Wharfedale W70D

Seven pounds of white sand packed between layers of hardwood — Wharfedale's four-way floor-stander was inert by design and priced like furniture.

Overview

The W70D is the one Wharfedale advertised by inviting you to rap your knuckles on it. Over seven pounds of fine white sand, densely packed between layers of hardwood, sat inside the cabinet — more than in the W60D, less than in the W90D — and the company's own copy dared skeptics to compare the low, dull thud of a sand-filled back panel against the resonant ring of ordinary plywood. The logic was straightforward: a cabinet that stays absolutely inert under bass energy can't color the sound with its own resonances. It was more costly to build, and Wharfedale said so plainly.

The driver complement was just as uncompromising. A 12½-inch woofer carried a massive nine-and-a-half-pound magnet assembly on a heavy cast aluminum chassis, with a 2-inch pole piece and magnet keeper plates of fine steel to keep flux density high and heat loss low. A heavy-duty 8-inch unit served double duty — passive radiator for the upper bass, energized driver for the lower midrange. An acoustically isolated 5-inch unit handled the upper midrange, and Wharfedale's advanced-design mylar pressure dome 3-inch tweeter covered the top. Individual, continuously variable controls let owners trim the mid and treble ranges to the room.

The cabinet itself was styled for two lives: upright as a "high boy," or on its side as a "low boy." Wharfedale's period advertising, reproduced in Audio (March 1969, p.13), made the sand-filled construction and the Achromatic sound the centerpiece of the pitch. The W70D was listed at $188.00 in a lineup that ran from the $49.95 W20D Minorette up through the W60D at $135.25 — the four-way sitting near the top of the range, below only the flagship W90D.

The published frequency response was ambitious for the era: 25 to 20,000 Hz. Recommended amplifier power ran from a minimum of 8 watts to a maximum of 40 watts per channel, according to the period specification sheet. That's a modest ceiling by later standards, and it tells you what the speaker was built for — high-efficiency listening rather than party-level output. The sand-filled enclosure was the engineering story, and it's the reason survivors are heavy, dead in the hand, and still distinctive today.

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