JTR Speakers Captivator 4000ULF vs Monoprice Monolith 16 THX Ultra

Last updated: August 9, 2026

Short answer: the JTR Speakers Captivator 4000ULF for the higher ranking, the Monoprice Monolith 16 THX Ultra for the lower price. The JTR Speakers Captivator 4000ULF ranks #4 of 97 subwoofers at $5000. The Monoprice Monolith 16 THX Ultra ranks #13 at $2300, $2700 cheaper.

The case for the Monoprice Monolith 16 THX Ultra: 16-inch ported driver and THX Ultra certification deliver 126.5dB CEA-2010-A average at a fraction of the price of the subwoofers ranked. The tradeoff: Heavy at 78 kg and ported design can interact with room acoustics.

Buy the JTR Speakers Captivator 4000ULF if the ranking matters more than the price. Buy the Monoprice Monolith 16 THX Ultra if the price matters more than the ranking.

Specifications Side By Side

JTR Speakers Captivator 4000ULF Monoprice Monolith 16 THX Ultra
Price$5,000$2,300
Ranked#4 of 97 in Large Powered Home Subwoofers (Over 75 lbs)#13 of 97 in Large Powered Home Subwoofers (Over 75 lbs)
Enclosureported, frontported, front
Output SPL at 10 Hz111.0 dB-
Output SPL at 12.5 Hz115.3 dB-
Output SPL at 15 Hz119.3 dB107.3 dB
Output SPL at 20 Hz122.3 dB118.4 dB
Output SPL at 25 Hz126.1 dB123.3 dB
Output SPL at 31.5 Hz129.3 dB125.1 dB
Output SPL at 40 Hz130.7 dB126.3 dB
Output SPL at 50 Hz131.2 dB126.5 dB
Output SPL at 63 Hz130.9 dB126.6 dB
Output SPL at 80 Hz130.6 dB126.8 dB
Output SPL at 100 Hz130.5 dB127.2 dB
Output SPL at 125 Hz129.5 dB127.6 dB
CEA-2010-A Average (40-80Hz)130.8 dB126.5 dB
Dimensions41.0"H x 20.5"W x 39.5"D (1041.4 x 520.7 x 1003.3 mm)25.6"H x 22.0"W x 28.1"D (650.2 x 558.8 x 713.7 mm)
Weight265 lbs / 120.2 kg171.5 lbs / 77.8 kg
Warranty5/35
Cabinet Colorblack, customblack
CountryUnited StatesUnited States
Measurement SourceData-bassAudioholics
Drivers2x 18" (457mm) driver16" (406mm) driver

The Two Speakers In Full

JTR Speakers Captivator 4000ULF: $5,000

JTR Speakers Captivator 4000ULF ranking card

CEA-2010-A Average (40-80Hz)130.8 dB
Cabinet Colorblack, custom
CountryUnited States
Dimensions41.0"H x 20.5"W x 39.5"D (1041.4 x 520.7 x 1003.3 mm)
Drivers2x 18" (457mm) driver
Enclosureported, front
Measurement SourceData-bass
Output SPL at 10 Hz111.0 dB
Output SPL at 12.5 Hz115.3 dB
Output SPL at 15 Hz119.3 dB
Output SPL at 20 Hz122.3 dB
Output SPL at 25 Hz126.1 dB
Output SPL at 31.5 Hz129.3 dB
Output SPL at 40 Hz130.7 dB
Output SPL at 50 Hz131.2 dB
Output SPL at 63 Hz130.9 dB
Output SPL at 80 Hz130.6 dB
Output SPL at 100 Hz130.5 dB
Output SPL at 125 Hz129.5 dB
Warranty5/3
Weight265 lbs / 120.2 kg

Monoprice Monolith 16 THX Ultra: $2,300

Monoprice Monolith 16 THX Ultra ranking card

Pros: 16-inch ported driver and THX Ultra certification deliver 126.5dB CEA-2010-A average at a fraction of the price of the subwoofers ranked above it.

Cons: Heavy at 78 kg and ported design can interact with room acoustics.

Notes: Product # 42031

CEA-2010-A Average (40-80Hz)126.5 dB
Cabinet Colorblack
CountryUnited States
Dimensions25.6"H x 22.0"W x 28.1"D (650.2 x 558.8 x 713.7 mm)
Drivers16" (406mm) driver
Enclosureported, front
Measurement SourceAudioholics
Output SPL at 15 Hz107.3 dB
Output SPL at 20 Hz118.4 dB
Output SPL at 25 Hz123.3 dB
Output SPL at 31.5 Hz125.1 dB
Output SPL at 40 Hz126.3 dB
Output SPL at 50 Hz126.5 dB
Output SPL at 63 Hz126.6 dB
Output SPL at 80 Hz126.8 dB
Output SPL at 100 Hz127.2 dB
Output SPL at 125 Hz127.6 dB
Warranty5
Weight171.5 lbs / 77.8 kg

As an Amazon Associate I earn from qualifying purchases.

Product prices and availability were last checked August 9, 2026 at 6:57 AM UTC 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.