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By C. J. LeBel, Vice President AUDIO DEVICES, Inc.

It is obvious that finding the finest recording lacquer is not, in itself, the only necessary guarantee of a good disc. In the May issue we discussed the problems underlying the development of a lacquer formula. Now we shall see what precautions are necessary in its use.

A manufacturing system without a definite organization to supervise quality maintenance is one without guidance, so we were fortunate that our 1938 contract with La Societe des Vernis Pyrolac started us off with all the disc quality control know-how they had developed since 1929. This system has been enlarged in accordance with our own experience in the nine years since then, and as we make our own lacquer, control of product characteristics is all under one roof.
Mistakes would be expensive, so a good quality control system keeps costs down at the same time that it improves quality.
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General tests are applied to all incomming raw materials, as follows:

• 1. Solvents and diluents are checked for acid number, distillation range, non-volatile residue, specific gravity, and water content. Some manufacturers' products must be checked drum by drum; other organizations have not had a rejectable shipment in eight years, and a spot check suflices.
• 2. Film forming material is tested for solid content, viscosity, water content, and clarity.
• 3. Plasticizers are checked for specific gravity, viscosity, and color.
• 4. Aluminum shipments may be spot checked for flatness, surface smoothness, and surface cleanliness. This is seldom necessary as the circles have to be individually inspected as they go on the production line, anyhow.

In addition to the general tests, special proecdures are applied to certain materials. These special tests are for contaminants which would not be shown up by the simple methods previously mentioned, yet which would be harmful in even small proportion. The test is repeated after purification, if the latter proves necessary. Drums of chemicals are tagged when approved.
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The individual mix is made and filtered by the Lacquer Department, using tagged drums of chemicals. Individual mixes are used because continuous mixing (apart from the difficulty of handling so large a number of ingredients) would not permit of testing before passage of lacquer into the main system.

The filtering calls for the finest work of the chemical engineer due to the high solid content and hence the high viscosity of the lacquer. The high solid content is essential to single layer, homogeneous automatic machine application; and the high viscosity results therefrom by the inherent law of nature. Many filtering methods and media are available: single, multiple filtering; plate-and-frame filters and centrifuges; paper, cloth, and other filter media; various filter aids. It is most important that filtration be done properly, for no combination of methods is such that it can be used without extremely careful supervision, hence individual mixes arc tested not only for viscosity and solid content, but also for filtration quality.

The Engineering Department then coats some test discs, and makes a recording. If this is satisfactory, a sample of the solution is retained in glass, and the mix is released to production. This mix is then blended with previous mixes in tanks and aged before use. Hence lacquer in the tanks and system at any given time is a blend of several mixes. This blend is refiltered just before passing to the coating machines.

The sample in glass is retained for several months, and is available in case of doubt as to absence of impurities, or question as to stability. It is always large enough to coat an adequate number of test discs, as well as provide material for analysis.

The Engineering Department quality control personnel make a regular check of factory process conditions. It is interesting to note that to check functioning of automatic controls they have to
read 118 thermometers. They must also check many air flow indicators, machine speeds, air filtering, and air conditioning settings. A most important test is that of lacquer thickness, done by weighing a disc before and after coating.

Discs which have passed factory inspection are sampled regularly throughout the day, and checked by engineering personnel for the following:

• 1 . Noise
• 2. Thread action
• 3. Static
• 4. Groove gloss
• 5. Wear
• 6. Coating thickness
• 7. Perfection of filtration

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On the basis of these tests production discs are released for packing and shipping. It should be pointed out that the control number on the disc is on a chronological basis. The blending mentioned above and the quantities of raw materials are so great that it has been quite impossible to change the control number every time we use another drum of any given chemical.

Production discs sampled as mentioned heretofore are retested periodically to check for:

• 1. Noise level increase - a groove cut today should not be noiser when played back next week, ne.xt month, or next year (if dust is excluded). A groove cut next month, or next year should be no noisier than the one cut today, in the same disc.
• 2. Delayed wear - A groove cut today should last for just as many playings, whether it is played right after cutting, a month, a year, or a decade later.

Discs are inspected 100 per cent by the factory staff at each of the following points in the process: aluminum circles before coating, discs leaving the coating machine, discs leaving the drying conveyor, and when completed.

Note that every disc manufactured is inspected, but not all discs manufactured need be test cut. Successive discs are chemically identical, and a test on one is a test of the next thousand. Scientific sampling procedure is the basis of good quality control in this case.

