} HK Audio LINEAR SUB 4000 18" Passive Subwoofer — Pro Audio Reserve
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HK Audio LINEAR SUB 4000 18" Passive Subwoofer front view

HK Audio LINEAR SUB 4000 18" Passive Subwoofer

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$3,299.00
$2,599.00
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Description

HK Audio LINEAR SUB 4000 Overview

  HK Audio LINEAR SUB 4000 18-inch passive subwoofer front view showing dual-vented bandpass enclosure

The Bass Foundation That Doesn't Ask Permission From the Room

There is a specific moment at outdoor festivals and large indoor events when a subwoofer stops keeping up. The crowd grows, the mix engineer pushes harder, and instead of more bass you get port noise, thermal compression, and a cabinet that sounds like it is working at its limit. The LINEAR SUB 4000 was engineered so that moment never arrives.

The dual-vented bandpass topology fires through one front port and one rear port simultaneously, each tuned to maximize efficiency in the 39 to 100 Hz range where subwoofers actually work for a live crowd. That design gets you deeper extension and higher output from the same cubic volume that a conventional ported box would waste. The 18-inch driver runs a 4-inch voice coil with ventilated voice coil gap technology, meaning active airflow channels around the coil dissipate heat during sustained high-power operation. At 2400W program handling with 4800W peak, this cabinet is built to run hard all night without thermally folding under a festival set. Usable response reaches 31 Hz at -10 dB. That is the fundamental frequency of a synthesizer bass note that most subwoofers quietly pretend does not exist.

 HK Audio LINEAR SUB 4000 rear panel with dual Speakon NL4 connectors and switchable pin assignment

German Engineering, Lab.Gruppen Ready, Array Scalable

HK Audio designed the LINEAR SUB 4000 as part of a complete system architecture, not a standalone box you figure out on site. Factory filter presets for Lab.Gruppen IPD and PLM 12K44 controllers are built around the SUB 4000's actual acoustic measurements. Load the preset and you get optimized EQ curves, crossover points, and driver limiting that protects the cabinet at full output without strangling dynamic headroom. No measurement rig required. No hours of tuning before doors open.

For larger productions, the SUB 4000 scales cleanly. Run it at the standard 100 Hz crossover beneath LINEAR 5 full-range cabinets for a complete main PA. Drop the crossover lower and stack it under LINEAR SUB 2000 units to create a layered bass array where the SUB 4000 covers the deepest octaves and the SUB 2000 handles the upper bass range. The 4-ohm nominal impedance and 106 dB sensitivity at 1W/1m make efficient use of high-output amplification, and the dual Speakon NL4 connectors with switchable pin assignment between 1+/1- and 2+/2- handle multi-cabinet wiring schemes and bi-amp configurations without adapter cables.

 HK Audio LINEAR SUB 4000 birch multiplex cabinet with MultiGrip handles in ground-stack array

125 Pounds of Birch Multiplex Built to Take the Work

Think about what a touring subwoofer actually goes through: loaded off trucks in the rain, stacked three high in a freight elevator, repositioned twice during load-in, then driven hard for eight hours. The cabinet that sounds good in a demo room needs to survive all of that before it ever reaches the audience. The LINEAR SUB 4000's birch multiplex construction resists warping, delamination, and moisture penetration in ways that particle board and lower-grade plywoods cannot. The black acrylic enamel finish takes scratches and scuffs without peeling.

Eight MultiGrip handles are positioned around the enclosure so crew can move and position the cabinet safely with balanced load distribution, whether it is going into a ground stack or being lifted onto rigging. Two M20 pole mounts on the top allow full-range cabinets to sit directly on the subwoofer for compact, single-stack systems where floor footprint matters. The 2mm steel grille backed with acoustic foam protects the driver from physical contact without audible diffraction. At 125.9 lbs and 35.75 inches wide, this is a two-person cabinet. It is also the cabinet that fills outdoor festival grounds with controlled, undistorted low end at 137 dB peak SPL without asking whether the room is cooperating.

