Technical Description: Cassette Tape

Jana Elwassif
Department of English, City College of New York
ENGL 21007: Writing for Engineering
Professor Sara Jacobson
November 17, 2022

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Introduction: History and Development

Prior to having pre-recorded music widely available to the public, the only way to enjoy music was live. However, technology evolved to allow for pre-recorded music to be available from the comfort of peoples’ homes. In 1877, the phonograph was invented, allowing for music to be recorded and played back. Music playing technology quickly transitioned into vinyl record players and to playing music on the radios
(Albright, 2015).  

Taking inspiration from reel-to-reel tapes, which were devices with magnetic tapes, that were vastly used in offices that could record speech, be reused, and allow for errors to be fixed easily, the compact cassette, later called the music cassette was created. Invented by the Philips Company in 1962, it took the basic technology of the reel-to-reel tape, and made it smaller, allowing for the tape to be portable (Technology Connections, 2016, 1:46).

This revolutionized the music industry, as it offerred a new format for recoding and selling pre-recorded music (“Music Cassette,” 2022). Pre-recorded music could now be listened to everywhere, like in cars, at home or outside easily, with the development of the Sony Walkman and cassette decks. It would become one the most common formats for pre-recorded music from the 70s to the 90s (“Music Cassette,” 2022).

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Internal Components

The tape “holds’ the actual music. It is made of thin plastic, coated with a substance that could be magnetized by an electromagnetic field. This coating is mixed with a binder that helps to keep the powder attached to the plastic tape. The type of powder depends on the type of cassette. Ferric oxide powder was used. This is found in Type I cassettes. Chromium dioxide powder was used in Type II cassettes. A mixture of ferric oxide and chromium dioxide powder is used in Type III cassettes. Pure metal particles were used in Type IV cassettes (“Compact Cassette,” 2022). The type of powder used effects the sound and frequency of the music being recorded on the cassettes (“Cassette Tape Types,” 2021). The tape is also coated with a lubricant to preserve the recorder/player from wearing out (Wallace, 2021).

These powders are then magnetized by being exposed to an electromagnetic field within the cassette recorder. As an audio signal is sent through an electromagnet, a magnetic field is created, which then forms a fringe pattern. This creates a unique pattern on the tape. When the cassette is played, the pattern on the tape creates a magnetic field when pulled, resulting in the formation of a signal that can then be amplified through speakers, to listen to the music that has been recorded on the tapes (Brain, 2000).

Depending on the length of the tape, each side of the tape can play 30 minutes of music which are called C60 tapes, 45 minutes of music called C90 tapes or 60 minutes of music, called C120 tapes (“Compact Cassette,” 2022). When played, only 1 side of the tape is being played. This means that when the cassette tape is turned, the other side of the tape can be played as well, as indicated from the labeling of the sides as Side A and Side B on the tapes (Technology Connections, 2016, 5:12).

The supply reel contains the tape that has yet to be played. The take-up reel contains the tape that has already been played. There needs to be two reels to allow for the tape to be pulled horizontally to be played and recycled onto the next reel (Mukerjee & Muju). These are often made of plastic (Noiseux, 2016). They have notches on the inside to attach to the cassette deck, so that they can be spun, helping to wind the tape neatly through the player, and reroll the tape onto the take-up reel.

There are multiple tape guides that the tape is wound up against, ensuring that the tape is pulled tightly against the cassette player, aligned properly, and is guided to the take-up reel (Technology Connections, 2016, 3:55).

The pressure pad holds the tape against the part of the cassette recorder that records music onto the tape. It is composed of a small felt pad, and a copper metal bar. It ensures that the tape is making direct contact with the recorder, preserving the quality of the recording (National Audio Company, 2018).

The magnetic shield ensures that external magnetic fields do not interfere with the pattern on the tape, helping to create a better quality recording, and preserve the recording while playing it back (Vance, 2007).

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External Components:

Though the design of the outer shell of the cassette may vary, they are all made of plastic (Noiseux, 2016). They protect the tape on the inside, keeping it from being exposed to outside forces, while also holding the inner components in place, to allow for the tape to move properly and smoothly. The two sides could be held together with glue or screws.

If the cassette tape is not fully clear, it will have a clear opening in the middle, called the window. This serves to allow the user to know how much of the tape has been used, allowing for an estimation on how much playing time is left on the tape.

The write-product tab allows for the cassette tape to be recorded on. If it is broken off, nothing new can be recorded on it. Pre-recorded cassettes do not have the write-product tab to ensure that users do not accidently record over the music (“Compact Cassette,” 2022).

The most important part of the cassette are the holes, which are uniform amongst all cassettes. These holes align perfectly with corresponding components of standard tape recorders/players. They allow for music to be played, recorded, replayed, and erased onto the cassette tape (Technology Connections, 2016, 3:26).

 

 

The small holes on the sides of the cassette, are called capstan holes. They correspond to the capstan of a tape recorder, which is a spindle that rotates the tape at a specific speed through the player, allowing for the tape to be recorded or played (National Audio Company, 2018). his opening allows for the capstan to go through the holes and directly contact the tape to roll the tape through the machine (Technology Connections, 2016, 3:26).

