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    Monolith 12" THX Ultra Certified 1000 Watt Powered Subwoofer
    Product # 24457
    In Stock This item should ship today (2/19/2018) if ordered within 8 hours 13 minutes

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    Monolith 12" THX Ultra Certified 1000 Watt Powered Subwoofer

    Monolith THX Select Subwoofer

    The Monolith THX® certified subwoofer sets the standard for bass output, low distortion, and affordability. With chest thumping bass that plays down to well under 20Hz, the Monolith subwoofer unleashes cinema level volume, with the ability to convey and articulate the subtle nuances of music.

    THX Ultra Certified
    500 Watt Amplifier
    THX Ultra Certified
    500 Watt Amplifier

    THX Ultra Certified: THX engineers completed hundreds of different scientific tests to ensure the highest audio performance possible. The tests ensure the speaker can reach the high volumes necessary to achieve THX Reference Level without creating audible distortion or artifacts. THX Certified Ultra products are for large sized rooms, up to 3,000 cubic feet in size, with a 10-12 foot viewing distance from the screen.

    12" Woofer: The Monolith 12" driver was developed from the ground up, with a design focus on achieving output, accuracy, dynamics, and linearity, while minimizing distortion. Enclosed in a cabinet made from HDF material, massive internal bracing, and outfitted with dual ports that can utilize a foam plugs to run the subwoofer in a sealed mode.

    500 Watt Amplifier: The 500W RMS amplifier is built around a Texas Instrument 48-bit data path (with 28-bit filter coefficients) and DSP engine. Each amplifier's transfer function, power output limiting and thermal protection are monitored to the millisecond and are customized for each individual driver. The high efficiency Class D amplifier modules are based on a proven topology that has been continuously refined over the past 4 years. The amplifier has vast reserves of power for highly accurate, deep bass for your home theater or music system.


    Performance Class

    THX Ultra

    THX Certified Ultra products bring the cinematic experience to large home theaters, 3,000 cubic feet in size, with a viewing distance of 12 feet or greater from the screen.*

    * Previously known as Select2


    Anatomy of a Subwoofer

    12-inch Subwoofer

    Cabinet and Internal Bracing

    HDF (High Density Fiberboard), not MDF, was utilized resulting in a sonically inert cabinet. Internal bracing has been strategically placed to increase overall cabinet strength and limit unwanted panel vibrations that would cause discoloration and distortion. The strong cabinet and bracing combine to ensure you hear massive amounts of bass, not cabinet resonances.

    Ports and Grille

    The 12" model uses a single 88.5mm port with inner and outer flares. Multiple ports are used to ensure high SPL capability at low frequency (fb=21Hz). The dual flares help reduce turbulence and asymmetrical distortions. Additional adjustments can be made by sealing one or more ports with the supplied plugs. The "floating" grille is made from non resonant MDF to provide rigidity, while the entire structure is offset from the cabinet to maximize air flow of the woofer and ports.

    12-inch Driver

    10-inch Subwoofer

    Every part of this driver has been developed from the ground up and customized to deliver high output, low distortion, and accurate bass. Our unique hybrid cone combines long fiber pulp and fiberglass, taking advantage of the pulp's superior stiffness with the additional rigidity and lightweight properties of fiberglass, to deliver a driver of massive durability and excursion. The result is a cone that achieves optimal motion at all frequencies it is asked to produce and beyond.


    1. Lower Suspension

    FEA (Finite Element Analysis) modeling and Klippel laser based optimizations were used to design a cone that is capable of astounding >80mm peak-to-peak excursions. The lower and upper suspensions are designed together with the motor structure. The lower suspension is critical for maintaining very low levels of distortion at high excursions, which are required for high SPL at low frequencies.

    2. Spider and Cone Venting

    The spider is made from multiple layers of NOMEX with integrated tinsel leads hand stitched in place for low mass yet high strength and durability. The purpose of these vents are twofold -- first, they allow convective air flow to cool the voice coil and, second, they reduce asymmetrical compliance due to air compression under the cone/spider, which would appear as unwanted distortions.

