Yamaha - Sound Reinforcement Handbook(2nd Edition)-Gary Davis-Ralph Jones

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YAMAHJrTJiESousdREiNfoRCEMENTHANdbookSECONd EdmoxWRiTTEN FORYAMAI-IA ByGARy DAvis &RALpl-l JONESINSIDEDESIGN &ILLUSTRATIONBYGARYDAVIS &ASSOCIATESCOVERDESIGNBYLEESAVOlTPublished by.Halle,nardPulllishingC,rp,rali,n7777 W. Bluemound Road, P.O. Box 13819Milwaukee, WI 53213Copyright 1987, 1989 by Yamaha Corporation ofAmerica and Gary Davis & Associates.ISBN: 0-88188-900-8All Rights Reserved. Written Permission fromYamaha Corporation of America (P.O. Box 6600,Buena Park, CA90622) is required for reproductionin any form, except short excerpts may be reproducedor quoted forpurposes of critical review.First EditionSecond EditionFirst Printing:Second Printing:Third Printing:First Printing:Second Printing:December, 1987February, 1989April, 1989June, 1989February, 1990Printed in the U.S.A.PREfACEIn 1974, the people at Yamahaasked me to write some spec sheets fora dozen or so new guitar amplifiers andsmall mixers. As soon as that job wasdone, they showed me a new product.It was a console, one intended to be amajor departure- a leap into theheart of the professional sound rein-forcement market - fora companythen known primarily as a musical in-strument manufacturer (or a motor-cycle manufacturer, if you were not amusician). Yamaha said they wantedto firmly establish themselves as aleader, and they felt that a comprehen-sive instruction manual for the newconsole would help do the job.We hadonly aprototype board and somesketchy specs, but no detailed draw-ings or data, so I contacted engineerJohn Windt, and we measured the per-formance. Working with pencil andportable typewriter, I created the firstdraft ofthe PM-wOOOperating Man-ual.The PM-WOOconsole did putYamaha on the map, insofar as theprofessional sound reinforcementbusiness is concerned. The manual wasso popular that it had to be reprintedmany times (far exceeding the numberof consoles built). It became a standardtext in several college courses due to itsdetailed discussions of the basics ofsound reinforcement.During the ensuing decade, Yamahaasked me to write manuals for avariety of amps, signal processors,mixers and so forth, and to maintainthe same standard of excellence webegan with the PM-WOOmanual. Un-fortunately, it is very expensive toproduce and print 30 to 60 pages ofinstructions forevery product, and it isdifficult to justify - especially whenonly 8 to16 pages contain the "hardcore" operational data. For this reason,both Yamaha and I had pondered theconcept of a generalized guide forsound reinforcement, apart fromanyindividual operating manuals.Finally, 10 years after the PM-WOOmanual was published, Yamahadecided to move forward with thisproject. We anticipated a book of 96 to160 pages in length, and expected itwould take a year to complete. Thefirst edition of The Sound Reinforce-ment Handbook was comprised of 384pages, some 256 illustrations, and tookthree years to complete. The firstprinting of 10,000 copies sold out in ayear, and while we were completingthis second edition, another two runstotalling nearly 5,000 more copies hadto be printed. Clearly, the book hasbeen wellreceived, and we're grateful.The Sound Reinforcement Handbookis the largest project I have everundertaken. It would not have beenpossible without the support andpatience of the people at YamahaCorporation of America, and at theirparent company, Yamaha Corporationof Japan. All of uswere able to endurethe strain of gathering data, editing it,and producing this book for one reason:we had an important goalto achieve.That goal was to create ausefulreference for anyone who is interestedin learning the basics of sound rein-forcement. In this second edition, wehave improved many ofthe illustra-tions, and added entirely new topics,corrected a number of minor errors andtypos (perhaps created new ones). Wehave made the book much easier to useby completely reorganizing the chap-ters and creating an index.We had originally planned the firstedition for looseleafbinding, with theintent to publish updates periodically.The cost, however, would have beenprohibitive, and so this soft coverformat was adopted, with the prospectof a new edition when the need arises.We all hope you enjoy and learn fromthis one.Gary D. DavisSanta Monica, CaliforniaJune, 1989This hANdbookis dEdiCATEdTOThESOUNdREiNfORCEMENTiNdUSTRY,ANdTOAllThOSE proplr whohAVE WORkEdSOhARdTObRiNGbETTERSOUNdANdMusicTOTIlEWORLd. WEpARTicuLARLy wishTOAckNOwLEdGEThELATEDEANEJENSEN fORhisAdVANCEMENT ofSOUNd.AckNowLEdGEMENTSMy associate Ralph Jones made asubstantial contribution to the writingand illustrations that are in this hand-book. Ralph's background with MeyerSound Labs, and his formal musiceducation, served to balance theknowledge I have gleaned from myinvolvement with many other soundequipment manufacturers, and my ownphysics background. Many thanks,Ralph. And thanks also to your wife,Claudette, who helped with some of theearly deadlines.As I mentioned in the