Short answer: the WW Speaker Cabinets X21 - B&C 21DS115-4. Both are rated 4.6/5 for sound quality (#3 and #4 of 110 subwoofers), and the WW Speaker Cabinets X21 - B&C 21DS115-4 costs $3995 against $10000 for the Pro Audio Technology LFC-24sm, so with nothing between them on sound quality, price settles it.
The case for the WW Speaker Cabinets X21 - B&C 21DS115-4: 21-inch driver in a large ported cabinet delivers 131.3dB CEA-2010-A average, the highest output of any passive subwoofer tested. Set against that: Premium $3,995 price, massive 52 kg (114.6 lbs) cabinet, and ported room gain dependency.
Buy the WW Speaker Cabinets X21 - B&C 21DS115-4. Both are rated the same for sound quality, and it costs $6005 less than the Pro Audio Technology LFC-24sm.
Looking for alternatives? See the complete Subwoofers rankings.
Specifications Side By Side
| Pro Audio Technology LFC-24sm | WW Speaker Cabinets X21 - B&C 21DS115-4 | |
|---|---|---|
| Price | $10,000 Passive | $3995 Passive |
| Ranked | #4 of 110 in Large Home Subwoofers (Over 75 lbs) | #3 of 110 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | ported, front |
| Passive | Yes | Yes |
| Output SPL at 20 Hz | 123.7 dB | 121.9 dB |
| Output SPL at 25 Hz | 131.4 dB | 120.8 dB |
| Output SPL at 31.5 Hz | 133.6 dB | 122.5 dB |
| Output SPL at 40 Hz | 135.4 dB | 126.7 dB |
| Output SPL at 50 Hz | 136.0 dB | 129.2 dB |
| Output SPL at 63 Hz | 135.2 dB | 132.9 dB |
| CEA-2010-A Average (40-80Hz) | 135.5 dB (avg of 3/4 bands) | 131.3 dB |
| Dimensions | 26"H x 60.5"W x 21"D (660.4 x 1536.7 x 533.4 mm) | 24"H x 32"W x 32"D (609.6 x 812.8 x 812.8 mm) |
| Weight | 266.1 lbs (120.7 kg) | 115.1 lbs (52.2 kg) |
| Cabinet Color | black | - |
| Country | United States | United States |
| Measurement Source | Brent Butterworth | Data-bass |
| Drivers | 24" (610mm) driver | 21" (533mm) driver |
| Output SPL at 12.5 Hz | - | 96.2 dB |
| Output SPL at 15 Hz | - | 111.9 dB |
| Output SPL at 80 Hz | - | 136.3 dB |
| Output SPL at 100 Hz | - | 139.0 dB |
| Output SPL at 125 Hz | - | 140.1 dB |
Related Speaker Comparisons
More top alternatives to WW Speaker Cabinets X21 - B&C 21DS115-4:
- JTR Speakers Captivator S2 vs WW Speaker Cabinets X21 - B&C 21DS115-4
- JTR Speakers Growler (2015) vs WW Speaker Cabinets X21 - B&C 21DS115-4
- Danley Sound Labs DTS10 vs WW Speaker Cabinets X21 - B&C 21DS115-4
- Monoprice Monolith 16 THX Ultra vs WW Speaker Cabinets X21 - B&C 21DS115-4
- Reaction Audio PV-15X vs WW Speaker Cabinets X21 - B&C 21DS115-4
Prices on this page were last checked September 23, 2026 at 11:24 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
Pro Audio Technology LFC-24sm: $10,000 Passive eBay
Pros: Independent CEA-2010 testing records 123.7 dB at 20 Hz and 135.5 dB (avg of 3/4 bands) through 40-80 Hz. The ported, front enclosure with 24” (610mm) driver is best suited to demanding film bass in a large room.
Cons: The 660.4H x 1536.7W x 533.4D mm cabinet and 120.7 kg mass still need deliberate placement and calibration.
