JTR Speakers Captivator S2 vs Monoprice Monolith M15-S

Short answer: the JTR Speakers Captivator S2 on measured sound quality, the Monoprice Monolith M15-S on price. The JTR Speakers Captivator S2 ranks #9 of 110 subwoofers, rated 4.5/5, at $3995. The Monoprice Monolith M15-S ranks #72, rated 4.1/5, at $999, $2996 cheaper.

Buy the JTR Speakers Captivator S2 when sound quality outweighs the price for you, and the Monoprice Monolith M15-S when the price outweighs sound quality instead.

Want more options? Browse the full 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.
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Monoprice Monolith M15-S: $999 eBay

Pros: Published CEA-2010 specifications list 105.6 dB at 20 Hz and 119.0 dB through 40-80 Hz. The sealed enclosure with 15” (381mm) driver has the headroom for demanding film bass in a large room.

Cons: The 596.9H x 424.2W x 500.4D mm cabinet and 36.3 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: Product # 35141

Full Monoprice Monolith M15-S review and specifications →

CEA-2010-A Average (40-80Hz)	119.0 dB
Country	United States
Dimensions	23.5"H x 16.7"W x 19.7"D (596.9 x 424.2 x 500.4 mm)
Drivers	15" (381mm) driver
Enclosure	sealed
Measurement Source	Manufacturer
Output SPL at 15 Hz	100.1 dB
Output SPL at 20 Hz	105.6 dB
Output SPL at 25 Hz	111.2 dB
Output SPL at 31.5 Hz	115.2 dB
Output SPL at 40 Hz	118.4 dB
Output SPL at 50 Hz	119.3 dB
Output SPL at 63 Hz	119.6 dB
Output SPL at 80 Hz	118.9 dB
Output SPL at 100 Hz	119.1 dB
Output SPL at 125 Hz	118.9 dB
Warranty	5
Weight	80 lbs (36.3 kg)

• Reviews, Comparisons and Sound Samples
  • These figures are manufacturer-specified rather than independently measured.
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