Bookshelf Speakers — Monitor Audio Radius 90

The Radius 90 is a small two-way speaker from the Monitor Audio Radius range. Sold as a pair, it carries a five-year warranty. It can stand on furniture or be fixed to a wall, with an optional bracket for built-in installations.

Key specs that matter

A 4 inch (100 mm) C-CAM cone handles the bass and midrange band, while a 1 inch (25 mm) C-CAM Gold Dome tweeter handles the treble. Frequency response is 80 Hz to 35 kHz. Sensitivity is 83 dB at 1 W and 1 m, and nominal impedance is 8 ohm. The drive units are rated for 75 W RMS, while the whole system handles 100 W RMS. Monitor Audio recommends amplifiers of 30 to 100 W and gives a maximum SPL of 102 dBA. The cabinet itself is 198 mm high, 125 mm wide and 140 mm deep. With the grille and terminals added, the depth grows to 164 mm, and with grille and wall bracket it reaches 203 mm. Each speaker weighs 2.1 kg. The drive units, power ratings and maximum SPL are all specified per speaker, and the pair ships in one box.

Engineering and use context

Low frequencies are reinforced by bass reflex loading through a rear-facing port. That port follows the HiVe II profile, which Monitor Audio describes as shaped to act on the airflow the way a gun barrel acts on a bullet. A single through-bolt secures every drive unit, a method that the company says provides mechanical decoupling and improves resolution in the mid-band. Both the cone and the dome are made of C-CAM, a ceramic-coated alloy of aluminium and magnesium. The cabinet supports single-point wall mounting, and for installations the Monitor Audio Speaker Mount (MASM) is available as an optional pre-construction bracket.

Pairing

Given its nominal impedance, the speaker is a straightforward load for most stereo amplifiers and home cinema receivers. Its modest sensitivity means that output depends more on amplifier power than with a more efficient design, and the recommended amplifier range is set accordingly. A subwoofer is the natural partner when the system has to reproduce content below the speaker's bass limit.

Alternatives

The Monitor Audio Silver 50 7G is a larger bookshelf model from another range of the brand, with a 135 mm RST II C-CAM bass-mid driver and a C-CAM tweeter.