    3. Woofer Surround

    FEA (Finite Element Analysis) modeling and Klippel laser based optimization were utilized to create this durable, high profile surround that’s made from a unique formulation of NBR (NITRILE RUBBER-acrylonitrile-butadiene copolymer). This formulation was developed after months of modeling and prototyping to ensure the highest levels of excursion, without sacrificing linearity or distortion.

    4. Motor Structure

    The motor is made of CNC milled low carbon steel in the modified undercut "T" pole assembly to focus the magnetic flux. Dual aluminum shorting rings are used to cancel eddy currents, further stabilizing the magnetic flux and significantly lowering distortion. The precision wound, high temperature, all aluminum bobbin (which has a lower thermal compression than copper) enable the voice coil to remain cool. The motor and suspension design is extremely critical for maintaining control of the driver's displacement over a very wide range of input signals, allowing the subwoofer to reach maximum performance and output levels while keeping distortion to a minimum.

    All Amp'd Up

    12-inch Subwoofer

    The Monolith subwoofer amplifier has an extraordinarily high power output of 500 watts RMS (900 watts peak), which can deliver massive amounts of power when needed. Each Class D amplifier is built around a Texas Instruments 48-bit data path (with 28-bit filter coefficients) DSP engine, allowing virtually unlimited design flexibility with the assurance of no signal degradation. Each amplifier's transfer function, power output limiting, and thermal protection are monitored to the millisecond and are customized for each individual woofer and cabinet air volume combination. This state-of-the-art Class D amplifier technology ensures maximum headroom capability, excellent transient response, high output, and very low distortion when driving the Monolith 12-inch THX Select certified subwoofer.

    CEA-2010 SPL Measurements @ 2 meters

    12-inch Subwoofer

    12-inch Subwoofer

    Ported (2 ports)

      SPL @ 2m Distortion
    Hz Peak (dB) RMS (dB) THD% 2nd
    16 99.7 96.7 8.1% 3.9% 6.5%
    20 108.3 105.3 9.5% 3.4% 8.0%
    25 112.3 109.3 5.7% 1.3% 5.2%
    31 113.6 110.6 4.3% 2.6% 2.9%
    40 114.2 111.2 4.0% 2.4% 3.1%
    50 114.6 111.6 2.7% 1.5% 2.2%
    63 115.0 112.0 2.6% 1.1% 2.3%
    80 115.4 112.4 1.6% 0.8% 1.0%
    100 115.9 112.9 1.2% 0.7% 0.8%
    125 116.3 113.3 1.2% 0.7% 0.6%

    Ported (1 port)

      SPL @ 2m Distortion
    Hz Peak (dB) RMS (dB) THD% 2nd
    16 101.8 98.8 9.2% 1.3% 8.5%
    20 106.3 103.3 11.7% 5.5% 8.7%
    25 108.5 105.5 8.0% 4.6% 4.5%
    31 110.8 107.8 4.7% 3.2% 2.4%
    40 111.5 108.5 3.6% 2.6% 2.1%
    50 111.9 108.9 2.5% 0.8% 2.1%
    63 112.6 109.6 2.3% 1.3% 1.2%
    80 113.6 110.6 3.3% 1.7% 1.4%
    100 114.3 111.3 1.9% 1.1% 1.5%
    125 115.0 112.0 1.3% 0.8% 0.9%


      SPL @ 2m Distortion
    Hz Peak (dB) RMS (dB) THD% 2nd
    16 95.0 92.0 15.3% 2.4% 13.5%
    20 100.3 97.3 17.1% 3.1% 15.4%
    25 105.4 102.4 12.7% 4.3% 9.9%
    31 108.1 105.1 3.5% 2.0% 2.3%
    40 109.9 106.9 2.9% 1.4% 2.1%
    50 110.9 107.9 2.2% 0.7% 1.2%
    63 112.1 109.1 2.1% 0.9% 0.9%
    80 113.1 110.1 2.6% 1.1% 1.2%
    100 113.9 110.9 2.1% 1.1% 1.7%
    125 114.8 111.8 1.4% 1.0% 0.8%

    5 Year Warranty

    Buy with Confidence

    Monoprice not only stands behind every product we sell with a 5 year replacement warranty, we offer a 30-day money back guarantee as well! If the product you purchase does not satisfy your needs, send it back for a full refund.

