THE MAGIC SPARK.

Auckland Star, Volume LVI, Issue LVI, 13 November 1925, Page 13

THE MAGIC SPARK.

LOUD SPEAKER ABUSE. ELECTION BROADCASTS AT SEA TREATMENT OF FILAMENTS. \ (By "PHONOS.") Next Friday evening will mark the taking over of the local station by the Radio Broadcasting Company. It is only fitting that on such an occasion the listeners of Auckland district should express their appreciation of the action of the contributing- dealers in maintaining a service under many difficulties, and should tender their thanks to the numerous performers who have gratuitously giveh their services for the entertainment of our growing radio public. Mr. George Rickard i secretary of the Kaitaia Radio Society' is paying a brief visit to Auckland. On the evening of the polls Mr. Rickard used a loud speaker to acquaint Northland residents with the reports that were broadcasted from IYA. His services were much appreciated, as residents in the winterless north were able to gather in the capital thereof and obtain particulars of the elections that would have arrived, by the ordinary channels, about a day later. Concerning these broadcasted results it may be noted that IYA, after a peculiar announcement last week, grudgingly admitted that it was indebted to the "Star's" loudspeaker service for the local results. Election Results Received at Sea. A good example of the service rendered by broadcasting was obtained aboard the Matangi on Wednesday night of last week. A neutrodyne set was placed aboard temporarily, and through it all particulars broadcasted from Auckland were most satisfactorily picked up. The captain cor/siderately installed a loud speaker in the saloon and here passengere for Tauranga were kept well in touch with the latest returns from the various districts, a result, they were able to supply Tauranga, on arrival tnere next morning, with many particulars of ballot box decisions that had not then reached the Bay of Plenty metropolis. There was a manifest appreciation of the innovation. . The Humour of It.

A valued correspondent contributes the following anent the ■ perpetual topic among local radions:—

"Dear Phonos, —Electioneering statics being now over (including the chaotic announcing of "Results' from.: local stations), I hope that the sparfc interference will be kept well under notice.' 'It gave the' Saturday programme a bid time and spoiled several excellent gramophone transmissions. This was not entirely without humour however, as, during the rendering by Dame Nellie Melba of Tosti's beautiful 'Good-bye,' we.came to the line 'What are we waiting for, Oh! my ——' and in came the spark at full blast. We were waiting for it, of course. ••■ . •

"On the other hand it has its merits, at times, as- when it effectually smothered an erotic soprano the other evening, and if yie listeners were only to look at the. thing from the proportional aspect I feel sure there is no cause to complain that the Government retains 7/6 of the license-fee. We surely get.2s per cent worth of spark in the transmieripna? That, perhaps is hardly* the point e£ installing*- .efc" " * *T

_ Loud Speaker Manipulation.

Far too many who use these popular appliances blame the instrument for harshness and distortion when they should really blame themselves for misusing it.

It is a common fault to over-drive" the loud-speaker by-using a far higher plate current than the valves require. This is a fault: easily corrected. Again, we arc too fond of- employing general-purpose valves as amplifiers in second and third stages. They are necessarily overloaded, and the tone in this case, is sometimes atrocious. The remedy here is to use loud-speaker, or power, valves when more than one etage of li j. is in service. A panel incorporating, detector and three stages [of L.F., should have a generalpurpose or special "soft" valve as detector, and an Ordinary amplifying valve aa first amplifier, followed by two power valves, to each of which a "negative grid bias is applied. The plate current must be thoughtfully regulated, and decided upon after suitable experiments have fixed the required voltages. Indiscreet iise of reaction is another caupe of impure tone. Do not couple your coils till you get the uttermost in volume. Ere you reach .that stage you have lost what purity you-had. Rather see how far you can*uncouple without losing such volume as you find necessary.. And here is another point: When tuning in the. local statum on the loud speaker, we are prone_ to set the condenser to* that reading which gives the loudest reception. This is all wrong. First find. that, then slightly detune. This will give a little less volume, but greater clarity and purer tone. Now, adjust your loud-speaker so that the, emission from the horn, instead of being directly - distributed through the room, is reflected from a plain walL By a plain wall tog mean a wall on which there are no pictures, ornaments, or any ofher gadgets, and certainly' no curtains. Finally, open the window! Fresh air is good for the loud speaker, a fact which is to be explained acoustically and not electrically. These few points, if considered and borne in mind during operation of the set, will make a world of difference to what your loud-speakers will do.

TREAT THOSE PELAMENTS GENTLY. * : If you wish your valves to last a Ion? time, treat them gently. Don't puh them roughly from their holders or srvikvtß. Don't interchange or insert with the high tension circuit completed. Switch it off. or, if you-'have no H.T. switch, remove negative . plug from battery. . ■- . When closing , down, do not turn out one valve at a time. If yon do, the-re-mainder will-receive a rush of* current. Surmosinz your set has thrpo values, half extinguish the last amplifier, then the middle yalve,_ and finally the detector orH.F. amplifier. -Now return, nnd completely extinguish each one. If ybuhnve a low-tension cut-out switch, all three are extinguished simultaneously and safely. -Do not switch on and off more often "..than necessary, and always cut his-h-tens-on e : renit whan first passing current to filaments. . . : .