-cut V-grooves at every panel intersection let the cabinet fold into shape with maximum glue surface. Dado joints lock the doubled baffle and rear panel into the side walls — no fasteners visible from outside, no exposed end grain at joints. Pre-Wired Terminal Cup Proline X ABS/carbon fiber composite terminal cup, pre-wired with 12-gauge OFC inside the cabinet, with stainless steel hardware accepting both spade and banana terminations on the input side. Every panel is cut on ShopSabre CNC routers in our Tullahoma, TN facility. Tolerances that manual fabrication can't hold — joints close cleanly, baffle concentricity stays accurate, and internal volume is consistent unit to unit. The doubled baffle at the mounting position is bonded under clamping pressure for a monolithic 1.5" stock at the point where structural integrity matters most. Customize Your Build Carpet Finish Dark Gray Trunkliner is the standard durable wrap, matched to most factory trunk and cargo-area carpet tones. Plush Black (+$10) is a deeper, more luxurious nap that pairs well with blacked-out interiors and show builds. Acrylic Insert Color Choose Black, Blue, Red, or White for the front baffle insert to match your build. Or skip the insert entirely (-$40) for a clean, understated look. The insert is purely cosmetic — performance is identical across colors. Box-Only or Loaded Add a Stereo Integrity SQL 12 Series 2 driver directly to your order in Dual 2-ohm or Dual 4-ohm impedance and Paper or Carbon Fiber dust cap configurations. Already own your SQL 12? Order the enclosure box-only and drop in the driver you have. Wiring the SQL 12 to Your Amplifier The Stereo Integrity SQL 12 is a dual voice coil driver available in Dual 2-ohm (D2) or Dual 4-ohm (D4) configurations. The pre-wired terminal cup accepts either impedance version via 12-gauge OFC, with stainless steel input hardware. A Dual 2-ohm SQL 12 wired in parallel presents a 1-ohm load. A Dual 2-ohm wired in series presents 4 ohms. A Dual 4-ohm SQL 12 wired in parallel presents 2 ohms, and wired in series presents 8 ohms. The SQL 12 is rated for 1000 watts RMS — aim for a clean, well-regulated amplifier delivering 750 to 1000 watts at your chosen impedance. At this power level, amplifier quality matters more than headline numbers — regulated power supply, low THD, and honest RMS ratings. Built in Tennessee, Backed by Audio Intensity Every Performance Optimized enclosure is CNC-cut, assembled, and finished in our Tullahoma, TN facility. Components are pulled from inventory after your order is placed, then bonded and wrapped — a 2 to 5 business day assembly window before the box ships. No pre-built inventory sitting in warehouses, warping in storage. Each unit is built to order. Backed by a 1-year limited warranty against structural failure and hardware defects. Questions on fitment, wiring, or amplifier pairing? Contact us — we install this gear ourselves, in our own vehicles. The SQL 12, Engineered Correctly Driver-specific 1.0 cubic foot airspace, doubled baffle construction, V-groove and dado joinery, and Performance Series build quality sized for the SQL 12's 1000-watt RMS capability. The correct cabinet for a serious single 12 build.