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Every Proline X enclosure is manufactured in our Tullahoma, Tennessee facility using materials and construction methods that most enclosure brands don't touch.
48.5 lb/ft³ density and 200 psi internal bond strength, the highest-grade MDF available for enclosure construction.
Full coverage on materials and construction defects. We stand behind every enclosure we build.
Internal volume, port tuning, and cabinet dimensions are spec'd to each driver diameter, not a universal fit applied across sizes.
CNC-manufactured in our Tennessee facility on ShopSabre routers. Not imported. Not outsourced.
The 6.5 inch subwoofer is the smallest practical sub size for vehicle audio. Below 6.5 inch and you're in midbass driver territory, where the cone simply can't move enough air to reproduce the sub-bass region (anything below 60Hz) with usable output. Above 8 inch and you're committing to a meaningful enclosure footprint that won't fit in compact cars, motorcycles, or behind-seat truck installs where every cubic inch counts.
The 6.5 inch sub fills the gap. It produces real low-frequency output (typically usable to 40-50Hz depending on the driver and alignment), fits in cabinet sizes that smaller installations can accommodate, and integrates cleanly with full-range door speakers without overlap. For powersports applications, motorcycles, side-by-sides, golf carts, and compact car builds, the 6.5 inch sub is often the only viable subwoofer option.
The Proline X 6.5 inch lineup is currently ported-only, and there's a technical reason for it. A 6.5 inch sub has limited cone area and limited Xmax compared to a 10 or 12 inch driver. To produce usable SPL, the driver needs help. A tuned port adds acoustic output to the cone's output in the same frequency range, producing meaningfully more bass per watt than a sealed alignment can achieve at this size class.
For larger drivers, the SPL gain from porting is a tradeoff with sealed accuracy. For 6.5 inch drivers, the SPL gain from porting is what makes the size class viable for subwoofer use. A sealed 6.5 inch enclosure produces tight bass at low volume but runs out of usable SPL quickly. A ported 6.5 inch enclosure delivers the output that makes the size class worth installing in the first place.
Sealed 6.5 inch enclosures are expanding in the Proline X lineup as additional driver-matched configurations are tooled. For now, the collection is ported.
The 6.5 inch lineup includes both Performance Series and Professional Series ported enclosures, in single and dual configurations.
Performance Series (P6-P-G, P6D-P-G): Universal-fit ported construction with internal volume and port tuning calculated for the typical 6.5 inch driver. Dado and V-Groove panel construction. The right pick when you want a quality 6.5 inch enclosure at the most accessible price point.
Professional Series (Pro 6-P XL, Pro 6D-P XL): Double-baffle construction with threaded inserts matched to driver bolt patterns, polyfill, and 12 gauge OFC pre-wiring landed at the Proline X composite terminal cup. The competition-grade choice when the 6.5 inch sub is doing serious work in a SPL-priority build, or when the cabinet needs to handle sustained high-output use without panel fatigue.
Powersports and motorcycle audio: The 6.5 inch sub is standard for fairing-mounted and saddlebag-mounted bass on touring motorcycles and side-by-sides. The enclosure footprint matches the available mounting volume in these applications, and the port-loaded output makes the size class viable for outdoor environments where ambient noise is high.
Compact vehicle behind-seat installs: Sedans, hatchbacks, and small SUVs where an 8 inch enclosure won't physically fit behind the rear seat or under a cargo cover. The 6.5 inch ported enclosure produces usable subwoofer output in cabinet dimensions that fit the space.
Stealth installs: Builds where the enclosure needs to disappear visually. A 6.5 inch box can hide in places a larger enclosure cannot, and the dual configuration produces meaningful output from a footprint that's still compact.
Front-stage bass reinforcement: Some SQ-focused builds use a 6.5 inch sub as a front-stage low-frequency anchor to extend the front speakers' low-end response below what a typical door speaker can produce. The 6.5 inch sub blends cleanly with the door speakers without creating a backward-biased bass image.
Every Proline X 6.5 inch enclosure is built from Langboard Elite MDF (48.5 lb/ft³ density, 200 psi internal bond strength), the highest-grade MDF available for enclosure construction. Cabinet panels are joined using Dado and V-Groove cuts that mechanically interlock at each panel intersection before bonding. Every enclosure is CNC-cut on ShopSabre routers in our Tullahoma, Tennessee facility.
Port dimensions are calculated from the target tuning frequency and driver Xmax to produce laminar airflow at maximum excursion. Even at this size class, port chuffing is a problem with poorly designed enclosures; the Proline X port geometry eliminates it within the operating range the driver was designed for.
The 6.5 inch sub is the smallest practical subwoofer size for vehicle audio. It fits in installs where an 8 or 10 inch enclosure won't physically work, including motorcycles, powersports vehicles, compact cars, and behind-seat truck applications. It produces usable bass to about 40-50Hz, which covers the fundamental frequencies of most musical content. For SQ-focused front-stage bass reinforcement, it integrates cleanly with door speakers without a backward-biased bass image.
A 6.5 inch sub in a properly tuned ported enclosure with a matched amplifier typically produces around 110-115 dB of usable output, depending on the specific driver. That's significantly less than a 10 or 12 inch sub but enough to add real bass impact to a system in vehicles where larger drivers won't fit. The Proline X Driv 650 is rated for 400W RMS, which is typical for the size class.
A 6.5 inch driver has limited cone area and Xmax. To produce usable SPL, the driver needs the acoustic gain that a tuned port provides. Sealed alignment at this size class produces tight bass at low volume but runs out of usable SPL quickly. Ported alignment is the right acoustic choice for 6.5 inch subwoofer use. Sealed configurations are expanding in the lineup for buyers who want sealed alignment specifically.
Yes, and arguably better than a larger sub. The crossover point between a 6.5 inch sub and typical 6.5 inch front door speakers is around 80-100Hz, which is high enough to be inaudible as a directional source but low enough to leave the front speakers handling their natural range. Run an active or passive crossover with a low-pass filter on the sub at 80-100Hz and a high-pass on the front speakers at the same frequency.
Match the amplifier's RMS output at your wired impedance to the driver's RMS rating. The Proline X Driv 650 runs 400W RMS. Most 6.5 inch subs run 200-500W RMS depending on the model. A small monoblock amplifier (300-500W class) matched to the driver at the final wired impedance is the standard approach. Don't underpower; underpowering and clipping is the most common cause of failure at this size class.
Yes. The dual 6.5 inch enclosures (P6D-P-G and Pro 6D-P XL) accept two drivers wired in series or parallel depending on amplifier impedance requirements. Two dual 4 ohm 6.5 inch subs in parallel present a 1 ohm load. Two dual 2 ohm subs in parallel present a 0.5 ohm load (most amps won't handle this). Confirm your amplifier's stable impedance specification before wiring.
Drivers Built to Match
The drivers below are matched to the enclosures above by Thiele-Small parameters. Buying together guarantees the alignment, port tuning, and damping work the way the engineering intended.
