HK Audio LINEAR SUB 4000 18" Passive Subwoofer

HK Audio LINEAR SUB 4000

The HK Audio LINEAR SUB 4000 is a passive 18-inch dual-vented bandpass subwoofer engineered for high-output touring systems where deep bass extension and SPL capability aren't negotiable. Handling 2400W program power and reaching 137dB peak SPL, this cabinet extends usable response down to 31Hz at -10dB—low enough to reproduce synthesizer sub-bass and kick drum fundamentals with authority. The dual-vented bandpass design optimizes efficiency in the 39-100Hz range, making this subwoofer the recommended pairing for LINEAR 5 LTS long-throw systems or as a sub-low extension beneath LINEAR SUB 2000 units when you need additional headroom and deeper extension.

In large venue and festival applications, the SUB 4000's 4-ohm impedance and 106dB sensitivity (1W @ 1m) deliver efficient power transfer from high-output amplifiers like Lab.Gruppen IPD and PLM 12K44 controllers, which have dedicated filter presets for this cabinet. The 18-inch driver features a 4-inch voice coil with advanced ventilated voice coil gap technology, maintaining thermal stability during sustained high-power operation. Dual Speakon NL4 connectors with switchable pin assignment (1+/1- or 2+/2-) support flexible wiring configurations in multi-cabinet arrays. The birch multiplex cabinet with acrylic enamel finish survives transport abuse, while eight MultiGrip handles positioned around the enclosure facilitate balanced rigging and ground-stacking. At 125.9 pounds with dual M20 pole mounts, the SUB 4000 integrates into LINEAR 5 systems or supplements existing subwoofer arrays requiring extended low-frequency performance. Explore our passive subwoofers for more touring-grade options.

Dual-Vented Bandpass Design For Deep Extension

The dual-vented bandpass topology optimizes low-frequency output in the critical 39-100Hz range by coupling the driver to two tuned ports—one front-firing, one rear-firing. This design delivers higher efficiency and deeper extension than sealed or single-ported enclosures of comparable size, while maintaining controlled output that doesn't turn into excessive port noise. The 18-inch driver features a 4-inch voice coil with advanced ventilated voice coil gap technology, where airflow channels around the voice coil reduce thermal compression during sustained high-power operation. This thermal management is critical when running 2400W program power in festival environments where the subwoofer operates continuously at high levels. Maximum SPL reaches 137dB peak at 10% THD in half-space, with usable response extending to 31Hz at -10dB—low enough to reproduce the fundamental frequencies of synthesized bass and large acoustic instruments without rolling off. 

Optimized For Lab.Gruppen Amplification

Factory filter presets for Lab.Gruppen IPD and PLM 12K44 controllers eliminate the guesswork in system tuning. These presets include optimized EQ, limiting, and crossover settings specifically matched to the SUB 4000's acoustic characteristics, ensuring you get maximum output and driver protection without hours of measurement and adjustment. The 4-ohm nominal impedance and 106dB sensitivity (1W @ 1m) provide efficient power transfer from high-output amplifiers, meaning you're getting usable SPL without requiring excessive amplifier wattage. The 100Hz active crossover frequency works for most full-range applications, but can be set lower when deploying the SUB 4000 as a sub-low extension beneath LINEAR SUB 2000 units—creating layered bass arrays where the SUB 4000 handles the deepest octaves while lighter cabinets cover the upper bass range. Dual Speakon NL4 connectors with switchable pin assignment (1+/1- or 2+/2-) support various wiring schemes in multi-cabinet arrays and bi-amp configurations.

Tour-Grade Construction With Flexible Rigging

The birch multiplex cabinet construction with black acrylic enamel finish provides the structural rigidity needed to survive repeated load-ins while maintaining acoustic integrity. Birch multiplex resists warping and delamination better than particle board or lower-grade plywood, which matters when the cabinet experiences temperature and humidity swings during touring. Eight MultiGrip handles positioned strategically around the enclosure support balanced lifting and positioning in ground-stacked arrays or flown configurations. The 2mm metal grille backed with black acoustic foam protects the driver from physical damage without introducing audible diffraction. Dual M20 pole mounts allow stacking mid/high cabinets directly on the subwoofer for compact system footprints in installations where floor space is limited. At 35.75" x 20" x 31.8" and 125.9 pounds, the SUB 4000 requires proper rigging equipment and crew for safe deployment, but delivers the output and extension needed for large-scale productions where smaller subwoofers simply can't keep up.

Highlights

• 2400W program power handling (4800W peak) with 18-inch driver featuring 4-inch ventilated voice coil
• Dual-vented bandpass design extends response to 31Hz (-10dB) with 137dB peak SPL capability
• 4-ohm nominal impedance and 106dB sensitivity optimized for Lab.Gruppen amplification
• Factory filter presets available for Lab.Gruppen IPD and PLM 12K44 controllers
• Dual Speakon NL4 connectors with switchable pin assignment (1+/1- or 2+/2-)
• Birch multiplex construction with eight MultiGrip handles for balanced rigging and transport
• Compatible with LINEAR 5 full-range systems and as sub-low extension for LINEAR SUB 2000

LINEAR SUB 4000 18" Specifications

What's in the Box

Note: This is a passive subwoofer requiring external amplification. Recommended amplifiers include Lab.Gruppen IPD and PLM 12K44 controllers with dedicated filter presets. Protective cover available separately (Art. 381686).