Ampex 351 (ca. late 1950s–1960s)

Not much is documented about the Ampex 351 in general-purpose archives, but period trade magazines and scattered classifieds fill in part of the picture. It was a professional 10½-inch reel-to-reel recorder that Ampex sold to broadcasters, recording studios, and educators. By early 1961 it had already logged more than 10,000 units in service worldwide, according to the company's own advertising in Audio (February 1961, p.47) and Audio (April 1961, p.35). The 351 was sold alongside the 354 as the "351/354 series," which suggests a two-model family of mono or stereo/track variants. The surviving ads don't spell out how the two relate.

A variant called the "Universal 351" appeared in Amateur Tape Recorder (August 1961, p.30). It likely means a model set up to handle multiple international tape equalization or speed standards. By 1974, used units were still changing hands. A classified in Recording Engineer (April 1974, p.59) offered an "Ampex 351-2P recorder" in excellent condition with new heads for $1,500. That confirms a two-track playback variant and suggests the machines stayed serviceable well into the 1970s.

That is all the archive has: the 10½-inch reel format, the "Universal" designation, the 351-2P variant, the 10,000-unit sales claim, and the 1974 used price. No technical specifications (frequency response, wow and flutter, track configurations beyond the 2P, circuit details) or original list prices have been preserved in the materials reviewed. The 351 was a professional tool reviewed in trade and industry publications rather than consumer hi-fi magazines, which may explain the thin paper trail.

Known Facts

Type: Professional reel-to-reel tape recorder, 10½-inch reels
Series: 351/354 series (two models, exact difference undocumented)
Variants documented: “Universal 351” (multi-standard), “351-2P” (2-track playback)
Sales milestone: Over 10,000 units claimed by early 1961
Market: Broadcast, recording studio, education
Used price (1974): $1,500 for a 351-2P in excellent condition with new heads
Approximate production era: Late 1950s through at least the mid-1960s