Short answer: the Paradigm Signature Sub 2. It ranks #33 of 143 subwoofers by sound quality, rated 4.3/5, at $9,494.56; the RBH Sound Unrivaled 21-SF/R ranks #91, rated 4.1/5, and costs $11,995, so there is little reason to consider the other one.
The case for the Paradigm Signature Sub 2: A sealed subwoofer with six 10 inch drivers, strong deep bass, and flexible stereo, LFE, and balanced inputs. The catch: The 622.3H x 603.2W x 568.2D mm cabinet and 229.9 lbs (104.3 kg) mass make this a serious placement and moving commitment.
The case for the RBH Sound Unrivaled 21-SF/R: A colossal sealed subwoofer with a 21 inch carbon fiber driver and extraordinary deep bass output for the biggest home theaters. Watch for: At about 151kg (333 lbs), moving or placing this cabinet is a multi-person job.
Buy the Paradigm Signature Sub 2. It is rated higher for sound quality than the RBH Sound Unrivaled 21-SF/R and costs less, so only choose the other one for a particular feature it does better.
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Prices on this page were last checked November 14, 2026 at 6:17 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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Specifications Side By Side
| Paradigm Signature Sub 2 | RBH Sound Unrivaled 21-SF/R | |
|---|---|---|
| Price | $9,494.56 | $11,995 |
| Ranked | #33 of 143 in Large Home Subwoofers (Over 75 lbs) | #91 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | sealed | sealed |
| Output SPL at 10 Hz | 97.7 dB | 91.3 dB |
| Output SPL at 12.5 Hz | 101.2 dB | 97.7 dB |
| Output SPL at 15 Hz | 105.6 dB | - |
| Output SPL at 20 Hz | 109.4 dB | 112.3 dB |
| Output SPL at 25 Hz | 112.9 dB | 117.2 dB |
| Output SPL at 31.5 Hz | 116.2 dB | 120.1 dB |
| Output SPL at 40 Hz | 119.9 dB | 119.5 dB |
| Output SPL at 50 Hz | 123.2 dB | 118.7 dB |
| Output SPL at 63 Hz | 125.5 dB | 118.4 dB |
| Output SPL at 80 Hz | 126.0 dB | 118.7 dB |
| Output SPL at 100 Hz | 125.1 dB | 119.2 dB |
| Output SPL at 125 Hz | 123.3 dB | - |
| CEA-2010-A Average (40-80Hz) | 123.7 dB | 118.8 dB |
| Dimensions | 24.5”H x 23.7”W x 22.4”D (622.3 x 603.2 x 568.2 mm) | 27.3”H x 43”W x 21”D (692.2 x 1092.2 x 533.4 mm) |
| Weight | 229.9 lbs (104.3 kg) | 332.9 lbs (151.0 kg) |
| Warranty | 3 | 10/3 |
| Cabinet Color | black, wood | - |
| Country | Canada | United States |
| Measurement Source | Audioholics | Manufacturer |
| Drivers | 6x 10” (254mm) driver | 21” carbon fiber driver |
| Inputs | RCA (stereo/mono), LFE, XLR (balanced) | - |
| XLR Input | Yes | - |
| RCA Input | Yes | - |
| TRS Input | No | - |
| Optical Input | No | - |
| Coaxial Input | No | - |
| USB Input | No | - |
| HDMI Input | No | - |
| AES Input | No | - |
| Aux Input | No | - |
| Output SPL at 14 Hz | - | 100.8 dB |
| Output SPL at 16 Hz | - | 105.5 dB |
| Frequency Response | - | 12-80Hz, ±3dB |
| Power Handling | - | 4000W thermal power handling |
Where the Ratings Come From
- Paradigm Signature Sub 2: manufacturer specifications and listening comparisons; no independent measurement has been published yet.
- RBH Sound Unrivaled 21-SF/R: manufacturer specifications and listening comparisons; no independent measurement has been published yet.
This comparison is generated from the ratings, specifications and measurements on each product’s own page, and it updates when that data changes. How we rank explains how each rating is decided.
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