Full Pro Audio Technology LFC-24sm review and specifications →
| CEA-2010-A Average (40-80Hz) | 135.5 dB (avg of 3/4 bands) |
|---|---|
| Cabinet Color | black |
| Country | United States |
| Dimensions | 26"H x 60.5"W x 21"D (660.4 x 1536.7 x 533.4 mm) |
| Drivers | 24" (610mm) driver |
| Enclosure | ported, front |
| Measurement Source | Brent Butterworth |
| Output SPL at 20 Hz | 123.7 dB |
| Output SPL at 25 Hz | 131.4 dB |
| Output SPL at 31.5 Hz | 133.6 dB |
| Output SPL at 40 Hz | 135.4 dB |
| Output SPL at 50 Hz | 136.0 dB |
| Output SPL at 63 Hz | 135.2 dB |
| Passive | Yes |
| Weight | 266.1 lbs (120.7 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Independently measured by Brent Butterworth; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons
- Pro Audio Technology LFC-24sm vs JTR Speakers Captivator S2
- Pro Audio Technology LFC-24sm vs JTR Speakers Growler (2015)
- Pro Audio Technology LFC-24sm vs Danley Sound Labs DTS10
- Pro Audio Technology LFC-24sm vs Monoprice Monolith 16 THX Ultra
- Pro Audio Technology LFC-24sm vs Reaction Audio PV-15X
- Pro Audio Technology LFC-24sm vs JBL 4645C
- Pro Audio Technology LFC-24sm vs Chase Home Theater SS18.1
- Pro Audio Technology LFC-24sm vs HSU Research VTF-15H MK2
- See all 9 comparisons
WW Speaker Cabinets X21 - B&C 21DS115-4: $3995 Passive eBay
Pros: 21-inch driver in a large ported cabinet delivers 131.3dB CEA-2010-A average, the highest output of any passive subwoofer tested.
Cons: Premium $3995 price, massive 52 kg cabinet, and ported room gain dependency.
Full WW Speaker Cabinets X21 - B&C 21DS115-4 review and specifications →
| CEA-2010-A Average (40-80Hz) | 131.3 dB |
|---|---|
| Country | United States |
| Dimensions | 24"H x 32"W x 32"D (609.6 x 812.8 x 812.8 mm) |
| Drivers | 21" (533mm) driver |
| Enclosure | ported, front |
| Measurement Source | Data-bass |
| Output SPL at 12.5 Hz | 96.2 dB |
| Output SPL at 15 Hz | 111.9 dB |
| Output SPL at 20 Hz | 121.9 dB |
| Output SPL at 25 Hz | 120.8 dB |
| Output SPL at 31.5 Hz | 122.5 dB |
| Output SPL at 40 Hz | 126.7 dB |
| Output SPL at 50 Hz | 129.2 dB |
| Output SPL at 63 Hz | 132.9 dB |
| Output SPL at 80 Hz | 136.3 dB |
| Output SPL at 100 Hz | 139.0 dB |
| Output SPL at 125 Hz | 140.1 dB |
| Passive | Yes |
| Weight | 115.1 lbs (52.2 kg) |
- Reviews, Comparisons and Sound Samples
- Independently measured by Data-bass; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons
- WW Speaker Cabinets X21 - B&C 21DS115-4 vs JTR Speakers Captivator S2
- WW Speaker Cabinets X21 - B&C 21DS115-4 vs JTR Speakers Growler (2015)
- WW Speaker Cabinets X21 - B&C 21DS115-4 vs Danley Sound Labs DTS10
- WW Speaker Cabinets X21 - B&C 21DS115-4 vs Monoprice Monolith 16 THX Ultra
- WW Speaker Cabinets X21 - B&C 21DS115-4 vs Reaction Audio PV-15X
- WW Speaker Cabinets X21 - B&C 21DS115-4 vs JBL 4645C
- WW Speaker Cabinets X21 - B&C 21DS115-4 vs Chase Home Theater SS18.1
- WW Speaker Cabinets X21 - B&C 21DS115-4 vs HSU Research VTF-15H MK2
- See all 9 comparisons