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Definition:
Magnetic tape is an acetate or plastic ribbon coated on one surface with a layer of magnetizable iron oxide particles (see illustration). The width tape is usually employed to record audio messages magnetically for subsequent reproduction.
The tape recorder, with which the magnetic tape is used, can record a message and play it back or play back of pre-recorded tape. The unit contains recording and playback amplifiers and heads (see illustrations). The heads may be full track, half track, dual track, or quarter track (see illustration).
Characteristics:
There is a variety of controls on every tape recorder. Some of the most common controls and their functions are listed in the table below :
Tape Recorder controls and their functions |
Controls and Indicators |
Tape Recorder Function |
On-off switch |
Controls flow or electric current to the tape recorder. |
Neutral or stop |
Permits motor to keep turning but tape is not in motion. |
Play or listen |
Moves tape forward for listening purposes. |
Speed selector |
Changes speed of tape (usually 17/8, 3 , 7 , in/Sec). |
Fast forward |
Moves tape forward at rapid speed. |
Reverse |
Rewinds tape at rapid speed to the beginning. |
Record |
Moves tape forward and activates recording heads; automatically erases any recording on tape. |
Speaker switch |
Turns speaker of during recording operations (done automatically in some machines). |
Volume |
Controls level of sound being recorded or reproduced. |
Tone |
Determines high or low pitch. |
Monitor |
Indicates volume level (see illustration). |
Counter |
Indicates number of reel revolutions. (see illustration). |
Recording formats
Recording and playing times of tape are governed by reel size, tape thickness, number of tracks used in the tape, and speed selected for recording.
As a general rule, the faster the tape speed, the better the quality of the recording. For example, a tape running at 1 7/8 inches per second (ips) or 3 , ips is adequate for recording speech, but 7 ips or, better still, 15 ips would be necessary to record music with a high degree of quality. If half track is used, the amount of recording time on the chart can be doubled. With quarter track, it would be four times the time stated. This assumes that the equipment will record and playback on half track or quarter track. It is the machine, not the tape, that determines recording time.
Tape can be used over and over many time. In addition, when a recording is no longer needed, the tape can be used for a new recording because each time a new recording is made, the old recording on the tape is automatically erased. It is difficult to estimate tape life; however, since the magnetic surface usually lasts a very long time, tape recordings rarely wear our. Tape can break when the equipment, is faulty, when the tape is especially cry, or when the tape is suddenly stopped while running at fast forward or rewind speeds. The process for repairing the tapes is simple (see the illustration on the next page). Be sure to use spillicing tape especially designed for repairing magnetic tapes, and not ordinary cellophane tape, which could endanger the recording or the playback heads of the recorder.
In an attempt to prevent some of the problems of breakage and mishandling of tapes, the tape cartridge and the cassette were introduced. The continuous loop cartridge is one reel of tape with ends joined together to form a endless loop (see illustration). Since there is only one reel, there is no provision for fast forward or rewind. It makes possible the repetitive playback of a recorded message without rewinding the tape. The tape is width moving at 3 ips. Four-track and eight track cartridges are the types usually available.
The cassette is an enclosed case which contains two little hubs that permit reel-to-reel recording and playback (see illustration). It differs from the normal reel-to-reel process in that both the tape and the hubs are captive within the cassette housing. Threading is eliminated, and fast forward and rewind functions are possible. Cassette recorders and playback units run at 1 7/8 ips and cassettes come in 30 minute to 2 hour units. The tape is 1/7 wide.
Advantages:
The tape recorder has become common place equipment in homes, cars and schools. A unit may cost as little as $10.00 (for battery-powered toy-type units) or as much as several thousands of dollars (for professional equipment). The availability of tape recorders is the first major advantage. Other advantages include:
- The opportunity to be in two places at one time is possible when a recording can substitute for an individual.
- Recording people and events for later use-radio and TV programmes phonograph records and the work of the students themselves is possible.
- The opportunity to hear ones self is a useful diagnostic tool for helping to improve speech or musical efforts.
- The operation of tape recorders is relatively easy. Cartridge and cassette recorders require no threadings.
Limitations:
Some people become confused about the operation of equipment which requires several distinct actions before it can be used. Difficulties with equipment operation cause tape to spill off the reel, to break, or to jam the machine.
Other limitations are:
- It is difficult to locate specific recorded items on a magnetic tape: if a recorded message is in the middle of a reel of tape and there is no record of the number of revolutions or no marker on the reel, the search may take a long time.
- The great variety of tape speeds and arrangement of tracks (half, quarter, stereo, etc.) may cause some difficulty if a recording is made on one machine and is played back on another which may not have the same features.
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