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Monitor Audio Radius 390

Compact powered subwoofer (High-gloss Black)

Item # 893R390PB

Looking for hard-hitting bass from a sub that looks good and doesn't hog lots of space? You've come to the right place.

Looking for hard-hitting bass from a sub that looks good and doesn't hog lots of space? You've come to the right place.

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Please click here for your Proposition 65 warning.

Item # 893R390PB

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$1,220.00 -$200.08 Outlet savings


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About the Monitor Audio Radius 390

Kramer Crane

The kind of bass you'll look forward to hearing

I remember the day I added a high-performance subwoofer to my home theater system. The difference in the quality — and quantity — of bass over my previous model was immediate, and showed me just how much I'd been missing with my beloved sci-fi movies and music playlists. 

The kind of bass you'll look forward to hearing

I remember the day I added a high-performance subwoofer to my home theater system. The difference in the quality — and quantity — of bass over my previous model was immediate, and showed me just how much I'd been missing with my beloved sci-fi movies and music playlists. 

If you want a similar high-impact bass experience, consider Monitor Audio's Radius 390 powered subwoofer. This elegant and surprisingly compact sub delivers the kind of bass you'll look forward to hearing (and feeling) with your favorite movies, albums, TV shows, and video games.

Monitor Audio Radius 390 compact powered subwoofer

An attractive grille-less design adds to the visual pop of this high-quality subwoofer.

The "secret sauce" behind Monitor's high-tech woofers

The keys to the Radius 390's powerful performance are its brawny 220-watt Class D amplifier and advanced driver design. Housed inside the Radius 390's enclosure are twin, side-firing 10" woofers working in tandem — one powered and one passive.

Each cone is made from a lightweight, ceramic-coated aluminum/magnesium alloy originally developed by the aerospace industry for jet engine components.

This ultra-rigid material resists the bending and twisting that causes distortion, while allowing the use of thinner, lighter, and more responsive materials. The result is tight, fast, and tuneful bass with exceptionally high output levels.

Attractive grille-less design

Please note that this subwoofer does not come with grilles. Instead, it uses color-matching cones that complement the enclosure's attractive finish.


Product highlights:

  • frequency response: 30-120 Hz
  • built-in Class D amplifier delivers 220 watts of continuous power
  • ultra-rigid, lightweight C-CAM® (Ceramic-Coated Aluminum/Magnesium) cone material provides high efficiency and low distortion
  • one 10" side-firing C-CAM long-throw woofer
  • one 10" side-firing C-CAM long-throw passive bass radiator
  • continuously variable low-pass 40-120 Hz crossover
  • phase switch (0/180°)
  • three-position bass EQ switch (Music/Movies/Impact) provides fine-tuning for different sources
  • auto on/off, plus 12-volt DC trigger input
  • left and right line-level, LFE RCA inputs
  • this subwoofer does not come with grilles
  • 13"W x 13-11/16"H x 12-9/16"D
  • weight: 30.3 lbs.
  • warranty: 2 years
  • Our 60-day money-back guarantee
  • MFR # R390PB

What's in the box:

  • Powered sub
  • 6' AC power cord
  • 10.75' Mono minijack cable
  • Owners Manual
  • Important Safety Instructions

Scratch & Dent items may be missing non-essential accessories. In some cases the manufacturer's accessories have been replaced with generic equivalents.

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Crutchfield response

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More details on the Monitor Audio Radius 390

Stacey B.

Features & specs

Enclosure Passive Radiator
Woofer Size (inches) 10
Woofer Composition C-CAM
Firing Direction Side
Amplifier Output (watts) 220
Frequency Response 30-120 Hz
Preamp-Level Inputs LFE, Stereo RCA
Speaker-Level Inputs No
Speaker-Level Outputs No
Wireless No
Low-Pass Crossover Freq 50-120
High-Pass Crossover Freq None
Phase Switch Yes
App Control No
Remote No
Other Info
Height (inches) 13-11/16
Width (inches) 13
Depth (inches) 15-1/8
Weight 30.3 lbs
Speaker Parts Warranty 2 Years
Speaker Labor Warranty 2 Years
Amplifier Parts Warranty 2 Years
Amplifier Labor Warranty 2 Years

Product Research


Twin Side-Firing 10" C-CAM Drivers: The Monitor Audio Radius 390 features twin side-firing 10" C-CAM drivers; one active 10" cone woofer and one passive 10" ABR (auxiliary bass radiator). The two drivers work in tandem to reproduce very clean, deep, and dynamic bass frequencies.

