JBL Expands the SRX900 Series with SRX915SF and SRX918SF Subwoofers

These new subwoofers promise to deliver robust low-frequency reinforcement for touring rigs, fixed installations, and a wide spectrum of performance venues. Below, we’ll take a deep technical dive into their capabilities, discuss how they slot into existing SRX900 systems, and highlight new opportunities for those looking to add or upgrade low-end support in their designs.

1. An Evolving SRX900 Family 

The SRX900 Series has already proven itself as a flexible platform for both line array and point-source applications, thanks to JBL’s advanced transducer designs, integrated DSP, and user-friendly networking. With the introduction of the SRX915SF (single 15-inch) and the SRX918SF (single 18-inch), JBL has filled an important gap—dedicated subwoofer solutions that can be flown alongside SRX900 mid/high elements or ground-stacked beneath them. 

Why This Matters 

• Existing SRX900 Users: Those who have already invested in SRX906LA or SRX910LA arrays can now add subwoofers that share the same rigging, DSP, and network ecosystem, ensuring seamless integration. 
• New Prospects: For operators seeking a fresh start with a compact, but powerful system, these subwoofers present a self-contained, highly controlled low-frequency option that supports a variety of show sizes and venue types. 

2. The SRX915SF: Compact and Flyable 

2.1 Design Philosophy & Rigging 

The SRX915SF is a single 15-inch powered subwoofer intended for both suspended and ground-based configurations. Its three-point rigging allows for direct attachment to SRX906LA line array elements, letting sound engineers fly subwoofers above or alongside the main arrays. This is particularly advantageous in venues where floor space is limited or when you need to maintain a clean line-of-sight for the audience. 

• Mixed Array Capability: You can create a flown cluster consisting of SRX915SF subwoofers and SRX906LA tops in the same vertical array. This has significant benefits for time alignment because the subs and mids/highs can originate from nearly the same vertical plane, minimizing destructive interference and providing more coherent coverage. 

2.2 Transducer & Amplifier 

At its heart is the JBL 2276H 15-inch Differential Drive® woofer. Differential Drive technology leverages a dual voice coil, dual gap design for: 

• Higher Power Handling: Two coils share the thermal load, reducing compression. 
• Lower Weight: Lighter ferrite magnets can be used without sacrificing performance, helping keep overall cabinet weight to about 39 kg (86 lbs). 
• Extended Dynamic Range: Minimizing thermal compression maintains consistent output over extended periods. 

A 1,100 W continuous Class D amplifier powers the woofer, passively cooled for reliability in challenging conditions. Built-in DSP includes user-adjustable EQ, delay, and specialized limiters to protect the driver. 

2.3 Dimensions, Porting & Construction 

• Dimensions: Approximately 19.4" x 20.0" x 24.0" (H x W x D). Truck-pack friendly for both touring and rentals. 
• Large, Optimized Ports: A carefully engineered low-frequency port design maximizes airflow, mitigating chuffing even at high SPL. This contributes to the sub’s 130 dB max SPL rating. 
• Rugged Birch Enclosure: An 18 mm birch plywood shell with DuraFlex™ finish protects against wear and tear. Integrated handles and rigging points complete the package. 

3. The SRX918SF: More Depth and Punch 

3.1 Design Philosophy & Rigging 

The SRX918SF is the bigger sibling in this new subwoofer duo. Sporting a single 18-inch Differential Drive woofer, it can also be flown or ground-stacked, typically pairing with the larger SRX910LA line array elements. It features a similar integrated three-point rigging system, enabling a variety of suspended configurations or stand-alone sub arrays in large-format deployments. 

• Flexibility for Different Venues: Where the SRX915SF might be best in smaller to mid-size venues (especially if array flying is needed), the SRX918SF offers deeper extension and higher SPL capabilities—up to 134 dB—ideal for larger concert halls, outdoor festivals, or clubs requiring substantial sub-bass presence. 

3.2 Transducer & Amplifier 

Central to the SRX918SF’s performance is the JBL 2279-1 18-inch Differential Drive® driver, designed to handle heavy low-frequency content with minimal distortion or power compression. Like the SRX915SF, the amplifier is a 1,100 W Class D module with a universal power supply, passively cooled for low noise and fewer moving parts. 

3.3 Dimensions, Porting & Construction 

• Dimensions: Approximately 22.6" x 28.0" x 26.9" (H x W x D). Bigger than the 15-inch model, offering a more authoritative bottom end. 
• Improved Port Design: With a larger cabinet volume, the port geometry is engineered to handle increased airflow at high power. This ensures low distortion across the 35 Hz – 100 Hz frequency range (-10 dB point). 
• Road-Ready Build: Constructed with 18 mm birch plywood and a tough DuraFlex™ coat, it resists the rigors of touring or high-traffic installations. 

