Harbottle Audio C24 L2 vs RBH Sound Unrivaled 21-SF/R

Last updated: September 29, 2026

Short answer: the Harbottle Audio C24 L2. It ranks #17 of 109 subwoofers by sound quality, rated 4.4/5, at $10,078.84; the RBH Sound Unrivaled 21-SF/R ranks #75, rated 4.1/5, and costs $11,995, which makes this an easy call rather than a real tradeoff.

Harbottle Audio C24 L2 vs RBH Sound Unrivaled 21-SF/R

The case for the Harbottle Audio C24 L2: Published CEA-2010 specifications list 117.0 dB at 20 Hz and 126.6 dB through 40-80 Hz. The tradeoff: The 899.9H x 722.1W x 512.1D mm cabinet and 68.0 kg mass make this a serious placement and moving commitment.

What the RBH Sound Unrivaled 21-SF/R does well: Manufacturer-supplied CEA-2010 data records 112.3 dB at 20 Hz and 118.8 dB through 40-80 Hz, with a passing result down to 10 Hz. The tradeoff: At around 333 lbs, moving or placing this cabinet is a multi-person job, and the price puts it well outside typical home theater budgets.

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.

Specifications Side By Side

Harbottle Audio C24 L2 RBH Sound Unrivaled 21-SF/R
Price$10,078.84$11,995
Ranked#17 of 109 in Large Home Subwoofers (Over 75 lbs)#75 of 109 in Large Home Subwoofers (Over 75 lbs)
Enclosureportedsealed
Output SPL at 10 Hz99.0 dB91.3 dB
Output SPL at 12.5 Hz103.0 dB97.7 dB
Output SPL at 15 Hz110.0 dB-
Output SPL at 20 Hz117.0 dB112.3 dB
Output SPL at 25 Hz120.7 dB117.2 dB
Output SPL at 31.5 Hz124.0 dB120.1 dB
Output SPL at 40 Hz126.3 dB119.5 dB
Output SPL at 50 Hz127.3 dB118.7 dB
Output SPL at 63 Hz126.7 dB118.4 dB
Output SPL at 80 Hz126.0 dB118.7 dB
Output SPL at 100 Hz125.0 dB119.2 dB
CEA-2010-A Average (40-80Hz)126.6 dB118.8 dB
Dimensions35.4”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)
Weight149.9 lbs (68.0 kg)332.9 lbs (151.0 kg)
Cabinet Colorblack, white, red, blue-
CountryCanadaUnited States
Measurement SourceManufacturerManufacturer
Drivers24” (610mm) driver21” carbon fiber driver
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

More worthwhile head-to-heads for Harbottle Audio C24 L2:

Prices on this page were last checked September 29, 2026 at 3:43 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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The Two Speakers In Full

Harbottle Audio C24 L2: $10,078.84 eBay

Harbottle Audio C24 L2 ranking card

Pros: Published CEA-2010 specifications list 117.0 dB at 20 Hz and 126.6 dB through 40-80 Hz. The ported enclosure with 24” (610mm) driver has the headroom for demanding film bass in a large room.

Cons: The 899.9H x 722.1W x 512.1D mm cabinet and 68.0 kg mass make this a serious placement and moving commitment. Ported output does not solve room modes, so careful placement and calibration remain essential.

Full Harbottle Audio C24 L2 review and specifications →

CEA-2010-A Average (40-80Hz)126.6 dB
Cabinet Colorblack, white, red, blue
CountryCanada
Dimensions35.4”H x 28.4”W x 20.2”D (899.9 x 722.1 x 512.1 mm)
Drivers24” (610mm) driver
Enclosureported
Measurement SourceManufacturer
Output SPL at 10 Hz99.0 dB
Output SPL at 12.5 Hz103.0 dB
Output SPL at 15 Hz110.0 dB
Output SPL at 20 Hz117.0 dB
Output SPL at 25 Hz120.7 dB
Output SPL at 31.5 Hz124.0 dB
Output SPL at 40 Hz126.3 dB
Output SPL at 50 Hz127.3 dB
Output SPL at 63 Hz126.7 dB
Output SPL at 80 Hz126.0 dB
Output SPL at 100 Hz125.0 dB
Weight149.9 lbs (68.0 kg)
Search eBay for Harbottle Audio C24 L2 →

RBH Sound Unrivaled 21-SF/R: $11,995 eBay

RBH Sound Unrivaled 21-SF/R ranking card

Pros: Manufacturer-supplied CEA-2010 data records 112.3 dB at 20 Hz and 118.8 dB through 40-80 Hz, with a passing result down to 10 Hz. The 21” carbon fiber driver and 4,000W thermal power handling gave this sub the first Extreme Bassaholic room rating on record.

Cons: At around 333 lbs, moving or placing this cabinet is a multi-person job, and the price puts it well outside typical home theater budgets.

Full RBH Sound Unrivaled 21-SF/R review and specifications →

CEA-2010-A Average (40-80Hz)118.8 dB
CountryUnited States
Dimensions27.3”H x 43”W x 21”D (692.2 x 1092.2 x 533.4 mm)
Drivers21” carbon fiber driver
Enclosuresealed
Frequency Response12-80Hz, ±3dB
Measurement SourceManufacturer
Output SPL at 10 Hz91.3 dB
Output SPL at 12.5 Hz97.7 dB
Output SPL at 14 Hz100.8 dB
Output SPL at 16 Hz105.5 dB
Output SPL at 20 Hz112.3 dB
Output SPL at 25 Hz117.2 dB
Output SPL at 31.5 Hz120.1 dB
Output SPL at 40 Hz119.5 dB
Output SPL at 50 Hz118.7 dB
Output SPL at 63 Hz118.4 dB
Output SPL at 80 Hz118.7 dB
Output SPL at 100 Hz119.2 dB
Power Handling4000W thermal power handling
Weight332.9 lbs (151.0 kg)
Search eBay for RBH Sound Unrivaled 21-SF/R →