Monitor Audio Radius 1 4G Bookshelf Speakers

Real Hi-Fi in a Five-Inch Cube

The Monitor Audio Radius 1 4G is the smallest speaker Monitor Audio makes, and it is nearly a cube: 135 x 135 x 156 mm, about 5.3 by 5.3 by 6.1 inches, at 1.8 kg each. It will sit on a desk, a shelf, a bracket or a stand without announcing itself.

Inside is a 4-inch C-CAM RST III bass-mid driver and a fully vented 19 mm C-CAM Gold Dome tweeter, crossing over at 3.2 kHz. In-room response runs from 100 Hz to 35 kHz, with a maximum peak SPL of 104 dB. Sensitivity is 82 dB and nominal impedance is 8 ohms, dipping to 3.8 ohms at 950 Hz. Finishes are high gloss black and satin white, and they are sold as a pair.

Monitor Audio launched the Radius Series 4G in June 2026, redesigning a range that has run since 2004. The Radius 1 is the entry point, below the larger Radius 3 4G.

Sealed, Not Ported, and That Is the Point

Here is the spec that separates this one from the rest of the range: the Radius 1 4G is a sealed box. No port, no tuning frequency, nothing to chuff or to fight a nearby wall. A sealed cabinet this small gives up bass extension, which is why response stops at 100 Hz, but what it keeps is control. Bass starts and stops when the signal does, and placement gets far more forgiving.

The drivers are the same family used across the 4G range. C-CAM is Ceramic-Coated Aluminium/Magnesium, and RST III cone geometry adds a ribbed surface that pushes breakup out of the audible band. The 19 mm Gold Dome tweeter is fully vented and driven by an external magnet motor. Through-bolt bracing locks the driver to the rear panel under a set torque, which matters in a cabinet this small.

Who Is This Compact Speaker Best For?

• Surround and height channels — Small, sealed and easy to mount is exactly what rear channels want.
• Desktops and near-field setups — A cube this size leaves room for a monitor, a keyboard and an amp.
• Multi-room and second systems — Bedroom, kitchen, office: places where a standmount is too much speaker.
• Anyone tight on placement options — With no port, you can put these near a wall without the bass turning to mud.
• Not your best pick as the main pair in a large room — Response stops at 100 Hz and sensitivity is 82 dB. For a primary music system, step up to the Radius 3 4G or another of our bookshelf speakers.

How Does It Connect to Your System?

These are passive speakers, so they need an amplifier or AV receiver. Monitor Audio recommends 25 to 50 W into 8 ohms, or 50 to 100 W into 4 ohms. At 82 dB, sensitivity is low even for a small speaker, so aim for the top of that range.

Mounting is where the Radius 1 earns its keep. Monitor Audio lists both the MASM and FIX-M brackets as compatible, and the Radius Floor Stand 4G and Desk Pad 4G fit as well, all sold separately. In a home theater, set your receiver crossover at 100 Hz or a little above. Place them, aim them, and let the sub carry the bottom.

Pairs Well With

Here is what usually goes around them.

• Subwoofers — Not optional with a 100 Hz roll-off. Browse our subwoofers.
• AV receivers — Bass management and room correction matter more here than usual. See our AV receivers.
• Integrated amplifiers — For a two-channel desk or bedroom system. See our integrated amplifiers.
• Speaker stands — Getting a small speaker to ear height changes more than any cable will. See our speaker stands.

Frequently Asked Questions

Are the Radius 1 4G sold as a pair?

Yes. Each speaker weighs 1.8 kg, just under 4 pounds.

Is the Radius 1 4G ported or sealed?

Sealed. Monitor Audio lists no port or tuning frequency here, unlike the ported Radius 3 4G and On Wall 4G.

Do I need a subwoofer?

For most uses, yes. In-room response is rated to 100 Hz, and Monitor Audio recommends adding a subwoofer for full-range performance.

Can they be wall mounted?

Yes. Monitor Audio lists the MASM and FIX-M brackets as compatible, both sold separately.

How much amplifier power do they need?

Monitor Audio recommends 25 to 50 W into 8 ohms. Continuous handling is 50 W, and sensitivity is 82 dB, so lean toward more power.

See It in Action

Monitor Audio’s channel introduces the whole Radius Series 4G, Radius 1 included.

Monitor Audio also unboxes the Radius Series 4G, carton by carton.

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Learn More

Want to learn more about surround speaker placement, sealed versus ported cabinets, or matching a subwoofer? Visit our Learning Center for guides, tips, and expert advice.