MAKING OUR OWN RECORDINGS

New Zealand Listener, Volume 17, Issue 438, 14 November 1947, Page 12

MAKING OUR OWN RECORDINGS

T the present time, if the NZBS_ makes a recording of an important speech or musical performance, copies of the record can be obtained in two ways. If only a few are required they can be made one at a time by playing over. the original disc and re-re-See it. This method, "dubbing," is slow and expensive, for at recording speed it would take half an hour to play over both sides the original in order to get one copy, while about ten playings the quality of the record deteriorates to such an extent that it is of no further use. If larger numbers are needed the record has to be sent to Australia, where at a record-pressing factory the additional discs are made and sent. back to us-which again involves considerable expense and loss of time for the

broadcasting authorities. -» To cut that expense, and save that time, the NZBS is preparing to set up a record-pressing plant of its own in Wellington. Early this year, officers of the Service who were in_ Australia arranged for the purchase there of all the equipment needed. Since then some of the plant, which includes two 200-ton . presses, has already arrived, and premises in Wellington are being converted to accommodate it. It is hoped that the completed workshop, which will employ up to half a dozen specially-trained men, will be producing records early next year. The manufacturing process which will be adopted here is a fairly recent

development in the use of plastics, and incorporates the use of a new material called vinylite, a flexible and _ transparent thermo-plastic. Vinylite discs are a great improvement over those normally available to the public in music shops, because they are light-weight, unbreakable, and extremely durable. In making them the sound is first recorded in the usual way on what is called the "master" disc, made of aluminium coated with a cellulose lacquer. A very thin coating of silver is then deposited on the disc by chemical means to render it electrically conducting and the disc then goes through an electro-plating (continued on next page)

— (continued from previous page) process, being suspended for about 12 hours in a plating tank while successive layers of nickel and copper are built up on its surface to a thickness of about one thirty-second of an inch. The plated metal or "matrix" containing the impressions of the grooves from the master disc is then peeled off and mounted on a solid backing-plate of steel, thus becoming the die from which the new discs are pressed. Two dies are made, one’ for each side of the record. These are placed in a steam-operated press, and between them is inserted a flat "biscuit" of vinylite which has previously been slightly heated. When the press is closed the vinylite is subjected to a pressure of over a hundred tons. Labels are pressed into the disc at the same time. After two minutes the press is opened and _the disc taken out and its edges trimmed. It is given a final polish and is then ready for use. The NZBS record processing plant will be mainly concerned with manu-_ . facturing records for use by National and Commercial stations-musical recordings by New Zealand artists or groups such as the National Orchestra, dramatic features from the NZBS production studios, and talks. But it will also supply recordings of important events, speeches, and personalities for libraries and official archives, while recorded lectures, lessons, foreign langu- © age and dictation tests, and other édu"J cational features will be produced for «use in schools and colleges. (The photographs on page 12 are reproduced ‘by courtesy of the Australian Record Company Pty., Ltd.) « ‘