Short answer: the JTR Speakers Captivator 4000ULF for better sound quality, the Monoprice Monolith M-15 V2 for the lower price. The JTR Speakers Captivator 4000ULF ranks #6 of 110 subwoofers, rated 4.5/5, at $5699. The Monoprice Monolith M-15 V2 ranks #64, rated 4.2/5, at $1500, $4199 cheaper.
Buy the JTR Speakers Captivator 4000ULF when sound quality outweighs the price for you, and the Monoprice Monolith M-15 V2 when the price outweighs sound quality instead.
Looking for alternatives? See the complete Subwoofers rankings.
Specifications Side By Side
| JTR Speakers Captivator 4000ULF | Monoprice Monolith M-15 V2 | |
|---|---|---|
| Price | $5,000 | $1,500 Discontinued |
| Ranked | #6 of 110 in Large Home Subwoofers (Over 75 lbs) | #64 of 110 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | ported, front |
| Output SPL at 10 Hz | 111.0 dB | - |
| Output SPL at 12.5 Hz | 115.3 dB | 91.0 dB |
| Output SPL at 15 Hz | 119.3 dB | 106.3 dB |
| Output SPL at 20 Hz | 122.3 dB | 112.6 dB |
| Output SPL at 25 Hz | 126.1 dB | 116.6 dB |
| Output SPL at 31.5 Hz | 129.3 dB | 119.5 dB |
| Output SPL at 40 Hz | 130.7 dB | 120.9 dB |
| Output SPL at 50 Hz | 131.2 dB | 120.6 dB |
| Output SPL at 63 Hz | 130.9 dB | 120.0 dB |
| Output SPL at 80 Hz | 130.6 dB | 118.7 dB |
| Output SPL at 100 Hz | 130.5 dB | 120.1 dB |
| Output SPL at 125 Hz | 129.5 dB | 120.2 dB |
| CEA-2010-A Average (40-80Hz) | 130.8 dB | 120.0 dB |
| Dimensions | 41"H x 20.5"W x 39.5"D (1041.4 x 520.7 x 1003.3 mm) | 28.7"H x 17.7"W x 26.8"D (729.0 x 449.6 x 680.7 mm) |
| Weight | 265 lbs (120.2 kg) | 132.9 lbs (60.3 kg) |
| Warranty | 5/3 | 5 |
| Cabinet Color | black, custom | black |
| Country | United States | United States |
| Measurement Source | Data-bass | Manufacturer |
| Drivers | 2x 18" (457mm) driver | 15" (381mm) driver |
| Inputs | XLR, RCA | XLR, RCA |
| XLR Input | Yes | Yes |
| RCA Input | Yes | Yes |
| TRS Input | No | No |
| Optical Input | No | No |
| Coaxial Input | No | No |
| USB Input | No | No |
| HDMI Input | No | No |
| AES Input | No | No |
| Aux Input | No | No |
| Discontinued | - | Yes |
Related Speaker Comparisons
How JTR Speakers Captivator 4000ULF compares with other leading options:
- JTR Speakers Captivator 4000ULF vs JTR Speakers Orbit Shifter PRO
- JTR Speakers Captivator 4000ULF vs JTR Speakers Orbit Shifter LFU
- JTR Speakers Captivator 4000ULF vs Power Sound Audio (PSA) TRIAX
- JTR Speakers Captivator 215PRO vs JTR Speakers Captivator 4000ULF
- JTR Speakers Captivator 4000ULF vs Power Sound Audio (PSA) T18
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.
As an eBay Partner, we may be compensated if you make a purchase.
The Two Speakers In Full
JTR Speakers Captivator 4000ULF: $5,000 JTR Speakers eBay
Pros: Independent CEA-2010 testing records 122.3 dB at 20 Hz and 130.8 dB through 40-80 Hz. The ported, front enclosure with 2x 18” (457mm) driver has the headroom for demanding film bass in a large room.
Cons: The 1041.4H x 520.7W x 1003.3D mm cabinet and 120.2 kg mass make this a serious placement and moving commitment. Ported output does not solve room modes, so careful placement and calibration remain essential.
