A ferrichrome cassette with a two-layer coating of iron oxide and chromium.
Fe-Cr Position. Since 1973.
First Generation, 1973
46 minutes - ¥750 / 60 minutes - ¥900 / 90 minutes - ¥1400.
The first generation was released above chrome tape as Sony’s highest-grade cassette. Its black and metallic-silver packaging had a premium appearance. The black shell, guide rollers and other components were made with high precision, with high-grade features including graphite-containing liners. Initially only C60 was available; C90 followed the next year, and C46 was added in 1975. This was an expensive cassette, with C90 costing as much as ¥1400.
Explanatory Note
Chrome tape, which appeared in the early 1970s, used chromium dioxide as its magnetic material and dramatically improved high-frequency performance, previously a weakness of cassettes. However, conventional iron-oxide tape still had the advantage in output performance at low and middle frequencies. Sony therefore developed a tape based on a new idea: combine the strengths of both magnetic materials through dual coating, applying a thin layer of chromium magnetic material over an iron-oxide coating. It was released in 1973 as Duad.
In this tape, iron oxide handled low and middle frequencies, while chromium handled high frequencies. The iron-oxide magnetic material was modified to balance the two. This provided high output across the entire frequency range and a wide dynamic range: even low timpani notes and high cymbal sounds with large peak levels, considered difficult to reproduce on cassette, could be recorded and played back with headroom.
To obtain the tape’s full performance, a dedicated tape selector providing optimal settings was required (the later TYPE III standard), but it could also be used in an ordinary deck. In that case, however, high frequencies were emphasized, so adjustment with the tone control during playback was recommended.
The tape was named Duad, but its package said duad ferri-chrome. As a result, two-layer tapes combining iron oxide and chromium came to be called ferrichrome (Fe-Cr) tapes in general. The wording on the package was later changed to dual layer cassette. For its time, it was a cassette with the highest performance, and an expensive tape as well.
The second generation was released in 1978, but metal tape appeared soon afterwards, while High Position tape performance also improved. Its performance advantage diminished, and decks with a dedicated tape selector gradually became less common. It slowly faded from the market. Although some minor changes were made along the way, the second generation was the last.
Second Generation, 1978
46 minutes - ¥650 / 60 minutes - ¥800 / 90 minutes - ¥1200.
Prices were changed later.
The second generation changed the name to uppercase DUAD. The package became printed film wrapping with a gold-based design, while all parts of the plastic case became transparent. The cassette adopted a new high-precision shell design with a large window. The newly developed DP (Dual Protection) mechanism used grooved liners and stepped hubs to stabilize tape travel. Although the price fell slightly, it was still Sony’s most expensive cassette at launch.