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Electro-Voice LR4A User's Manual

1. ENGINEERING DATA DESCRIPTION and APPLICATIONS The Electro Voice Model LR4A Line Radiator represents a new concept in controlled sound pro jection This curved speaker utilizing nine 3 x 5 and three 3 1 2 cone speakers has eliminated many of the problems of feedback spotty cover age and excessive size previously associated with high level projectors The LR4A is ideally suited for churches theaters and auditoriums where it is necessary to cover a large audience with a minimum of speakers It may be mounted high above the microphone to elimi nate difficult feedback problems and fill the room uniformly with sound while retaining close control of the pattern of sound being projected U S Patent No 3 125 181 SPECIFICATIONS FREQUENCY RESPONSE 200 to 15 000 cps SOUND PRESSURE LEVEL 112 db at 4 with 25 watts input between 2 kc and 4 kc EIA PRESSURE RATING 49 db POWER HANDLING CAPACITY PROGRAM 25 watts PEAK 50 watts NOMINAL IMPEDANCE 8 ohms DISPERSION 60 vertical 160 horizontal line radiator mounted with long dimension vertical MOUNTING Universal bracket SIZE 49 x 7 1 2 x 13 WEIGHT NET 26 pounds SHIPPING 30 pounds PLACEMENT To make bestuse of the unique polar characteristics of the LR4A the unit should be mounted with its long axis vertical The broad horizontal projection pattern thus aids in covering large audiences while the limited vertical dispersion makes possible projectio
2. e 30 inch brackets to the cabinet The speaker may then be mounted on a wall ledge or arch or suspended by a wire from the ceiling as necessary NOTE The curved back panel of the model LR4A is constructed of 1 4 hardboard It is recom mended that all mounting screws or bolts be used at the top bottom or sides of the cabinet as these are constructed of 1 2 plywood WIRING Connection is made to the LR4A at the terminal strip on the top of the unit Nominal impedance is eight ohms and the eight ohm amplifier output should be employed When the LR4A is used in 70 7 volt line systems the matching transformer suchas the E V TR30 or TM30 is installed under the metal coverplate supplied providing a depend able attractive transformer mounting Figure 1 Dimensions Lad See NOTES Bestresults from any voice reinforcement system will be obtained if a quality microphone is used Normally a unidirectional type is preferred since the directional characteristics of such a micro phone complement those of the LR4A further re ducing the possibility of feedback Microphones which have proved highly successful invoice re inforcement applications are the E V 666 676 and 664 cardioid types and the 642 and 644 Cardi line units A problem commonly encountered in large rooms is excessive low frequency reverberation often the cause of muddy reproduction andfeedback The limited vertical dispersion of the LR4A greatl
3. n over long distances without unwanted reflections from floor and ceiling In addition when mounted above the system microphone the LR4A is capable of outstanding coverage without the troublesome acoustic feedback which almost always accompanies less sophisticated reproducers Since most of the LR4A s output is projected for ward and comparatively little is allowed to come from the ends a microphone placed under the LR4A will receive much less direct sound than if similarily placed with respect to other loudspeakers thereby greatly reducing or eliminating feedback In a typical theater installation for example one or more LR4A s may be mounted at the center of the proscenium and microphones may then be placed in the footlights or elsewhere in the stage area as needed with a minimum of feedback When mounted high as in a proscenium the LR4A will be found to cover even very long audiences with minimum front to back loudness change The 60 vertical dispersion may even provide balcony coverage in many instances without the need for additional speakers INSTALLATION The LR4A canbe easily installed using the universal brackets supplied These brackets may be formed to accomodate any mounting location Ilustrated below are several ofthe many possible methods of LR4A LINE RADIATOR LOUDSPEAKER YaMVadSaGNO YOLVIAGVY ANID Vr Part No 531033 mounting the LR4A The four lag screws supplied may be used to fasten the flexibl
4. persion with long axis vertical shall be 160 and vertical dispersion shall be 60 Sound pressure level at 4 feet on axis shall be 122 db when full rated power of 25 watts from 2 kce to4ke with 1 cps sweep is applied Nominal impedance shall be 8 ohms Weight shall be 26 pounds and mounting hardware shall be sup plied Provision shall be made for internal mounting of line matching transformer Electro Voice Model LR4A is specified Litho in U S A
5. y U S Patent No 3095084 E ELECTRO VOICE INC f Buchanan Michigan reduces reverberation In addition two of the above microphones Models 642 and 676 are equipped with integral low frequency attenuation filters to aidin eliminating unwanted low frequencies When the problem is severe however the E V Model 513 high pass filter is recommended This is an extremely sharp cutoff filter which is effective at 100 cps The 100 cps cutoff point is ideally suited to the elimination of troublesomelow frequencies yet vital mid frequency response is not altered The Model 513 may be inserted in any low im pedance microphone line and affects only micro phone response Use of the Model 513 can often turn a difficult or borderline system into a com plete success vertical dispersion 500 cps 1000 eps 3000 cps HOTT TTT PTT sa TTU ANAA LANI T PE E AE TTT E A T EE E E Eea RESPONSE IN OB y eing gE FREQUENCY IN CYCLES PER SECONO Figure 3 Frequency Response ARCHITECTS AND ENGINEERS SPECIFICATIONS The loudspeaker shall be of the curved line radiator type utilizing nine 3 x 5 and three 3 1 2 cone speakers in a concave array The speakers shall be enclosed in a wooden cabinet painted a neutral tan A metal grille shall be provided The over all size shall be 49 inches by 7 1 2 inches Fre quency response shall be uniform from 200 to 15 000 cps Horizontal dis

Electro-Voice LR4A User's Manual

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