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Monoprice Monolith Sealed Subwoofer Line Preview

Monolith Sealed Subwoofer

Monolith Sealed Subwoofer


  • Product Name: Monolith THX subwoofers: M10-S, M12-S, and M15-S
  • Manufacturer: Monoprice
  • Review Date: February 28, 2019 08:00
  • MSRP: $499.99 - M10-S, $799.99 - M12-S, $1,299.99 - M15-S
  • First Impression: Gotta Have It!

  • Type: sealed, front-firing woofer
  • Drive Units: 10”, 12”, and 15”
  • Input Connectors: RCA (2), XLR
  • Output Connector: XLR 
  • Power Output: 500 watts for 10” and 12”, 1000 watts (RMS) for 15”
  • Finish: Black Ash
  • Crossover: Inline/Bypass variable 40-160Hz
  • Xmax (one way): 10”:18mm, 12”:18mm, 15”:25mm
  • Xmech (peak-to-peak): 10”:78mm, 12”:80mm, 15”:90mm
  • Enclosure: Sealed HDF cabinet with horizontal and vertical bracing
  • 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 butadiene rubber)
  • Motor: FEA optimized, undercut T-pole focused field with 2 aluminum shorting rings

Last yearmonolith sealed 10 front view.jpg we reviewed Monoprice’s new THX-certified Monolith subwoofer line including the Monolith THX 10" and 12" Sub and the Monolith 15” THX Ultra sub review. The great sounding and affordable subs from Monoprice were unveiled to great interest from the audio community. At CES this year, Monoprice unveiled sealed versions of these subs for those who want a similarly excellent price to performance ratio but in a smaller package. Much of the specs remain the same as the ported models: 10”, 12”, and 15” long-throw woofers using 500-watt amplifiers, and, in the case of the 15”, a 1,000-watt amplifier, and all in robust HDF cabinets. Since the drivers for the ported THX subwoofers were already so over-built, the recipe for turning these subs into sealed designs is simple: place the drivers in an optimum enclosure size for a sealed configuration, and adjust the onboard DSP software accordingly. The existing driver platform makes it easy to do that since it has such powerful motor strength and tremendous linear throw. Giving them plenty of amplification wattage is also a critical ingredient, but Monoprice does this; we are still wondering how Monoprice can put a beefy 500-watt amplifier in a $500 subwoofer, but they did manage to do it!

There are several advantages that these sealed subwoofers have over the ported versions. Their smaller size allows them to fit in many more places than their ported counterparts. That can lead to a better response in-room since optimal placement is so crucial in getting the best performance from your subwoofer system. Their smaller size also helps to make a multiple subwoofer system more of a possibility, which can greatly increase the sound quality at bass frequencies. Audioholics has long been an advocate as well as evangelist of multiple subwoofer systems, which can be seen in articles such as: Subwoofer Placement - The Place for Bass, Subwoofer Placement Guide: Finding the Optimal Location for Best Sound, Home Theater Multiple Subwoofer Set-Up & Calibration Guide, so we can whole-heartedly get behind a product which makes such systems more feasible.

monolith sealed 12 angle view.jpg   monolith sealed 15 side view.jpg

The Sealed Subwoofer Advantage

Another advantage of a sealed design is they are able to produce output at extremely deep frequencies compared to an equivalent ported design. Ported subs can generate a lot more output at port tuning frequencies compared to sealed subs, but below port tuning, their output rapidly diminishes. Sealed subs, on the other hand, only see a gradual lessening of output below their resonant frequency, so they are still producing output down even to single digit frequencies, although not normally at very loud levels. However, multiple sealed subs could have very low-frequency output at palpable levels with enough units. As more sealed subwoofers are added to a system, monolith sealed 10 angle view.jpgthe air displacement potential of that system is increased, and eventually, a system with massive infrasonic capability can be had. The question then becomes how much pressure can the structural integrity of your home take before it crumbles?

The new sealed Monolith subwoofers are scheduled to start shipping by mid March 2019 and are priced the same as their ported counterparts: $500 for the 10”, $800 for the 12”, and $1,300 for the 15”. Shipping is free. With the addition of these sealed subs, Monoprice is poised to become one of the premier internet destinations for high-powered yet affordable home theater components.  Audioholics may get some of the new sealed Monolith subs in for a full review, so stay tuned to get a full tour of Monoprice’s latest gambit in the Monolith line.

Do you prefer sealed or ported subs? Share your thoughts in the forum thread below.

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

About the author:
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James Larson is Audioholics' primary loudspeaker and subwoofer reviewer on account of his deep knowledge of loudspeaker functioning and performance and also his overall enthusiasm toward moving the state of audio science forward.

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