    Quality at a Fair Price

    Quality at a Fair Price

    Monoprice's rugged design and rigid quality control standards deliver high quality products at fair prices.

    Hassle Free Packaging

    Hassle Free Packaging

    Monoprice exists to bring simplicity, fairness, and confidence to technology choices. This product features recyclable packaging that is simple to open, cost effective, with minimal waste, and fully protective as it travels to you.

    Service & Support

    Service & Support

    You're never on your own with Monoprice products! We have a full team of friendly and knowledgeable technicians available to answer your questions, both before and after the sale. Contact our technical support team for questions about our products, troubleshooting, or even suggestions for products to fit your particular needs. Not to be outdone, our friendly and helpful customer service team is here to make your ordering, delivery, and any possible returns a quick and painless operation, from start to finish!


    Support Files:

    THX® and the THX logo are trademarks of THX Ltd., registered in the U.S. and other countries.

    Model 24457
    Woofer 12" cone
    Cone Material 2 layer long fiber pulp/glass fiber cone
    Voice Coil 60mm with high temperature aluminum wire and black anodized aluminum bobbin
    Surround FEA optimized NBR (nitrile budadiene rubber)
    Motor FEA optimized, 2 aluminum shorting rings, undercut T-pole focused field
    Magnet Ceramic Y35, 2 pcs total 144 oz.
    Xmax 18mm (one-way)
    Xmech 80mm (peak-to-peak)
    Enclosure Sealed or vented HDF cabinet with horizontal and vertical bracing
    Finish Black Ash
    Amplifier Class D 500Wrms
    Frequency Response (-6dB) Sealed Vented (1 port) Vented (2 ports)
         Extended EQ 26-200Hz 19-200Hz 18-200Hz
         THX EQ 29-200Hz 23-200Hz 20-200Hz
    Harmonic Distortion <1% 20-100Hz (90dB @ 1m)
    Variable Level Control +15/-20dB
    Crossover Inline/Bypass variable 40-160Hz
    Inputs RCA (2), XLR
    Outputs XLR
    Signal Turn On Selectable always on/auto
    Auto Turn Off 30 minutes
    Dimensions (H x W x D) 22.8" x 16.7" x 23.6" (580 x 425 x 600mm)
    Net Weight 98.5 lbs. (44.7 kg)
    Gross Weight 125.7 lbs. (57 kg)

    Start typing your question and we'll check if it was already asked and answered. Learn More
    Browse 4 questions Browse 4 questions and 4 answers
    Can you add maximum SPL in the various modes (THX, etc.) to the spec sheets for all of these new subwoofers? Thanks!
    Jason G on Sep 2, 2017
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    BEST ANSWER: We will be adding CEA-2010 @2M burst and RMS measurements by frequency in the near future.
    Can you please provide specifications in terms of power requirements for a North American household? I'd like to run 2 of these in my home theater currently under construction and want to know if I can run them both on the same dedicated 15 A circuit... or if I need to run them both on a dedicated 20 A circuit. Thanks!
    A shopper on Oct 27, 2017
    BEST ANSWER: I has a 20 amp circuit put in for this sub and a 12" SVS sub.
    Hello. I just looked at the manual and it appears the 10” goes lower than the 12 according to the manual. Is this correct?
    New User U on Nov 8, 2017
    BEST ANSWER: The 12" subwoofer goes lower and plays louder, as a 12" should. The Monolith 12" subwoofer has a 4 to 6 dB advantage over the 10" at 16Hz and 20Hz.
    Can these sub woofers be positioned on their side for a lower profile? I have a large projection screen and plan on placing two subs up front.
    Shawn P on Oct 29, 2017
    BEST ANSWER: Yes, you can lay the subwoofer on its side with no loss in performance.
    4.8 / 5.0
    5 Reviews
    5 Stars
    4 Stars
    3 Stars
    2 Stars
    1 Stars
    Hits better than my SVS SB 2000
    Great sub! Tested it out yesterday ,finally ,and i am impressed. I do not have complex measurement instruments but definitely plays louder and lower than my SVS. (As it should). Pleased thus far.
    December 11, 2017
    3 months ago
    Awesome. Very capable subwoofer.
    This thing rocks. I purchased this subwoofer to complete my 7.2.2 home theater system. As expected per the spec sheets and the views online it's highly configurable. However I didn't notice how heavy and big it is until I received a call from UPS Freight asking me if they can get a semi truck and trailer down my somewhat narrow street. This subwoofer has a huge footprint compared to all the other ones I tested. You're not carrying this one up or down the stairs by yourself. But the sound, sounds (and feels), like movie theater quality.