The pinch hole corresponds to the pinch roller of cassette player, which is a rubber roller that pushes the tape against the capstan to allow the tape to move (National Audio Company, 2018).  This opening allows for the pinch roller push up against the tape inside the cassette and squeeze the tape between itself and the spinning capstan roller (Technology Connections, 2016, 3:32).

The head holes correspond to the heads of the cassette deck, which are electromagnets that either erase the previous recording, or convert an electrical signal to a magnetic pattern to recording, new music, or take the already existing pattern and convert it to an electrical signal to play the music. The erase head hole is for erasing music and  play/record head hole is for playing and recording music (“Music Cassette,” 2022).These holes allow for the tape to directly contact on the electromagnets on the cassette deck, so that it can read the pattern on the tape to play the music, create a pattern on the tape to record music, or erase the pattern to erase music (National Audio Company, 2018). 

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Conclusion

While the components of a cassette tape are simple, they come together to create a piece of technology that complement cassette players and recorders well. They were able to maintain the quality of music, while also making music vastly available in a variety of settings through its compactness and portability. Despite rising in popularity during the 80s and 90s, they would become obsolete by the early 2000s, as newer music formats were invented, such as CDs and later iPods (“Music Cassette,” 2022). Regardless, cassettes will still hold the title of revolutionizing the music industry, as they introduced the first form of portable music.

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References

Albright, D. (2015, April 30). The evolution of music consumption: How we got here. MUO. Retrieved November 17, 2022, from https://www.makeuseof.com/tag/the-evolution-of-music-consumption-how-we-got-here/#:~:text=Before%20his%20invention%20of%20the,concert%20hall%20or%20at%20home

Anderson, D. (2015) [Mechanism of Cassette Deck Heads With Q-Tip for cleaning]. Cleaning Your Cassette Deck Transport. Retrieved from https://tapesponding.wordpress.com/2015/02/16/cleaning-your-cassette-deck-transport/.

The Audio Owl. (2021, October 10). Blank cassette tape types and how to choose the right one. The Audio Owl. Retrieved November 17, 2022, from https://theaudioowl.com/cassette-tapes/blank-cassette-tape-types/#:~:text=Choosing%20the%20right%20type%20of,hiss%2C%20even%20bass%20and%20treble

Brain, M. (2000, April 1). How tape recorders work. HowStuffWorks. Retrieved November 17, 2022, from https://electronics.howstuffworks.com/gadgets/audio-music/cassette.htm

Chun, R. (2015). Tascam Br-20. The Verge. [photograph]. Vox Media. Retrieved November 17, 2022, from https://www.theverge.com/2015/10/5/9409563/reel-to-reel-tape-retro-audio-trend.

Elwassif, J. (2022). Cassette Tape. [photograph]. New York City.

Elwassif, J. (2022). Pressure Pad and Magnetic Shield. [photograph]. New York City.

[Image of Counterfeit prerecorded cassette]. (2020). https://commons.wikimedia.org/wiki/File:Counterfeit_prerecorded_cassette_in_a_counterfeit_Maxell_shell_01.jpg.

Mesaddek, R. (n.d.). Anatomy of an Audio Cassette. [drawing]. Retrieved November 17, 2022, from https://www.redbubble.com/people/thisisramzi/works/31782450-audio-cassette-anatomy.

Mukerjee, A., & Muju, M. K. (n.d.). Audio Player’s Cassette deck mechanism. Cassette Player’s Deck Mechanism. Retrieved November 17, 2022, from https://www.cse.iitk.ac.in/users/amit/courses/371/adarsh/contents.html#:~:text=There%20are%20two%20spools%20and,head%20in%20the%20tape%20player.

Museum of Obsolete Media. (2022, August 28). Music Cassette (1965 – ). Museum of Obsolete Media. Retrieved November 17, 2022, from https://obsoletemedia.org/music-cassette/

Museum of Obsolete Media. (2022, August 9). Compact Cassette (1963 – ). Museum of Obsolete Media. Retrieved November 17, 2022, from https://obsoletemedia.org/compact-cassette/

National Audio Company. (2018, March 9). Cassette Glossary. National Audio Company. Retrieved November 17, 2022, from https://www.nationalaudiocompany.com/cassette-duplication/release-audio-cassette-tape/cassette-glossary/

Noiseux, K. (2016, October 27). Recycling Cassette Tapes: It’s complicated. The Providence Journal. Retrieved November 17, 2022, from https://www.providencejournal.com/story/lifestyle/home-garden/how-to/2016/10/27/trash-tutorial-recycling-cassette-tapes-its-complicated/24663876007/

Technology Connections. (2016, June 23). Exploring the good ol’ Cassette Tape [Video]. Youtube. https://youtu.be/H5m6zs1UIVg

Vance, R. (2007, April 28). Magnetic Shielding Basics. Interference Technology. Retrieved November 17, 2022, from https://interferencetechnology.com/magnetic-shielding-basics/

Wallace, D. (2021, June 28). Inner working of cassette tapes. Legacybox. Retrieved November 17, 2022, from https://legacybox.com/blogs/analog/inner-working-of-cassette-tapes