Highlights

  • Passive 18" subwoofer with dual-vented bandpass design for maximum efficiency in the 39 to 100 Hz range
  • 2400W program handling, 4800W peak, 1200W RMS continuous
  • 137 dB peak SPL at 10% THD half-space, 135 dB continuous
  • Usable extension to 31 Hz (-10 dB), flat response from 39 Hz within +/-3 dB
  • 18" driver with 4-inch ventilated voice coil gap for thermal management at sustained high power
  • 4-ohm nominal impedance, 106 dB sensitivity at 1W/1m for efficient high-output amplifier pairing
  • Factory filter presets available for Lab.Gruppen IPD and PLM 12K44 controllers
  • 100 Hz active crossover (adjustable lower for sub-low extension use)
  • Compatible with LINEAR 5 full-range systems and as sub-low extension beneath LINEAR SUB 2000 units
  • Dual Speakon NL4 connectors with switchable pin assignment (1+/1- or 2+/2-)
  • Dual M20 pole mounts for full-range cabinet stacking
  • 8x MultiGrip handles for balanced crew handling and positioning
  • Birch multiplex cabinet with black acrylic enamel finish
  • 2mm metal grille backed with black acoustic foam
  • Dimensions: 35.75" x 20" x 31.8" (91 x 51 x 81 cm)
  • Weight: 125.9 lbs (57.1 kg)
  • Protective cover available separately (Art. 381686)

LINEAR SUB 4000 18" Specifications

Specification Details
Type Passive subwoofer, dual-vented bandpass
Driver 1x 18" with 4-inch ventilated voice coil gap
Power Handling (RMS) 1200W
Power Handling (Program) 2400W
Power Handling (Peak) 4800W
Frequency Response (+/-3 dB) 39 Hz to crossover
Frequency Response (-10 dB) 31 Hz to crossover
Sensitivity (1W/1m) 106 dB half-space
Max SPL (10% THD) 135 dB half-space
Max SPL Peak (10% THD) 137 dB half-space
Impedance 4 ohms nominal
Crossover Frequency 100 Hz active (via controller amp, adjustable lower for sub-low use)
Connections 2x Speakon NL4, pin assignment switchable 1+/1- or 2+/2-
Pole Mounts 2x M20
Handles 8x MultiGrip
Recommended Amplification Lab.Gruppen IPD or PLM 12K44 (factory filter presets available)
Compatible Systems LINEAR 5 Full-Range, LINEAR 5 LTS, LINEAR SUB 2000 (sub-low extension)
Cabinet Birch multiplex, black acrylic enamel finish
Grille 2mm steel backed with black acoustic foam
Dimensions (W x H x D) 35.75" x 20" x 31.8" (91 x 51 x 81 cm)
Weight 125.9 lbs (57.1 kg)

What's in the Box

Included Items
HK Audio LINEAR SUB 4000 Passive Subwoofer
User Manual

This is a passive subwoofer requiring external amplification. Lab.Gruppen IPD and PLM 12K44 controllers are recommended and include dedicated factory filter presets. Protective cover available separately (Art. 381686).

Shipping

Shipping & Returns

  • We deliver all US orders in 3–5 business days
  • Free cancellations
  • Returns accepted within 30 days (unused items)

Order Confirmation

Once your order is placed, you will receive an order confirmation email. This confirms that we have received your order and have pre-authorized your credit card for the purchase. After confirming availability with our suppliers, we will proceed accordingly:

  • If your item is available and ready to ship within 1–2 business days, we will process the charge and arrange for shipment.

  • If your item is on backorder or unavailable, the pre-authorization will be voided and you will be notified by email.

  • Please note: While most items ship out within 1–2 business days, total delivery time is typically 3–5 business days, depending on your location and carrier handling.

Order Shipment

If your item is in stock and your payment has been processed, your order will typically ship within 1–2 business days. Total delivery time is approximately 3–5 business days from the date of order. Once shipped, you will receive tracking information at the email address provided during checkout within 24 hours of dispatch.

If you have not received tracking information within 3–5 business days of placing your order, please contact us at support@proaudioreserve.com.

