Proline X
Proline X P8-S | Single 8" Sealed Subwoofer Enclosure | V3
SKU: P8-S III G
- Best For: Sound Quality (SQ) builds / Compact installs
- Volume: 0.45 ft³ (Net)
- Enclosure Type: Sealed
- Sonic Character: Tight, Accurate, Musical
Financing available — choose Shop Pay Installments at checkout.
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Proline X P8-S | Single 8" Sealed Subwoofer Enclosure | V3
Proline X P8-S
Single 8" Sealed Subwoofer Enclosure | V3
Accurate Bass. Compact Footprint. No Compromises on Build Quality.
The Proline X P8-S is a single 8" sealed enclosure built for installs where accuracy and controlled bass response matter more than raw output. Sealed alignment on an 8" driver produces tight, transient-accurate low frequencies that integrate cleanly with a front stage — no port resonance, no boost peak, no frequency-specific coloration. The response is flat and predictable, which makes it easy to tune with a DSP or amplifier bass control and gives you a bass foundation that works with the music rather than over it.
At 13" wide, 10" tall, and 10.5" deep, the P8-S fits behind most rear seats, under most truck bench seats, and in trunk corners that a larger enclosure would not clear. The 6.125" max mounting depth accommodates the majority of standard 8" drivers including high-excursion SQ-oriented motors that would exceed the depth limit on shallower boxes.
Every panel is CNC-cut from Langboard Elite MDF to exact internal volume and assembled by hand in our Tennessee facility. A single recessed ABS/Carbon Fiber Composite terminal cup handles wiring, pre-wired with 12g OFC speaker wire. Finish options are Dark Gray Trunkliner or Plush Black. Shipping is included.
Why Sealed for an 8" SQ Build
The 8" driver occupies a specific role in car audio — it is the preferred size for sound quality competition and critical listening installs because its low moving mass allows it to start and stop faster than larger drivers. Pairing that speed advantage with a sealed enclosure preserves the transient accuracy that makes the 8" format valuable in the first place. A ported 8" produces more output but trades some of that precision for efficiency. The P8-S is built for the listener who wants the 8" to do what it does best.
At 0.45 ft³ net, the P8-S puts most standard 8" drivers in the middle of their recommended sealed range — not undersized, not oversized. No damping material required to correct an oversized box. No excursion limiting from a box that is too small. The volume is matched to the driver category.
Transient Accuracy
Sealed alignment allows the driver to start and stop precisely with the music. Bass notes have distinct attack and decay. The P8-S preserves the speed advantage that makes the 8" format the preferred choice for SQ competition and critical listening.
Flat, Predictable Response
No port resonance. No tuning peak. No frequency-specific coloration. The P8-S produces a smooth, controlled rolloff below resonance that integrates cleanly with a front stage and responds accurately to DSP correction.
DSP-Friendly Alignment
Sealed enclosures exhibit a predictable 12 dB/octave rolloff that responds accurately to DSP bass boost and crossover adjustments. If you are running a Goldhorn DSP or any active processor, sealed is the alignment that gives you the most control over the final response.
0.45 ft³ — Correctly Sized
Most 8" drivers intended for sealed alignment specify optimal volumes between 0.35 ft³ and 0.60 ft³. The P8-S lands in the center of that range, providing universal compatibility without requiring volume correction or damping material.
Construction: Built to the Same Standard as Every Proline X Enclosure
The P8-S uses the same construction methodology as every enclosure in the Proline X Performance Series. Langboard Elite MDF. V-groove and dado joinery. In-house terminal cup. Hand-assembled in Tennessee. The only variables between SKUs are dimensions, volume, and alignment — the build quality is consistent across the lineup.
Langboard Elite MDF — Named, Verified, Documented
Every panel is cut from Langboard Elite MDF — 3/4" (18mm), a named, mill-documented panel stock produced in the United States. Generic MDF descriptions like "high-density" or "premium" carry no defined standard. Langboard Elite carries published mill data that is verifiable and consistent sheet to sheet.
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
Every panel joint uses V-groove and dado joinery — CNC-cut interlocking grooves that mechanically lock panels before adhesive is applied. The dado creates a tongue-and-groove mechanical interlock that resists shear forces regardless of glue condition. Every corner is locked. Every seam is airtight. Sealed enclosures in particular depend on joint integrity — a single air leak degrades bass output and response accuracy. The P8-S does not leak.
