Bowers & Wilkins HTM81 D4

The HTM81 D4 is the flagship centre channel loudspeaker in the 800 Series Diamond range — engineered as the perfect acoustic partner for the 801 D4 and 802 D4 floorstanders, and the only centre channel worthy of that company. A centre channel carries the majority of the dialogue, the lead vocal, and the anchor point of every cinematic soundtrack — and in a reference home cinema system built around the 800 Series Diamond, it must match the performance of the main speakers without compromise or qualification. The HTM81 D4 does exactly that. Martins Hi-Fi is the second oldest Bowers & Wilkins dealer in the world, and the HTM81 D4 is available to hear in our Norwich showroom.

Diamond Tweeter and Solid Body Tweeter-on-Top

The HTM81 D4 uses the same solid diamond dome tweeter as the 801 D4 and 802 D4 — machined from synthetic diamond and housed in its own Solid Body aluminium enclosure, mounted in the Tweeter-on-Top configuration above the main cabinet. The isolation this arrangement provides is absolute — the diamond dome operates entirely free from the vibrations generated by the midrange and bass drivers, reproducing high-frequency detail with a precision and purity that a conventionally mounted tweeter cannot approach. In a centre channel application, where the intelligibility of consonants and the clarity of vocal overtones are paramount, this level of high-frequency resolution is not a luxury — it is a necessity.

Continuum FST Midrange Driver

The midrange driver employs Bowers & Wilkins' Continuum cone in a Fixed Suspension Transducer mounting — the same driver technology used in the flagship floorstanders. Continuum's woven composite structure eliminates the characteristic resonance colouration of conventional synthetic cone materials in the critical midrange frequencies where the human voice lives. The FST mounting removes the conventional foam surround entirely, eliminating the intermodulation distortion it introduces and allowing the midrange to pass dialogue and vocals with a transparency and low-level resolution that defines the performance standard of the 800 Series Diamond. Biomimetic Suspension refines the driver's mechanical behaviour at low signal levels, recovering the fine detail that lesser midrange designs leave behind.

The midrange unit is housed in a dedicated aluminium enclosure within the main cabinet — a stiff, precisely engineered structure that provides a controlled acoustic environment for the driver, prevents unwanted air leakage into the surrounding cabinet, and decouples the midrange from the mechanical activity of the bass drivers on either side.

Aerofoil Bass Drivers and Anti-Resonance Plug

Two Aerofoil profile bass drivers flank the midrange unit — the same variable-thickness composite cone technology used across the 800 Series Diamond floorstander range. Their cross-section varies from centre to edge, providing the precise combination of stiffness and compliance that the Aerofoil design demands, without the mass penalty of a conventionally stiffened cone. Each bass driver is fitted with an Anti-Resonance Plug — a solid mass positioned within the motor system to damp its primary internal resonance — ensuring that the HTM81 D4's bass output is as controlled and articulate as the midrange and treble it supports.

Matrix Cabinet Construction

The HTM81 D4's enclosure employs Bowers & Wilkins' Matrix internal bracing — the lattice of interlocking panels bonded throughout the cabinet that eliminates panel resonances and ensures the enclosure contributes nothing of its own character to the sound. The D4 generation brings a stiffened aluminium top plate and updated internal geometry that further reduces cabinet colouration, ensuring that the HTM81 D4's already exceptional transparency is maintained across the full dynamic range of a demanding cinematic soundtrack.

Technical Specifications

Who Is It For?

The HTM81 D4 is the definitive centre channel choice for those building a reference home cinema system around the 801 D4 or 802 D4 — the only centre channel that matches those loudspeakers' performance without asking for any concession in tonal coherence or dynamic capability. It demands a capable AV processor and amplification of equivalent quality, and it rewards that investment with a centre channel performance that sets a standard very few installations anywhere in the world can match. Those completing the surround system should consider the Bowers & Wilkins DB1D or DB2D subwoofers, or explore the full 800 Series Diamond range to understand the complete system Bowers & Wilkins have engineered around this centre channel.

Buying from Martins Hi-Fi

Martins Hi-Fi has been in Norwich since 1968. Elizabeth Gould runs the business today, and we stock only brands we have heard properly and stand behind. As the second oldest Bowers & Wilkins dealer in the world, we have a depth of experience with the 800 Series Diamond range that very few retailers can match. Dave and Chris can demonstrate the HTM81 D4 in our Norwich showroom as part of a complete 800 Series Diamond surround system, and advise on the amplification and processing that will allow it to perform at its considerable best.

Contact us at info@martinshifi.co.uk, call 01603 627010, or WhatsApp on 07554 687137. You can read more about how we work on our Why Martins Hi-Fi page. We are at 85–91 Ber Street, Norwich, NR1 3EY.