CASSETTE TAPES & CASSETTE RECORDERS

Almost everyone, even in the relatively remote parts of the country, has heard audio played off a cassette player at some point in time. The cassette recorder has been the standard for small radio stations around the world for a long time; and though MiniDisc recorders and solid state flash memory recorders have increasingly begun to replace them, they still remain a useful part of the CR station's equipment list.
                 
                                              


The cassette recorder is an analog audio recording system, and uses a recording system which we refer to as magnetic recording. There are two parts to any audio magnetic recording system:

• the tape it uses as the storage medium.

• the recorder, which also acts as the playback device

The Tape
 
Cassette tapes - and their predecessors, the spool or reel tape - are a typical example of the media used in magnetic audio recording systems. The three main features of the cassette tape are the tape box, the tape ribbon and the plastic cassette.
                                        

The box is a plastic case, usually with a hinged top that you open to remove the tape. The lid is often of clear plastic so that you can insert labels identifying the tape, which can then be read without opening the box.

A typical audio cassette, also known as a compact cassette. The tape ribbon is contained in a transparent plastic shell.

 

 

The tape (often also referred to as the ribbon) is essentially a long strip of plastic coated with a layer of magnetic particles. If you expose these magnetic particles to a magnetic field, they are permanently magnetized by the field until they are exposed to a fresh field. This is the property that magnetic recording utilizes to store the recording on the tape. This ability gives magnetic tape two of its most appealing features:

• Firstly you can record audio instantly and the tape will "remember" what was recorded for playback.

• Secondly you can erase the tape and record something else on it.

Tape Type & Length
 
Cassettes are available in of various lengths. The ones most commonly sold in shops are 60-minute or 90-minute cassettes. A 90-minute cassette has 135 meters of tape inside it, which runs at 1 7/8th inches per second in the recorder.

Cassettes are also usually available in three types of coatings. In increasing order of audio quality, these are:

• Ferric oxide, where the magnetic particles are actually particles of an iron compound called ferric oxide. This is the most common type, and the kind most cassette recorders can record on

• Chrome, where particles of chromium dioxide are mixed in with the ferric oxide

• Metal tape, which uses particles of pure metal rather than an oxide compound

Metal tapes can be played back on all cassette players, but can only be recorded on recorders which have a special setting for metal tapes. Most professional cassette recorders will have a small switch that lets you shift between 'Normal' (Ferric Oxide), 'Chrome' and 'Metal' settings

The Cassette
 
The cassette is a fairly simple protective covering and case for the tape. In cassettes, the tape is usually attached to and wound around two plastic cores, two rollers and the plastic outer shell that protects the tape. (In spool tapes, the tape ribbon is loose, and is physically wound around the core of a plastic spool by the user.) There is also a small felt pad that keeps the tape pressed against the the record/playback head in the tape player.

 Maxell UR-60 Blank Audio Cassette Tape, 8 Pack

The cassette also has two protective tabs on top. When these tabs are broken off, you can no longer record on the tape. Use a pen or something similar to gently break the tabs when necessary. If you have broken these tabs, but want to record onto the cassette again, you can cover the holes you have made by covering the tab slots with two small pieces of sticky tape. Be sure that the tape is securely stuck down, so that it cannot come loose while inside the cassette recorder.


Things to remember when using cassette tapes and recorders

 
The relatively poor quality compared to CD and reel-to-reel, and lack of editing facility, mean many broadcasters believe cassettes are not appropriate for regular use. Nevertheless, the cassette tape's small size and the almost universal access to cassette tape decks in studios make it a very useful medium.
Because the tape is contained inside the cassette, compact cassettes are very robust. However to protect your recordings, you should handle tapes with care.

• Keep cassettes in their cases when not in use.

• Keep tapes away from magnetic fields. The tape is a magnetic medium, so exposing the tape to a strong magnetic field will affect the stored sound. In the studio, computer screens and loudspeakers often have strong magnetic fields. So leaving tapes near the computer, or on top of a loudspeaker, is not good practice.

• Always label the cassettes you are using. A fresh blank tape usually includes a labelling sheet. People finding unlabelled cassettes lying around in the studio may record over them, and you may lose important sound that you will never be able to record again. Another reason is that you may lose your cassette and it will take time to listen to a whole lot of unmarked or poorly marked tapes to find the sound you need. Ensure that labels and stickers identifying tapes are not loose or peeling off. The labels can cause the tape to get stuck in the tape deck and will damage the machine. 

Most tape decks have an unbalanced stereo output, although some more expensive broadcast tape decks have a balanced stereo output. RCA connectors are usually used for the unbalanced output. The left and right channels are usually colour coded, with red indicating right, and white left. These outputs are connected to the tape channel inputs on the mixing desk. In some instances these can be passed through a balancing amplifier before being connected to the mixer. In some studios they may also be connected to the studio patch panel.



Most cassette recorders and decks also have a stereo input for recording. Again this is most often through unbalanced RCA connectors or phono connectors. The tape deck is usually fed with audio directly from the recording bus of the mixing desk, or via a distribution amplifier connected to the recording bus. Some broadcast tape decks have a control input that allows the tape-deck to be controlled from the mixer.
                       

Cleaning & Maintenance of cassette recorders

On the whole, however, tape recorders needs very little maintenance. The most important thing to remember is to clean tape heads and the compartment.

The tape heads should ideally be cleaned after every five hours of use. To clean the heads, take a cotton wool earbud and cleaning alcohol such as surgical spirits. Both earbuds and surgical spirit are available from most pharmacies. After shave lotion will work in an emergency.

Dip the earbud into the spirit so that it is moist but not dripping wet. Then gently rub the earbud over the heads in the tape deck. Avoid touching the plastic and rubber parts of the device with the spirit.

The main dirt that collects in the compartment will be dust and fluff. It is difficult to avoid getting dust in the compartment, but you can minimise the problem by keeping the compartment closed when not in use and by regularly cleaning the studio. If you see any bits of fluff or other dirt, gently pull them out using a pair of tweezers.

Most tape decks come with a noise reduction system to minimise unwanted noise during recording and playback. Dolby Noise Reduction is the most common system. Using the Dolby system properly will improve tape sound quality. For the best results, a recording made using a noise reduction system must be played back using the same system. If your station chooses to use noise reduction, then all the tape decks in the station need to be set to use the same noise reduction system.