Tape Notes · Tape types

Cassette tape types explained: Type I, II, III and IV

10 October 2026 · 6 min read

Pick up a few old blank tapes and you'll see “Type I”, “Type II”, “normal position” or “high bias” printed on the J-cards. These are the four cassette types set by the international standard for audio cassettes. They differ in the magnetic coating on the tape, and each one needs the deck set up a little differently. Here's what they mean and which one to choose today.

The four types at a glance

TypeAlso calledCoatingBiasPlayback EQGood for
INormal, ferricIron oxideNormal120 µsAny player, everyday mixtapes, bass-heavy music
IIChrome, high biasChromium dioxide or cobalt-treated iron oxideHigh (about 150% of normal)70 µsLess hiss and crisper treble on a good deck
IIIFerrichromeTwo layers: iron oxide under chromeVaried70 µsCollectors; long discontinued
IVMetalPure metal particlesVery high (about 250% of normal)70 µsMaximum level and detail on a metal-capable deck

Bias and EQ in plain English

Bias is a high-frequency signal a deck mixes in while recording, so the tape records cleanly instead of distorting. Each coating needs a different amount, which is why decks have a tape selector, or read the type automatically.

EQ (equalisation) is how much the deck turns the treble down on playback, measured as a time constant: 120 µs for Type I, 70 µs for the others. Play a chrome tape on the normal setting and it sounds brighter and hissier than it should; play a normal tape on the chrome setting and it sounds dull. Dolby noise reduction is a separate setting again (see our Dolby guide).

Type I: normal

The original and still the most common. Type I tape uses iron oxide particles, records with normal bias and plays back at 120 µs. It's the cheapest, works in every player and recorder ever made, and most pre-recorded albums were released on it. Good Type I tape handles bass well, so it suits a lot of music. Its weakness is a little more hiss and less headroom at the top end than chrome or metal.

Type II: chrome (high bias)

Type II was first made with chromium dioxide, hence “chrome”. Most later Type II tapes actually used cobalt-treated iron oxide, which behaves the same way, so the name stuck. It needs high bias when recording (about one and a half times normal) and plays back at 70 µs, which gives a lower noise floor than Type I. Simple recorders often can't record it properly, so it's at its best on a decent deck.

Type III: ferrichrome

Introduced by Sony in 1973, ferrichrome put a thin chrome layer on top of an iron oxide layer to get Type I's bass and Type II's treble in one tape. It was expensive, never caught on, and was overtaken by cobalt Type II tapes. Decks stopped offering a Type III setting by the early eighties and production ended later that decade, so today it's a curiosity.

Type IV: metal

Metal tape arrived in 1979. It uses pure metal particles rather than oxides, so it can hold a much stronger signal: more level, more treble before it distorts. It needs very high bias (about two and a half times normal) and a deck with heads that can handle it, then plays back at 70 µs like chrome. On the right machine it can sound the best of all, but it was always the priciest.

How a deck tells them apart

Look at the back edge of a cassette, next to the two small write-protect tabs. A Type I shell has no extra notches. A Type II shell has two more, next to the tabs, and a metal (Type IV) shell has four. Decks with automatic tape selection feel for these notches and set the right EQ, and often the bias too. Older or simpler machines have a switch you set by hand.

Tip: if you record a chrome tape on a deck set to normal, it will sound harsh and hissy. Check the selector before you press record.

Which should you use for a mixtape today?

  • Type I for most people. It's what most new blank tapes are, it plays properly on any player the recipient owns, and a good one sounds great.
  • Type II if you have a good deck and want less hiss. New Type II stock has been scarce for years; small new runs do appear (a Japanese maker released a limited batch in 2026), and plenty of unopened tapes from the eighties and nineties are still sold.
  • Type IV only if your deck records metal. Otherwise it gives you nothing extra.

Length matters too. Longer tapes use thinner tape: a C-60 is about 16–18 µm thick, a C-90 about 11–12 µm and a C-120 around 9 µm, so very long tapes are more fragile. For mixtapes, C-60 and C-90 are the sweet spot. Our guide to tape lengths shows how much music fits on each side.

Make the J-card match the tape

On jcard.studio Speed Stripes says Type I · Normal position, Chrome Type II, Studio Black and Crystal use the high-bias Type II wording, and Metal Tape is labelled Type IV, so the insert matches what is in the case. Pick one, paste your tracklist and print. To decode the rest of the jargon on a blank tape's packaging, see reading a blank tape's J-card.

Making a tape? Design a J-card that fits the case.

Try the Chrome looks →

Sources

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