Experience has indicated the value of a number of precautions. Perhaps our readers will find them of interest:
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• 1. Lint-free smocks for operators
• 2. Periodical washing of floors and walls
• 3. Special ventilation systems with low air velocity
• 4. Extremely large filters, each now as large as and rather heavier than an automobile
• 5. Minimum number of personnel in certain critical areas of theplant
• 6. Lint-free packaging - special wrapping for all discs; lacquer impregnated spacing rings to separate masters

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Nevertheless, just as good filtration will not cure a bad formulation, every step in the process is a vital link in the chain. Break one link and the chain is broken. This intricate chain that is the disc making process is maintained by our personnel. Good personnel are as important as good equipment, so we are exceedingly fortunate in that over half of our key production personnel started with us in the early days of automatic-machine disc-coating.

by C. I. LeBel, Vice President AUDIO DEVICES. Inc.

A wide study of disc recording standards will begin this fall, as the industry resumcs a standardization program interrupted by the war. Probably the most violent discussion will take place over the problem of groove and stylus contour, one of the oldest and most pressing and yet the least standardized of all laterl recording aspects. Groovecontour and reproducing-stylus tip bear a lock and key interrelation in this era of permanent-point styli, and the lack of general agreement on dimensions has been very objectionable. In the olden days a steel reproducing stylus would grind itself to a fit - now that fit must be predetermined. In this and subsequent issues of the Audio Record we plan to discuss the matter in some detail.

It is generally agreed that the most reliable tracking occurs when the radius of the reproducing stylus tip is slightly greater than that of the groove, so that the curve rides on the straight side of the groove. If this is overdone, the tip will ride on the top corners of the groove, which makes for noisy reproduction and complete tracking failure at high volume passages. This imposes no mininuim limit on the groove radius.

Improved fidelity requirements in current recording practice make it highly desirable that the new standards be set so as to minimise di.uneter effect. Consider what happens when we attempt to trace a sine wave groove with a point, whose effective diameter is equal to the wavelength of the groove. It can be seen that two factors affect tracking. Pinch effect (narrowing of the groove at higher velocities) distortion cancels out, if the stylus is free to lift slightly when necessary. In the particular illustration given it will be found that, even when lifted, the stylus tip still cannot follow the extremely small radius of the peaks of the wave. The point stylus is too huge to track correctly at that frequency and velocity, a fault which occurs chiefly at the smaller diameters.

While practical factors make a drastic decrease in point radius questionable, clearly even a small change would be of help. To help visualize the dimensions involved we have drawn Figure 5.

The discussion will be continued in the next issue.

By Gordon Sherman, Recording Engineer KMOX-St. Louis

KMOX has made approximately 30.000 records during the past eleven years. Many of these recordings were made under unusual circumstances in the field. Today at KMOX we have four permanent recording channels and four field units. These field units consist of every type of recording equipment, including disc, wire and tape.

Since 1936, however, practically all field records have been made with our disc equipment. These field assignments have taken me into 25 states, Mexico and out on the high seas. It would be difficult to pick out any one assignment as the most interesting, as practically all involved different subjects and different technical problems.

In the summer of 1937, KMOX inaugurated a society page of the air and the field department was assigned to cover summer resorts frequented by prominent St. Louis citizens. Marvin Miller, former KMOX announcer, and I visited a number of exclusive Michigan beaches. At each location we set up our equipment on the beach. Miller, attired in a bathing suit and with a mike in hand, waded into Lake Michigan to interview St. Louisans at play.
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The same year, Dan Donaldson, also a former KMOX announcer, and I were assigned to cover the erection of the Alton (Illinois) Dam, reporting various phases of construction and interviewing the workers on the job. At one time, my recorder and I located on a ledge no more than four feet wide and about 500 feet in the air. Danny, suspended in a basket by cable and swinging in mid-air,
shouted to workmen nearby and received their shouted replies to his queries.

On several occasions, the recording department was requested to furnish unusual, authentic sound effects.

On one occasion, I had to set up my equipment in the bottom of a lead mine shaft and run a mike and cable several hundred feet to a portion of a shaft that was being dynamited. Dressed as a miner, I had to do some crawling in a low, dark section of the mine - the only light coming from the miners' lamp on my cap - to get to the spot where the mike had to be installed.

The mike was placed in a small cavity of the shaft to protect it from flying debris. When the dynamite went off, the recorder, even though quite a distance away, lifted a full inch off the bench it was on. By careful dubbing back at the studio, we produced an authentic record of a dynamite blast, with all of the accompanying reverberations heard in a mine. The record is still in the sound effects file, carefully guarded.

