Sony AHF 90 Audio Cassette (1981)

The Sony AHF was an excellent normal bias cassette from the renowned hi-fi manufacturer.

At the dawn of the 1980s, there were three normal bias ferric oxide tapes in the Sony range.

The CHF was the basic offering. Light on treble definition, fairly noisy, and low in price – but in its class, still pretty good value.

The next step up was the BHF. This had noticeably better treble response, and whilst noise/hiss wasn’t exactly minimal, it was certainly more under control than with the CHF. The price was typically around 30% higher than that of the CHF.

Stepping up again to the most expensive Sony ferric, you found the technically superior AHF.

The Type III Ferrichrome / Ferro-chrome Audio Cassette

Most cassette-buying consumers of yesteryear will remember normal tapes (classified Type I), high bias tapes (classified Type II), and to a lesser extent, metal tapes (classified Type IV). These were the three options from which consumers would choose.

And if you look back at the cassette decks from the heyday of analogue home recording, you’ll probably see a reference to each of these three cassette types. Perhaps a physical selector (if it’s a very old deck), but more likely just a series of LED indicators, showing which of the three types the deck has auto-detected, once the cassette is in the machine.

Type I, Type II, and Type IV. No Type III…

The Type II Chrome Bias Audio Cassette

A classic blast from the past, in the shape of a mid 1980s BASF CR-E II cassette. A real chromium dioxide formulation, and for many, the epitome of the high bias tape.

The Type II high bias audio cassette is actually much older a development than many people realise. The rise of the Type II tape is generally associated with the 1980s, but in fact, it was introduced, with a chromium dioxide (CrO2) tape formulation, at the dawn of the 1970s.

Chrome tapes were, technically, a big advancement from the start. Du Pont’s chromium dioxide formulation gave an undeniable increase in high frequency response over the often rather muffled tone of the existing Type I ferric cassette. This meant much better definition – a major improvement in fidelity, and an ability to preserve all the zing and sparkle at the treble end of the original sound.