TDK LB-3600
A quarter-inch reel of TDK's Audua metal tape, priced by the reel in the trade-press columns of the late Seventies - and almost invisible everywhere else.
Overview
Almost everything known about the TDK LB-3600 comes from one recurring line item in the back pages of the British studio magazines, where blank tape was catalogued by type and price. One example is Studio Sound (September 1985, p.107), whose buyers' guide listed blank tape alongside the manufacturer directory. Through the late Seventies, dealer ads in Studio Sound listed the LB-3600 with the rest of the quarter-inch tape trade stock, priced per reel on a 10½-inch spool. It shows up repeatedly as "TDK AUDUA LB3600 Met" at £11.40 per reel, exclusive of VAT. "Met" is shorthand for metal-formulation tape, and "Audua" is the product line. The sources don't explain the "3600" designation.
That listing is the entire documented footprint. There is no manual text, no measured review and no spec sheet in the available sources. The LB-3600 is known almost entirely through dealer price columns, not manufacturer documentation. What can be confirmed is narrow but specific: it is a TDK Audua metal quarter-inch tape on a 10½-inch reel, sold in the UK trade channel at £11.40 a reel.
The pricing tells you a few things. In the same dealer columns the LB-3600 sat at the top of the TDK metal tier, with the L3600M below it at £9.50 - £10.00 depending on the dealer listing. The £11.40 figure put it above Maxell UD180 at £8.89, above Scotch 207 metal at £9.81, and level with the Revox 601 metal reel at £11.80. The dealers priced it as a premium metal tape, not a budget stock item. The £1.90 gap to the L3600M is the more interesting number: two TDK Audua metal reels, same 3600 designation, priced a couple of pounds apart. The available sources don't say what separated them, so any claim about the difference is speculation.
The "3600" in the model number is a designation, not a running time. The LB-3600 and the L3600M both carry it, and the dealer listings describe both as quarter-inch tape on 10½-inch reels. Whether the number refers to a specific length, a formulation batch code or a spool designation isn't stated anywhere in the available documentation.
The period press does confirm that TDK's Audua metal tape was a serious item in the UK trade channel through the late Seventies and into the early Eighties. That suggests the reel was a steady catalogue item, not a short-run special. It was also never a consumer-facing product the way TDK's cassette line was. It lived in the pro-audio dealer channel, sold to studios and duplicators who bought tape by the reel.
The formulation is the one technical claim the sources support. Metal tape - Type IV in cassette terms, and the corresponding metal-particle formulation in open-reel - was the performance ceiling of the magnetic tape era, and TDK built the Audua line around it. The dealer listings consistently tag the LB-3600 with the "Met" suffix, and the pricing hierarchy places it at the premium end of the metal tier. The sources give no measured performance figure: no MOL, no frequency response, no bias recommendation.
The LB-3600 is a hard item to chase because so little is written about it. It surfaces occasionally as part of larger tape lots, not as a standalone collectible, and the documentation is too thin for a buyer to verify much beyond the reel label and the dealer listing. The £11.40 trade price is the only hard number the sources give, and it is a 1978-1980 wholesale figure exclusive of VAT, not a current market value. Anyone pricing one today is working from the dealer columns and from the condition of the tape itself, and metal tape of this vintage is old enough that condition is the whole game.
The dealer listings confirm the TDK LB-3600 existed, and they confirm its formulation family, its reel format and its trade price. The length, the performance, the design rationale and the production run are absent from the available sources. The LB-3600 was a premium metal quarter-inch tape sold through the UK trade channel at £11.40 a reel.
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