One of the oldest and best programs on KMOX is the "Land We Live In." A great deal of work and expense are put into this show to keep it the best St. Louis production. For an episode on the story of Bagnall Dam, a complete musical score was written and special musical effects simulating the turbines and generators was to be used. The field department was asked to bring back all of the authentic sounds heard in the various sections of the dam and the generating rooms. We recorded every large separate piece of mechanical equipment and even had the operators of the dam open the water locks so that we could record the water rushing over the locks. From these sound effects, three musical arrangers designed a musical score that was indeed unusual and authentic.

In the summer of 1945, our news editor and I set out for Camp Kilmer, New Jersey. We were assigned to cover the return of the 86th (Blackhawk Division) from Europe. At Camp Kilmer, we set our equipment up on a Coast Guard cutter and put out to sea. Several hours out, we met the transports. While our cutter crossed the wake of these ships, we recorded at close range the return of the boys to U. S. ports.

We stayed with the G.I.'s and returned with them on a troop train to Jefferson Barracks in St. Louis, Missouri. Whenever the troop train stopped for water we would jump out, find an a.c. outlet and start recording interviews with the boys. In Pittsburgh, the train started pulling out in the middle of a recording. The recording continued until our cable slack gave out, and then, with the train picking up speed and with the aid of several helping hands, the cable was reeled back into the coach.

Yeh, who said a recording engineer's life is dull?
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By Elmer G. Siilzer, Radio Director - UNIVERSITY OF KENTUCKY - Lexington, Ky.

• Anmerkung : 1947 gab es noch nicht viele FM Stationen in den USA, weil die Versorgungsfläche der UKW Frequenzen viel kleiner war als bei Mittelwelle. Doch für kleinere Ortschaften reichte ein Radius von 5km schon aus. Wichtiger war, die bisherige Platte und der Stahldraht konnten die Qualität von UKW nicht erreichen

The plaintive strains of Barbara Allen, sung by the Kentucky mountain girl, and accompanied on a home'made dulcimer, will not be lost to posterity, because of an activity which has been carried on for a number of years now by WBKY, the University of Kentucky's Frequency Modulation station. As often as opportunity permits, well-known performers of Southern Appalachian Balladry are brought to the University's studios and their entire repetoires recorded. Usually three copies of each record are made - the original which reposes undisturbed in the station files; a copy of which is used on programs; and another copy which is usually dubbed at 78 RPM and given to the performer.

As a result of this policy, the University of Kentucky's FM station is accumulating a definitive set of American folk records that some day will be priceless. Among the performers brought into the studios are John Jacob Niles and Tom Scott, both nationally known collectors and performers of American folk music; the famous Ritchie sisters of Viper, Kentucky, and numerous mountain individuals and ensembles whose fame may be only lacal, but whose musical interpretations have great value for the student.

Not only balladry is recorded by WBKY. The final commencement address of a retiring University president, the 'round-the-world broadcasts on the "V" days, and many similar occasions have been recorded for possible programs in the future.

But it is not only for the preservation of material that recording services are valuable. A potential radio performer can realise more of his defects by listening to an audition recording, than by hearing hours of verbal criticism. Therefore, we record all doubtful portions of proposed programs so the performers can hear and study the dubious parts.

Of direct training value is the use of recordings in our classes. We have three courses in radio speech at the University of Kentucky - Radio Announcing, Advanced Radio Announcing, and Radio Dirama, respectively. In all of these courses at the first of the quarter, each student must record certain material. At the end of the quarter, he does an additional recording, and a careful comparison between the two recordings forms a factor in the grade he gets.

Our third use of recordings is in the transcription of programs to be used by other stations, for in addition to the operation of WBKY, the University of Kentucky radio studios provides innumerable programs for Kentucky's commercial stations. At various times during the year, a single recording, such as Founders' Day Program, may be dubbed and sent to fifteen or more stations. The University broadcasts eight live programs a week over WHAS - Louisville, but recorded stand-by programs are kept at WHAS to be used in emergencies caused by line failures or other causes. Even on its own station, WBKY, transcriptions of its talent may be used when the time the talent can perform doesn't coincide with the time available on the air.

By John Alexander, General Manager KODY-North Platte, Neb.

Every small market station in the United States, interested in covering the special events of its own territory, will find their recorders of inestimable value. Truly, they are worth their weight in gold!
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• Anmerkung : Alleine aus der Titelzeile kann man entnehmen, die Macher dachten vornehmlich an den "Werbemarkt", dessen Einnahmen den Sender überhaupt am Leben erhielten. Und kleine Sender in kleinen Orten waren/sind nun mal "small market stations".

