Short answer: the Monoprice Monolith 16 THX Ultra for better sound quality, the Monoprice Monolith M12-S for the lower price. The Monoprice Monolith 16 THX Ultra ranks #18 of 110 subwoofers at $2300. The Monoprice Monolith M12-S ranks #101 at $599, $1701 cheaper.
What the Monoprice Monolith 16 THX Ultra offers: 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. Watch for: Heavy at 78 kg and ported design can interact with room acoustics.
What the Monoprice Monolith M12-S offers: Published CEA-2010 specifications list 100.1 dB at 20 Hz and 112.7 dB through 40-80 Hz. The sealed enclosure with 12” (305mm) driver delivers substantial upper-bass output for movie effects and music. Watch for: Deep-bass output is more limited than the strong 40-80 Hz result suggests, so it is not the right choice when the lowest movie effects are the priority. The 500.4H x 391.2W x 424.2D mm cabinet and 44.7 kg mass still require deliberate placement and calibration.
Buy the Monoprice Monolith 16 THX Ultra if sound quality is the priority over the price, or the Monoprice Monolith M12-S if the price is the priority over sound quality.
If sound quality matters at all to you, skip the Monoprice Monolith M12-S. It ranks near the bottom of the 110 subwoofers, so look higher up the list instead.
Looking for alternatives? See the complete Subwoofers rankings.
Specifications Side By Side
| Monoprice Monolith 16 THX Ultra | Monoprice Monolith M12-S | |
|---|---|---|
| Price | $2,300 | $599 |
| Ranked | #18 of 110 in Large Home Subwoofers (Over 75 lbs) | #101 of 110 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | sealed |
| Output SPL at 15 Hz | 107.3 dB | 95.2 dB |
| Output SPL at 20 Hz | 118.4 dB | 100.1 dB |
| Output SPL at 25 Hz | 123.3 dB | 104.0 dB |
| Output SPL at 31.5 Hz | 125.1 dB | 108.0 dB |
| Output SPL at 40 Hz | 126.3 dB | 110.6 dB |
| Output SPL at 50 Hz | 126.5 dB | 112.8 dB |
| Output SPL at 63 Hz | 126.6 dB | 113.7 dB |
| Output SPL at 80 Hz | 126.8 dB | 113.8 dB |
| Output SPL at 100 Hz | 127.2 dB | 113.7 dB |
| Output SPL at 125 Hz | 127.6 dB | 113.7 dB |
| CEA-2010-A Average (40-80Hz) | 126.5 dB | 112.7 dB |
| Dimensions | 25.6"H x 22"W x 28.1"D (650.2 x 558.8 x 713.7 mm) | 19.7"H x 15.4"W x 16.7"D (500.4 x 391.2 x 424.2 mm) |
| Weight | 171.5 lbs (77.8 kg) | 98.5 lbs (44.7 kg) |
| Warranty | 5 | 5 |
| Cabinet Color | black | - |
| Country | United States | United States |
| Measurement Source | Audioholics | Manufacturer |
| Drivers | 16" (406mm) driver | 12" (305mm) driver |
Related Speaker Comparisons
How Monoprice Monolith 16 THX Ultra compares with other leading options:
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- Monoprice Monolith 16 THX Ultra vs WW Speaker Cabinets X21 - B&C 21DS115-4
- Monoprice Monolith 16 THX Ultra vs Pro Audio Technology LFC-24sm
- Monoprice Monolith 16 THX Ultra vs Power Sound Audio (PSA) TRIAX
Prices on this page were last checked September 16, 2026 at 12:41 AM 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
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 →
| CEA-2010-A Average (40-80Hz) | 126.5 dB |
|---|---|
| Cabinet Color | black |
| 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 |
| Measurement Source | Audioholics |
| 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 |
| Warranty | 5 |
| Weight | 171.5 lbs (77.8 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Independently measured by Audioholics; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons
- Monoprice Monolith 16 THX Ultra vs Harbottle Audio C24 L2
- Monoprice Monolith 16 THX Ultra vs Funk Audio Ultra 21.0LX
- Monoprice Monolith 16 THX Ultra vs Funk Audio Classic 18.0
- Monoprice Monolith 16 THX Ultra vs JTR Speakers Captivator 2400
- Monoprice Monolith 16 THX Ultra vs Reaction Audio PV-15X
- Monoprice Monolith 16 THX Ultra vs Harbinger V2218S
- Monoprice Monolith 16 THX Ultra vs Danley Sound Labs DTS10
- Monoprice Monolith 16 THX Ultra vs Rythmik FV25HP
- See all 88 comparisons
Monoprice Monolith M12-S: $599 eBay
Pros: Published CEA-2010 specifications list 100.1 dB at 20 Hz and 112.7 dB through 40-80 Hz. The sealed enclosure with 12” (305mm) driver delivers substantial upper-bass output for movie effects and music.
Cons: Deep-bass output is more limited than the strong 40-80 Hz result suggests, so it is not the right choice when the lowest movie effects are the priority. The 500.4H x 391.2W x 424.2D mm cabinet and 44.7 kg mass still require deliberate placement and calibration.
Notes: Product # 35142
Full Monoprice Monolith M12-S review and specifications →
| CEA-2010-A Average (40-80Hz) | 112.7 dB |
|---|---|
| Country | United States |
| Dimensions | 19.7"H x 15.4"W x 16.7"D (500.4 x 391.2 x 424.2 mm) |
| Drivers | 12" (305mm) driver |
| Enclosure | sealed |
| Measurement Source | Manufacturer |
| Output SPL at 15 Hz | 95.2 dB |
| Output SPL at 20 Hz | 100.1 dB |
| Output SPL at 25 Hz | 104.0 dB |
| Output SPL at 31.5 Hz | 108.0 dB |
| Output SPL at 40 Hz | 110.6 dB |
| Output SPL at 50 Hz | 112.8 dB |
| Output SPL at 63 Hz | 113.7 dB |
| Output SPL at 80 Hz | 113.8 dB |
| Output SPL at 100 Hz | 113.7 dB |
| Output SPL at 125 Hz | 113.7 dB |
| Warranty | 5 |
| Weight | 98.5 lbs (44.7 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- These figures are manufacturer-specified rather than independently measured.
- Head-to-Head Comparisons