BUYING HEAD-PHONES.

New Zealand Herald, Volume LXVI, Issue 20162, 24 January 1929, Page 17

BUYING HEAD-PHONES.

GUIDE TO SELECTION,

Performance, not price, is the ultimate standard of radio economy, and this applies to the selection of head-phones as much as to any other components, The sensitiveness of a receiving set and the quality of its receptions depend to a great extent on the type, and quality of the phones used. All good dealers, and they are in the majority, will test the 'phones before selling them, but even so, a pair that may pass examination when sold may fail later, or not be entirely suitable for the set used. Some_ hints as to actual selection are given in the "Listener In." as follow: — " For crystal sets, the minimum resistance desirable is 2000 ohms, and the set will be more sensitive if 4000 ohm phones are used, for it should be remembered that the receiver maenets are energised by the current that flows through their windings, and the greater the number of turns of wire the greater will be its effect on the diaphragm. The resistance value shows rouphlv the amount of wire on the magne f s, and so gives some indication of the sensitiveness of the phones. " For valve sets, low resistance receivers, with a telephone transformer, are to be preferred. High resistance phones may be used, and probably give purer reception, since the transformer means adding another iron core to the set, which always increases the chance of distortion. The drawback to their use is that they have to carry the full voltage of the plate circuit, which may cause the burning out of the magnet windings. If high resistance phones are nsed, they should not have a higher value than 2000 ohms, as the wire will most likely be too fine to stand up to the work.

" Another important point is comfort. 'A heavy set of receivers that holds the ears in a vice-like grip is torture to wear for more than a few minutes at a time. The head-set should be light, and the hand should have just sufficient tension to hold the ear pieces in place. Ear caps of sponge rubber also add to phone comfort."