Audio-1955-May.Pdf

tiKIVLRAL LIBRARY oseIifAFnf4 Ingtietcf %chln A , 1955 50c MAY 2 4 .1e9 ENGINEERING MUSIC SOUND REPRODUCTION 3/4' PLYWOOD THROUGHOUT EXCEPT AS INDICATED. SCREW, NAIL, AND GLUE ALL JOINTS FOR AIRTIGHT SEAL KIMSUL PAD Designed for modern phonograph records, and for use wit', tuner and tape recorder, the "Preamp with Presence" has been miniaturized. and construction is simplified by using a printed circuit panel which is availcble. See page 20. Complete constructional data is given for a small corner enclosure using the tuned -pipe prin- ciple to enhance bass reproduction. See page 18. SELECTING YOUR LOUDSPEAKER A QUALITY AMPLIFIER FOR THE HOME MINIATURIZED "PREAMP WITH PRESENCE" ARTIFICIAL EAR FOR MEASUREMENT OF HEADSET RESPONSE www.americanradiohistory.comAmericanRadioHistory.Com AXIETTE 8 -inch 5 watts 40-15,000 cps $23.20 AXIOM 80 10 -inch 4-6 watts Admittedly, the performance quality of a 20-20,000 cps $68.50 loudspeaker depends upon design and construction. But we know that you intend neither to design nor build one. You will select one already designed and built. And when you sit back to an evening of musical enjoyment, the chances are you won't be thinking of flux density, Mark II AXIOM 150 impedance or cone suspension. 12 -inch 15 watts 30-15,000 cps $53.50 Certainly, the facts and figures are available for Goodmans High Fidelity Speakers ... and we know they will impress you. But, the point we make is that you select your speaker as you intend to use it... not on paper but by critical listening. The more critical you are, the more confident are we that your choice will be Goodmans-for the best reason in the world-because they sound better. Complete Service Facilities maintained for your convenience Sold by Leading Sound Dealers Prices Slightly Higher on West Coast For Complete Literature, write to: Dept. CE -1 Mark II AXIOM 22 ROCKBAR CORPORATION 215 East 37th Street, New York 16, N.Y. 12 -inch 20 watts 30-15,000 cpr $72.95 www.americanradiohistory.comAmericanRadioHistory.Com MAY, 1955 'VOL. 39, No. 5 Successor to RADIO, Est. 1917. CetNew FREE PUBLIC ADDRESS AUDIO HANDBOOK ENGINEERING MUSIC SOUND REPRODUCTION sy C. G. McProud, Editor and Publisher Henry A. Schober, Business Manager .,. 00t Ilarrie K. Richardson, Associate Editor A Y' ItOMPODRD Manager DLt1'en Florence Rowland, Production ORDAotttT Edgar E. Newman, Circulation Director trt/ - Sanford L. Cahn, Advertising Director si Special Representatives- f e H. Thorpe Covington and Dick Knott, 'ABC 7530 Sheridan Road, Chicago 30, 111. es,s vo, yet 0,rs llid West Representative- Sanford R. Cowan, 67 West 44th St., Valuable Facts New York 36, N. Y. Help You Install West Coast Representatives- Better PA Systems James C. Galloway and J. W. Harbison, the first time, such helpful 816 West 5th St., Los Angeles 17, Calif. For information in a compact Handbook! Shows how to make sound surveys and recommendations-with factory and arena examples. CONTENTS Discusses public address require- Audio Patents 2 ments in auditoriums, stadiums, large rooms, etc. Letters 8 Explains operational factors of impor- Editor's Report 12 tance in public address loudspeaker A Quality Amplifier For The Home-Albert Preisman 15 systems for all types of applications, A Tuned -Pipe Enclosure for Bass Enhancement-Raymond H. Bates 18 indoors and outdoors. Miniaturized "Preamp with Presence"-C. G. McProud 20 Explains three major points to con- sider in public address loudspeaker Selecting Your Loudspeaker-Charles T. Morrow 24 projectors. Hi-Fi and the Dragon Pup-Eleanor Edwards 26 Tells what the CDP Compound Dif- Patent Law Changes in the 1952 Statute-Albert Woodruff Gray 27 fraction Projector* is-what it does- An Artificial Ear for Measurement of Headset Response-Chandler Stewart 28 and how it provides a PA speaker system of much greater range, effi- Equipment Report-Craftsmen "Solitaire" Amplifier-Rex-A Special Record ciency and dispersion. Changer-Electro-Voice 666 Microphone-Browning L-300 Tuner 31 Includes illustrations, diagrams, Record Revue-Edward Tatnall Canby 38 charts, formulas, engineering data, Coming Events 43 technical & architectural specifications. 'Design Patent 169.904 New Literature 45 Additional Patent Pend. New Products 48 Send for your FREE copy now E Distributor Audio ETC-EdwardTatnall Canby 52 or see your -V About Music-Harold Lawrence 60 Industry Notes 63 gieCeSICZ Advertising Index 64 1 ELECTRO-VOICE, INC. BUCHANAN, MICH. Without obligation, send me FREE copy of the CDP Public Address Handbook. AUDIO (title registered U. S. Pat.. Off.) is published monthly by Radio Magazines, Inc., Henry A. Schober, President; C. G. McProud, Secretary, Executive and Editorial Offices, 204 Front St., Mineola, N. Y. Subscription rates-U. S. NAME Possessions, Canada and Mexico, $4.00 for one year, $7.00 for two years, all other countries, $5.00 per year. Single copies 50e. Printed