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.

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

$ 149.99

Color

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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 38

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

Proline X P6-P

Single 6.5" Ported Subwoofer Enclosure | V3

0.30 ft³ Net 38Hz Tuning Ported Bass Reflex 1.5" Double Baffle Langboard Elite MDF Built in Tennessee

Built for the Install That Has No Room for Compromise

The Proline X P6-P is a single 6.5" slot-ported enclosure engineered for installs where space is the primary constraint but output is still a requirement. A 6.5" driver in a properly tuned ported box at 38Hz produces real, audible bass — not the thin, overworked low-end you get from a 6.5" running full-range through a factory system. This enclosure gives that driver the air space and port geometry it needs to perform at its efficiency peak.

At 16" wide, 8" tall, and 10.75" deep, the P6-P fits behind seats, under cargo floors, and in door-adjacent trunk positions that a 10" or 12" enclosure could never reach. It is the right tool for compact vehicles, rear deck builds, and stealth installs where the box has to disappear into the vehicle while the bass does not.

This is not a box built to a price point. Every panel is CNC-cut from Langboard Elite MDF to exact internal volume, assembled by hand in our Tennessee facility, and finished in your choice of Dark Gray Trunkliner or Plush Black. Shipping is included.

Why Ported at 38Hz for a 6.5" Driver

Ported alignment on a small driver is a deliberate engineering choice, not a compromise. A sealed 6.5" enclosure produces tight, accurate bass but rolls off quickly below 60Hz — audible, but not impactful. A ported enclosure tuned to 38Hz extends usable output significantly lower, allowing the driver to produce bass that you feel, not just hear.

At 38Hz, port output peaks at a frequency that covers the majority of kick drum fundamentals, bass guitar low notes, and the upper sub-bass range in electronic music. The driver works less at and below tuning — excursion is minimized where port output is maximized — which protects the driver and improves efficiency simultaneously.

Extended Low-Frequency Output

Ported alignment extends usable bass output to frequencies a sealed box of equal volume cannot reach. The P6-P produces audible output below 40Hz — territory most 6.5" sealed enclosures cannot access.

Higher Efficiency

Ported enclosures convert amplifier power to acoustic output more efficiently than sealed designs. The P6-P gets more output per watt, which matters in compact installs where amplifier headroom is often limited.

Reduced Driver Excursion at Tuning

At and near 38Hz, the port handles the acoustic load — driver excursion drops significantly. This reduces mechanical stress on the driver at the frequencies where small drivers are most vulnerable.

38Hz — The Right Tuning Point

38Hz provides strong output through the upper sub-bass and bass range without the port velocity issues that come with tuning too low on a compact driver. It is a general-purpose tuning that works across music genres without being optimized for just one.

Construction: What Separates Proline X From the Rest

Most enclosures in this size category are built to hit a retail price point. Panel thickness is reduced, joinery is simplified to butt joints, and MDF is sourced from wherever is cheapest that week. The result is boxes that flex under pressure, lose their acoustic seal over time, and sound progressively worse as the joints loosen. The P6-P is built to a different standard.

Langboard Elite MDF — Named, Verified, Documented

Every panel in the P6-P is cut from Langboard Elite MDF — 3/4" (18mm), a named, mill-documented panel stock produced in the United States. Most manufacturers source generic MDF and describe it as "high-density" or "premium" without any supporting data. We name our panel stock because naming it holds us accountable to the spec.

Langboard Elite — Published Mill Data

Density: 48.5 lbs/ft³ — higher density means less porosity, better screw retention, and reduced resonance

Internal Bond: 200 psi — resistance to delamination under sustained bass pressure cycling

Modulus of Elasticity: 410,000 psi — panel stiffness under load; less flex means less resonance

Face Screw Holding: 325 lbs — baffle hardware stays locked under vibration

Edge Screw Holding: 250 lbs — joint integrity at every panel edge connection

V-Groove and Dado Joinery

The P6-P uses V-groove and dado joinery — CNC-cut interlocking grooves that mechanically lock every panel before adhesive is applied. A dado joint cuts a groove into one panel that accepts the edge of the adjoining panel, creating a tongue-and-groove style mechanical interlock. The result is a joint that resists shear forces mechanically, not just through glue strength. Every corner is locked. Every seam is airtight. The box does not flex.

