In 1898 Valdemar Poulsen invented the first magnetic tape recorder. In fact it used a steel wire as the recording medium, but with the same principle of encoding sound waves as magnetised pulses. Magnetic tape (thin plastic tape, coated on one surface with magnetic oxide) soon became the standard for tape recorders. Sound is recorded by a microphone that converts sound waves to small electrical pulses. The magnetic tape is drawn over a recording head that generates a signal in the magnetic oxide. This signal can they be replayed by passing the tape over a playback head which converts the signal back to electrical pulses that can be electrically amplified to drive loudspeakers. The tape is stored in open reels. The quality of the recording depends on the width of tape and the speed the tape passes over the heads, there are several standards. This is the first recording medium that is reusable. By erasing the tape (recording a blank signal) it can then be used over and again. Of course the recording must be protected from strong sources of magnetism, otherwise the signal will be destroyed causing drop-outs. Also if the tape is thin, and stored on a reel, it can suffer from print-through, where the magnetic signal on one loop of the tape prints through to the next and previous loops, manifesting itself as an echo before or after the actual sound when played back. The most common form of magnetic tape in the home is the Compact Cassette which encloses the tape reels in a fixed housing, thus making it portable, but the small width of tape reduces the quality from large tape recorders (of course modern cassette recorders can compensate for certain problems with noise reduction etc).
Around 1948 the vinyl record as we now know it was born - the first twelve inch "long player" microgroove records that played at 33 1/3rpm for up to 30 minutes per side, and seven inch 45rpm singles and Extended Plays. The format is capable of producing full frequency range recordings with the improved light weight pickup arms and styli. These vinyl records are produced in a similar way to the Shellac 78s, they are pressed from plates produced from a master. The only difference being the recording will have been recorded on magnetic tape before generating the master disc. Quite often the original tape is used to create second generation tape copies, from which the master discs are taken. Each generation copy from the original will, however slightly, reduce the quality of the reproduction. Early record players included an amplifier and speaker in the same cabinet as the turntable. The simplicity of design of turntables, and minimal components (plinth, motor, bearing, platter, tonearm, cartridge and stylus) is such that they can work for many years without breaking down, and easily fixed if they do go wrong. Initially these vinyl records were monaural, as all sound recording previously, but soon stereo records were also available. Stereophonic recordings are generated with two distinct channels, to match left and right as the listener would hear with his/her ears. Initially this was achieved with two microphones recording onto two tracks on a tape recorder. Later, as tape technology improved, it was possible to record individual instruments or sections of music which are then mixed together to produce the final stereo recording.
In the late 1970s Digital Audio Tape (DAT) recording technology was introduced to recording studios, where the analogue sound waves are sampled at a high frequency (at least twice the frequency of the sound you wish to record) and converted to digital data which can be stored and manipulated by computers. Once in digital format the data can be stored more reliably on magnetic tape. The digital signal is then converted back to analogue to produce the vinyl master disc. In the early 1980's small DAT recorders were made for home use, but didn't take the world by storm. Only musicians seemed to take to the technology.
In 1983 the Compact Disc introduced digital recordings for domestic use. Instead of recording the digital data on a magnetic medium, the stream of data is stored as tiny pulses on an aluminium disc coated in plastic. The data is then read using a laser beam, thus eliminating physical wear on the discs. Initially the cost of the CD players was high due to the new technology. After several years, these Compact Discs have found mass appeal as people bought the new players when they came down in price, and the record manufacturers and retailers pushed the new format and reduced the availability of vinyl records. Problems with CD player were quite frequent, especially early and cheap models. Due to the complexity of the electronics that control a CD player, it can often be more expensive to get one repaired than to buy a new one! Recently a recordable CD has been released, but the CD writers are expensive, and the discs can only be written to once, not erased and re-used. Other variations of the compact disc are being developed, including using different colour lasers, one to write and one to erase, so as to produce a re-usable CD.
Other formats that the manufacturers have tried to impose on the domestic market in recent years include Digital Compact Cassette (DCC) and the Mini-Disc. Both offered digital recording, one on tape, the other on disc. Neither have taken off, partly due to the lack of pre-recorded tapes/discs, and partly because people are getting a bit sick of having to fork out loads-a-money for new equipment each time a new format comes out.
