RBH UNRIVALED 21 – 21" Passive Subwoofer

RBH Sound UNRIVALED 21 Subwoofer

Experience the raw power of true infrasonic performance. If you haven’t felt high-output infrasonic frequencies, you owe it to yourself to experience the UNRIVALED 21. With an anechoic frequency response down to 10 Hz, single-digit in-room frequencies are possible. Pioneering G.A.D.S. technology gives the UNRIVALED 21 the mass it needs to control the raw power of its driver, for incredibly tight, accurate reproduction with exceptional in-room response. Immerse yourself in the movie with definitive power.

• (1) 21″ (533mm) Sandwiched Carbon Fiber Cone Driver
• Sealed Enclosure with Double-Walled HDF Construction
• 10 – 100 Hz (±0.5 dB); 12 – 80 Hz (±3 dB) Frequency Response
• 92 dB Sensitivity
• 4 Ω Impedance
• Recommended Amplifier Power: 2000 – 4000 Watts
• 371 lbs (168.3 kg) Weight
• Designed, Engineered, Tested and Assembled in USA
• 10 Year Limited Warranty

Highlights & Key Technologies

Award-Winning Infrasonic Performance
The UNRIVALED 21 delivers high-output infrasonic frequencies with an anechoic frequency response down to 10 Hz, making single-digit in-room frequencies possible. It was named Best Infrasonic Subwoofer by Audioholics in 2023 and Best Extreme Subwoofer by Home Theater Review in 2024.

21″ Sandwiched Carbon Fiber Cone Driver
The 21″ (533mm) proprietary driver was co-engineered by RBH Sound and Pierce Audio. This groundbreaking, low-distortion design, made exclusively for RBH, features a sandwiched carbon fiber cone, shorting cap, copper sleeve, and custom machine work, with stacked neodymium magnet cylinders in the motor structure for unbelievable low-frequency output. Pierce Audio has built precision subwoofer and speaker drivers by hand in the Pacific Northwest since 2004.

G.A.D.S. (Granular Acoustic Damping System)
The patent-pending Granular Acoustic Damping System is employed in this sealed design to keep the cabinet stable under the load of a high-powered driver. It provides mass-loading effects that improve the rigidity of the cabinet and serves as an excellent acoustic absorber at the lowest frequencies. Although the granular particulates occupy a significant amount of space within the enclosure, their impact on the total internal volume is negligible, so the tuning of the box remains nearly unaffected.

Double-Walled HDF Cabinet & Anti-Resonance Construction
The UNRIVALED 21 is built into a heavily braced, double-walled High-Density Fiberboard (HDF) enclosure. Each UNRIVALED cabinet is internally lined with an anti-resonance material made from rubber and aluminum, adhered to the internal walls to add to the absorption of unwanted vibrations. For this sealed enclosure, wool is used as the primary acoustic absorber for its greater density and absorptive ability over polyfill.

Internally Wired with Kimber Kable
As part of the no-compromise pledge of UNRIVALED systems, the UNRIVALED 21 is internally wired with Kimber Kable, using their proven braided geometry to further improve crosstalk rejection and reduce external influences.

Linear Response
An incredibly linear response throughout the bandwidth delivers accurate, faithful reproduction across the entire operating range.

Details & Specifications

TECHNICAL SPECIFICATIONS
Model Name: UNRIVALED 21
System Type: Freestanding Subwoofer
Series: UNRIVALED
Frequency Response: 10 – 100 Hz (±0.5 dB) (per product page); 12 – 80 Hz (±3 dB) (per technical information sheet)
Sensitivity: 92 dB
Amplifier Power: 4000 watts
Impedance: 4 Ω
Recommended Power: 2000 – 4000 Watts
Crossover Frequencies: Variable
Crossover Slope: 6 – 48 dB/Octave

DRIVER
Drivers: (1) 21″ (533mm) Carbon Fiber Cone
Design: Sandwiched carbon fiber cone with shorting cap, copper sleeve, and stacked neodymium magnet motor structure
Co-Engineering: RBH Sound and Pierce Audio

CABINET
Enclosure: Double-Walled HDF, Sealed
Acoustic Damping: G.A.D.S. (Granular Acoustic Damping System); wool fill; rubber/aluminum anti-resonance lining
Internal Wiring: Kimber Kable
Finish: Satin Black or Satin White
Grille: Magnetic beauty-baffle and fabric grille included

CONNECTIONS & CONTROL
Features: XLR Input/Output, Variable Phase

PHYSICAL
Dimensions (H × W × D): 27-1/4″ × 43″ × 21″ (692 × 1092 × 533 mm)
Weight: 371 lbs (168.3 kg)
Outriggers: Heavy-duty outriggers included
Country of Origin: Designed, Engineered, Tested and Assembled in USA from American and imported parts

WARRANTY
Warranty: 10 Year Limited