Overview

The 804 D4 is a 3-way, reflex-loaded tower in Bowers & Wilkins’ 800 Series Diamond line, using a 1-inch diamond-dome tweeter, 5-inch Continuum-cone FST midrange, and dual 6.5-inch Aerofoil-cone woofers. Official dimensions and weight are 42.2 in (H) × 12.0 in (W) × 15.4 in (D) and 81.2 lb each; enclosure features include the Reverse-Wrap cabinet, Matrix bracing, and a downward-firing Flowport on an aluminum plinth [2].

Scientific Validity

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Stereophile’s measurements (John Atkinson) document multiple concerns: impedance magnitude dips to 2.55 Ω at 121–131 Hz with severe electrical phase; EPDR falls below 2 Ω over wide bands and reaches 1 Ω at 88–110 Hz, implying high amplifier stress. Treble shows excess energy between ~3.5–15 kHz relative to the midband. The port output exhibits high-Q resonances at 308 Hz and 567 Hz. While sensitivity is ~89 dB (B-weighted estimate), these traits depart from neutral/benign behavior and constrain transparency and amplifier compatibility [1]. Manufacturer specs (24 Hz–28 kHz ±3 dB; nominal 8 Ω, min 3 Ω) are noted but contradicted in critical respects by the third-party data [2][1].

Technology Level

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Genuine diamond tweeter fabrication, Continuum midrange, Aerofoil woofers, Reverse-Wrap cabinetry, and Matrix bracing are advanced, high-precision implementations. Mechanical engineering and finish quality are exemplary. However, the measured acoustic integration (treble balance, port behavior, load severity) shows the expensive hardware is not fully translated into transparent results [1][2].

Cost-Performance

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Using the cheapest equivalent-or-better option as required, the KEF Q7 Meta is a 3-way floorstander with Uni-Q coax and MAT, manufacturer-stated 46 Hz–20 kHz (±3 dB) and 87 dB sensitivity; it carries a pair price of 1,999.98 USD (999.99 USD each). The 804 D4 official price is 16,000 USD per pair [3][2].
Calculation (explicit): 1,999.98 USD ÷ 16,000 USD = 0.125 → score 0.1 (rounded to one decimal).

Equivalence note (user perspective): Same floorstanding 3-way function; manufacturer FR coverage within the mid/treble band is comparable, and KEF’s published data/spin indicates controlled directivity, while its rated 4-ohm load (min ~3.2 Ω) is markedly more benign than the 804 D4’s EPDR minima [3][4][1]. (Where independent lab data are limited for Q7 Meta, this comparison is provisional pending further third-party measurements, as allowed by our method.)

Reliability & Support

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B&W maintains established dealer/service networks and typical warranty coverage for passive loudspeakers. No model-specific failure-rate data are published. As a passive design, no firmware support considerations apply. Build quality is high, but the diamond tweeter and complex construction may increase repair costs if damage occurs [2].

Rationality of Design Philosophy

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Investments in exotic materials and cabinetry are rational if they yield audibly cleaner results. Here, however, independent data show treble imbalance, port resonances, and an extreme electrical load, which undermine the claimed advantages. The direction emphasizes materials prestige over achieving robust neutrality and amplifier friendliness [1].

Advice

If you prioritize transparent response and amplifier compatibility, the 804 D4 is a weak value. The KEF Q7 Meta offers similar functional scope with more benign loading at a fraction of the price [3][4]. If you prefer alternatives with published third-party measurements, consider Polk Reserve R700 (~2,200 USD/pair at launch; commonly ~1,099 USD each) which demonstrates ±~2 dB linearity and ~40 Hz F3 in independent Klippel NFS testing [5][6]. Should you choose the 804 D4, pair it with high-current amplifiers stable into 2-ohm regions to avoid clipping or protection trips given the measured EPDR minima [1].

References

[1] Stereophile — John Atkinson, “Bowers & Wilkins Diamond Series 804 D4 loudspeaker — Measurements.” https://www.stereophile.com/content/bowers-wilkins-diamond-series-804-d4-loudspeaker-measurements (accessed Aug 18, 2025). Key points: min 2.55 Ω @121–131 Hz; EPDR 1 Ω @88–110 Hz; port peaks 308/567 Hz; treble excess ~3.5–15 kHz; mic 50” axis; 1/6-oct smoothing for room curves.

[2] Bowers & Wilkins — “804 D4 — Tower speaker.” Specs, dimensions, and official 16,000 USD/pair price. https://www.bowerswilkins.com/en-us/product/loudspeakers/800-series-diamond/804-d4/150240.html (accessed Aug 18, 2025).

[3] KEF (US) — “Q7 Meta — HiFi Speaker.” Specs and 999.99 USD each list price. https://us.kef.com/products/q7-meta (accessed Aug 18, 2025).

[4] KEF Japan (Press release) — “Qシリーズ（Meta）発売。Q7 Meta: 264,000円/ペア.” https://prtimes.jp/main/html/rd/p/000000045.000088183.html (accessed Aug 18, 2025).

[5] Erin’s Audio Corner — “Polk Audio Reserve R700 — Klippel NFS measurements.” https://www.erinsaudiocorner.com/loudspeakers/polk_r700/ (accessed Aug 18, 2025). Notes: ~±2 dB linearity; F3 ≈ 40 Hz.

[6] Polk Audio — “Reserve R700 — Price per each 1,099 USD (typical).” https://www.polkaudio.com/en-us/product/home-speakers/floor-standing/reserve-r700/300035.html (accessed Aug 18, 2025).

(2025.8.20)