1.5" Double Baffle

The front panel on the P6-P is a 1.5" double baffle — two layers of 3/4" Langboard Elite MDF laminated together at the front panel. This is the panel that takes the most mechanical stress: it holds the driver, absorbs motor vibration, and maintains the acoustic seal at the cutout. At 1.5" thickness it does not flex, does not resonate at driver frequencies, and holds mounting hardware with the grip of a solid panel rather than a thin baffle that loosens over time.

In-House ABS/Carbon Fiber Composite Terminal Cup

The terminal cup on the P6-P is built in-house at our Tennessee facility — not sourced from a generic hardware catalog. The ABS/Carbon Fiber Composite recessed cup features stainless steel hardware, aluminum landing plates, and copper ring terminals, pre-wired internally with 12g OFC speaker wire. The recessed mount protects the terminals from cargo contact. The copper ring terminals ensure a clean, corrosion-resistant connection that does not loosen over time.

ShopSabre CNC Routers

Every panel is machine-cut on ShopSabre industrial CNC routers. Consistent geometry, no hand-cut variance, no gaps at the joints. Panel #1 and panel #500 are dimensionally identical.

Hand-Assembled in Tennessee

CNC cutting is only half the process. Every enclosure is hand-assembled at our Tennessee facility and inspected before it ships. No overseas manufacturing. No batch assembly shortcuts.

Dark Gray Trunkliner or Plush Black

Both finish options are professionally applied. Dark Gray Trunkliner matches factory trunk materials for a stealth install. Plush Black provides the traditional aftermarket aesthetic. Both are durable and bonded for long-term wear.

Shipping Included

No freight charges at checkout. The price you see is the price you pay. The enclosure ships assembled and ready to install.

Fitment Guide

The P6-P is sized for installs where larger enclosures simply will not fit. At 16"W x 8"H x 10.75"D it occupies a footprint smaller than most factory spare tire wells and fits behind the rear seat of virtually every compact vehicle on the market.

Dimensional Specifications

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

Net Internal Volume: 0.30 ft³

Tuning Frequency: 38Hz

Subwoofer Cutout: 5.95"

Max Mounting Depth: 7.25"

Front Panel Thickness: 1.5" Double Baffle

Driver Compatibility

The P6-P accommodates any 6.5" subwoofer with a cutout diameter at or below 5.95" and a mounting depth at or below 7.25". Verify both dimensions against your driver's published specifications before ordering.

Compatible Driver

The following driver is available from Audio Intensity and has been verified for fitment in the P6-P:

Triton SX6D4 — 6.5" Dual 4-Ohm Subwoofer →

Note: The Proline X 6" subwoofer will be available shortly and will replace this recommendation once live.

Ideal Install Applications

Behind Rear Seat

At 8" tall and 10.75" deep, the P6-P fits behind the rear seat of most compact sedans, coupes, and hatchbacks without requiring seat modification or custom fabrication.

Compact Trunk Builds

The 16" width fits comfortably in most compact trunk configurations without blocking access to the spare tire or cargo floor latches.

Stealth Installs

The compact footprint and Dark Gray Trunkliner finish make the P6-P essentially invisible in most trunk environments — the bass is present but the box is not obvious.

Dual Configuration

Two P6-P enclosures side by side measure 32" wide — a viable dual setup in most full-size sedan trunks for significantly increased output and cone area.

Precision-Built. Tennessee-Made. Shipping Included.

The Proline X P6-P is a single 6.5" ported enclosure built to a spec, not a price point. Langboard Elite MDF. V-groove and dado joinery. 1.5" double baffle. In-house terminal cup. Hand-assembled in Tennessee and inspected before it ships.

If you need real bass in a space where larger enclosures will not fit, this is the correct enclosure. $149.99 Dark Gray Trunkliner. $159.99 Plush Black. Shipping included.

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.