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At KODY we have five recorders. All of them are put to good useage practically every day. Our equipment consists of two portable transcription recorders, two tape recorders and one wire recorder.

If Other small market stations are similar in operation to KODY, they do not have large program budgets. Money for direct lines and loops throughout our territory simply is not available. Consequently, our recorders are on the job night and day. At KODY, we have a policy of covering every special event that has significance in our area. 80% of these coverages are accomplished with discs, wire or tape.

At KODY, we carry a heavy schedule of commercial network. Consequently, recordings must he utilized so the various special event programs can be delayed to periods of time that are available. Example: In the winter, we cannot carry the Basketball Games at the time they are actually played due to commercial network commitments. We transcribe each game in its entirety and
replay later the same evening.

Like many other stations today, we find the wire and tape recorders of tremendous value in obtaining up-to-the-minute news. Practically all our locally-originated newscasts carry one or more recorded statements from local official celebrities visiting our city, or people who are in the news.

At KODY, we look upon our recorders as a great asset to our Program Department. We promote them and publicize the things we are able to accomplish with their help. We have displayed and demonstrated our wire and tape recorders before innumerable civic clubs and organizations in KODY-land.

It has been a profitable move on our part to invest in good recording equipment and the finest in discs, wire and tape.

By C. J. LeBel. Vice President AUDIO DEVICES, Inc.

Hier wird ein Thema betrachtet, das in der Dissertation von Dr. Schwartz aus 1969 eine große Rolle gespielt hatte, die Ursachen für den Verschleiß.

Last month we began a study of conditions for good reproduction from lateral cut discs: the conditions under which the reproducing stylus will faithlully track the groove contour. In its most simple form, we discovered that when the effective radius of the stylus tip was large compared to the wavelength of the groove, poor tracking would result. This is an oversimplification of the problem, and we now take the matter up in more detail.

There are three factors which govern tracking:

• 1. Reproducing stylus tip must be positively coupled to the groove walls. Such positive coupling can he achieved by having the spherical portion of the stylus tip ride on the straight side walls of the groove. This is easily achieved, when desired, by using a slightly larger radius for the reproducing stylus tip than was used for the cutting stylus tip. Incidentally, this mismatch increases the unit area pressure on the area in contact.
  To be sure that our recording lacquer will withstand this pressure increase, Audiodisc wear tests for years have been run with such a radius difference. Positive coupling is no longer a problem.
• 2. Pinch effect - When the groove lateral velocity is high, the width of the groove diminishes. Pierce and Hunt (*1) showed that this effect produced a second harmonic distortion in the vertical direction, which would cancel out in lateral reproduction only, it the reproducing styius could lift freely without giving electrical output. This lift is an extremely minute amount; in phonograph record reproduction with an ordinary steel needle the needle can often flex enough to produce the lift without record damage. When reproducing from Vinylite this is not enough, and vertical compliance must be engineered into the design. All modern transcription pickups are so designed, and at least two high fidelity home phonograph pickups have this feature. In short, pinch effect is no longer a problem.
• 3. Needle radius and groove radius - This portion of the problem is more mathematical in nature, but it may be appreciated by considering the effect of trying to follow minute groove convolutions of small radius with a stylus tip of larger effective radius. This is an oversimplification (if a problem which is profoundly mathematical in nature, but it is nevertheless an apt illustration. A complete treatment has been given by Pierce and Hunt (*1) and Lewis and Hunt (*2).

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Mehr über die Schnelle steht hier.

Brief consideration will show that if we are to faithfully reproduce high frequency tones at high velocity - which combination occurs when using NAB pre-equalization - we require a very small stylus tip. Unfortunately we cannot reduce the tip radius ad finitem, for a number of problems arise:
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• A. There is a lower limit to the radius which the lapidary can produce, whilst still retaining other tip dimensions at their correct values.
• B. The unit pressure on the reproducing tip rises to an excessive value, producing rapid stylus and record wear, unless the total stylus force is also reduced. The smallest total stylus force so far commercially available, 15 grams, is about half the minimum available before the war.
• C. Processing problems may arise. Nevertheless some consideration will undoubtedly be given to all these factors by the various subcommittees just formed by the NAB.

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References :

1. J. A. Pierce and F. V. Hunt, Distortion in Sound Reproduction from Phonograph
Records, J.SMPE, vol. 31, no. 2, pp. 157-186, Aug., 1938.

