About the Monitor Audio Radius 90

High-performance sound from a tiny speaker
High-performance sound from a tiny speaker
We couldn't believe our eyes when we first unpacked the Monitor Audio Radius R90s. These speakers are downright beautiful, and almost impossibly small. But the real surprise came when we got our first listen. Despite their compact size, the sound they delivered was open and spacious, with true-to-life imaging and a big soundstage.
Use them with a subwoofer for deep bass
If you're looking for big, powerful bass, you will definitely want to add a powered subwoofer. Use a pair of R90s in a 2.1-channel stereo system for room-filling sound. Or mount four or more around your home theater room for surround sound with superb detail and clear dialogue.
Monitor Audio's secret sauce
The Radius R90 benefits from many of the technical advances, materials, and construction techniques found in Monitor's renowned, top-of-the-line Platinum series speakers. Both its 4" woofer cone and 1" dome tweeter are made of a high-tech ceramic-coated aluminum/magnesium alloy. This exceptionally stiff, lightweight material allows the drivers to respond swiftly and precisely to the audio signal for greater accuracy. The tweeter also gets an anodized coating of gold that helps ensure smooth, extended highs.

Whether you choose high-gloss black, white, or walnut veneer, Monitor Audio's R90 speakers look as fantastic as they sound.
Instead of using conventional screws, Monitor mounts each driver firmly into the cabinet using a single bolt that threads into its backplate, then attaches to the back of the enclosure. This mechanically decouples the driver and front baffle to enhance clarity and resolution, while acting as rigid cross bracing for a more solid, non-resonant cabinet. The lack of visible mounting hardware also adds to the R90's overall look of elegance.
Gorgeous build quality and design
Monitor Audio speakers have long been known for their sturdy, vault-like cabinet construction. The R90's enclosure feels solid and substantial, with an exterior clad in a beautifully finished high-gloss black, white, or real walnut wood veneer.
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Product highlights:
- frequency response: 80-35,000 Hz
- for deep, hard-hitting bass, consider adding a powered sub
- sensitivity: 83 dB
- recommended amplifier power: 30-100 watts
- impedance: 8 ohms
- ultra-rigid, lightweight C-CAM® (Ceramic-Coated Aluminum/Magnesium) cone material provides high efficiency and low distortion
- 1" C-CAM gold dome tweeter for detailed sound and extended high-frequency response
- 4" C-CAM mid/bass drivers for clear midrange and punchy bass
- bass-reflex (ported) design with HiVe® II technology for reduced turbulence and higher velocity airflow
- single bolt-through driver attachment provides mechanical decoupling and increased cabinet rigidity for greater clarity and resolution
- five-way binding post speaker terminals
- 4-7/8"W x 7-13/16"H x 6-9/16"D
- weight: 4.6 lbs. each
- warranty: 5 years
- Our 60-day money-back guarantee
- MFR # R90PB
What's in the box:
Monitor Audio Radius 90 owner's manual
- 2 Bookshelf loudspeakers
- 2 Grilles (installed)
- 8 Rubber feet
- Grille removal tool
- Owner's Manual
- Important Safety Instructions
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More details on the Monitor Audio Radius 90