In-House ABS/Carbon Fiber Composite Terminal Cup
The terminal cup is built in-house at our Tennessee facility. The ABS/Carbon Fiber Composite recessed cup features stainless steel hardware, aluminum landing plates, and copper ring terminals, pre-wired with 12g OFC speaker wire. The recessed mount protects terminals from cargo contact. Copper ring terminals provide a clean, corrosion-resistant connection point that does not loosen over time under vibration.
ShopSabre CNC Routers
Every panel is machine-cut on ShopSabre industrial CNC routers. Consistent geometry, no hand-cut variance, no gaps at the joints. The internal volume of every P8-S is identical to spec.
Hand-Assembled in Tennessee
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 blends with factory trunk materials for a clean, stealth appearance. Plush Black delivers the traditional aftermarket look. Both are durably bonded.
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 P8-S is one of the more compact single 8" sealed enclosures in the Performance Series. At 13"W x 10"H x 10.5"D it fits behind most rear seats in compact and mid-size vehicles and under most truck bench seats without modification.
Dimensional Specifications
External Dimensions: 13" W x 10" H x 10.5" D
Net Internal Volume: 0.45 ft³
Tuning Frequency: N/A — Sealed
Subwoofer Cutout: 7.25"
Max Mounting Depth: 6.125"
Front Panel Thickness: 0.75" Single Baffle
Driver Compatibility
The P8-S accommodates any 8" subwoofer with a cutout diameter at or below 7.25" and a mounting depth at or below 6.125". Verify both dimensions against your driver's published specifications before ordering.
Compatible Drivers
The following drivers are available from Audio Intensity and are compatible with the P8-S:
Image Dynamics ID8 V4 → Prodigy NB2-8D4 → Image Dynamics IDQ8 V4 → Prodigy NB5-8D4 → Arc Audio Arc Series 8" →Always verify cutout diameter and mounting depth against your specific driver's published specifications before ordering.
Ideal Install Applications
Under Truck Bench Seat
At 10.5" deep and 10" tall, the P8-S fits under most full-size truck bench seats without modification. A clean, invisible install that does not sacrifice cab space.
Behind Rear Seat
The compact footprint fits behind most rear seats in compact and mid-size sedans. The 13" width leaves room for spare tire access in most configurations.
SQ and Competition Builds
Sealed alignment and 0.45 ft³ net volume make the P8-S the correct enclosure for 8" drivers used in sound quality competition builds where accuracy and integration with the front stage are the priority.
DSP-Controlled Systems
The flat, predictable sealed rolloff makes the P8-S the preferred enclosure format for systems running a Goldhorn DSP or any active processor. Sealed alignment responds accurately to DSP correction and equalization.
Tight Bass. Tennessee-Built. Shipping Included.
The Proline X P8-S is a single 8" sealed enclosure built to a spec, not a price point. Langboard Elite MDF. V-groove and dado joinery. In-house terminal cup. Hand-assembled in Tennessee and inspected before it ships.
If you are building an SQ system, running a DSP, or just need accurate controlled bass from a compact footprint — this is the correct enclosure. $129.99 Dark Gray Trunkliner. $139.99 Plush Black. Shipping included.
| Material | Langboard Elite MDF, 3/4" (18mm) |
| Enclosure Type | Sealed (Acoustic Suspension) |
| Net Internal Volume | 0.45 ft³ |
| External Dimensions | 13" W x 10" H x 10.5" D |
| Subwoofer Cutout | 7.25" |
| Max Mounting Depth | 6.125" |
| Front Panel Thickness | 0.75" |
| Finish | Dark Gray Trunkliner / Plush Black (+$10) |
| Terminal Cup | ABS/Carbon Fiber Composite, recessed mount, stainless hardware, copper ring terminals |
| Wiring | Pre-wired 12g OFC speaker wire |
| Warranty | 1-Year Limited |
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.
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 |
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.
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.
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.
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.
Handcrafted in USA
Hand-assembled at our facility in Tullahoma, TN. Every enclosure is inspected before it ships.
Tuned to the Build
Internal volume and port geometry are calculated to spec and CNC-cut to exact dimensions. The box performs the same way every time.
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