Radio Broadcast - 1927, May - 61 Pages, 4.9 MB ... - VacuumTubeEra

The ElectricalA Non-Technical Explanation of thePrinciples Involved in Electrical Recordingand Reproduction The New"Panatrope" and "Electrola" Datafor the Home-Constructor Wishing toBuild His Own Electrical PhonographByJAMES MILLENTHE "PANATROPE"An entirely electrically operatedphonograph. Provision is madeso that the amplifier system, includingthe baffleboard loud speaker, may be usedfor radio purposes after the detector in any radiocircuit. This photograph was taken in the RADIOBROADCAST LaboratoryMOST fascinating experience for one interestedin radio especially one whohas long been connected with its developmentis to spend an evening with the earlyissues of some of the older radio magazines.A study of the advertisement section not onlyrecalls the queer contraptions that were lookedupon in their day as the acme of engineeringperfection, but also throws light upon the foundingand first products of small companies, regardednow as leaders in the radio industry. Notonly do large things often develop from a humblestart, but also large concerns of one decade oftenpass into oblivion by the next.Aside from this,also read what thewe may"prophets" of but just a few years ago outlinedfor the future of the radio industry. For instance,in the November, 1922, issue of this magazine,appeared an -article entitled: "Will Radio Replacethe Phonograph:"Apparently there existed some doubt in themind of the public as to whether the new novelty,radio, could ever reach the "perfection" of thephonograph as regards tone quality, service,and reliability. Now, on the other hand, thereappearsto be some doubt in the mind of thepublic regarding the same question, but from adifferent angle: "Can today's phonograph competewith the radio in tone quality, service, andreliability r"But, why not, from comparisons of the two.draw one's own conclusions? It is not at alla difficult or costly task to construct a trulyfineelectric phonograph. Before going intothe construction of such devices, however,let us first find out just what this new instrument,known commercially as the "Panatrope"and "Electrola," really is, and justhow it works.The grooves in a phonograph record are socut as to cause the needle to vibrate from sideto side. In the old phonograph these transversevibrations of the needle were conveyed mechanicallyby a system of multiplying levers toa mica diaphragm located at the small endof a horn. The vibration of the needle causedvibration of the diaphragm which set the aircolumn in the horn moving, and thus producedsound.Such a system, while low in manufacturingcost and reliable in operation, resulted in considerabledistortion. The horn was resonant atcertain frequencies and the diaphragm at othersThus some notes were greatly over-emphasizedwhile others were entirely missing.The new electric system depends for its operationupon the vibrations of the needle to producea constantly varying electric voltage. Theminute electric voltage generated by the movementof the needle is amplified by a high-qualityaudio-frequency amplifier, such as is a componentpart of the better radio sets, and thenconverted into sound by a loud speaker.While the new phonograph will play the oldrecords, the results are not the same as whenthe new Orthophonic (correct-tone) type records,made especially for the purpose, are used. Informer years, records were made mechanicallyby a machine much resembling the old-stylephonograph, into the horn of which orchestrasplayed while closely and uncomfortably huddledtogether.Now, however, studios much the same as thoseof modern broadcast stations, are employed forrecord making. Standard radio microphones,as many as needed, are so placed as to properlyblend all the instruments of even a large symphonyorchestra. No longer must the player infront play softer than natural in order not to"drown out" those in back. Everyone plays asifgiving a regular recital, and the various microphonesare so placed as to produce the properresults.In fact, the output of the electric phonograph,when one gets right down to the matter, is buta standard broadcast program which, instead ofbeing sent over the air, is recorded and deliveredto the consumer without picking up static,heterodyne whistles, and other disturbances enroute.The acoustical difference between the samepiece played by the same orchestra over a highgradebroadcast station on a quiet night andplayed on an electric phonograph, is nil, assuming,of course, that the same quality audiofrequencyamplifier and loud speaker are used inboth instances.With these improvements, and one otherthe elimination of the record scratch the modernphonograph becomes a highly desirablecompanion to the modern radio receiver. Staticand sos signals no longer need spoil an evening'sentertainment. Favorite selections, beautifullyrendered and reproduced, are availableat a moment's notice when the radio programis not tempting.Even the inconvenience of constantly changingrecords seems soon to be done away withaccording to recent announcements, of some ofthe leading phonograph concerns.But do not understand this article to be anargument in favor of the phonograph over theradio. The phonograph can never take the placeof the radio. First, the radio brings news andentertainment into the home as it is actually occurringbanquets, speeches, sporting eventsand many others; and second, radio suppliesits own program; its repertoire is not limited bythe number of records in the album.But, as a companionto modern radio, thereis a distinct service to be performed by theelectrically operated phonograph.THE NEW PHONOGRAPHBEFORE considering the re-vamping of theold-style phonograph, perhaps a briefsemi-technical description of the "Panatrope"or the "Electrcla" may not be amiss. In orderto make such a description more clear and tobetter "tie itup" with what is to follow, thecomplete device will be divided into its varioussub-units.