Features & specs
Enclosure | Ported | |
Finish | Lacquer | |
Color | Gloss Black | |
Tweeter Type | Hard-Dome | |
Tweeter Size (inches) | 1 | |
Midrange Size (inches) | N/A | |
Woofer Size (inches) | 4 | |
Woofer Composition | C-CAM | |
Woofer Surround | Rubber | |
Power Range | 30-100 | |
Sensitivity | 83 dB | |
Impedance (Ohms) | 8 | |
Frequency Response | 80-35k Hz | |
Connector Type | 5-Way post | |
Bi-amp Inputs | No | |
Height (inches) | 7-13/16 | |
Width (inches) | 4-7/8 | |
Depth (inches) | 6-9/16 | |
Weight (pounds) | 4.6 | |
Wall-mountable | With optional bracket | |
Bracket Included | No | |
Recommended Stand Height (inches) | 31-36 | |
Parts Warranty | 5 Years | |
Labor Warranty | 5 Years |
Product Research
Features
Two-Way Speaker Design: The Monitor Audio Radius 90 bookshelf loudspeaker features a two-way speaker design with one 1" C-CAM gold dome tweeter and one 4" C-CAM cone woofer. The 1" C-CAM gold dome tweeter is optimized to deliver the finest and widest performance within the compact speaker cabinet. It benefits from a more efficient rear-venting design, releasing air trapped and compressed at the back of the tweeter dome, and guiding it around the drive assembly to a rear-loading chamber. The 4" C-CAM woofer features a large motor and voice coil for increased excursion, high power capability and reduced distortion. The C-CAM tweeter and woofer share an audible consistency producing a smooth transition of frequencies and a sense of realism and cohesion in the soundstage.
C-CAM Technology: The 1" tweeter and 4" woofer of the Radius 90 bookshelf loudspeaker utilize Monitor Audio's proprietary C-CAM speaker technology.
- C-CAM Gold-Dome Tweeter: The gold dome tweeter is formed from a ceramic-coated aluminum/magnesium alloy, gold anodized to a specific thickness for ideal stiffness and damping characteristics. Its new profile and surround geometry have been developed using advanced modeling tools, to provide the optimum qualities for accurate sound reproduction. The new design moves the first order of breakup to beyond 35kHz, producing a linear response way beyond audibility, which matches the wide frequency bandwidth available from HD music and cinema sound formats. The gold dome is thinner, lighter, more rigid and therefore more efficient than domes made from other materials which are prone to distortion in the audio band.
- C-CAM Cone Woofer: Ceramic-Coated Aluminum/Magnesium is a material originally developed by the aerospace industry for jet engine components. Its properties are ideal for loudspeaker cones being extremely rigid, yet light enough to yield high overall efficiency. In manufacture, aluminum/magnesium alloy undergoes a three-stage stress-relieving process to remove surface deformation and molecular weakness. Once formed, the alloy cone is subjected to a high temperature anodic coating process in which a layer of pure ceramic alumina is depleted onto its surfaces to a depth of 50 microns, producing a completely rigid sandwich of alloy and heat-dissipating ceramic material. Conventional cones are liable to flex or twist in operation, producing a significant level of audible distortion. C-CAM cones have a much higher resistance to bending stress and therefore exhibit much greater fidelity over their entire operating range.
Single Through-Bolt Mount: The tweeter and woofer are fixed to the cabinet with a single through-bolt driver fixing mount. This single-through-bolt mount design provides mechanical de-coupling and enhanced midband clarity and resolution. The through-bolts also act as rigid cross bracing to give a very solid non-resonant cabinet.
HiVe II Bass Reflex Port: The Radius 90 uses a bass reflex cabinet with Monitor Audio's HiVe II port design for greater efficiency and bigger bass response from a smaller speaker. The HiVe II bass reflex port is shaped to have the same effect on airflow as a gun-barrel on a bullet. Rifled grooves inside the port help to accelerate the flow and reduce turbulence, so air moves in and out of the port more efficiently, for a faster more dynamic bass response.
Stylish Cabinet: The Monitor Audio Radius 90 features a beautiful precision cabinet in a gloss black, satin white, or walnut veneer lacquer finishes. The cabinet's smooth rounded edges, silver trim, and metal mesh grille add to the style and look of the speaker.
Gold-Plated Binding Posts: The Radius 90 is fitted with gold-plated binding post speaker terminals that will accept bare wire (up 12AWG), pin-connectors, spade connectors, and banana plugs (single or dual).
Mounting Options: Self adhesive rubber feet are provided to prevent movement due to vibration when using the Radius 90 loudspeakers on a table, shelf, or stand. And thanks to its rear-panel 1/4"-20 threaded insert, the Radius 90 can also be fixed to a wall using an optional wall-mount bracket (sold separately).
Note: Because the threaded insert and the binding-post terminals are positioned so close together, many optional wall-mount brackets will not fit.
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Customer Q&A
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I needed a small bookshelf speaker for my surround speakers. My front is made of Monitor Audio Silver speakers. The Silver bookshelf were too big, but these fit the bill perfectly. Sound just like the Silver line, just smaller with less bass, perfect for my application.
DanS from Colorado