Marantz HD770 (c. 1977–1979)

The Marantz HD770 was the flagship floorstanding model of the company's HD loudspeaker series, sold from roughly 1977 to 1979. It was a three-way bass reflex design, sitting above the HD660, HD550, and HD440 in the lineup. Marantz's own sales literature positioned it against high-end speakers from JBL, Infinity, and Klipsch.

The driver complement is well documented. There's a 10-inch (250 mm) woofer with rubber surrounds, a 5-inch (130 mm) midrange, and a 1-inch (25 mm) dome tweeter. Crossover points are generally listed at 600 Hz and 3,500 Hz, with air-core coils in the network. The cabinet is internally braced. The HD series as a whole was notable for foam surrounds treated with a special compound - a material that decays over time and is the most common issue owners face today.

Specs across sources are somewhat inconsistent, and that's a recurring problem with this model. The most commonly cited figures are an impedance of 8 ohms, a frequency response of 45 Hz to 20,000 Hz (though a Marantz brochure claims extension to 25,000 Hz), and a sensitivity of 89 dB/W/m. Power handling is usually given as 15-100 watts, though one source lists 100W/150W. Dimensions are typically listed as 380 × 650 × 300 mm (W×H×D) and weight around 23.5 kg. Walnut vinyl was the standard finish. HiFI-Stereo (1981, p.181) listed a Marantz speaker system of the period at $875, which gives a rough sense of where these sat in the market. The exact original retail price of the HD770 itself is not documented.

Owner reports are positive. Comments mention very tight bass, excellent imaging, and a forgiving nature when it comes to amplifier choice, with classical and jazz cited as strong suits. Used prices tend to land around $200-300 per pair depending on condition. Replacement drivers are hard to find, so collectors recommend checking the foam surrounds carefully and budgeting for crossover capacitor replacement if needed.