Short answer: the JTR Speakers Captivator 4000ULF. It ranks #6 of 143 subwoofers by sound quality (rated 4.5/5) at $5,699 and is still sold new; the Monoprice Monolith 16 THX Ultra ranks #19 (rated 4.4/5) and is discontinued, so it is only an option used.
Buy the JTR Speakers Captivator 4000ULF. It is rated higher for sound quality and still sold new, while the Monoprice Monolith 16 THX Ultra is discontinued.
Looking for alternatives? See the complete Subwoofers rankings.
Prices on this page were last checked November 7, 2026 at 7:34 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
| JTR Speakers Captivator 4000ULF | Monoprice Monolith 16 THX Ultra | |
|---|---|---|
| Price | $5,699 each | $2,300 Discontinued |
| Ranked | #6 of 143 in Large Home Subwoofers (Over 75 lbs) | #19 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | ported, front |
| Output SPL at 10 Hz | 111.0 dB | - |
| Output SPL at 12.5 Hz | 115.3 dB | - |
| Output SPL at 15 Hz | 119.3 dB | 107.3 dB |
| Output SPL at 20 Hz | 122.3 dB | 118.4 dB |
| Output SPL at 25 Hz | 126.1 dB | 123.3 dB |
| Output SPL at 31.5 Hz | 129.3 dB | 125.1 dB |
| Output SPL at 40 Hz | 130.7 dB | 126.3 dB |
| Output SPL at 50 Hz | 131.2 dB | 126.5 dB |
| Output SPL at 63 Hz | 130.9 dB | 126.6 dB |
| Output SPL at 80 Hz | 130.6 dB | 126.8 dB |
| Output SPL at 100 Hz | 130.5 dB | 127.2 dB |
| Output SPL at 125 Hz | 129.5 dB | 127.6 dB |
| CEA-2010-A Average (40-80Hz) | 130.8 dB | 126.5 dB |
| Dimensions | 41”H x 20.5”W x 39.5”D (1041.4 x 520.7 x 1003.3 mm) | 25.6”H x 22”W x 28.1”D (650.2 x 558.8 x 713.7 mm) |
| Weight | 265 lbs (120.2 kg) | 171.5 lbs (77.8 kg) |
| Warranty | 5/3 | 5 |
| Cabinet Color | black, custom | black |
| Country | United States | United States |
| Measurement Source | Data-bass | Audioholics |
| Drivers | 2x 18” (457mm) driver | 16” (406mm) driver |
| Inputs | XLR, RCA | XLR, RCA, XLR out |
| XLR Input | Yes | Yes |
| RCA Input | Yes | Yes |
| TRS Input | No | No |
| Optical Input | No | No |
| Coaxial Input | No | No |
| USB Input | No | No |
| HDMI Input | No | No |
| AES Input | No | No |
| Aux Input | No | No |
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