Short answer: the Harbottle Audio C24 L2. It ranks #18 of 143 subwoofers by sound quality, rated 4.4/5, at $10,078.84; the RBH Sound Unrivaled 21-SF/R ranks #91, rated 4.1/5, and costs $11,995, which makes this an easy call rather than a real tradeoff.
The Harbottle Audio C24 L2 is the better-sounding option. A 24 inch ported subwoofer with deep, powerful bass and plenty of headroom for demanding film soundtracks in large rooms. The catch: The 899.9H x 722.1W x 512.1D mm cabinet and 149.9 lbs (68.0 kg) mass make this a serious placement and moving commitment.
What the RBH Sound Unrivaled 21-SF/R does well: A colossal sealed subwoofer with a 21 inch carbon fiber driver and extraordinary deep bass output for the biggest home theaters. The tradeoff: At about 151kg (333 lbs), moving or placing this cabinet is a multi-person job.
Buy the Harbottle Audio C24 L2. It is rated higher for sound quality than the RBH Sound Unrivaled 21-SF/R and costs less, which makes it the one to get unless you need something the other one does better.
Want more options? Browse the full Subwoofers rankings.
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
| Harbottle Audio C24 L2 | RBH Sound Unrivaled 21-SF/R | |
|---|---|---|
| Price | $10,078.84 | $11,995 |
| Ranked | #18 of 143 in Large Home Subwoofers (Over 75 lbs) | #91 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported | sealed |
| Output SPL at 10 Hz | 99.0 dB | 91.3 dB |
| Output SPL at 12.5 Hz | 103.0 dB | 97.7 dB |
| Output SPL at 15 Hz | 110.0 dB | - |
| Output SPL at 20 Hz | 117.0 dB | 112.3 dB |
| Output SPL at 25 Hz | 120.7 dB | 117.2 dB |
| Output SPL at 31.5 Hz | 124.0 dB | 120.1 dB |
| Output SPL at 40 Hz | 126.3 dB | 119.5 dB |
| Output SPL at 50 Hz | 127.3 dB | 118.7 dB |
| Output SPL at 63 Hz | 126.7 dB | 118.4 dB |
| Output SPL at 80 Hz | 126.0 dB | 118.7 dB |
| Output SPL at 100 Hz | 125.0 dB | 119.2 dB |
| CEA-2010-A Average (40-80Hz) | 126.6 dB | 118.8 dB |
| Dimensions | 35.4”H x 28.4”W x 20.2”D (899.9 x 722.1 x 512.1 mm) | 27.3”H x 43”W x 21”D (692.2 x 1092.2 x 533.4 mm) |
| Weight | 149.9 lbs (68.0 kg) | 332.9 lbs (151.0 kg) |
| Cabinet Color | black, white, red, blue | - |
| Country | Canada | United States |
| Measurement Source | Manufacturer | Manufacturer |
| Drivers | 24” (610mm) driver | 21” carbon fiber driver |
| Warranty | - | 10/3 |
| 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
- Harbottle Audio C24 L2: 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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