    So far this subwoofer knows what to do with and handles everything cleanly, without any error, that I can detect. I can pop in a Star Wars (THX) Blu-Ray disc and set all the subwoofer switches and dials to Auto THX settings and then sit back and enjoy like I am at home in the movie theater. Or if I'm streaming a movie and don't know which audiocodes they have used in the recording I can manually set the subwoofer and come pretty close to the auto THX sound. This thing sounds awesome and so far has handled all the volume and bass I've given it.

    I do happen to have a THX receiver but I don't know if it's necessary to match it with the subwoofer as most of the time I have the settings on the subwoofer set manually and I have LFE turned or set to zero at the receiver end. Where I use THX the most is in selecting cinema sound. I've liked the pre-selected THX surround and bass settings for a long time. I guess I'm just used to it. But they can probably be matched playing around with the equalizer settings on your receiver if you don't have THX and you want to get the most out of this subwoofer. Onkyo has reasonably priced THX receivers for the most part. Everybody else seems to have stopped paying to get THX certified. Integra is Onkyo's Pro installation product line. I haven't hooked a guitar up to it but I have listened to rock and roll through it and this thing rocks too. I was impressed with this subwoofer from day one and it seems to be continually getting better and better with each movie I watch. And I'm watch back to watching movies for the special sound effects as much as possible or as much as I can find a decent movie where they paid attention to sound effects.

    I have zero regrets from this purchase. Course I'm not ready for my original subwoofer to fail anytime soon but when it does I'll get another 12 in. This is exactly what I was after testing all those subwoofers this summer.

    Thank you Monoprice for providing what comparably has to be a very high-end subwoofer for a realistically not high end price.

    Sorry I don't know Professional stats so I'm not able to provide in depth technical feedback. To go on would be to say over and over again how much I love this subwoofer.

    PS this thing arrived in a couple of days or so. I waited months for this to become available and then had to get creative to be able to spend the extra money for the 12 over the 10in but now it's oh Happy Days, happy, happy, happy...
    January 3, 2018
    2 months ago
    Best at this price point.
    This thing rocks. My main theater room has a powersound 15v and I bought this for my family room so the kids have a great system as well. I am going to be switching subs, because this sub is much better. Much less distortion and plays lower and louder. I also own an SVS SB12 Plus in my office, and the monoprice sub seems to play tighter even though the SVS is sealed.
    January 8, 2018
    very impressive
    I was very pleased with the build quality of the sub and the sound was one the was deep not as fast as some higher priced subs but can truly hold its own ,,,,,with subs costing much more .For movies you cannot go wrong... but recommend 2 subs in such a set up. I used it for music listening there it proved it self to be a power house it made most music very enjoyable,, if your looking for a sub that is priced much lower than those higher priced subs and one that can move some air in a room this one is for you ...my only concern was how big it was I had trouble fitting it in my room
    December 31, 2017
    2 months ago
    I have two Dayton 15's and an older Cerwin Vega 12. Because I never got any cabling I disconnected my Cerwin and cobbled enuf cable to hook up two Monoliths. Wow they really perform. I then found out one monolith was not running. I fixed that and double WOW. They dig down deep.
    January 30, 2018
    1 month ago


    In Stock This item should ship today (2/19/2018) if ordered within 8 hours 13 minutes