  • C-CAM Woofer Technology: Refined over many years by Monitor Audio, C-CAM (Ceramic-Coated Aluminum/Magnesium) woofer technology is used in the Radius 390 Powered sub. Originally developed by the aerospace industry for jet engine components, C-CAM's properties are ideal for subwoofer cones being extremely rigid, yet light enough to yield high overall efficiency. C-CAM bass drivers are able to resist the bending distortion imposed by sudden and extreme bass excursions to reproduce very clean, deep and dynamic bass frequencies. Conventional cone materials are more likely to flex in operation, producing a significant level of audible distortion.
  • ABR (Auxiliary Bass Radiator): For open environments sound quality can be further enhanced through the use of a sealed ABR (Auxiliary Bass Radiator). The ABR works like a piston moving back and forth generated by the movement of the air via the motion of the mid/bass driver inside the sealed cabinet. This makes the ABR ultimately act like a conventional port resulting in superior low frequency punch and extra penetration whilst keeping the elements at bay.
Note: The drivers have no grilles, but are color-coded to coordinate with cabinet finish.

220W Class D Amplifier: The Monitor Audio Radius 390 utilizes a powerful 220W Class D amplifier to drive the 10" C-CAM woofer. The 200W Class D amplifier is highly efficient, runs extremely cool, and offer distortion free bass.

MDF Cabinet: The Radius 390 powered sub features a durable 18mm MDF cabinet with internal bracing. The MDF enclosure is rigid and protects against unwanted vibration and distortion.

Controls: The level control, low pass crossover, phase switch, and EQ allow you to blend the powered subwoofer's low-frequency tones with your system's other speakers, as well as establish the ideal level of bass for your type of movie, music, and room.

  • Level Control: The level control adjusts the subwoofer's volume relative to the rest of your home audio system. After the sub's level control has been set, the volume control of your AV receiver will be the volume control for both the Monitor Audio powered subwoofer and your connected loudspeakers.
  • Low-Pass Crossover: The variable low-pass crossover is adjustable from 50-120Hz. The crossover point chosen determines where low bass frequencies are "handed-off" from your AV system's loudspeakers to the Monitor Audio powered subwoofer. Set the crossover point based on the size of your systems' main left/right speakers.
  • Phase Switch: The Phase switch is used to acoustically match the subwoofer's output to your main speakers. Select the position either 0˚ or 180˚ in which your subwoofer has more output at the listening position.
  • Bass EQ: The Radius 390 powered subwoofer offers Impact, Movie, and Music presets for easy EQ operation. Movie mode provides a relatively flat response down to 35Hz. Music mode is -2dB down from Movie mode but goes lower, all the way down to 30Hz. Impact mode is +3dB up from Movie mode and comfortably goes down to 40Hz.

LFE/RCA Inputs: The Monitor Audio Radius 390 powered subwoofer is equipped with a dedicated LFE input and a stereo RCA input to connect the powered sub to a variety of AV receivers or integrated amplifiers.

  • LFE Input: Most of today's AV receivers have a line-level subwoofer output (LFE). If your receiver has an LFE output, connect one end of a subwoofer cable (sold separately) to this output and connect the other end of the cable into the powered subwoofer's dedicated LFE input. This type of connection bypasses the powered sub's crossover and uses the low-pass crossover built into your AV receiver.
  • Stereo Input: In absence of a subwoofer (LFE) output on your receiver, as an alternative hookup, you can connect Left & Right channel pre-amp outputs from the receiver to the stereo RCA inputs (Left/Right) on the powered subwoofer. This type of connection will use the low-pass crossover built into the powered sub.

12V Trigger Input: A 12V trigger input (3.5mm) syncs the Radius 390 powered sub with other AV components when the system is activated.

Auto Power On/Off: The powered subwoofer will automatically turn On when it senses an audio signal. You can also choose to turn the powered sub On manually from the rear-switch on the back. It will automatically go into "Standby mode" after 15 minutes with no audio signal.

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