2. W. D. Lewis and F. V. Hunt, Theory of Tracing Distortion in Sound Reproduction
from Phonograph Records, J.ASA, vol. 12, no. 3, pp. 348-365, Jan., 1941.

Discs - Tape - Wire Used
Equipped with both a wire recorder and two large recording tables for cutting discs, Syracuse University's Radio Center is kept busy transferring sound to groove and wire.

The uses to which recordings are put at the New York School are in general two-fold; for broadcast and for instruction. Regular program series are transcribed in the Radio Center studios and pressings made of the discs which are sent throughout New York state. "Forestry Journal" is one of such programs, which is cut every two weeks and used on 17 stations. The program is done by  the College of Forestry and is aimed at education in conservation and better forestry.

Among its recording functions, the Syracuse Radio Center cuts commercial discs for advertising agencies, records its own shows for playback on AM stations, WFBL and WSYR, when time is not available for live pick-up, and makes recordings for community groups for use by them.

Students also find recordings to be extremely helpful in performance courses. In Radio Announcing extensive use is made of recordings. Students in Radio Production cut entire dramas, music shows, etc., for playback to the class and criticism.

The equipment is used in making disc recordings synchronised to motion pictures for later transferral of sound to combined print of sound on film.

Another important function is the documentation of special events and University activities. Among the work done in this line were the recording of the entire day's ceremonies at the installation of Dr. Paul H. Appleby as Dean of the Maxwell School of Citizenship and the day-long celebration of Spring Weekend, both of which have been "retained as historical university material.

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• Anmerkung : "candid" bedeutet zwar offen und ehrlich, hier aber "verstecktes Mikrofon"

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The trademark of radio the microphone - is conspicuously absent when producer Allen Funt gathers material for the newest and most novel experiment in radio, "Candid Microphone," the Thursday evening ABC network feature which presents real life conversations of persons unaware that their words are destined for broadcast.

Anmerkung : Damals war das einfach normal, nämlich nicht direkt erlaubt, aber auch nicht direkt verboten, das heimliche Aufnehmen auf Magnetband bzw. sofortiges Senden über die Antenne.

Seeking to capture the spontaneous reactions of persons in all walks of life to situations both common and uncommon, Funt brought a new twist to the interview type of radio program early this Summer by working with "mikes" concealed in dozens of different ways, depending upon the situations with which he dealt. The program, airing about six recorded vignettes each week, brings ABC listeners the frank, unrehearsed conversations of Funt's subjects in a manner that affords amusement as well as an insight into human nature.

With his portable recording equipment close at hand but hidden from view, Funt
approaches his carefully conceived "human interest" situations with a tiny microphone hidden under his scarf or coat lapel, in an arm sling, or as a hearing aid. In an office, store or home, it might be concealed in a flower vase, under a book or in a cigarette box.

 - (oder : Der größte Quatsch oder Unsinn kommt an und bringt die Quote)

Once, when Funt collusively posed (in Absprache) as a barber and frightened the light of day out of an unsuspecting customer by bragging, in a trembling voice which betrayed nervousness, that "this is the first time I've shaved anybody" - and adding "do you bleed much" (blutest Du viel ?) - the microphone was concealed in a sun lamp near the chair in the barber shop where the connivance occurred.

The under-the-lapel technique was used when Funt visited a bewildered garment maker on another occasion to negotiate a tailor-made zoot suit for a boxing kangaroo. A vase was used when the whimsy-loving producer and the banquet manager of a swank New York hotel arranged an eightcourse dinner, with caterers, for six cats who, Funt, with tongue in cheek, told the maitre de hotel, had "won blue ribbons in a feline beauty contest."

Not all of Funt's ventures arc primarily comical, however. Human interest vies with laughs in some situations, and in others, serious thoughts are provoked as the "Candid Microphone" makes its rounds.
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Since a tape recorder is used, extensive editing is possible to avoid repetitious dialogue, before the show goes on the air. In order to obtain an entertaining sequence, often as many as 100 splices are made on a single program. Finally, the entire program is re-recorded on discs for the actual broadcast.

"Candid Microphone" goes on the air with the only audible censor in radio. Instead of a blue pencil assault on a prepared script, the audible censor blots out words unusable on the air when an interviewee (der oder die Befragte) occasionally bristles at Funt's always deliberate affrontery.

Naturally, nothing objectionable to the parties concerned is aired, and no names are used. After a sequence is recorded, Funt's subject - or sometimes, victim -
is told that their conversation was recorded and his or her permission is obtained to use it on the air, with anonimity assured. And Funt seldom encounters a refusal.

