ADC C-90
Little is documented about the ADC C-90. A 1981 Audio retailer listing (March 1981, p.84) shows it priced at $3.95. It appears to have been a blank audio cassette tape. The "C-90" designation indicates a 90-minute total recording time (45 minutes per side), following the standard Philips Compact Cassette naming convention. Beyond that listing and some period retail advertisements and pricing guides, almost nothing is recorded. No release year, no tape formulation (ferric, chrome, or ferri-chrome), no shell type, no packaging details and no specifications have survived in the available sources.
The 1981 Audio retailer listing (March 1981, p.84) shows the C-90 at $3.95 in a column of ADC tape products. The column includes standard ferric tapes (ADC-45, -60, -90, -120) and premium formulations (SAX C-90 at $4.95, MA C-90 at $7.59). That puts the C-90 in the middle of the lineup, so it was probably a mid-range or standard offering. Neither the tape type nor any performance claims were stated. There is no factory literature, service manual or review, so the C-90 is one of ADC's least-documented products. It survives only in scattered price lists and discount ads from the early 1980s.
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