Sony Model 850 Stereo Tape Deck
Three speeds, a scanner that finds your song for you, and a price that made the competition sweat.
Overview
The first thing a collector notices about the Sony 850 is the reel size: it takes professional 10½-inch reels, which in the late 1960s was the sort of thing you expected to see in a studio rack, not on a home shelf. According to the period advertising and the manual listings of the era, the deck ran three speeds — including 15 inches per second — and came in two-track and quarter-track record versions, each with a fourth head for playback of both two-track and quarter-track tapes. That fourth head is the detail that matters most to anyone actually using one today: it means a single machine can play back a library recorded either way, and Sony's optional plug-in head block reportedly let an owner convert a two-track machine to quarter-track record in seconds.
The feature that got the most ink was the APS Program Scanner, which used fast forward to locate recorded material by sensing a foil strip, then reverted to play mode for reproduction. In plain terms, it was an automatic search function decades before anything digital — cue your tape with foil and the deck found your selection without rethreading. The transport itself was closed-loop dual-capstan, with interlocked "logic controlled" push buttons that the manufacturer claimed made it impossible to break or damage tape.
The published wow and flutter was only 0.03% at 15 in/s.
The pitch in the pages of the day was blunt. Audio (October 1970, p.19) carried Sony/Superscope's claim that the 850 was "something to compete with" and that rivals were "really finding it tough" — marketing copy, plainly, but the same advertisement laid out the 10½-inch reels, the three speeds, the logic-controlled buttons, and the APS scanner as the differentiators. HiFi-Stereo (November 1970, p.141) ran the same pitch, which tells you how hard Sony pushed the model in the fall of 1970. Treat those as the manufacturer's own billing rather than an independent verdict; the feature list is what survives scrutiny, not the swagger.
Where the deck sits for a collector today is a matter of condition and completeness. The dual-capstan transport and the foil-sensing scanner are mechanical systems with wear points, and a unit that has sat unused will need the usual going-over before it earns trust. The 10½-inch reel capability and the fourth playback head are the reasons to bother: this is a machine that can handle a serious tape library at studio speed, and the two-track/quarter-track flexibility means it isn't locked to one format. Buyers should confirm which record version they're getting — two-track or quarter-track — and whether the optional head block is present, because that accessory is the difference between a flexible deck and a fixed one.
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