Editing Cassette tape (section)

==Features==
[[File:Visualisierung der magnetisch gespeicherten Informationen auf einer Stereo-Audiokassette (Aufgenommen mit CMOS-MagView)..jpg|thumb|Visualization of the magnetic field on a stereo cassette containing a 1&nbsp;kHz audio tone]]
The cassette was the next step following [[reel-to-reel audio tape recording]], although, because of the limitations of the cassette's size and speed, it initially compared poorly in quality. Unlike the 4-track stereo open-reel format, the two stereo tracks of each side lie adjacent to each other, rather than being interleaved with the tracks of the other side. This permitted monaural cassette players to play stereo recordings "summed" as mono tracks and permitted stereo players to play mono recordings through both speakers. The tape is {{convert|0.15|in|mm|sigfig=3|abbr=on}} wide, with each mono track {{convert|1.5|mm|in|sigfig=2}} wide, plus an unrecorded guard band between each track. In stereo, each track is further divided into a left and a right channel of {{cvt|0.6|mm|in|sigfig=2}} each, with a gap of {{cvt|0.3|mm|in|sigfig=2}}.<ref name=philips-1970>{{cite journal |url=http://www.extra.research.philips.com/hera/people/aarts/_Philips%20Bound%20Archive/PTechReview/PTechReview-31-1970-077.pdf |title=Audio tape cassettes |journal=[[Philips Technical Review]] |first1=P. |last1=van der Lely |first2=G. |last2=Missriegler |volume=31 |issue=3 |page=85 |date=1970 |access-date=3 September 2018 |archive-url=https://web.archive.org/web/20181110131544/http://www.extra.research.philips.com/hera/people/aarts/_Philips%20Bound%20Archive/PTechReview/PTechReview-31-1970-077.pdf |archive-date=10 November 2018 |url-status=dead }}</ref> The tape moves past the playback head at {{convert|1+7/8|in/s|cm/s|2}}, the speed being a continuation of the increasingly slower speed series in open-reel machines operating at 30, 15, {{frac|7|1|2}}, or {{frac|3|3|4}} inches per second.<ref name="TDK specs">{{cite web |url=http://legacyproducts.tdk.com/support/pdfs/d.pdf |publisher=TDK |type=spec sheet |url-status=dead |archive-url=https://web.archive.org/web/20070620193131/http://legacyproducts.tdk.com/support/pdfs/d.pdf |archive-date=20 June 2007 |title=D NORMAL-BIAS AUDIO TAPES |access-date=4 April 2019}}</ref> For comparison, the typical open-reel {{frac|1|4}}-inch 4-track consumer format used tape that is {{convert|0.248|in|mm|1}} wide, each track {{convert|.043|in|mm|1|abbr=on}} wide, and running at either twice or four times the speed of a cassette.{{citation needed|date=July 2022}}

Very simple cassette recorders for dictation purposes did not tightly control tape speed and relied on playback on a similar device to maintain intelligible recordings. For accurate reproduction of music, a [[tape transport]] incorporating a capstan and pinch roller system was used, to ensure tape passed over the record/playback heads at a constant speed.

=== Locating write-protect notches ===
If the cassette is held with one of the labels facing the user and the tape opening at the bottom, the write-protect notch for the corresponding side is at the top-left.

{{anchor|tapelength}}<!-- For internal and external links to section, do not change -->

=== Tape length ===
[[File:Maxell compact cassette boxes, 60 and 90 minutes.jpg|thumb|Maxell compact cassettes, C60 (90&nbsp;m) and C90 (135&nbsp;m)]]
Tape length usually is measured in minutes of total playing time. Many of the varieties of blank tape were C60 (30 minutes per side), C90 (45 minutes per side) and C120 (60 minutes per side).<ref name="Common" /> Maxell makes 150-minute cassettes (UR-150) - 75 minutes per side. The C46 and C60 lengths typically are {{convert|15|to|16|μm|mil|abbr=off|sp=us}} thick, but C90s are {{convert|10|to|11|μm|mil|abbr=on|sp=us}}<ref>{{Cite web|url=http://en.wikiaudio.org/Audio_tape_length_and_thickness|title=Audio tape length and thickness|website=en.wikiaudio.org|language=en|access-date=16 March 2018|archive-url=https://web.archive.org/web/20180317035749/http://en.wikiaudio.org/Audio_tape_length_and_thickness|archive-date=17 March 2018|url-status=dead}}</ref> and (the less common) C120s are just {{convert|6|μm|mil|abbr=on|sp=us}} thick,<ref>{{Cite web|url=http://nactape.com/anablog/glossary|title=NAC Audio Cassette Glossary – Cassetro|website=nactape.com|language=en-US|access-date=16 March 2018|archive-url=https://web.archive.org/web/20180316214327/http://nactape.com/anablog/glossary|archive-date=16 March 2018|url-status=dead}}</ref> rendering them more susceptible to stretching or breakage. Even C180 tapes were available at one point.<ref>{{cite web|title=VintageCassettes.com|url=http://www.vintagecassettes.com/|access-date=26 September 2011|archive-date=6 August 2011|archive-url=https://web.archive.org/web/20110806194751/http://vintagecassettes.com/|url-status=live}}</ref>

