Performance Series 6.5 inch Subwoofer Box - Ported|Proline X|Audio Intensity

Proline X

Proline X P6-P | Single 6.5" Ported Subwoofer Enclosure | V3

SKU: P6-P-G

QUICK SPECS

Best For: High-excursion 6.5" subwoofers / Space-limited installs
Volume: 0.30 ft³ (Net)
Tuning: 38Hz
Sonic Character: Tight, High-Output, Dynamic

Shipping Included No freight charges at checkout. What you see is what you pay.

Built in Tennessee CNC cut from 3/4" Langboard Elite MDF. V-groove and dado joinery. 1.5" front panel.

Advanced Terminal Cup Built in-house. ABS/Carbon Fiber. Stainless steel hardware. Copper ring terminals.

$ 149.99

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Proline X P6-P | Single 6.5" Ported Subwoofer Enclosure | V3

Enclosure Type Ported

External Dimensions 16" W x 8" H x 10.75" D

Net Volume .3cu ft

Tuning Frequency 38Hz

Cutout Diameter 5.95"

Front Panel Thickness 1.5"

Max Mounting Depth 7.25"

INSTALLER'S TAKE

The P6-P V3 is our go-to for "stealth" builds where the client wants real bass without losing their trunk. Most 6.5" boxes on the market use 1/2" or 5/8" wood to save weight, but Proline X sticks to 3/4" MDF here, which is critical. When you throw 300-500W at a high-end 6.5" sub, the internal pressure is immense; this box doesn't flex or rattle. The 38Hz tuning is the "sweet spot"—it’s low enough to catch the deep notes but high enough that the sub stays protected and responsive. If you're running a DD Audio, Ground Zero, or Sundown 6.5, this is the exact airspace they’re looking for.

Product Details

The Proline X P6-P is a single 6.5" ported subwoofer enclosure built to the Version III standard. It is designed for daily drivers running a 6.5" subwoofer who want real output from a compact footprint. The slot port is tuned at 38Hz — balanced low enough to capture deep bass content without rolling off prematurely, and high enough to keep the driver protected and responsive under sustained power.

Every panel is CNC-cut from 3/4" Langboard Elite MDF at our Tennessee facility — a mill-certified panel stock with a 200 psi internal bond rating, 410,000 psi modulus of elasticity, and 325 lb face screw holding strength. The front baffle is 1.5" thick — two layers of 3/4" MDF laminated together. At this driver size most enclosures run a single 3/4" baffle. The double baffle eliminates the flex point directly behind the driver where internal pressure is highest during high-excursion playback.

Version III construction uses V-groove combined with dado joinery throughout. A dado cut channels each mating panel into a mechanical lock before adhesive is applied — increasing glue surface area and eliminating the micro-gaps that develop in standard butt joint construction over time. Internal bracing is increased over the previous Version II design. The result is a box that does not flex, does not develop air leaks at the joints, and does not degrade acoustically under sustained use.

The terminal cup is built in-house at our Tennessee facility — ABS/Carbon Fiber Composite body, recessed mount, stainless steel hardware, aluminum landing plates, and copper ring terminals. Every P6-P ships pre-wired with 12g OFC speaker wire. Connect your amplifier output to the terminal and the enclosure is ready to use. Nothing to source, nothing to upgrade.

Available in Dark Gray Trunkliner (standard) or Plush Black (+$10). Both finishes use the same Langboard Elite MDF and full V3 build spec. Shipping is included in the price — no freight charges at checkout. What you see is what you pay.

Specifications

Material	3/4" High-Density MDF
Net Volume	0.30 ft³
Tuning Frequency	38Hz
Mounting Depth	7.25"
Cutout Diameter	5.95"
Dimensions	16" W x 8" H x 10.75" D
Finish	Grey Trunk liner or Plush Black Carpet
Manufacturing	CNC Cut - Made in USA

Materials

Material

Built From a Spec Sheet, Not a Sales Sheet

Every Proline X Performance Series enclosure is CNC-cut from Langboard Elite MDF — 3/4" (18mm) panels produced to published mill specifications. Most enclosure manufacturers source generic MDF without published data. We can tell you the internal bond rating, the modulus of elasticity, the modulus of rupture, and the face and edge screw holding strength for every panel in this enclosure — because we chose the material based on those numbers, not on price or availability.