Preface, thepeople at Yamaha Corporation ofAmerica and of Japan (formerly Nip-pon-Gakki in Japan) have supportedthis project - both financially and withconsiderable assistance in terms ofsuggested contents, proof reading, andhelping to secure expert consultingassistance when that was required.They also deserve praise for giving mea free hand to write as much as wasrequired, to include all we wished(including a number of competitors'names, when that information seemedimportant), and to not make this asales presentation for any particularYamaha equipment. Special thanks goto John Gatts and Bob Davis foroverseeing the project at Yamaha, andto Craig Olsen for his help with theinitial outline. Nancy Mastroianni, askilled proof reader, was employed byYamaha to highlight my inconsistenthyphenation, dangling participles, andother typographical errors. SoundmanSteve Getson of Trenton, NJ, kindlyidentified many typos after the firstprinting. At our request, Brian WeissofWord'sworth also did extensive proofreading. Mind you, we exercised ourright of editorial license, so if some ofthe usage remains non-standard, itmay not be Brian's or Nancy's fault.Bob Davis, who collated all thecomments and edits at Yamaha forboth editions, was assisted byYamahaDistrict Manager Ray Bloom and by in-dependent consultant Rolly Brook.Without this valuable input, I wouldstill be choking on my left foot. Thanks,guys.I made many phone calls to engi-neer John Windt, whose extensiveknowledge of system grounding andsystem design added considerably tothis book. Thanks also to the lateDeane Jensen (of Jensen Transform-ers, Inc.), who provided very usefulinformation on transformer anddifferential balancing, mic splitting,and other aspects of circuit design.Lynn McCroskey and Alvis Wales ofSonics, Associates were very helpfulwith regard to interconnect of balancedand unbalanced circuitry, and theyalso made some useful suggestionsregarding the relatively minor directeffects of wind on sound propagation.Bill Swintek of Swintek WirelessMicrophones gave uspermission to useportions of data we wrote for himseveral years ago, and the people atlIMEsubmitted a major portion ofthedata dealing with wireless micro-phones and wireless intercom systems,which together make this portion of thebook far more accurate and completethan it otherwise would have been.Thanks to engineer Bob Ludwig forexplaining the pros and cons of consoleplacement. Thanks to Crown Interna-tional Corporation for sending photosand information on their PZM micro-phones.Composer/synthesist/consultantChristopher L. Stone of DragonsenseStudio was most helpful in guiding ourMIDI and SMPTE discussions, andspecial thanks go to Jim Cooper of J.L.Cooper Electronics for proof readingthe MIDI material and offeringvaluable corrections and suggestions.I also wish to thank Carolyn andDonDavis, whose Syn-Aud-Con semi-nar and whose book, Sound SystemEngineering,have significantly aug-mented my understanding of soundand acoustics.Last, but certainly not least, manythanks to Georgia Galey, my hard-working office manager who did somuch to help bring this book fromconcept to reality: typing some datainto the computer, proofing the typedand typeset copy, following uponphone calls, photocopying and thenecessary go-fer jobs - in other words,filling in wherever and whenever shecould. GDDPS: The answer to the unasked question:No. Bob Davis, Don Davis and Gary Davisarenot related to one another. They all justhappen toshare the same surname andwork in the same general industry.SOUNdREiNfoRCEMENT HANdbookTAbLE ofCONTENTSPage Section/Subsection & Title Page Section/Subsection & TitleSection1. Whatis a Sound System Section 5. Sound Outdoors1 1.1 The audiosignal43 5.1 The inverse square law1 1.1.1 Sound waves44 5.1.1 Inverse square law calculations2 1.1.2 The electrical representation of sound45 5.2 Effectsof environmental factors2 1.1.3 Phase45 5.2.1 Wind3 1.1.4 Adding sine waves46 5.2.2 Temperaturegradients4 1.2 The basic purpose of asound system46 5.2.3 Humidity4 1.3 A conceptual model of asound system47 5.3 Feedback control5 1.4 Inputtransducers47 5.3.1 Maximum gain (available gain before5 1.5 Output transducersfeedback)6 1.6 A practical model of asound system49 5.3.2 Using directional microphones andloudspeakersSection 2. Frequency ResponseSection 6. SoundIndoors9 2.1 A definition53 6.1 Boundaries10 2.1.1 Basicspecificationmethods54 6.1.1 Theabsorption coefficient11 2.1.2 Octaverelationships andmeasurements55 6.2 Standing waves12 2.2 Frequency response of practical audio devices56 6.2.1 Standing waves inaroom12 2.2.1 Electronic circuits and cables14 2.2.2 Microphones57 6.3 Reverberation58 6.4 Critical distance14 2.2.3 Loudspeakers60 6.4.1 Implicationsfor sound reinforcement15 2.3 Voiceand instrument ranges15 2.3.1 The speaking voiceSection 7. Block Diagrams15 2.3.2 Thesinging voiceand musical instruments16 2.3.3 Harmonics61 7.1 General discussion17 2.4 Effect of acoustical factors 63 7.2 Symbolicconventions66 7.3 Notational conventionsSection 3. The Decibel, SoundLev