JTR Speakers Captivator S2 vs Monoprice Monolith 16 THX Ultra

Short answer: the JTR Speakers Captivator S2 if sound quality matters most, the Monoprice Monolith 16 THX Ultra if price matters most. The JTR Speakers Captivator S2 ranks #9 of 110 subwoofers, rated 4.5/5, at $3995. The Monoprice Monolith 16 THX Ultra ranks #18, rated 4.4/5, at $2300, $1695 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 (172 lbs) and ported design can interact with room acoustics.

Buy the JTR Speakers Captivator S2 when sound quality outweighs the price for you, and the Monoprice Monolith 16 THX Ultra when the price outweighs sound quality instead.

Looking for alternatives? See the complete Subwoofers rankings.

Specifications Side By Side

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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

JTR Speakers Captivator S2: $3995 eBay

Pros: Independent CEA-2010 testing records 115.1 dB at 20 Hz and 129.4 dB through 40-80 Hz. The sealed enclosure with 2x 18” (457mm) drivers has the headroom for demanding film bass in a large room.

Cons: The 1016.0H x 533.4W x 457.2D mm cabinet and 99.8 kg mass make this a serious placement and moving commitment. A sealed cabinet still needs careful placement and calibration to avoid room-mode peaks.

Notes: Replaced by “RS2”

Full JTR Speakers Captivator S2 review and specifications →

AES Input	No
Aux Input	No
CEA-2010-A Average (40-80Hz)	129.4 dB
Coaxial Input	No
Country	United States
Dimensions	40"H x 21"W x 18"D (1016.0 x 533.4 x 457.2 mm)
Drivers	2x 18" (457mm) drivers
Enclosure	sealed
HDMI Input	No
Inputs	XLR (balanced), RCA
Measurement Source	Data-bass
Optical Input	No
Output SPL at 10 Hz	100.3 dB
Output SPL at 12.5 Hz	103.3 dB
Output SPL at 15 Hz	108.7 dB
Output SPL at 20 Hz	115.1 dB
Output SPL at 25 Hz	119.7 dB
Output SPL at 31.5 Hz	124.8 dB
Output SPL at 40 Hz	129.3 dB
Output SPL at 50 Hz	130.3 dB
Output SPL at 63 Hz	129.4 dB
Output SPL at 80 Hz	128.5 dB
Output SPL at 100 Hz	128.1 dB
Output SPL at 125 Hz	128.0 dB
RCA Input	Yes
TRS Input	No
USB Input	No
Warranty	5/3
Weight	220 lbs (99.8 kg)
XLR Input	Yes

• Links
  • JTR Speakers Captivator S2 Website
• 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
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  • JTR Speakers Captivator S2 vs Funk Audio Custom 21.0
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  • JTR Speakers Captivator S2 vs JTR Speakers Growler (2015)
  • See all 48 comparisons

Monoprice Monolith 16 THX Ultra: $2,300 eBay

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

Full Monoprice Monolith 16 THX Ultra review and specifications →

AES Input	No
Aux Input	No
CEA-2010-A Average (40-80Hz)	126.5 dB
Cabinet Color	black
Coaxial Input	No
Country	United States
Dimensions	25.6"H x 22"W x 28.1"D (650.2 x 558.8 x 713.7 mm)
Drivers	16" (406mm) driver
Enclosure	ported, front
HDMI Input	No
Inputs	XLR, RCA, XLR out
Measurement Source	Audioholics
Optical Input	No
Output SPL at 15 Hz	107.3 dB
Output SPL at 20 Hz	118.4 dB
Output SPL at 25 Hz	123.3 dB
Output SPL at 31.5 Hz	125.1 dB
Output SPL at 40 Hz	126.3 dB
Output SPL at 50 Hz	126.5 dB
Output SPL at 63 Hz	126.6 dB
Output SPL at 80 Hz	126.8 dB
Output SPL at 100 Hz	127.2 dB
Output SPL at 125 Hz	127.6 dB
RCA Input	Yes
TRS Input	No
USB Input	No
Warranty	5
Weight	171.5 lbs (77.8 kg)
XLR Input	Yes

• Links
  • Monoprice Monolith 16 THX Ultra Website
• Reviews, Comparisons and Sound Samples
  • Independently measured by Audioholics; the published figures above come from this ASR subwoofer measurement thread.
• Head-to-Head Comparisons
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