• Solche Sendungen liefen bei uns auch unter den Titel : "Verstehen Sie Spaß ?", drifteten bei uns aber recht bald in problematische Zonen bzw. künstlich an den Haaren herangezogene Geschichten rüber.

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By C. J. LeBel, Vice President - AUDIO DEVICES, Inc.

Now is an especially fitting time to discuss the subject, for this article is being
written just as the 1947 Conference of the "Association for Education by Radio" comes to a close. Many broadcast and recording organizations have been called on to advise their local educational institutions on recording problems and facilities, - as our correspondence shows. Hence the discussion is addressed to both commercial broadcaster and educational recordist.
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It has been interesting to watch the growth of American educational recording. Attention to educational applications began shortly after Edison's original invention, but for many years the complexities of wax recording restricted its use to commercial recording companies, and to production of regular catalog items.

In the early thirties the process of embossing grooves in aluminum was perfected. Its quality being too poor for general professional use, some attempt was made to sell it to the educators. This was not very successful. Shortly thereafter recording on lacquer (coated on aluminum - eine beschichtete Alu-Platte oder Folie) was developed and came into limited professional use. Being a cut groove, the sound quality was definitely better, and some educational applications were found.

The same factors that hindered professional use were objectionable to the educator, viz., the blank discs hardened rapidly, the cut disc developed high distortion and noise in a short time on the shelf, the record could only he played a few times before being completely worn out, and the thread was explosively inflammable. Lacquer thickness was often uneven.

These defects were due to use of incorrect plasticizers in the coating, in insufficient amount, and poorly developed coating methods. The introduction of the first "Audiodiscs" changed this: the plasticizer formula was much more complex (Anmerkung : ein französisches Patent lag jetzt darunter), the plasticizer was utilized in much higher proportion, and machine application (maschinelle Herstellung) of lacquer was used. The correct plasticizers gave the lacquer high stability, changes with time were no longer a problem, and thread inflammability was reduced to a reasonable value. Machine application gave complete uniformity of thickness.

These improvements made recording on lacquer a professional success, but they also made educational recording universally available, and fostered its rapid growth. While some attempt was made to sell low cost home recorders and home recording discs for educational use, it was soon found that professional standards of clarity and durability were necessary.

While the first educational applications were for speech correction work, broader
vistas soon opened. Educational broadcasting was growing. Whereas a single microphone and recording machine were ample for speech correction, broadcasting posed new problems. The student was accustomed to professional broadcast standards, and to hold his interest production methods and mechanics had to be equally well handled.

It was found that better sound quality was essential, for fifteen to thirty minutes of listening to unclear sound was very fatiguing. The student became restless, his attention wandered, and without formalizing the matter, it became generally recognized that sound quality would have to conform to professional standards. The "fatigue factors" in sound reproduction would have to be kept at an absolute minimum.

If we may presume to coin a new phrase, the following psycho-acoustic equation was developed:

Sustained Student Interest = Interesting Subject Matter + Aural Presentation in a Non-Fatiguing Manner.

All of this experience has had considerable effect on the educational recordist's
requirements in the way of facilities. The dramatic recording facilities suggested may appear over-elaborate to some, but this is incorrect. While work can be done with less complete equipment, it will be smaller in scope, or poorer in production quality, or will be produced at an excessive cost in time and material (due to need for test cuts or retakes). A glance at current educational practice indicates that these facilities are gradually becoming the standard for a complete educational recording setup.

The facilities required will vary with the work to be done, of course, but some
form of each of the following must be provided :
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• A. Studio
• B. Speech input system - input controls, amplifiers
• C. Recording machine
• D. Recording raw material
• E. Reproducing facilities

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Speech correction recording has generally been done right in the classroom, and with one student performing at a time. Since acoustical conditions are seldom good, this indicates that the single microphone used should be of a directional form. The recording machine is generally of simple form, often a single-speed type cutting only up to 12" diameter.
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While inside-to-out recording is more convenient, it has been found preferable to use outside-to-in cut for records so made can be played on the home phonograph, which the student usually wishes to do. Cut in the reverse direction, they cannot be played on a turntable fitted with the usual automatic stop or changer.

Since faithful reproduction, "presence", is highly desirable, it becomes necessary to use a professional cutting stylus - "stellite" has been preferred because of greater ruggedness - and a professional quality disc.

As before and after comparisons are desirable, it is necessary to use a disc with unquestioned permanence - one which will be as quiet and undistortcd a year after as on the day of recording.

