Unique Sound Recording

Radio Record, Volume III, Issue 31, 14 February 1930, Page 30

Unique Sound Recording

Music on Reels of Wire ee

(By

Megohm

AS§ early as 1928, particulars were published of a new system of sound recording that gave great promise of superseding the phonograph and gramophone, at least for some purposes. Briefly stated, the invention of Valdemar Poulsen, of "Poulsen Arc" fame, consists in magnetically recording sound upon a steel wire, which may be stored in spools and used for reproduction of the record at any time. Owing to the possibility of employing large-sized spools, lengthy records could be made without a break. The

great. value of the invention, so far as broadcasting is concerned, would be in the ease with which a complete studio programme could be recorded, for reproduction at some subsequent time, or on several occasions. It would thus be a simple matter for a studio to put on a previous evening concert at any time, and considerable additional variety could thereby be introduced into the’ afternoon or other sessions. Complete concerts could also by this means be obtained from leading broadcast studios and utilised at a later date by distant or less favourably situated stations. It would thus be possible, under suitable arrangement, for New Zealanders occasionally to enjoy without interference of any kind, a complete evening session from, say, 2L0, London, broadcast from one of the YA stations. The whole process of recording and reproducing is effected by means of comparatively simple apparatus. The principle depends upon the fact that when a steel wire is brought near to

the poles of a magnet having a field of varying intensity, such variations will be impressed upon and retained, by the steel wire. af By arranging fine windings of wire! in series with a microphone, it is a comparatively simple matter to obtain the variable field strength of the magnet, with the result that a record of the voice or music at the microphone is recorded upon the wire in a semi-per-manent form which will remain for several months. Reproduction is effected by passing the prepared wire in front of a second magnet similar to that used for recording, but in this case the windings are connected to a suitable amplifier. The lines of magnetic force radiating from the wire induce .currents in the magnet windings which, when amplifies and passed into a loudspeaker or rai id, transmitter, give an accurate repetition of the original performance in front of the microphone. A useful phase of the system is that it is possible to use a length of wire for another record when the original matter is no longer of use. This is accomplished in‘a very simple way, by passing the wire near a magnet that ig arranged to demagnetise the wire, thus removing all traces of previous records. The wire then passes the recording magnet to receive the new record. HE principle of the apparatus is shown in the accompanying diagram, in which the three magnets are seen in line, their opposite poles facing, and the wire passing between. When the denagnetiser is not required, no current will be passed through, and it, will have no effect. Guides for the wire, _)" stop-work and turning mechanism for ’ the spools are not shown. In practice it could be arranged that a _ record would rewind upon another spool ready for a repeat, at the same time that another record of a different subject was being made. In this respect there is the same condition which attaches to picture films, which must be rewound before they can be used again. Poulsen called his apparatus the "Telegraphone," but the writer believes that "Pallophone" was another name given to similar apparatus. Just why the invention was used so little is not clear, but no doubt the great hold obtained by the gramophone obscured what was in some ways, perhaps, @ rival. Now that the talking film has arrived, it appears quite possble that a use may still be found for this system. especially on account of the lon lengths which can be recorded a break. i