The Distributor-Direct Advantage

To ensure you receive the most recent hardware revisions and 100% factory-sealed units, Pro Audio Reserve utilizes a Distributor-Direct fulfillment model. Unlike big-box retailers that may ship "floor models" or gear that has been sitting in general-purpose warehouses, your equipment is pulled directly from the primary manufacturer hub, serialized, and dispatched. This process ensures the highest level of quality control for professional-grade recording equipment.

Shipping Policy

We currently offer free shipping within the United States only. If the checkout process on our website allows you to enter a shipping address and complete your order, your location is eligible to receive delivery.

Changing Shipping Address

If you need to change your shipping address after your order has been processed or shipped, we will do our best to accommodate the request. Please note that address changes may result in delivery delays. Any additional costs incurred due to address changes, including carrier fees or rerouting charges will be the responsibility of the customer. No exceptions.

Shipping Times

All shipping times provided are estimates and should not be considered guarantees. Most orders ship out within 1–2 business days from the time payment is processed. However, total delivery time is typically 3–5 business days, depending on your location, carrier performance, and supplier fulfillment timelines.

We work closely with our vendors to ensure timely deliveries, but please note that supply chain disruptions, high-demand periods, or weather events may occasionally cause delays beyond our control.

  • To avoid misunderstandings: The “shipping time” refers to the total time from order placement to final delivery, not just when the item leaves the warehouse.

  • Cancellations: If you choose to cancel your order because it has not arrived within the estimated delivery window, you may be responsible for applicable shipping charges, restocking fees, warehouse handling costs, and other related fees.

  • Chargebacks: Customers who initiate chargebacks due to shipping delays without contacting us first may be held legally responsible for losses. We strongly encourage open communication so we can resolve any delivery concerns directly and efficiently via our Atlanta-based support team.

Delivery Options

  • Threshold Shipping: Your item will be delivered to your front door, porch, garage, or a covered entryway.

 

Why Buy From Us

We get it. You've got a lot of choice when it comes to online retailers.
Here's why we think you should shop with us at ProAudioReserve.

  • Free Shipping USA wide. 
  • 30 Day Easy Returns. Not happy with your product, we'll take it back noquestions asked.
  • Great Service. We pride ourselves on the best service, anywhere.

Reviews

Customer Reviews

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Description

HK Audio LINEAR SUB 4000 Overview

  HK Audio LINEAR SUB 4000 18-inch passive subwoofer front view showing dual-vented bandpass enclosure

The Bass Foundation That Doesn't Ask Permission From the Room

There is a specific moment at outdoor festivals and large indoor events when a subwoofer stops keeping up. The crowd grows, the mix engineer pushes harder, and instead of more bass you get port noise, thermal compression, and a cabinet that sounds like it is working at its limit. The LINEAR SUB 4000 was engineered so that moment never arrives.

The dual-vented bandpass topology fires through one front port and one rear port simultaneously, each tuned to maximize efficiency in the 39 to 100 Hz range where subwoofers actually work for a live crowd. That design gets you deeper extension and higher output from the same cubic volume that a conventional ported box would waste. The 18-inch driver runs a 4-inch voice coil with ventilated voice coil gap technology, meaning active airflow channels around the coil dissipate heat during sustained high-power operation. At 2400W program handling with 4800W peak, this cabinet is built to run hard all night without thermally folding under a festival set. Usable response reaches 31 Hz at -10 dB. That is the fundamental frequency of a synthesizer bass note that most subwoofers quietly pretend does not exist.

 HK Audio LINEAR SUB 4000 rear panel with dual Speakon NL4 connectors and switchable pin assignment

German Engineering, Lab.Gruppen Ready, Array Scalable

HK Audio designed the LINEAR SUB 4000 as part of a complete system architecture, not a standalone box you figure out on site. Factory filter presets for Lab.Gruppen IPD and PLM 12K44 controllers are built around the SUB 4000's actual acoustic measurements. Load the preset and you get optimized EQ curves, crossover points, and driver limiting that protects the cabinet at full output without strangling dynamic headroom. No measurement rig required. No hours of tuning before doors open.

