B&W CM4 Towers – Rosenut, Made in England, Nautilus Tweeter

B&W CM4 — Nautilus Tweeter, Rosenut Veneer, Built in England

The flagship of B&W’s CM series, in real Rosenut veneer, built in England — and a pair with a history we can account for completely, because we have sold them before.

The Nautilus Tweeter

The tweeter is where to start. This is B&W’s Nautilus design, tube-loaded so that energy radiating from the rear of the diaphragm is absorbed rather than reflected back through it. That principle came from B&W’s cost-no-object flagship work and it does something specific and audible: it removes the fine haze that sits over the treble of most speakers, leaving high frequencies focused and properly placed rather than smeared across the soundstage.

The 2.5-Way Arrangement

Below it the CM4 runs a 2.5-way arrangement, which is more thoughtful than the driver count suggests. A 165mm aluminium cone handles bass only, rolling off at 150 Hz, while a 165mm woven Kevlar cone covers low bass through the midrange up to the tweeter crossover at 4 kHz. That gives the radiating area of two bass drivers without forcing one large driver to reproduce both a kick drum and a voice — the compromise that muddles most towers this size. Kevlar was B&W’s own patented application of a DuPont material developed for body armour, chosen because it breaks up standing waves rather than storing and re-releasing them as coloration.

Flowport Design

Twin Flowports at the rear are dimpled like golf balls, for the same aerodynamic reason: dimples smooth airflow over a surface and reduce turbulence, which in a reflex port means less chuffing and cleaner low frequencies at volume. The lower port is moulded integrally with the terminal tray.

Cabinet Construction

The cabinet deserves attention too. The baffle is brushed aluminium rather than veneered MDF, and the grilles attach to the baffle’s own allen screws — so there are no grille holes drilled into the front of the speaker, grilles off or on. Real Rosenut veneer covers the rest, one of only two wood finishes B&W offered on the CM4, and the more striking of the pair.

What We Know About This Particular Pair

Here is something we can tell you about this particular pair that almost no seller of used audio could. We have sold them twice, and on both occasions the owner returned them to us through our Perpetual Trade-Back Program to move up to something more expensive. We mention it because of what it says rather than what it costs us. These are the speakers that make people care. Someone buys a proper pair of B&W towers, hears what a real Nautilus tweeter and a Kevlar midrange actually do, and within a year wants to know what the next rung sounds like. That is a compliment to the CM4, not a criticism — and because the trade-back credit applies against the full purchase, climbing that ladder costs far less than most people expect.

Placement and Practical Notes

Practical notes, because they matter. These are rear-ported and want some breathing room from the wall; B&W supplied foam port bungs for rooms that will not allow it, which restrict airflow and tame midbass when the speakers must sit close. They are also unshielded, so keep them away from any CRT display. Terminals are gold-plated and bi-wire and bi-amp capable.

Condition

Cosmetically they are graded Good, with honest wear consistent with use and nothing affecting performance. They have been thoroughly inspected and tested in-house and are working perfectly.

The CM4 sat at the top of its series and shows it — a Nautilus tweeter, Kevlar and aluminium bass drivers, an aluminium baffle and real wood veneer, assembled in England. Slim enough for a normal room, and good enough that two previous owners used them as the reason to go further.

B&W CM4 Specifications

• Design: 2.5-way rear-ported floorstanding loudspeaker
• Tweeter: 25mm (1 inch) Nautilus tube-loaded aluminium alloy dome
• Bass/midrange: 165mm (6.5 inch) woven Kevlar cone
• Bass: 165mm (6.5 inch) aluminium cone
• Frequency response: 38Hz-20kHz (+/-3dB)
• Sensitivity: 90dB (2.83V/1m)
• Impedance: 8 ohms nominal, 4.4 ohms minimum
• Recommended amplifier power: 50-150 watts
• Ports: Twin dimpled Flowports, rear-firing, foam bungs supplied
• Baffle: Brushed aluminium, grilles mount to baffle screws
• Terminals: Gold-plated, bi-wire and bi-amp capable
• Magnetic shielding: None
• Finish: Rosenut real wood veneer
• Original manufacturer: Bowers & Wilkins – Made in England
• Dimensions: (Width x Height x Depth) 7.8 x 35.8 x 11.5 inches (200 x 910 x 293 mm)
• Weight: 40 lbs (18 kg) each

✅ Buy With Confidence — The Radique Promise

Backed by Radique Audio’s Bumper-to-Bumper Warranty and our Perpetual Trade-Back Program. When you’re ready to move on, we’ll take it back. That’s the Radique difference.

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