Langboard Elite is produced in the United States. The specifications below are pulled directly from Langboard's published mill data and are verifiable. This is the same panel stock used in our full Proline X lineup.

Specifications

Langboard Elite MDF — Published Mill Data

Property	Value	Why It Matters
Panel Stock	Langboard Elite MDF	Named, verifiable panel source — not generic "high-density MDF"
Thickness	3/4" (18mm)	Industry standard for subwoofer enclosures; panels below this flex under pressure
Density	48.5 lbs/ft³	Higher density = less porosity, better screw retention, reduced resonance
Internal Bond	200 psi	Measures resistance to delamination under sustained internal pressure — the most enclosure-relevant spec on this sheet
Modulus of Rupture (MOR)	4,200 psi	Bending strength before the panel breaks — relevant for larger unsupported baffle spans
Modulus of Elasticity (MOE)	410,000 psi	Stiffness under load; higher MOE means less panel flex under bass pressure, less resonance
Face Screw Holding	325 lbs	How firmly the panel surface holds a screw; critical for baffle joint integrity over time
Edge Screw Holding	250 lbs	Panel edge retention — relevant for every joint that isn't face-to-face

Internal Bond

200 psi — The Number That Actually Matters for Enclosures

The internal bond rating measures how well the MDF panel resists delamination under sustained pressure applied perpendicular to the face. In a subwoofer enclosure, every bass transient generates a pressure pulse that pushes outward on every panel simultaneously. A panel that begins to delaminate internally loses stiffness gradually — the symptoms are slow: a box that starts to sound softer, less defined, less punchy over months of use. 200 psi internal bond is the spec that determines how long this enclosure holds its acoustic integrity under daily use at real power levels.

Stiffness

410,000 psi MOE — Less Flex, Less Resonance

The modulus of elasticity measures panel stiffness — resistance to bending under load. A stiffer panel flexes less under the pressure generated by a high-excursion driver at volume. Panel flex is a source of acoustic coloration: the panel itself begins to radiate sound at its own resonant frequency, adding distortion to the output. 410,000 psi stiffness combined with V-groove and dado joinery means the panels stay rigid and the bracing controls resonance at the structure level — not the panel level. The bass you hear comes from the driver, not the box.

Screw Holding

325 lb Face / 250 lb Edge — Joints That Stay Locked

Screw holding strength determines how firmly the panel grips a fastener at the face and at the edge. This matters most at the baffle joint — where the front panel meets the side panels and where the driver is mounted. A panel with low screw holding strength allows fasteners to loosen over time under vibration, leading to air gaps at the joint and loss of acoustic seal. 325 lb face screw holding strength means the baffle hardware stays put. Combined with dado joinery and adhesive, the front panel on a Proline X Performance Series enclosure is not going anywhere.

Sourcing

Named Panel Stock — Not "Premium MDF"

The phrase "premium MDF" or "high-density MDF" appears on marketing copy for enclosures across every price point, from $40 to $400. It is not a specification — it is a description with no defined standard. Langboard Elite is a named, sourced, mill-documented product with published data. We name it in our copy because naming it holds us accountable to the spec. You can look up Langboard Elite independently, verify the numbers on this page, and confirm you are getting what we say you are getting. That is the point.

Why Proline X?

Most enclosures are built to a price point. Proline X is built to a spec. Every box starts with published-data MDF, gets CNC-cut to exact internal volume, and is assembled by hand in our Tennessee facility. The difference shows up in the measurements — and in how the box holds up two years into daily use.

CNC-Cut to Spec

Panels are machine-cut on ShopSabre CNC routers and joined with V-groove and dado joinery. Consistent geometry, no hand-cut variance, no gaps at the joints.