Sony VSU-3310
A rack-mounted afterthought that turned a digital multitrack into a pitch-shifting workhorse.
Overview
The VSU-3310 is not the star of Sony's DASH story — it's the accessory that made the star more useful. Sony's own advertising described it plainly: the VSU-3310 was added, alongside the IF-3310, "to further improve system flexibility" for owners of the PCM-3324 multitrack. That's marketing copy, and it reads like marketing copy. But the trade press gave the box a much sharper job description.
Studio-Sound (February 1987, p.37) described the VSU-3310 as a rack-mounted accessory added to further improve system flexibility for the PCM-3324 multitrack. That single sentence tells you most of what matters. The PCM-3324 was a 24-track DASH-format digital machine, and the VSU-3310 sat alongside it in the rack to let engineers nudge playback speed — and therefore pitch — across a genuinely useful range, while locking to house sync.
Why does that matter? Because a digital multitrack that can only run at one clock is a tape machine that refuses to play well with the rest of the room. Var-speed control is the kind of feature that never appears on a brochure's front page but gets used on every session — dropping a vocal a few cents to sit in the track, chasing a reference, matching a piece of outboard gear that wants to run slightly fast. Sony's ad copy never mentions any of this; it just says the box improves flexibility. The period press filled in the blanks.
What the VSU-3310 is not, despite the "VSU" prefix, is a video switcher or a general-purpose sync box. It exists in the Sony ecosystem as a dedicated companion to the PCM-3324, and collectors should treat it that way. A VSU-3310 without a 3324 to control is a rack panel with a specific purpose and no obvious use.
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