4. Control, Networking, and DSP 

4.1 HControl Protocol & JBL Performance Software 

A defining feature of the SRX900 Series is networked control via HControl protocol. Both the SRX915SF and SRX918SF include dual Neutrik etherCON connections, allowing for: 

• Redundant or Daisy-Chained Networking: Build robust audio networks or simple single-line solutions, depending on your application. 
• Centralized System Management: Access key parameters (EQ, crossover presets, delay, limiter thresholds) through JBL Performance software, Venue Synthesis, or ArrayLink. 

4.2 On-Board DSP & Presets 

Every cabinet includes a rear-panel LCD interface for local adjustments and status monitoring. In addition, advanced features like LevelMax limiters protect the transducers from over-excursion. You can fine-tune: 

• Crossover Frequency: Match sub/low transition precisely to the main line array or point-source boxes. 
• Delay: Align subwoofers to the top boxes or to a distributed system. 
• EQ & Cardioid Configuration: Built-in processing provides modes to shape tonality or establish directional low-frequency patterns (in ground-stack mode only). 

5. Practical System Applications 

5.1 Flown 15" Subs with SRX906LA + 18" Subs on the Floor 

A particularly powerful combination is to fly SRX915SF units alongside SRX906LA elements (for improved LF localization and reduced throw distance from the stage), while supplementing overall low-frequency impact with SRX918SF subwoofers on the ground. This approach provides: 

1. Unified Vertical Axis: Mid/high and sub energy originate from a closer plane, enhancing coherence for near- to mid-field areas. 
2. Extended Bass Impact: Ground-stacked SRX918SF units deliver more potent sub-bass for the entire audience area, especially those further from the arrays. 
3. Flexibility in Tuning: Engineers can selectively EQ and time-align the flown 15-inch subs to blend with the ground-based 18s, maintaining smooth response throughout the venue. 

5.2 Ground-Stacked Cardioid Array 

For operators looking to reduce stage wash or keep low frequencies away from backstage areas, cardioid configurations are crucial. These subwoofers allow for front-back-front driver alignments when ground-stacked. By harnessing the built-in DSP presets for cardioid patterns, you can achieve significant rear cancellation—improving sound quality onstage and reducing low-frequency build-up in sensitive areas. 

Note: JBL specifies that cardioid setups cannot be flown with these particular subwoofers, so plan for ground-based arrays if cardioid directivity is required. 

5.3 Large-Format Arrays for Tours & Festivals 

When scaling up to larger events (e.g., major festivals or stadium shows), the network capabilities and robust build of these subs become invaluable. Technicians can quickly configure a wide range of subwoofer placements and angles while monitoring performance via the software suite. Coupling multiple SRX918SF or SRX915SF units expands SPL headroom and coverage uniformity. 

6. Future-Proof with Firmware & Software 

JBL continues to release firmware updates and plugins (e.g., Q-SYS, AMX modules), ensuring the SRX900 Series subwoofers remain compatible with evolving control standards. These updates frequently refine DSP algorithms, add user-requested presets, and streamline network stability. For permanent installations, these subwoofers can be integrated into building-wide management systems, offering remote control and health monitoring to authorized staff. 

7. Conclusion 

Welcomed by Existing SRX900 Owners 

• The SRX915SF and SRX918SF expand low-frequency options for anyone already using SRX906LA or SRX910LA. Because they share the same rigging system, DSP architecture, and networking protocol, they can be seamlessly added without retraining crews or reconfiguring the entire system. 

Attractive to New Users and Venues 

• The combination of high-power, compact enclosures, integrated Class D amplification, and advanced network control makes these subwoofers appealing as a standalone solution. Nightclubs, houses of worship, theaters, and touring outfits can deploy a cutting-edge system without needing external amplification racks or cumbersome outboard processing. 

Technical Highlights 

• Differential Drive® Transducers minimize thermal compression, yielding high continuous SPL and extended dynamic range. 
• Unified Control & Monitoring via HControl protocol and JBL Performance software fosters quick, precise system optimization. 
• Rugged, Tour-Grade Enclosures with easy rigging solutions, large ports for reduced turbulence, and thoughtful truck-pack dimensions. 
• Cardioid Ground-Stack Capabilities for better stage management and targeted audience coverage. 

From flown 15-inch sub arrays that neatly integrate with SRX906LA elements to ground-stacked 18-inch stacks designed to shake larger venues, the SRX915SF and SRX918SF collectively raise the bar for low-frequency performance within the SRX900 family. With robust design, flexible configuration options, and network-based control, these newest additions are poised to meet the needs of a wide range of live sound professionals—whether they’re upgrading an existing JBL rig or building an entirely new system. 

For further details on specifications, presets, and array configurations, consult the official SRX900 Series User Manual, Rigging Manual, and Performance Software guides.