Sound Barrier SWX121 — Single 21″ Passive Subwoofer
SWX121 Overview
The Sound Barrier SWX121 is a high-performance 21-inch passive subwoofer built for professional sound reinforcement applications demanding powerful, controlled low-frequency output. At its core is a long-excursion 21-inch low-frequency driver featuring a 6-inch voice coil and neodymium motor structure, delivering 141dB max SPL and a usable frequency range of 28Hz–200Hz (-3dB). The horn-assisted resonant enclosure design maximizes electroacoustic efficiency while maintaining tight, musical bass reproduction. The SWX121 is purpose-built for touring engineers, system integrators, nightclub installers, and live event production companies requiring scalable, high-output subwoofer solutions.
With 4-ohm impedance and NL4 connectivity, the SWX121 integrates directly into touring-grade amplification and DSP processing chains, and its passive architecture supports flexible multi-cabinet array configurations including ground-stacked and vertically stacked deployments.
Key Features
- 21-Inch Long-Excursion Driver — High-efficiency transducer with a 6-inch voice coil and neodymium motor structure for exceptional thermal capacity, precise cone control, and high-volume air displacement
- Horn-Assisted Resonant Enclosure — Optimized enclosure geometry enhances sensitivity and output efficiency while maintaining articulate, musical low-frequency reproduction
- High Power Handling — Rated at 1500W AES continuous and 6000W peak, supporting high-output amplification in demanding live and installed environments
- 102dB Sensitivity — Measured at 1W / 1M, enabling high SPL output with efficient amplifier utilization
- Interlocking Anti-Slip Stacking Grooves — Enclosure geometry allows secure multi-cabinet stacking to improve low-frequency coupling and overall system efficiency in multi-sub arrays
- 18mm Multi-Ply Birch Plywood Construction — Extensive internal bracing minimizes cabinet resonance and maximizes acoustic efficiency across demanding touring and installation cycles
- Touring-Grade Hardware — Protective steel grille, durable textured finish, integrated handles, pole-mount capability, and caster provisions support reliable transport, setup, and long-term operation
- NL4 Connectivity — Professional Neutrik NL4 input ensures compatibility with touring-standard amplification and system processing infrastructure
Connectivity & I/O
- Neutrik NL4 speaker input connector
Technical Specifications
| Driver Size | 21 inch |
| Voice Coil | 6 inch |
| Motor Structure | Neodymium |
| Frequency Response | 28Hz–200Hz (-3dB) |
| Extended Low-Frequency Range | 28Hz–300Hz |
| Sensitivity | 102dB / 1W / 1M |
| Max SPL | 141dB |
| Power Handling (AES) | 1500W |
| Power Handling (Peak) | 6000W |
| Impedance | 4 ohms |
| Enclosure Type | Horn-assisted resonant |
| Cabinet Material | 18mm multi-ply birch plywood |
| Connector | Neutrik NL4 |
| Configuration | Passive |
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