For making a quick survey of a class at the beginning of a term, it has been found
very economical to cut a 16" disc at 33 1/3 rpm. It is possible to place fifteen to twenty voices on each side of the disc, separated one from the other by short spirals.

Whether played over the school public address system or over an educational broadcast station, the dramatic recording must stand comparison with professional broadcasting, to which the student daily listens. The mechanics of the production must be well executed, the sound quality good. This imposes definite equipment requirements.

The studio must be adequate in sound isolation, reverberation characteristics, and size. Inadequate isolation means that many records will be spoiled by extraneous sounds, and inadequate acoustical treatment implies serious problems in setting up to record. It is apt to mean a "tricky" studio, full of bad spots, and most difficult to use.

In practice this is apt to make recording quality rather uneven, for available time is limited, and likely to be used in rehearsing the cast, rather than in rehearsal for sound. The studio should be large enough to accommodate the largest group. There is nothing so futile as trying to put a school orchestra of fifty in a small speech studio.

Fortunately, the trend in school design shows a growing appreciation of the fact that broadcast dramatics has become as important as stage dramatics, and a studio is often provided for use with the public address system. Recording from the same studio is easily accomplished.

The speech input system must provide adequate flexibility. Facilities for simultaneous use of three microphones are the minimum necessary, and four mixer positions are more convenient. Two turntables for music are also necessary. Means of inserting a sound effects filter to control at least one microphone circuit are highly desirable. It goes without saying that the amplifiers must have both good performance and reliability. Unlike a broadcast station, most schools have no maintenance man, and an amplifier breakdown is a serious matter.

The recording machine should be complete in its facilities. Both speeds should be available, and provision should be made for change of pitch. A spiralling device should be provided. Outside-to-in cutting should be used, and this will make a suction device (Absaugung) for removing the thread (das ist der Span) highly desirable.

The recording disc must provide professional recording quality, of course, but more is required. Complete uniformity is necessary and long life. Educational discs form part of a library, which must be reproduced next year, the year after, and the year after that. They must be durable, as regards repeated playing, but lack of deterioration with time is equally essential. Chemicals used in the formulation must be time tested for proven permanence. A disc which becomes noisy or distorted in two or three years is not satisfactory.
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Playback machines of professional quality are available for use in playing an educational transcription to a class. If any criticism may be made of them, it is that the portable loudspeakers are generally too small and too inadequately baffled for satisfactory reproduction of anything but speech.

The educational broadcaster needs especially a definite setup for re-recording. One concomitant of the production of successful program series is the process of exchanging copies with other groups. Very seldom do the quantities warrant processing, so the amount of re-recording to be done is very considerable - a serious burden unless a regular setup is made for that purpose.

It has been very interesting to watch the development of educational recording from an idea to a rapidly growing movement of well documented value. We salute those who have made recording an essential part of the modern educational process.

By Frank Sinatra - SINGING STAR OF COLUMBIA RECORDS

It is the very rare exception when a musical artist, particularly a singer, achieves any amount of success without substantial assistance from records. This is clearly evidenced when one analyzes the success formula for any number of the top singers enjoying popularity today. Frankie Laine is a perfect illustration of this point. For years Frankie knocked around waiting for his "big break". It finally came in the form of a disc with "That's My Desire" printed on it. Now he's a big star.

There is no doubt that live radio shows play a tremendous part in the growth of an artists' reputation, but stop and consider a moment the important part being played by approximately two-thousand "disc-jockeys" all over the country, not to mention the hundreds of thousands of juke boxes that reach an audience that very rarely see live talent. The average independent station devotes a very large part of its schedule to the playing of records. In short, all other mediums combined cannot equal the vast audience being reached daily by these platter spinners (den Schallplatten-"Schleudern").

Up to this point, we have concentrated mainly upon the promotional effect of records - and have completely ignored an equally important phase of this question - money. A record contract almost guarantees a singer some sort of steady income - depending of course on the singer's talent and reputation. A couple of hit records not only can insure the success of an artist, but can provide more than ample financial support, until he gets a radio show or a movie contract - and from there it continues to be a reliable and often sizable source of income.

And then too, thanks to the improvements made in recording equipment and techniques, during the last few years, the singer is able to reach his unseen audience with a more truly life-like reproduction of his voice.

What the result of the approaching "recording ban" will be I certainly cannot predict, but I sincerely hope that the parties involved come to some sort of agreement before many months have passed.

By C. J. LeBel, Vice President - AUDIO DEVICES, Inc.

