Monoprice Monolith M-15 V2 vs Rythmik F18

Last updated: September 17, 2026

Short answer: the Rythmik F18, if you are buying new. The Monoprice Monolith M-15 V2 ranks higher than it (#64 vs #69 of 110 subwoofers, 4.2/5 vs 4.1/5) but is discontinued, so only consider it used; the Rythmik F18 is still sold new at $2344.

Monoprice Monolith M-15 V2 vs Rythmik F18

Buy the Rythmik F18 if you want one new; the Monoprice Monolith M-15 V2 is discontinued, so only look for it used.

Looking for alternatives? See the complete Subwoofers rankings.

Buy the Rythmik F18 at Rythmik Audio ($2,344) →

Specifications Side By Side

Monoprice Monolith M-15 V2 Rythmik F18
Price$1,500 Discontinued$1,850
Ranked#64 of 110 in Large Home Subwoofers (Over 75 lbs)#69 of 110 in Large Home Subwoofers (Over 75 lbs)
Enclosureported, frontsealed
Output SPL at 12.5 Hz91.0 dB97.4 dB
Output SPL at 15 Hz106.3 dB102.0 dB
Output SPL at 20 Hz112.6 dB106.2 dB
Output SPL at 25 Hz116.6 dB110.9 dB
Output SPL at 31.5 Hz119.5 dB114.3 dB
Output SPL at 40 Hz120.9 dB117.1 dB
Output SPL at 50 Hz120.6 dB119.1 dB
Output SPL at 63 Hz120.0 dB120.5 dB
Output SPL at 80 Hz118.7 dB121.2 dB
Output SPL at 100 Hz120.1 dB121.4 dB
Output SPL at 125 Hz120.2 dB121.4 dB
CEA-2010-A Average (40-80Hz)120.0 dB119.5 dB
Dimensions28.7"H x 17.7"W x 26.8"D (729.0 x 449.6 x 680.7 mm)20.5"H x 20.5"W x 21"D (520.7 x 520.7 x 533.4 mm)
Weight132.9 lbs (60.3 kg)115.1 lbs (52.2 kg)
Warranty55/3
Cabinet Colorblackblack
CountryUnited StatesUnited States
Measurement SourceManufacturerData-bass
Drivers15" (381mm) driver18" (457mm) driver
DiscontinuedYes-
InputsXLR, RCAXLR (2), RCA (line/LFE)
XLR InputYesYes
RCA InputYesYes
TRS InputNoNo
Optical InputNoNo
Coaxial InputNoNo
USB InputNoNo
HDMI InputNoNo
AES InputNoNo
Aux InputNoNo
Output SPL at 10 Hz-93.7 dB
Buy the Rythmik F18 at Rythmik Audio ($2,344) →

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The Two Speakers In Full

Monoprice Monolith M-15 V2: $1,500 Discontinued eBay

Monoprice Monolith M-15 V2 ranking card

Pros: Published CEA-2010 specifications list 112.6 dB at 20 Hz and 120.0 dB through 40-80 Hz. Its front-ported 15-inch design has substantial deep-bass and midbass headroom for cinema playback.

Cons: Discontinued and no longer sold new. At 60.3 kg and 729.0H x 449.6W x 680.7D mm, it needs committed floor space and careful room integration. Discontinued.

Notes: Product # 42851

Full Monoprice Monolith M-15 V2 review and specifications →

AES InputNo
Aux InputNo
CEA-2010-A Average (40-80Hz)120.0 dB
Cabinet Colorblack
Coaxial InputNo
CountryUnited States
Dimensions28.7"H x 17.7"W x 26.8"D (729.0 x 449.6 x 680.7 mm)
DiscontinuedYes
Drivers15" (381mm) driver
Enclosureported, front
HDMI InputNo
InputsXLR, RCA
Measurement SourceManufacturer
Optical InputNo
Output SPL at 12.5 Hz91.0 dB
Output SPL at 15 Hz106.3 dB
Output SPL at 20 Hz112.6 dB
Output SPL at 25 Hz116.6 dB
Output SPL at 31.5 Hz119.5 dB
Output SPL at 40 Hz120.9 dB
Output SPL at 50 Hz120.6 dB
Output SPL at 63 Hz120.0 dB
Output SPL at 80 Hz118.7 dB
Output SPL at 100 Hz120.1 dB
Output SPL at 125 Hz120.2 dB
RCA InputYes
TRS InputNo
USB InputNo
Warranty5
Weight132.9 lbs (60.3 kg)
XLR InputYes
Search eBay for Monoprice Monolith M-15 V2 →

Rythmik F18: $1,850 Rythmik Audio eBay

Rythmik F18 ranking card

Pros: Independent CEA-2010 testing records 106.2 dB at 20 Hz and 119.5 dB through 40-80 Hz. The sealed enclosure with 18” (457mm) driver has the headroom for demanding film bass in a large room.

Cons: The 520.7H x 520.7W x 533.4D mm cabinet and 52.2 kg mass make this a serious placement and moving commitment. A sealed cabinet still needs careful placement and calibration to avoid room-mode peaks.

Full Rythmik F18 review and specifications →

AES InputNo
Aux InputNo
CEA-2010-A Average (40-80Hz)119.5 dB
Cabinet Colorblack
Coaxial InputNo
CountryUnited States
Dimensions20.5"H x 20.5"W x 21"D (520.7 x 520.7 x 533.4 mm)
Drivers18" (457mm) driver
Enclosuresealed
HDMI InputNo
InputsXLR (2), RCA (line/LFE)
Measurement SourceData-bass
Optical InputNo
Output SPL at 10 Hz93.7 dB
Output SPL at 12.5 Hz97.4 dB
Output SPL at 15 Hz102.0 dB
Output SPL at 20 Hz106.2 dB
Output SPL at 25 Hz110.9 dB
Output SPL at 31.5 Hz114.3 dB
Output SPL at 40 Hz117.1 dB
Output SPL at 50 Hz119.1 dB
Output SPL at 63 Hz120.5 dB
Output SPL at 80 Hz121.2 dB
Output SPL at 100 Hz121.4 dB
Output SPL at 125 Hz121.4 dB
RCA InputYes
TRS InputNo
USB InputNo
Warranty5/3
Weight115.1 lbs (52.2 kg)
XLR InputYes
Check current price at Rythmik Audio ($2,344) →Search eBay for Rythmik F18 →