Full JTR Speakers Captivator 4000ULF review and specifications →
| AES Input | No |
|---|---|
| Aux Input | No |
| CEA-2010-A Average (40-80Hz) | 130.8 dB |
| Cabinet Color | black, custom |
| Coaxial Input | No |
| Country | United States |
| Dimensions | 41"H x 20.5"W x 39.5"D (1041.4 x 520.7 x 1003.3 mm) |
| Drivers | 2x 18" (457mm) driver |
| Enclosure | ported, front |
| HDMI Input | No |
| Inputs | XLR, RCA |
| Measurement Source | Data-bass |
| Optical Input | No |
| Output SPL at 10 Hz | 111.0 dB |
| Output SPL at 12.5 Hz | 115.3 dB |
| Output SPL at 15 Hz | 119.3 dB |
| Output SPL at 20 Hz | 122.3 dB |
| Output SPL at 25 Hz | 126.1 dB |
| Output SPL at 31.5 Hz | 129.3 dB |
| Output SPL at 40 Hz | 130.7 dB |
| Output SPL at 50 Hz | 131.2 dB |
| Output SPL at 63 Hz | 130.9 dB |
| Output SPL at 80 Hz | 130.6 dB |
| Output SPL at 100 Hz | 130.5 dB |
| Output SPL at 125 Hz | 129.5 dB |
| RCA Input | Yes |
| TRS Input | No |
| USB Input | No |
| Warranty | 5/3 |
| Weight | 265 lbs (120.2 kg) |
| XLR Input | Yes |
- Links
- 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
- JTR Speakers Captivator 4000ULF vs JTR Speakers Captivator 215PRO
- JTR Speakers Captivator 4000ULF vs Power Sound Audio (PSA) TRIAX
- JTR Speakers Captivator 4000ULF vs Power Sound Audio (PSA) T18
- JTR Speakers Captivator 4000ULF vs JTR Speakers Captivator S2
- JTR Speakers Captivator 4000ULF vs JTR Speakers Orbit Shifter LFU
- JTR Speakers Captivator 4000ULF vs JTR Speakers Orbit Shifter PRO
- JTR Speakers Captivator 4000ULF vs Monoprice Monolith 16 THX Ultra
- JTR Speakers Captivator 4000ULF vs Reaction Audio PV-15X
- See all 15 comparisons
Monoprice Monolith M-15 V2: $1,500 Discontinued eBay
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 Input | No |
|---|---|
| Aux Input | No |
| CEA-2010-A Average (40-80Hz) | 120.0 dB |
| Cabinet Color | black |
| Coaxial Input | No |
| Country | United States |
| Dimensions | 28.7"H x 17.7"W x 26.8"D (729.0 x 449.6 x 680.7 mm) |
| Discontinued | Yes |
| Drivers | 15" (381mm) driver |
| Enclosure | ported, front |
| HDMI Input | No |
| Inputs | XLR, RCA |
| Measurement Source | Manufacturer |
| Optical Input | No |
| Output SPL at 12.5 Hz | 91.0 dB |
| Output SPL at 15 Hz | 106.3 dB |
| Output SPL at 20 Hz | 112.6 dB |
| Output SPL at 25 Hz | 116.6 dB |
| Output SPL at 31.5 Hz | 119.5 dB |
| Output SPL at 40 Hz | 120.9 dB |
| Output SPL at 50 Hz | 120.6 dB |
| Output SPL at 63 Hz | 120.0 dB |
| Output SPL at 80 Hz | 118.7 dB |
| Output SPL at 100 Hz | 120.1 dB |
| Output SPL at 125 Hz | 120.2 dB |
| RCA Input | Yes |
| TRS Input | No |
| USB Input | No |
| Warranty | 5 |
| Weight | 132.9 lbs (60.3 kg) |
| XLR Input | Yes |
- Reviews, Comparisons and Sound Samples
- These figures are manufacturer-specified rather than independently measured.
- Head-to-Head Comparisons
- Monoprice Monolith M-15 V2 vs SVS PB-4000
- Monoprice Monolith M-15 V2 vs Arendal 1723 Subwoofer 2S
- Monoprice Monolith M-15 V2 vs Rythmik F18
- Monoprice Monolith M-15 V2 vs Monoprice Monolith M15-S
- Monoprice Monolith M-15 V2 vs HSU Research VTF-3 MK5 HP
- Monoprice Monolith M-15 V2 vs HSU Research VTF-15H MK2
- Monoprice Monolith M-15 V2 vs Rythmik FV15HP
- Monoprice Monolith M-15 V2 vs Monoprice Monolith M-215
- See all 16 comparisons