TDK MA-90
A metal-bias cassette that shows up in mail-order price lists more reliably than in any spec sheet. That says something about who was buying it.
Overview
The surviving documentation for the TDK MA-90 is almost all incidental. There is no manufacturer spec sheet in the archive, no owner's manual, and no review with measured coercivity or remanence figures. What exists is a paper trail of dealer ads in the audio press of the early-to-mid 1980s, the dense agate-type "BLANK TAPE" listings that ran in the back pages of Audio and High Fidelity. Those listings are useful anyway. They show what the MA-90 cost, how it was positioned against TDK's own line, and how the market treated it next to rival metal tapes.
In the same advertisement, TDK's premium "MAR-90" sat at $6.49, the SAX-90 at $3.19, the ADX-90 at $2.79, the SA-90 at $2.19, and the plain D-90 at $1.25. Read that ladder and you can see where the MA-90 lived. It was the most expensive tape in the ordinary TDK range, but it was not the top of the line. The MAR-90 cost a full two dollars more. The MA-90 was the metal tape for people who wanted metal performance without paying for the fancy housing.
That positioning held steady across several years of listings. A 1983 dealer ad in Audio (August 1983, p.104) shows the MA-90 at $4.49, again above the SAX-90. An August 1984 Audio ad from a different dealer, Quality Tapes, quoted $4.19. Across dealers and years the spread runs roughly $3.79 to $4.49. The MA-90 was a premium metal cassette whose street price drifted slowly downward as the decade wore on and metal tape became less of a novelty.
The listings say nothing about the tape itself. Whether the MA-90 was a true Type IV metal formulation, what its bias and EQ settings were, how long the C-90 actually ran in minutes, what the shell was made of - none of that is documented here, and the archive won't invent it. The model number strongly implies a 90-minute length, and the "MA" prefix places it in TDK's metal family, but those are inferences from naming convention, not verified specifications. Anyone after hard technical data will need a period TDK catalog or the tape's own J-card, and neither survives in this archive.
What can be said with confidence is that the MA-90 was a commodity item. It was widely stocked, competitively priced, and sold through the same mail-order channels that moved Maxell, Sony, Fuji, and BASF metal tapes. The dealer listings repeatedly bracket it against Maxell's MX-90 and XL II-S, Sony's UCXS-90, and Fuji's metal offerings, which is where a mid-tier metal cassette would be expected to compete. It was not a halo product. It was the workhorse metal tape, and the price lists treat it that way.
For a period cassette collection today, the MA-90 is common enough that it turns up, but it is not the showpiece the MAR-90 became. The surviving evidence is thin.
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