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Show To Mae Volume cf t':o Radio Sot Diverge Veil?.:; ft Applied to rJatos of riaJ-ic-Fre-cuency Tubes. Py CHA1!! E3 GONrA Aci-I I. Mil h;l M : f I Lm'.jui .i :ori. 1'iinirf'il Mg:i,il-i from .:-.si!it il l y III intI. ii' lug Hnllot.4, 1'.rtlliT with the use of M.vr tubes, ni'lio-f"-qmney iiuiplllicitlcti iiihI lil'.;li vult-m;'i--i nf ilic reccPIng ciui, Pave mud' It ni-i iii i y I') provMe iuiie iiietiiis of rcilin -In q: 1 1 1 loml wpenker volume! win H ileslred. Im fact, the Ideal state of radio affairs af-fairs U when there h far more vol-1 vol-1 1 1 j than Is ordinarily require,!, to-tiiluT to-tiiluT with a satisfying means of thmltling ilmvn tills volume to any desired decree from the full tone of mi oi'i-ln-si ra (l'iwn to Just a faint whisper 'lint kitvh nx a pleasing hut iii'iicniillliilng background for the (lliui-r conversation, bridge game or friendly visit. IiiiIim d, this seems nliout as good a litre us any to say ft few words regarding re-garding radio manners. Only too often ratlin enterlainii'i lit lias become radio nuisance by blasting away and making mak-ing conversation most difficult, or. aenln, going to the other extreme, hy hem;; so weak as to cause conscious or Huhrnpsrlous t;trnlnlng of the hearing hear-ing families to distinguish the voice or music Issuing from the loud Hpea krr. After all. the radio entertainment (should he of sufficient volume to form the mil In Interest of the listeners, when those listeners are primarily an-Jons to enjoy radio, or of amply lihlued volume, without distortion. Ho as to form Just the desired decree of musical background or setting for conversational or other mental activities. activi-ties. Kadio, In the hands of the w"ll-imvni.'ig w"ll-imvni.'ig hut sadly mb'gulded radio enthusiast, has dope morr- to break up topvi rsatlons, friend-hips, households : nd ether things than almost any other oth-er force. Hence at this time we plead 1110' I earnestly for safe and sanfc radio as just discussed. '.ays of Reducing Volume. Now it is one thine to cut down the loud-speaker volume and quite another an-other to da so without impairing Urn tu:e ipi.iliiy. There are correct ways "lul means of reducing volume, Just as there are Incorrect ways and means. As a general rule, the sooner the volume is reduced In the process of reception the hotter the results. Thus, if tlte volume control Is in the railio-frequency railio-frequency end. the results are hound to he hotter than if the volume control con-trol is placed In the audio-frequency end after the signals have heen needlessly need-lessly amplified and where any change may cause distortion or serious loss of quality. It Is a m'stakeii Idea, yet one that has nevertheless gained very general acceptance, that the simplest volume control Is rciunlng the receiver. This Is entirely wrong. Uranieri that it Is the simplest, since it onfalls no luhll-li.m.il luhll-li.m.il .ittachineiitH and stands for i:o(!.h.g more than turning o::e or more tuning controls off the pouit of sharpen tuning, this- mo'ie,d often introduces in-troduces Kerlous distortion, for the n a -'oii that a cit tin wave is no longer available and some of the valuable baridn or latest sound components are I'till.I'-s ;!y chopped off. Also, the variation of the filament current, which is aiso resorted to as a volume control, is by no means good practice, slnoo the tune functions properly at the given filament temper-tttre temper-tttre or filament voltage, and any reduction re-duction Is certain to revolt In InsulIV ch lit electronic emls-doli, followed by distortion, which may or may not be noticeable lu the reduced loud-speuk-, er vol nine. The most satisfactory method, both from the simplicity and the t-onal standpoints, is to vary the plate voltage vol-tage of the vacuum tubes. In the case of "H" battery operation, the best pro-oeduro pro-oeduro is to insert a variable resistance resist-ance unit In the "IV plus lead going to the radlo-freqiN ncy tube or tubes, or to the detector tube In the event that there Is no radio-frequency amplification. Regulating Plate Voltage. In fact, most of, the lending radio-frequency radio-frequency receivers now on the market mar-ket are employing this form of volume vol-ume control, which permits of bringing bring-ing the radio-frequency end right up to maximum sensitivity and volume, while just a shade below the oscillating oscillat-ing point, If full volume Is desired, or down to a mere whisper, with perfect per-fect tone quality, If the otiier extreme is sought. The plate voltage of the detector and the audio-frequency tubes may also be controlled, if desired, although al-though once the proper values are. attained at-tained for good tone quality the voltages vol-tages should not be changed merely j for the purpose of cutting down loudspeaker loud-speaker volume. It is far better practice prac-tice to let these values remain at their best settings and to alter the plate voltage of the radio-frequency tubes as already outlined. Some radio authorities au-thorities recommend" a resistance unit for regulating the plate. This is real-, ly unnecessary, since in the first place a power tube should be employed to handle all the necessary volume w't.h-o.:t w't.h-o.:t choking or distorting: secondly. he utmost plate voltage within the capacity of the tube should he applied ap-plied for best results, even with reduced re-duced loud-speaker volume: thirdly, the "("" battery should be adjusted to provide the necessary grid bias for whatever voltage may be applied on the plate of the power tube. Hence a variable plate voltage is har,!ly necessary nec-essary nor desired for the last or power tube, although it sometimes serves 9 good purpose for the preceding preced-ing audio tube or tubes. |