Proline X Micro Series Dual 15" Sealed Enclosure | Built for ResoNix GUS-15

1.35 cu ft Net Acoustic Per Driver: Exactly ResoNix's 0.707 Qtc Target

ResoNix publishes a 0.707 Qtc target of 1.35 cubic feet of net acoustic airspace for the GUS-15. The GUS-15 has a driver displacement of 0.072 cubic feet. Each chamber in the M15D-S GUS is built to a gross internal volume that delivers 1.35 cubic feet of net acoustic airspace after the driver is installed. Both chambers are identical. Both drivers see identical acoustic conditions. Both produce identical T/S response curves.

This is exactly double the acoustic volume of the single M15-S GUS enclosure, by design. Each driver in this dual build gets the same acoustic environment a single GUS-15 gets in the single-driver enclosure. The dual configuration produces roughly 3 dB more low-frequency output than a single GUS-15 at equivalent power, and combined thermal capacity is 3,000 watts RMS. This is the highest-output single enclosure in the Proline X Micro Series lineup.

"If I Do the Math on the External Dimensions, the Volume Looks Too Big"

This is the most common question we get on Micro Series enclosures. The math customers run looks like this: external dimensions of 38" × 12" × 18" subtract 1" walls on all six sides (the M15D-S uses 1-inch walls, not 3/4"), leaving an assumed internal cavity of 36" × 10" × 16". That works out to 5,760 cubic inches, or roughly 3.33 cubic feet. The listed total net acoustic volume is 2.70 cubic feet (1.35 per chamber × 2 chambers), a difference of about 0.63 cu ft, which looks like the enclosure must be oversized by about 23%.

That math assumes five things that are not true on a Proline X dual-chamber stack-fab enclosure:

1. The walls are not 1-inch on every side. The front baffle is a double-face flush-mount build at 1.5 inches thick, thicker than the exterior walls. That alone removes more internal depth than a 1-inch calculation accounts for.

2. The enclosure is not a perfect rectangle. Viewed from above, all four corners are radiused at 3 inches. This is a deliberate design choice for two reasons: the rounded corners break up the parallel-wall geometry that creates internal standing waves, and they produce a finished shape that fits cleanly against vehicle interior surfaces without sharp corners catching on trim or upholstery. The 3" radii remove measurable internal volume that an external-minus-walls calculation assumes is open airspace.

3. The chamber divider takes up internal volume. A full CNC-cut chamber divider at 1-inch thickness separates the two driver chambers completely. That divider itself displaces internal volume that a single-cavity calculation ignores.

4. The area directly behind each driver's magnet is precision-milled. This is a deliberate engineering step that serves two purposes. First, it allows us to make fine volume adjustments to hit the target airspace exactly. Second, and more importantly, it increases the open area immediately behind each driver's rear vent. The GUS-15's pole vent is part of the driver's voice coil cooling system. Air flows through the vent during cone movement, carrying heat away from the voice coil former. If the area immediately behind the vent is restricted, backpressure builds against that airflow and voice coil cooling is compromised. Most enclosure manufacturers do not understand this airflow dynamic, and even fewer engineer around it. We do.

5. Each driver displaces 0.072 cubic feet of internal airspace once installed. Two drivers displace 0.144 cubic feet total. This is not subtracted from a back-of-napkin external calculation, but it is subtracted from what the drivers acoustically load into.

How we actually calculate volume. Our engineering approach is built on precision, and it is different from how most enclosure manufacturers calculate airspace and different from the math any customer can do from external dimensions. A Proline X stack-fab enclosure is built from individually CNC-cut layers, each with its own machined opening. We calculate the precise internal volume of every layer's opening on both sides of the chamber divider, then sum those layer-by-layer volumes to arrive at the actual net airspace inside each assembled chamber. No one else in this industry calculates net volume this way. It is the only method that produces a genuinely accurate account of the airspace each driver sees once the enclosure is built. The 1.35 cubic foot per-driver figure is exact, not approximate.

1" Walls. 1.5" Flush-Mount Double-Face Baffle. Chamber Divider. Internal Bracing.

The M15D-S GUS is constructed to a different structural standard than the rest of the Micro Series. The exterior walls are 1-inch thick Langboard Elite MDF, thicker than the standard 3/4" panels used elsewhere in the series. Panel rigidity scales with the cube of thickness, so moving from 3/4" to 1-inch produces a substantially stiffer wall than the numerical difference alone suggests. At 3,000 watts RMS combined driver output, the structural demands justify the additional thickness across the entire enclosure shell.

The front baffle is a double-face 1.5-inch build: two bonded layers of Langboard Elite combined into a single rigid panel. Both GUS-15 drivers are flush-mounted into the 1.5-inch baffle, with the mounting cutouts CNC-machined to sit each driver's flange perfectly flush with the baffle surface. Flush-mounting eliminates the frame-lip resonance that surface-mounted drivers can develop at high-excursion listening levels, and it produces a cleaner airflow path across the front of the cones.

The chamber divider is CNC-cut at the same 1-inch thickness as the exterior walls. Additional internal bracing is integrated into the panel layering to control diaphragm-driven wall flex under sustained high-power operation. The stack-fab assembly is reinforced with dowels throughout, adding between-layer tension reinforcement that locks the panel stack against shear movement. Both chambers maintain their acoustic isolation independently under sustained 3,000-watt combined operation.

Where It Fits

The M15D-S GUS is the largest and heaviest enclosure in the Micro Series. External footprint in downfire orientation is 38 inches wide, 12 inches tall (before adding the 1.75-inch downfire feet), and 18 inches deep. Total installed height in downfire mode is 13.75 inches. Measure carefully:

• Truck bed: full-size crew cab and long-bed trucks
• Cargo floor: full-size SUVs and vans
• Trunk floor: full-size sedans with wide trunk openings
• Behind-seat: full-size crew cab trucks (verify cab depth)
• SQ competition: maximum dual-driver GUS-15 output
• Show vehicle builds: maximum bass capability at minimum depth

Made in Tennessee

Every Proline X Micro Series enclosure is CNC-cut and hand-assembled in Tullahoma, Tennessee on ShopSabre CNC routers. Chamber volume, divider placement, cutout geometry, layer-by-layer opening dimensions, baffle layer count, dowel placement, terminal positioning, and wall thickness are all held to spec on every unit. Langboard Elite MDF throughout: named, mill-documented, published density and bond specifications.