Other lengths are (or were) also available from some vendors, including C10, C12 and C15 (useful for saving data from early [[home computer]]s and in telephone [[answering machine]]s), C30, C40, C50, C54, C64, C70, C74, C80, C84, C94, C100, C105, C110, and C150. As late as 2010, [[Thomann (retailer)|Thomann]] still offered C10, C20, C30 and C40 IEC Type II tape cassettes for use with 4- and 8-track [[portastudio]]s.<ref>{{cite web |title=Compact Cassettes |publisher=Thomann U.K. International Cyperstore |url=http://www.thomann.de/gb/compact_cassettes.html |url-status=dead |archive-url=https://web.archive.org/web/20100811024556/http://www.thomann.de/gb/compact_cassettes.html |archive-date=11 August 2010 |access-date=22 October 2010 }}</ref>

=== Track width ===
The full tape width is 3.8&nbsp;mm. For [[Monaural|mono]] recording the [[Track (disk drive)|track]] width is 1.5&nbsp;mm. In stereo mode each channel has width of 0.6&nbsp;mm with a 0.3&nbsp;mm separation to avoid [[crosstalk]].<ref name=happ2>{{cite web|title=Happy 50th birthday, Compact Cassette: How it struck a chord for millions
|website=[[The Register]]|date=30 August 2013|access-date=29 April 2016|pages=2|url=https://www.theregister.co.uk/2013/08/30/50_years_of_the_compact_cassette/?page=2
|quote=In a mono arrangement, each track is 1.5mm per side across the 3.8mm tape width. For stereo, the left and right tracks are only 0.6mm apiece, with 0.3mm separation to avoid crosstalk.}}</ref>

=== Head gap ===
The head-gap width{{clarify|reason=is this a typical value? A standard value? Something originally spec'd by Philips? Just stating that it "is" is problematic, esp when we go on to say that sometimes it's markedly narrower|date=March 2018}} is 2&nbsp;μm{{according to whom|date=March 2018}} which gives a theoretical maximum frequency{{citation needed|date=March 2018}} of about 12&nbsp;kHz (at the standard speed of 1 7/8 ips or 4.76&nbsp;cm/s). A narrower gap would give a higher frequency limit but also weaker magnetization.<ref name=happ2/>

=== Cassette tape adapter ===
[[Cassette tape adapter]]s allow external audio sources to be played back from any tape player, but were typically used for [[car audio]] systems. An attached audio cable with a [[Phone connector (audio)|phone connector]] converts the electrical signals to be read by the tape head, while mechanical gears simulate reel to reel movement without actual tapes when driven by the player mechanism.<ref>[https://youtube.com/watch?v=dH4n8fUjtLQ Cassette adapters are remarkably simple]</ref>

===Optional mechanical elements===
[[File:Compact_Cassette_BASF_SM_Security_Mechanism_guided_tape_IMG_8286.JPG|right|thumb|upright|Tape Guide via Security Mechanism (SM)]]
In order to wind up the tape more reliably, the former [[BASF]] (from 1998 [[EMTEC]]) patented the Special Mechanism or Security Mechanism advertised with the abbreviation SM in the early 1970s, which was temporarily used under license by [[Agfa]]. This feature each includes a rail to guide the tape to the spool and prevent an unclean roll from forming.<ref>[https://patents.google.com/patent/EP0078997A2 ''Patent EP 0078997 A2 – Bandkassette mit einem Aufzeichnungsträger mit Magnetspur und Echolöscheinrichtungen für solche Bandkassetten''], eingetragen am 28. Oktober 1982</ref>

===Flaws===
Magnetic tape is not an ideal medium for long-term archival storage, as it begins to degrade after 10 – 20 years, with some experts estimating its lifespan to be no more than 30 years.<ref>{{cite web |last=Pogue |first=David |author-link=David Pogue |url=https://www.scientificamerican.com/article/digitize-those-memory-filled-cassettes-before-they-disintegrate/ |magazine=[[Scientific American]] |title=Digitize Those Memory-Filled Cassettes before They Disintegrate |url-status=live |date=1 September 2016 |access-date=12 August 2023 |archive-date=12 August 2023 |archive-url=https://archive.today/20230812194200/https://www.scientificamerican.com/article/digitize-those-memory-filled-cassettes-before-they-disintegrate/ }}</ref><ref name="LegacyBox">{{cite web|url=https://legacybox.com/blogs/analog/history-of-the-cassette-tape |publisher=[[Legacy Box]] |title=History of the Cassette Tape |last=Somerfield |first=Katy |access-date=12 August 2023 |archive-date=12 August 2023 |archive-url=https://archive.today/20230812194210/https://legacybox.com/blogs/analog/history-of-the-cassette-tape }}</ref>

A common mechanical problem occurs when a defective player or resistance in the tape path causes insufficient tension on the take-up spool. This would cause the magnetic tape to be fed out through the bottom of the cassette and become tangled in the mechanism of the player. In these cases, the player was said to have "eaten" or "chewed" the tape, often destroying the playability of the cassette.<ref>{{cite web|url=http://beradio.com/mag/radio_trends_technology_recording/|title=Trends in Technology: Recording Sound |first=Steve |last=Fluker |archive-url=https://web.archive.org/web/20040923212542/http://beradio.com/mag/radio_trends_technology_recording/ |archive-date=23 September 2004}}</ref>{{failed verification|reason=eating is mentioned as a bane but the exact cause is not explained. See also  [[Talk:Cassette tape#chewing hides the sound]]|date=August 2021}}