As our standards of fidelity improve, new materials and methods become necessary. In disc reproduction this change started first in the professional field, but now even the serious music-lover is anxiously installing the newest in postwar pickups, amplifiers, and loudspeakers. This has prompted the introduction of a new Audiopoint, a sapphire for home reproduction. Perhaps our readers will be interested in some of fhe factors we considered while investigating the problem.

Sapphire Audiopoints for the professional have been steady sellers for a number of years. The factors which have made them popular are of interest also to the serious home listener:
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• A. Tracking distortion is at a minimum because the tip radius can be accurately controlled. The extreme hardness of sapphire (9 on the "Moh"-scale) makes it feasible to lap the radius, with high precision, to a value which will ensure its riding on the straight sides of the groove. As was pointed out by Pierce and Hunt'in 1938, this condition is essential to accurate reproduction of the groove contour.
• B. The surface noise is reduced by at least several db because of the extremely high polish of the tip. The extreme hard-ness of sapphire makes it easy to lap the surface to such perfection that a surface character indicator will give no roughness indication at all. While such perfect lapping could be applied to steel, the surface would wear rough again within the first second of use on ordinary phonograph records.

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There are two classes of users who would be interested in "permanent" reproducing styli. One group is interested in its ultimate durability, regardless of how badly it may sound toward the end of life. Another group wish to know how long the point may be used before the sound quality is adversely affected, and before the point causes excessive record wear.

When a sapphire stylus is used to reproduce Audiodiscs, no detectable wear results, and the stylus life can be considered indefinitely long. The same is true of pure Vinyl pressings. With ordinary phonograph records, and a pickup operating at about two ounces load, wear is much more rapid, hence the ultimate life is of the order of several thousand playings.

If we measure the sound quality, we find that it begins to deteriorate long before the ultimate life has been reached. While it is true that sapphire is the second hardest material (softer only than diamond), it is certain also that the phonograph record is quite abrasive. Under the pressure of many "thousands of pounds to the square inch" existing at the tip, the wear is slow but sure, and flats are worn on the end and sides. Long before the time has been reached when the needle will no longer stay in the groove, three things will bother the serious listener:
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• 1. The tip will be worn so flat that poor tracking will result at high frequencies. Sound will be "fuzzy".
• 2. Scratch will be much worse.
• 3. Record-wear will be excessive.

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Engineering judgment is that fuzzy sound becomes pronounced before the other two factors have deteriorated much. With a typical pickup of today we find that this situation is reached at about 250 to 350 playings. A light weight pickup (1 1/4 ounce force) would about double the "quality life".

While it can be shown mathematically(*2), that a worn stylus will create distortion, experiment shows that the critical listener will be annoyed long before the harmonic distortion meter readings look serious. Intermodulation readings provide a more sensitive indication, but they merely serve to confirm the ear's judgment. (*3)

Incidentally, in choosing the tip radius it is essential to have the size such that the point will track part way up the straight side of the groove. The bottom of the groove generally is considerably distorted by polishing of the stamper, and it is wise to be well clear of it. Of course, if the point is too large, it will create excessive tracking distortion, and may even refuse to stay in the groove. A compromise value is therefore desirable.

All of this discussion, of course, presupposes that the pickup is not dropped hard on the disc, nor on the metal turntable-rim. A hard drop is likely to chip the tip, for all hard materials are somewhat brittle. Chipping leaves razor-sharp broken edges, and the point is valueless.
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It is evident that the critical listener will find the cost of buying a new stylus, so often, quite appreciable. We have found an answer to this, an answer which the professional has found very satisfactory for many years: resharpening. By using a slightly longer piece of sapphire at the tip, at a very small increase of cost, we leave enough gem exposed so that several resharpenings become possible. A resharpened point of course is as good as new, and will wear as long as the original. Resharpening being much lower in cost than a whole new stylus, the saving in overall operating cost is quite worth while.

Since quality deterioration is gradual, it is easy to overlook the onset of poor sound quality. Hence it is wise to keep a rough count of the number of discs played, and change styli by disc count. In case of doubt another point can be tried, of course.

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In introducing the idea of resharpenable sapphire reproducing styli for home use
we believe that we have an idea which is well grounded in both engineering and
economics.

Im Januar 1948 läßt Mr. Speed, der Präsident von "AUDIO DEVICES, Inc.", "die Wuzz raus". Sie würden auch bereits an einem Tonband, einem Magnetophonband Clone - mit höchster Priorität arbeiten. - Sie haben also die "Glocken läuten" hören. Lesen Sie darum weiter, was sich im Jahr 1948 getan hatte.
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