JTR Captivator 2400ULF | 18" 2400W Ultra-Low-Frequency Subwoofer

The JTR Captivator 2400ULF is a high-output, ultra-low-frequency powered subwoofer engineered for serious home theater and high-performance audio systems. Combining a high-excursion 18-inch driver, built-in 2400-watt RMS DSP-controlled Class D amplifier and a large bass-reflex enclosure tuned to 10 Hz, the Captivator 2400ULF delivers the deep extension and tremendous dynamic capability for which JTR subwoofers are known in a more manageable single-driver format.

With a manufacturer-rated frequency response of 12 Hz to 165 Hz ±3 dB and in-room response extending below 10 Hz, the 2400ULF is capable of reaching well into the infrasonic region while maintaining the output required for demanding movie soundtracks and reference-level playback.

High-Excursion 18-Inch Driver

At the heart of the Captivator 2400ULF is JTR's 18-inch high-excursion driver with 36 mm of Xmax.

The current driver incorporates a redesigned motor structure with more than a pound of aluminum within the motor and less than 1 mH of inductance. JTR states that the design produces approximately 30% lower distortion than its previous reference drivers, while also increasing output and extending low-frequency capability.

The driver is completely front-firing, providing additional flexibility when integrating the subwoofer into dedicated theaters and listening rooms.

2400-Watt RMS DSP Amplifier

The Captivator 2400ULF incorporates a built-in 2400-watt RMS Class D amplifier capable of operating at up to 95% efficiency.

Integrated DSP is optimized specifically for the driver and enclosure, allowing JTR to shape the system for smooth frequency response, high output and minimal distortion.

The current DSP platform also provides automatic input selection, advanced automatic turn-on and a reduced noise floor.

Both RCA and balanced XLR inputs are provided, along with a 12-volt trigger for integration with surround processors and control systems.

Bass-Reflex Enclosure Tuned to 10 Hz

The Captivator 2400ULF isn't simply designed to produce powerful conventional bass. Its large bass-reflex enclosure is tuned to 10 Hz, allowing the system to reproduce extremely deep low-frequency information.

A large slot port is designed to minimize turbulence and compression at high output levels, while the substantial cabinet volume allows the 18-inch driver to operate effectively at frequencies that smaller subwoofers may struggle to reproduce.

JTR specifies the Captivator 2400ULF at:

12 Hz – 165 Hz ±3 dB

JTR also specifies in-room response below 10 Hz, with actual room response dependent on placement, room dimensions and boundary reinforcement.

Serious Output in a More Manageable Format

The 2400ULF provides an important alternative to JTR's enormous dual-18-inch Captivator models.

Its 41" H × 20.5" W × 22.5" D enclosure retains the narrow frontal profile of the larger Captivator designs while requiring substantially less depth than the 4000ULF.

That can make the 2400ULF considerably easier to incorporate into dedicated theaters, media rooms and multi-subwoofer installations without giving up true ultra-low-frequency capability.

LF Adjust for Room Integration

JTR includes LF Adjust to provide additional flexibility when adapting the Captivator 2400ULF to different acoustic environments.

Room gain can substantially alter the lowest frequencies produced by a powerful subwoofer. LF Adjust provides another tool for optimizing response in applications ranging from smaller enclosed rooms to environments with less low-frequency reinforcement.

Combined with appropriate placement, room correction and professional calibration, the 2400ULF can serve as either an extremely capable standalone subwoofer or part of a multi-subwoofer bass system.

Baltic Birch Construction

Extreme low-frequency reproduction creates tremendous mechanical forces, making enclosure construction particularly important.

The Captivator 2400ULF is built from 18 mm, 13-ply void-free Baltic Birch plywood with extensive internal bracing. This provides a strong, rigid enclosure designed to withstand the forces generated by the high-excursion 18-inch driver.

The cabinet is finished in Matte Black Paint and includes a magnetically attached grille.

Built for High-Performance Home Cinema

The Captivator 2400ULF offers an appealing combination of deep extension, substantial output and a more manageable cabinet size than JTR's dual-18-inch flagship Captivator configurations.

Its 18-inch driver, 36 mm Xmax, 2400-watt RMS amplifier and 10 Hz bass-reflex tuning make it an exceptional candidate for dedicated home theaters where genuine ultra-low-frequency performance matters.

For larger theaters, multiple 2400ULF subwoofers can also be incorporated into a professionally designed bass system to provide additional output and more consistent low-frequency response across multiple seating positions.

Technical Specifications

Shipping / Freight Notice

JTR Speakers products require additional freight charges. Freight is not included at checkout. After your order is received, JTR will calculate the applicable shipping/freight cost based on the product and delivery destination. An additional freight charge will be invoiced after order entry.

JTR Captivator 2400ULF at The Grid HiFi

The JTR Captivator 2400ULF brings serious ultra-low-frequency performance to systems that don't require the enormous enclosure and dual-driver configuration of the Captivator 4000 series. With an 18-inch high-excursion driver, 2400 watts RMS of amplification, 10 Hz port tuning and rated extension to 12 Hz ±3 dB, it provides a formidable foundation for high-performance home cinema.

At The Grid HiFi in Houston, Texas, we can help design and integrate JTR subwoofers into complete private cinema and home theater systems, including single- and multi-subwoofer layouts, surround processing, room acoustics, system integration and professional calibration.