Editing Digital Compact Cassette (section)

=== Magneto-resistive stationary heads ===

Unlike [[helical scan]] systems such as DAT or [[VHS]], the head is stationary and the tape moves in linear direction relative to the head. Like analog audio tapes, the heads use half of the tape width in each direction. There are 9 tracks per side: eight tracks for the audio, and one track for auxiliary information. The track pitch is 195&nbsp;μm. The head assembly has what Philips called "Fixed Azimuth Tape Guidance" (FATG) pins, which work together with the "Azimuth Locking Pins System" (ALPS) in the cassette to guide the tape.<ref name="Philips DCC page"/>

DCC used [[magnetoresistance|magneto-resistive]] (MR) heads 70&nbsp;μm wide for playback, and miniaturized coils 185&nbsp;μm wide for recording. The heads were produced using [[photolithography]].{{citation needed|date=February 2019}} Some DCC head assemblies had separate MR heads to play analog tapes, others re-used two DCC heads to pick up the left and right analog audio tracks from the tape.

All DCC players and recorders are auto-reverse, so every player and recorder must have a way to position the heads for the A-side as well as the B-side of the tape. In stationary recorders, the mechanism switched sides by pivoting the head assembly 180 degrees (Philips used a modified version of an analog auto-reverse cassette deck during development, on which this mechanism was based),<ref>[http://www.dutchaudioclassics.nl/Philips_early_DCC_deck_prototype/ Philips Early DCC Deck Prototype], Dutch Audio Classics.</ref> but in portable recorders and players, the head assemblies had heads for the tracks on both sides, which saved space in the mechanism, but made the head assembly more complicated:

* Pivoting head mechanisms in stationary recorders such as the DCC-900 used a head assembly that had 9 (MR) playback heads and 9 (coil) recording heads for DCC, plus two (MR) heads for playing analog compact cassettes. The head assembly was mounted on a pivoting mechanism that rotated the head assembly by 180&nbsp;degrees when it switched from one side of the tape to the other.
* Playback-only portable players such as the DCC-130 and DCC-134 used head assemblies with 18&nbsp;MR heads, nine for each side of the tape. When playing analog cassettes, two of the DCC MR heads were used to pick up the analog audio.
* Portable recorders such as the DCC-170 and DCC-175 used head assemblies with 18&nbsp;MR heads for DCC playback, 18&nbsp;coil heads for DCC recording, and 4&nbsp;MR heads for analog playback (a total of 40 heads in one head assembly).

Magneto-resistive heads do not use iron so they do not build up residual magnetism. They never need to be demagnetized, and if a magnetic field from e.g. a [[cassette demagnetizer]] is applied to MR heads, it [[Electromagnetic induction|induces]] so much current into the heads that they are damaged or destroyed. Also, it is recommended never to use a [[Tape head cleaner#Dry cleaners|cleaning cassette]] as DCC heads are fragile and this operation could ruin them permanently.<ref>{{Cite web|title=fixing DCC audio cassette tape {{!}} www.reeltoreel.nl|url=https://www.reeltoreel.nl/blog/?p=779|access-date=2020-08-11|language=en-US}}</ref>