JTR Captivator 4000ULF | Dual 18" 4000W Ultra-Low-Frequency Subwoofer

Freight is calculated by JTR after the sale

The JTR Captivator 4000ULF is an extreme-performance powered subwoofer engineered for reference home theaters and high-output audio systems where genuine infrasonic extension is a priority. Combining dual high-excursion 18-inch drivers, a built-in 4000-watt RMS DSP-controlled Class D amplifier and a massive bass-reflex enclosure tuned to 10 Hz, the Captivator 4000ULF is built to reproduce the lowest frequencies in demanding movie soundtracks with tremendous authority.

With a rated frequency response of 10.5 Hz to 125 Hz ±3 dB, the Captivator 4000ULF reaches far below conventional bass frequencies, delivering the combination of deep extension, displacement and dynamic capability required for serious private cinema.

Dual 18-Inch High-Excursion Drivers

The Captivator 4000ULF uses two 18-inch drivers with 36 mm of Xmax, giving the subwoofer enormous displacement capability for reproducing extremely low frequencies at high output levels.

JTR's current-generation drivers feature redesigned motor structures, more than a pound of aluminum within each driver's motor and less than 1 mH of inductance. JTR states that the design produces approximately 30% lower distortion than its previous reference drivers.

Both drivers are completely front-firing, helping simplify placement and integration in dedicated theater environments.

4000-Watt RMS DSP-Controlled Amplifier

Power comes from an integrated 4000-watt RMS Class D amplifier capable of operating at up to 95% efficiency.

The amplifier incorporates DSP optimized specifically for the Captivator's drivers and enclosure. JTR's current DSP platform includes automatic input selection, advanced automatic turn-on and a lower noise floor, providing both substantial output capability and convenient system integration.

Connections include balanced XLR and unbalanced RCA inputs, along with a 12-volt trigger.

Bass-Reflex Enclosure Tuned to 10 Hz

The Captivator 4000ULF is designed from the ground up for ultra-low-frequency reproduction.

Its large bass-reflex enclosure is tuned to 10 Hz and incorporates a substantial slot port engineered to minimize turbulence and compression when the subwoofer is operating at extreme output levels.

The combination of dual 18-inch drivers, enormous displacement, 4000 watts of amplification and the ultra-low enclosure tuning gives the 4000ULF a manufacturer-rated response of:

10.5 Hz – 125 Hz ±3 dB

This allows the system to reproduce infrasonic content that extends well below the traditional audible bass range.

High Output With Low Distortion

Producing deep bass is only part of the challenge. Producing it at substantial output while maintaining control requires considerable driver capability, amplifier power and enclosure volume.

JTR designed the Captivator 4000ULF around this combination. Its latest driver platform provides 36 mm Xmax, while the heavily braced enclosure and large low-tuned port are engineered to support the tremendous mechanical forces generated during demanding low-frequency passages.

The result is a subwoofer intended for systems where both extension and output matter.

LF Adjust for Room Integration

The Captivator 4000ULF incorporates JTR's LF Adjust, providing additional flexibility when adapting its low-frequency behavior to the installation.

Room dimensions, placement and boundary reinforcement can dramatically influence bass response. LF Adjust provides another tool for integrating the subwoofer into environments ranging from smaller enclosed theaters to spaces with significantly less low-frequency room gain.

For sophisticated installations, the 4000ULF can also be incorporated into a professionally calibrated multi-subwoofer system to improve bass consistency across multiple seating positions.

Baltic Birch Construction

The enormous mechanical forces generated by dual high-excursion 18-inch drivers require an exceptionally rigid enclosure.

JTR constructs the Captivator 4000ULF from 18 mm, 13-ply void-free Baltic Birch plywood, with extensive internal bracing to minimize unwanted cabinet movement.

The enclosure is finished in Matte Black Paint and includes a magnetically attached grille for a clean appearance in dedicated theater installations.

A Serious Foundation for Reference Cinema

The Captivator 4000ULF is designed for systems where sub-bass isn't simply an effect—it is a fundamental part of the home theater experience.

Its combination of dual 18-inch drivers, 36 mm Xmax, 4000 watts RMS, 10 Hz bass-reflex tuning and 10.5 Hz rated extension makes it particularly suited to large dedicated theaters, reference media rooms and high-output multi-subwoofer installations.

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 4000ULF at The Grid HiFi

The JTR Captivator 4000ULF is built for home theaters where extreme low-frequency extension, enormous dynamic capability and substantial output are part of the system design. With dual 18-inch high-excursion drivers, 4000 watts RMS of amplification and bass-reflex tuning at 10 Hz, it provides a formidable low-frequency foundation for reference private cinema.

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