Maxell UD-50
A half-inch mastering tape that studio engineers reached for when they wanted headroom without paying premium prices.
Overview
The UD-50 is a 1.5-mil polyester open-reel tape. Maxell built it to sit at the top of the Ultra Dynamic range. The company's own literature positioned it above the LNE line, described it as similar in character to the LNE formulation but with greater headroom, and called it "one of the best." That's marketing copy, but the numbers held up under measurement.
In Audio (May 1973), the magazine's tape tests recorded the UD50-7 at an output of -0.5 dB with a signal-to-noise ratio of 70.5 dB. Distortion measured 0.7% at 0 VU and 1.5% at +3 VU. The tape also shows up in studio equipment manuals as a reference blank. TEAC's documentation for its A-3300S and A-7300 decks lists the Maxell UD-50 among recommended low-noise tapes, with specific bias and EQ switch positions spelled out for it. When a tape machine maker prints your model number next to a switch setting, that's a working endorsement.
The high-frequency behavior was the other half of the story. In a frequency-response comparison published in Audio (May 1973) against a Scotch 207 reference, the UD50-7 measured +2.5 dB at 10 kHz, +3.1 dB at 15 kHz, and +3.6 dB at 20 kHz. That rising top end is typical of a hot, high-output formulation, and it's why the tape needed its own bias setting rather than a generic one. The same test roundup said the new generation of low-noise and super-dynamic tapes genuinely delivered a worthwhile improvement, but that recorders had to be adjusted to suit them, or the divergences between formulations would eat the gains.
Tascam's documentation for the 80-8 eight-track recommends the Maxell UD50 alongside Ampex 456 and Scotch 206. That's a narrow-track, half-inch format where tape choice matters a great deal.
The archive can't say when the UD-50 entered production or left it, what it originally cost at retail, or how the formulation changed over the years. The paper trail here is test benches, alignment charts and studio manuals.
Period dealer price lists in the UK trade press quoted the UD 50-7 (10½-inch NAB reel, 2500 ft) at £7.25, with the half-inch UD 50-10 at £9.25 and the one-inch at £18.35, before VAT. Those figures come from Acoustico Enterprises' distributor advertising in Studio Sound (1974). Sealed examples turn up, but the tape is old enough that sticky-shed and binder breakdown are real risks on any used reel. Expect to need a spare machine to wind off a shedding pancake.
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