Monoprice Monolith Unveils 10", 12" and 15" THX Ported Subwoofers

Online A/V accessories store Monoprice.com is positioning themselves further into a hi-fi and home theater solution by expanding their Monolith line with a set of heavy-duty subwoofers. At this year’s CEDIA, Monoprice has announced their Monolith THX subwoofer line that, as its name implies, carries THX certification for the entire line. The Monolith THX subwoofer line is comprised of three subwoofer models named the 10” THX Select, 12” THX Select, and 15” THX Ultra. Monoprice could hardly have picked a more literal naming scheme for these subs since the names can also serve as short descriptions. The 10” THX Select uses a 10” cone and is THX Select certified, the 12” THX Ultra uses a 12” cone and is THX Ultra certified, and the 15” THX Ultra uses a 15” cone and is THX Ultra certified. The Monolith THX subwoofers all have front-firing cones and ports, with the 12” THX Ultra and 15” THX Ultra having variable tuning capability.

Monoprice Monolith THX Subwoofers YouTube 2017 CEDIA Preview

There is no shortage of manufacturer-direct subwoofer companies, so Monoprice is going to need something special to set themselves apart from the crowd. THX certification is one way to do that. THX certification is a guarantee of a certain amount of dynamic range with low distortion. In the case of THX Select, you should be able to hit 115 dB in a 2,000 cubic feet room with a seating distance of 10 to 12 feet of the subwoofer, and with THX Ultra, 115 dB should be possible in a 3,000 cubic foot room with a distance of 12 feet or greater from the subwoofer. In our recent review of one of the few subs to have THX Ultra certification (Outlaw Audio’s Ultra-X13), it was found that distortion could hardly exceed 5% THD within the frequency range of 31.5 Hz and above, and we took this to be a guideline of THX performance certification. That is a promise of extremely clean bass from any subwoofer with THX certification.

THX's 'Ultra' certification is roughly analogous to our Bassaholic 'Extreme' Room Rating. However, THX's very strict distortion limits only certify an 'Ultra' subwoofer for a 3,000 cubic foot room, whereas our Bassaholics room rating system, which is based on the CEA-2010 subwoofer performance standard, is more lenient regarding distortion limits, and so we qualify a similarly performing subwoofer for a 5,000 cubic foot room. 

For more information see: Audioholics Bassaholics Room Size Rating and the THX speaker certification specification

Driver for 15” THX Ultra (left) and 12” THX Ultra (right)

Note the triple stacked magnets of the 15" and double stacked magnets of the 12" driver.

Even disregarding THX certification, there is a lot of promise for performance in the base specs of the Monolith THX subwoofers. The listed Xmax of 18 mm for the 10” and 12” and 25 mm for the 15” is a tremendous amount of linear throw for those cone sizes. Furthermore, the cabinets are also quite large for the cone sizes which bodes well for deep bass efficiency. Indeed, the 15” THX Ultra is specified for a -6 dB low-end response of 14 Hz. The large cabinet sizes are not without a weight penalty, with the entry-level 10” THX Select weighing in at a hefty 72.5 lbs., and the 15” THX Ultra weighing in at a daunting 128.5 lbs. Amplification is provided in abundance with 500 watt RMS amplifiers for the 10” and 12” and 1,000 watts RMS for the 15”. The drivers look serious, with large roll surrounds and beefy cast-iron baskets. All these ingredients can add up to excellent performance in the hands of a competent subwoofer designer, and Monoprice has handed the task of design to a highly-experienced and very qualified subwoofer designer. 

A New Benchmark in Price/Performance Subwoofers?

It is a safe bet that these subwoofers will cause a splash in the subwoofer market with the promise of heavy-duty performance backed by the kind of presence and reliability that Monoprice is known for. Pricing looks to be very aggressive, with the 10” bruiser starting at $500. However, the question of how much these subs can really deliver will be answered in planned full reviews here at Audioholics, so keep an eye open on our front page in the coming months to see what Monoprice’s new THX certified subwoofers are really capable of.

Unless otherwise indicated, this is a preview article for the featured product. A formal review may or may not follow in the future.