For larger productions, the SUB 4000 scales cleanly. Run it at the standard 100 Hz crossover beneath LINEAR 5 full-range cabinets for a complete main PA. Drop the crossover lower and stack it under LINEAR SUB 2000 units to create a layered bass array where the SUB 4000 covers the deepest octaves and the SUB 2000 handles the upper bass range. The 4-ohm nominal impedance and 106 dB sensitivity at 1W/1m make efficient use of high-output amplification, and the dual Speakon NL4 connectors with switchable pin assignment between 1+/1- and 2+/2- handle multi-cabinet wiring schemes and bi-amp configurations without adapter cables.

 HK Audio LINEAR SUB 4000 birch multiplex cabinet with MultiGrip handles in ground-stack array

125 Pounds of Birch Multiplex Built to Take the Work

Think about what a touring subwoofer actually goes through: loaded off trucks in the rain, stacked three high in a freight elevator, repositioned twice during load-in, then driven hard for eight hours. The cabinet that sounds good in a demo room needs to survive all of that before it ever reaches the audience. The LINEAR SUB 4000's birch multiplex construction resists warping, delamination, and moisture penetration in ways that particle board and lower-grade plywoods cannot. The black acrylic enamel finish takes scratches and scuffs without peeling.

Eight MultiGrip handles are positioned around the enclosure so crew can move and position the cabinet safely with balanced load distribution, whether it is going into a ground stack or being lifted onto rigging. Two M20 pole mounts on the top allow full-range cabinets to sit directly on the subwoofer for compact, single-stack systems where floor footprint matters. The 2mm steel grille backed with acoustic foam protects the driver from physical contact without audible diffraction. At 125.9 lbs and 35.75 inches wide, this is a two-person cabinet. It is also the cabinet that fills outdoor festival grounds with controlled, undistorted low end at 137 dB peak SPL without asking whether the room is cooperating.

Highlights

  • Passive 18" subwoofer with dual-vented bandpass design for maximum efficiency in the 39 to 100 Hz range
  • 2400W program handling, 4800W peak, 1200W RMS continuous
  • 137 dB peak SPL at 10% THD half-space, 135 dB continuous
  • Usable extension to 31 Hz (-10 dB), flat response from 39 Hz within +/-3 dB
  • 18" driver with 4-inch ventilated voice coil gap for thermal management at sustained high power
  • 4-ohm nominal impedance, 106 dB sensitivity at 1W/1m for efficient high-output amplifier pairing
  • Factory filter presets available for Lab.Gruppen IPD and PLM 12K44 controllers
  • 100 Hz active crossover (adjustable lower for sub-low extension use)
  • Compatible with LINEAR 5 full-range systems and as sub-low extension beneath LINEAR SUB 2000 units
  • Dual Speakon NL4 connectors with switchable pin assignment (1+/1- or 2+/2-)
  • Dual M20 pole mounts for full-range cabinet stacking
  • 8x MultiGrip handles for balanced crew handling and positioning
  • Birch multiplex cabinet with black acrylic enamel finish
  • 2mm metal grille backed with black acoustic foam
  • Dimensions: 35.75" x 20" x 31.8" (91 x 51 x 81 cm)
  • Weight: 125.9 lbs (57.1 kg)
  • Protective cover available separately (Art. 381686)

LINEAR SUB 4000 18" Specifications

Specification Details
Type Passive subwoofer, dual-vented bandpass
Driver 1x 18" with 4-inch ventilated voice coil gap
Power Handling (RMS) 1200W
Power Handling (Program) 2400W
Power Handling (Peak) 4800W
Frequency Response (+/-3 dB) 39 Hz to crossover
Frequency Response (-10 dB) 31 Hz to crossover
Sensitivity (1W/1m) 106 dB half-space
Max SPL (10% THD) 135 dB half-space
Max SPL Peak (10% THD) 137 dB half-space
Impedance 4 ohms nominal
Crossover Frequency 100 Hz active (via controller amp, adjustable lower for sub-low use)
Connections 2x Speakon NL4, pin assignment switchable 1+/1- or 2+/2-
Pole Mounts 2x M20
Handles 8x MultiGrip
Recommended Amplification Lab.Gruppen IPD or PLM 12K44 (factory filter presets available)
Compatible Systems LINEAR 5 Full-Range, LINEAR 5 LTS, LINEAR SUB 2000 (sub-low extension)
Cabinet Birch multiplex, black acrylic enamel finish
Grille 2mm steel backed with black acoustic foam
Dimensions (W x H x D) 35.75" x 20" x 31.8" (91 x 51 x 81 cm)
Weight 125.9 lbs (57.1 kg)

