The first cassette machines (e.g. the Philips EL 3300, introduced in August, 1963 ) were simple mono record and playback units. Early machines required attaching an external dynamic microphone. Most units after the 1970s also incorporated built-in condenser microphones, which have extended high frequency response, but may also pick up noises from the recorder motor. A common portable recorder format still common today is a long box, the width of a cassette, with a speaker at the top, a cassette bay in the middle, and "piano key" controls at the bottom edge. Another format is only slightly larger than the cassette, also adapted for stereo "Walkman" player applications. The markings of "piano key" controls were soon standardized, and are a legacy still emulated on many software control panels. These symbols are commonly a square for "stop", a right-pointing triangle for "play", double triangles for "fast-forward" and "rewind", a red dot for "record", and a vertically-divided square (two rectangles side-by-side) for "pause".
Stereo recorders eventually evolved into high fidelity and were known as cassette decks, after the reel-to-reel decks. Many formats of cassette players and recorders have evolved over the years. Initially all were top loading, usually with cassette on one side, VU meters and recording level controls on the other side. Older models used combinations of levers and sliding buttons for control.
A major innovation was the front-loading arrangement.Pioneer's angled cassette bay and the exposed bays of some Sansui models were eventually standardized as a front-loading door into which a cassette would be loaded. Later models would adopt electronic buttons, and replace conventional meters (which could be "pegged" when overloaded) with electronic LED or vacuum fluorescent displays, with level controls typically either being controlled by rotary controls or side-by-side sliders. BIC and Marantz briefly offered models which could be run at double speeds, but Nakamichi was widely recognized as one of the first companies to create decks which rivaled reel-to-reel decks with frequency response from the full 20–20,000 Hz range, low noise, and very low wow and flutter. The 3-head closed-loop dual capstan Nakamichi 1000 (1973) is one early example. Unlike typical cassette decks that use a single head for both record and playback plus a second head for erasing, the Nakamichi 1000, like the better reel-to-reel recorders, used three separate heads to optimize these functions.
Other contenders for the highest, "HiFi" quality on this medium were two companies already widely known for their excellent quality reel-to-reel tape recorders: Tandberg and Revox (consumer brand of the Swiss professional Studer company for studio equipment). Tandberg started with combi-head machines like the TCD 300 and continued with the TCD 3x0 series with separate playback and recording heads. All TCD-models possessed dual capstan drives, beltdriven from a single capstan motor and two separate reel motors. Frequency range extended to 18 kHz. After a disastrous overinvestment in colour television production, Tandberg folded and revived without the HiFi-branch these came from.
Revox went one step further: after much hesitation about whether to accept cassettes as a medium capable for meeting their strict standards from reel to reel recorders at all, they produced their B710MK I (Dolby B) and MK II (Dolby B&C) machines. Both cassette units possessed double capstan drives, but with two independent, electronically controlled capstan motors and two separate reel motors. The head assembly moved by actuating a damped solenoid movement, eliminating all belt drives and other wearable parts. These machines rivaled the Nakamichi in frequency and dynamic range. The B710MKII also achieved 20–20 kHz and dynamics of over 72 dB with Dolby C on chrome and slightly less dynamic range, but a larger headroom with metal tapes and Dolby C. Revox adjusted the frequency range on delivery with many years of use in mind: when new the frequency curve went upwards a few dB at 15–20 kHz, aiming for flat response after 15 years of use and headwear to match.
A last step taken by Revox produced even more advanced cassette drives with electronic finetuning of bias and equalization during recording. Revox also produced amplifiers, a very expensive FM tuner and a pickup with a special parallel arm mechanism of their own design. After releasing that product, Studer encountered financial difficulties. It had to save itself by folding its Revox-branch and all its consumer products (except their last reel to reel recorder the B77).
Note that while Nakamichi violated the tape recording standards to achieve the highest dynamics possible, producing non-compatible cassettes for playback on other machines, both Tandberg and Revox kept to the standards and produced cassettes which could be played back on other machines.
A third company, the well known Danish Bang & Olufsen, invented a special, improved system for improving headroom at high frequencies, to reduce tape saturation despite lower bias levels. This "head room extension method, HX" was called Dolby HX Pro in full and patented. Their finest machine with HX Pro was the Beocord 9000, which indeed performed excellently. However, this machine's transport possessed only a single capstan and a single drive motor - as opposed to multiple motors dual capstan arrangement. This did not make the B&O contender a popular choice with HiFi enthusiasts. Most of them favored Nakamichi, Tandberg or Revox instead, which were all more mechanically complex. HX Pro was adopted by other manufacturers including Technics, while Aiwa incorporated the technology into their top of the rangepersonal stereos.
As they became aimed at more casual users, fewer decks had microphone inputs. Dual decks became popular and incorporated into home entertainment systems of all sizes for tape dubbing. Although the quality would suffer each time a source was copied, there are no mechanical restrictions on copying from a record, radio, or another cassette source. Even as CD recorders are becoming more popular, some incorporate cassette decks for professional applications.
Another format that made an impact on culture in the 1980s was the radio-cassette, aka the ghetto-blaster or "boom box" (a name commonly used only in the USA), which combined the portable cassette deck with a radio tuner and speakers capable of producing significant sound levels. These devices became synonymous with urban youth culture in entertainment, which led to the somewhat derisive nickname "ghetto blaster."
Applications for car stereos varied widely. Auto manufacturers in the U.S. would typically fit a cassette slot into their standard large radio faceplates. Europe and Asia would standardize on DIN and double DIN sized faceplates. In the 1980s, a high end installation would have a Dolby AM/FM cassette deck, and they rendered the 8-track cartridge obsolete in car installations because of space, performance and audio quality. As the cost of building CD players declined, many manufacturers offered a CD player, but some cars, especially those targeted at older drivers still offer the option of a cassette player, either by itself, or sometimes in combination with a CD slot. In fact, the 2009 Lexus ES 350 still comes with a cassette player as standard equipment. The newest cars are not often designed to accommodate cassette players, but the auxiliary jack advertised for MP3 players can also be used with portable cassette players.
Although the cassettes themselves were relatively durable, the players required regular maintenance to perform properly. Head cleaning may be done with long swabs, or cassette-shaped devices that could be inserted into a tape deck to polish the heads and remove smudges and dirt. Similarly shaped demagnetizers used magnets to degauss the deck, which kept sound from becoming distorted. A common mechanical problem occurred when a worn-out or dirty player rotated the supply spool faster than the take-up spool or failed to release the heads from the tape upon ejection. 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" the tape, and it often destroyed the playability of the cassette altogether, and resulted in the common sight of tangled tape on the side of the road. Cutting blocks, analogous to those used for open reel 1/4" tape were readily available,though mainly used for retrieving valued recordings, could be used to remove the damaged portion of, or repair the break in the tape. Creation of compilations was usually by re-recording rather than splicing sections of songs because of the much smaller tape area.