Broadcasting (Oct 1931-Dec 1932)

I Borne Practical Facts About Transcriptions By J. R. POPPELE Chief Engineer, WOR, Newark, N. J. lanufacture of Modern Disks Explains Why They Are qual to Studio Broadcasts in Fidelity of Tone THERE HAS BEEN much talk pro and con recently about transcriptions in comparison with studio broadcasts, but few persons outside the disk manufacturing field are familiar with the painstaking process followed in making electrically transcribed programs. WOR, along with other large independent stations, is well pleased with the excellence of recorded programs. Mr. Poppele in this article goes into considerable detail to convince the skeptical that there is a wide difference between the modern disk and the old phonograph record. He contends that much of the dwindling opposition to disks is based on sheer prejudice rather than facts. f;jtlr. Poppele IN THE FIRST place, let me say disk programs are not new. They are as old as broadcasting. In fact, most of the early broadcast programs consisted largely of phonographic records and piano rolls. lit on the other hand, with elecjjical transcriptions, we are not jtrogressing back to those days. Jpr between then and now devel>ment in recording has been as ftable as in broadcasting. "I'jBack in 1921 neither the phonou'aph record nor the broadcasting las very good. When broadcastg was combined with disks, the suit was often downright terble. Then broadcasting advanced, ore quickly than the older phonoaph industry, until within a ort time broadcasting resorted direct performance in order not ' be burdened with the lower iiality of the disks. And we have i||id direct performances ever since. me i Faults of the Old Disks _t JUT AFTER broadcasting had ta|i!en considerably improved, radio Tnt the phonograph a hand; in met, most of its technique has "\ ijben carried right over to the later 'jionographic industry. Whereas lie old disks that had once done soman's duty as program mate,al were mechanically recorded, ie electrical transcriptions of toay are electrically inscribed. Before radio technique had been dapted to disks, the actual voice the singer, or sound waves of ie instrument, would motivate the igraving needle that cut the wax icord. Often lack of volume in the )ice made the impression indefite. Or a great blast of sound .ade the needle tremble in all arts of odd ways. And there mi$|>Jiere many other factors that preSnted the old records from being fen near perfect. To mention but anffie point, the frequency range was pofisry limited. That is to say, either the very high notes nor ie very low were recorded. And any overtones were entirely lost. On the receiving end the differice between the old phonograph id modern receiver is enormous. Ihe phonograph, prior to the use radio technique, was a mechaniil device, the vibrations of the sedle caused by the grooves in »e disk being amplified mechaniilly by the diaphragm and sound )x. But now the radio receiver >rves also as phonograph receiver, ith its vacuum tube amplifier that beeijiieps up the volume any desired igree with absolute fidelity. In t(t':her words, the same refined ethods now used to put broadcast programs on the air are used to make electrical transcriptions, and the same refined receivers, amplifiers and loud speakers that turn the electrical impressions back into sound for the direct broadcast do the same for the recorded variety. An Answer to Prejudices I SPEAK of these matters lest the reader become preiudiced against electrical transcriptions on the basis that radio has gone beyond that stage; lest he say, "Those electrical transcriptions are mediocre. Just another name for phonograph records, and you remember what these old records are like that we used to play on the talking: machine." In the first place, neither the disk nor the machines on which they are heard are the same as formerly. In the second place, electrical transcriptions are different from phonograph records; thirdly, minute tests assure qualitv of disk and reproduction; fourthly, as the December issue of Fortune says in an article concerning broadcasting and electrical transcriptions: "the listener who should decry the Chevrolet broadcast as a recorded program is listening not so much with his ears as with his prejudices." All this vast improvement came about through the efforts of radio engineers and the large electrical companies. A contributory factor was the rapid rise of the talkies. Western Electric used its vast experience in the telephone field in developing the talkies, and then it accumulated knowledge gained in this field as well as that of the telephone in perfecting electrical transcriptions. It might be of interest to follow the making and broadcasting of such a program. Let us assume that a sponsor desires to go on the air with transcribed rather than network pro grams. He goes, let us say, to World Broadcasting System, whose presentations are prepared and recorded by its affiliated company, Sound Studios of New York. This concern is fully equipped with the latest apparatus. Frank Black and Gustave Haenschen prepare the program, enlist and rehearse the talent and in every respect make ready for the recording. The recording studios are in appearance, equipment and characteristics identical with the finest broadcast studios. But in addition there are the turntables on which the wax disks revolve and the recording apparatus. The speed of the synchronous turntables, 33 1/3 revolutions per minute for the large disks, or 78 r.p.m. for the small ones, is kept absolutely constant by the cycles generated at the power house furnishing the current. Since the trend is ever more toward the large 16-inch disks that revolve at a slow speed and play for about 10 minutes or more, let us follow a program through on one of these. The process is the same for the small disks. Intricate Procedure TWO WAXES are set on two of the slow speed turntables. The motor is started, the signal given in the studio and the program commences; opening chord, announcement, commercial credit, music, announcement of selections, more music and so on. The microphones have been properly placed, the monitor in the control room has his cues by which he varies his microphone volumes as he hears the program through the loud speaker; another technician in the amplifier room sees that all is right there and in the recording room each of the two waxes is cut. This recording equipment, turntables, recorders, needles, advance balls and other refinements not even dreamed of in the old phonograph days is most intricate. The disks play from the center to the rim, the reverse from the usual commercial record. As the wax nears the end of its course, two more waxes are placed on two more turntables and set going; then slowly the inscription is faded from the first set of waxes to the second. Accurate stop-watch time is kept of the moment the first set is placed in motion, how many seconds and tenths of a second before the recording begins, when the second is set in motion, when its recording begins and so on. The selection having been recorded, one set of waxes is played back to the interested parties: the engineers, who look for technical flaws; the musical directors, who look for false notes; and the sponsor's representatives. Approved by all parties, the set of waxes which have not been played back are placed in the galvano baths. The cut sides of the waxes are prepared for electroplating, which takes place in the galvano baths, where the waxes swing back and forth on suspended rods in the baths. The resultant copper master is then peeled from each wax, the latter being carefully shaved for future use in recording. Each Step Checked THE MASTER, of course, is a negative, its lines being raised above the surface, since it was plated from the wax, whose lines were indented. From the master are made two test pressings. These are of an earth-shellac material which is heated to approximately the consistency of kneaded dough, placed in the press with the master, and under enormous pressure and heat, baked. These test pressings are then played before all the interested parties for approval or rejection. Thus it can be seen that tests accompany every process in the fabrication of the final disks. The test pressings approved, the master is in turn plated. The final disks, in sufficient numbers for all the stations booked to broadcast the program, are not pressed directly from the master because in the pressing there is always a slight danger of injuring the master. And if the master were injured no impression of the performance would remain, for the wax was spoiled in the plating. Again the factor of safety enters, the master being electroplated, the process resulting in a "mother". Then the master is filed for emergency use or in filling future orders for more disks. But the "mother", having been plated from the negative stamper, is itself positive, hence unsuited for pressing the positive final pressings. So the "mother" too is plated and the resulting stamper is used to make the final pressings. These pressings are then (Continued on page 27) ttUctober 15, 1932 • BROADCASTING Page 7