in U. S. A. at Lancaster, Pa. All rights reserved. Entire contents copyright 1955 by Radio Maga- zines, Inc. Entered as Second Class Matter February 9, 1950 at the Post Office. Lancaster, Pa. under the Art of March 3, ADDRESS 1879. CITY ZONE_STATE RADIO MAGAZINES, INC., P. O. Box 629, MINEOLA, N. Y. L _J AUDIO MAY, 1955 l www.americanradiohistory.comAmericanRadioHistory.Com AUDIO PATENTS RICHARD H. DORF* T11E UNITED STATES is not, of course, the tion of patents in Great Britain is com- only country in the world that has a monly based on a strict interpretation of the patent system; almost every country actual words of the claims. Engineering has one. However, we are so used to our The British Office follows U. S. phi- own system-which, of course, contains the losophy in requiring that an invention be largest number of patents of all, perhaps original, and it searches the prior art to Writing more than all other countries lumped-that determine this. However, prior use out- many of us are not aware of the great side of Great Britain is not a bar to a for Advancement in Electronics differences that exist between our own patent, while in the U. S. prior use any- patent laws and those of some other coun- where is considered anticipation and pre- are based vents allowance of claims. In Britain the If you are an tries. Almost all patent systems on those of the U. S., Britain, Germany, inventor himself need not apply; his as- Electrical Engineer or and France. Of the foreign group, the signee or even the first importer may apply. Physicist with aptitude British system is most like ours (as it is Even the granting of a British patent for writing, here in most matters of law) and the French is not anything like final. At any time is a way to broaden your is the most different. within the following three months anybody experience and may oppose the patent by alleging a legal enter a fascinating bar such as prior use in Great Britain. In British Patents area of advanced the U. S. patent matter is kept secret until electronics in The British system, though much like the actual granting date, after which no one of the nation's ours (or vice versa), has significant differ- opposition is possible without deliberate invite patentee to sue. leading organizations ences. In the first place, it is not necessary infringement to the is With the British system those in each field in its field .. to wait until a complete application ready before establishing a filing date in can watch for the issue of patents and can the Patent Office. It is possible to submit have time after publication of the material Hughes a "provisional specification" (in Canada to oppose it, if they wish, without a great Engineering and formerly when allowed in the U. S. deal of fuss and expense. called a caveat) in advance of formal Two other British features are interest- Writers submission of the application. The effective ing. First, there is not a single fixed fee; filing date then is that of the caveat. The there is a "tax" on every patent which work directly with design, develop- is payable yearly. The second and more ment, test formal and complete specification need not and maintenance engi- interesting point is this : if a patent has neers-performing the vital then be filed for a year, and sometimes work in not been worked-actually used-within of transforming complex theory there is a three-month extension addi- must be three years after it is granted, any person and procedure into clear, concise tion. However, the application approved within a year after submission. can apply to the Comptroller for relief technical information contained in from "abuse of monopoly right." After manuals, handbooks and other pub- This is important, because it means that the monopoly resulting from the granted investigation, the Comptroller can order lications for use by military and grant of a license, indorse the patent civilian technical people. patent cannot last more than 17 years from the formal application's filing date. "License of Right," which means then any- In the United States a patent may take one can practice the invention on terms set Here are some years to issue. There may be as much as up by the Comptroller, or even revoke the of the advantages of being six months delay before the Examiner patent entirely. This tends to make it im- an Engineering Writer takes action, and the applicant is allowed possible to use a patent for the purpose of at Hughes: six months to answer each action, of which suppressing an invention, as is sometimes done in the U. S. Training there may be as many as four or five. This at full pay to become fa- coverage because there miliar with Hughes-developed and effectively extends is the 17 years after granting plus the years manufactured radar, computer sys- Patents in Germany tems and guided missiles.

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