What's in the Box

Included Items
HK Audio LINEAR SUB 4000 Passive Subwoofer
User Manual

This is a passive subwoofer requiring external amplification. Lab.Gruppen IPD and PLM 12K44 controllers are recommended and include dedicated factory filter presets. Protective cover available separately (Art. 381686).

Shipping

Shipping & Returns

  • We deliver all US orders in 3–5 business days
  • Free cancellations
  • Returns accepted within 30 days (unused items)

Order Confirmation

Once your order is placed, you will receive an order confirmation email. This confirms that we have received your order and have pre-authorized your credit card for the purchase. After confirming availability with our suppliers, we will proceed accordingly:

  • If your item is available and ready to ship within 1–2 business days, we will process the charge and arrange for shipment.

  • If your item is on backorder or unavailable, the pre-authorization will be voided and you will be notified by email.

  • Please note: While most items ship out within 1–2 business days, total delivery time is typically 3–5 business days, depending on your location and carrier handling.

Order Shipment

If your item is in stock and your payment has been processed, your order will typically ship within 1–2 business days. Total delivery time is approximately 3–5 business days from the date of order. Once shipped, you will receive tracking information at the email address provided during checkout within 24 hours of dispatch.

If you have not received tracking information within 3–5 business days of placing your order, please contact us at support@proaudioreserve.com.

The Distributor-Direct Advantage

To ensure you receive the most recent hardware revisions and 100% factory-sealed units, Pro Audio Reserve utilizes a Distributor-Direct fulfillment model. Unlike big-box retailers that may ship "floor models" or gear that has been sitting in general-purpose warehouses, your equipment is pulled directly from the primary manufacturer hub, serialized, and dispatched. This process ensures the highest level of quality control for professional-grade recording equipment.

Shipping Policy

We currently offer free shipping within the United States only. If the checkout process on our website allows you to enter a shipping address and complete your order, your location is eligible to receive delivery.

Changing Shipping Address

If you need to change your shipping address after your order has been processed or shipped, we will do our best to accommodate the request. Please note that address changes may result in delivery delays. Any additional costs incurred due to address changes, including carrier fees or rerouting charges will be the responsibility of the customer. No exceptions.

Shipping Times

All shipping times provided are estimates and should not be considered guarantees. Most orders ship out within 1–2 business days from the time payment is processed. However, total delivery time is typically 3–5 business days, depending on your location, carrier performance, and supplier fulfillment timelines.

We work closely with our vendors to ensure timely deliveries, but please note that supply chain disruptions, high-demand periods, or weather events may occasionally cause delays beyond our control.

  • To avoid misunderstandings: The “shipping time” refers to the total time from order placement to final delivery, not just when the item leaves the warehouse.

  • Cancellations: If you choose to cancel your order because it has not arrived within the estimated delivery window, you may be responsible for applicable shipping charges, restocking fees, warehouse handling costs, and other related fees.

  • Chargebacks: Customers who initiate chargebacks due to shipping delays without contacting us first may be held legally responsible for losses. We strongly encourage open communication so we can resolve any delivery concerns directly and efficiently via our Atlanta-based support team.

Delivery Options

  • Threshold Shipping: Your item will be delivered to your front door, porch, garage, or a covered entryway.

 

Why Buy From Us

We get it. You've got a lot of choice when it comes to online retailers.
Here's why we think you should shop with us at ProAudioReserve.

  • Free Shipping USA wide. 
  • 30 Day Easy Returns. Not happy with your product, we'll take it back noquestions asked.
  • Great Service. We pride ourselves on the best service, anywhere.

Reviews

Customer Reviews

Be the first to write a review
0%
(0)
0%
(0)
0%
(0)
0%
(0)
0%
(0)