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Home My WebLink About8.2 ModifyChamberMicrophones , e e CITY OF DUBLIN AGENDA STATEMENT CITY COUNCIL MEETING DATE: May 22,1995 ~,...,{Modification of Council Chamber Microphones VJF ,Prepared by: Paul S. Rankin, Assistant City Manager) 1. /. Microphone "Window of Acceptance" 2. / Catalog Description of Proposed Lavaliere Microphone RECOMMENDATION,~~i;!t~: Authorize Staff to proceed with the modifications as outlined. SUBJECT EXHIBITS ATTACHED FINANCIAL STATEMENT: Estimated Cost For 11 New Microphones is $2,640. Estimated cost of manufacturing new connection and installation is $2,360. Funds are available in the current year Building Management Budget. DESCRIPTION As part of the annual Goals and Objectives, the City Council had requested that Staff evaluate potential modifications to the Council Chamber audio system. The intent was to provide a better amplification without requiring each speaker to look straight into their microphone. During deliberations it is not uncommon for the seated Staff positions or City Councilmembers to address individuals seated to their right or left. System Configuration The original system had the pyramid microphones mounted on the desk top and there was not a lighted mute switch. In 1990, the City contracted with Coast Business Communications, Inc. (CBC) to modify the system to raise the microphones and install the lighted mute switch. The current system is manufactured by Shure and is from their Automatic Microphone System (AMS) line of products. The AMS system is designed to solve problems typically encountered with a multiple microphone installation. All of the microphones are "direction-sensitive" and are designed to turn on only when they are addressed within a 120 degree window.(See Exhibit 1) When the system is operated in the automatic mode, and more than one microphone is used simultaneously, the gain level on the amplifier will automatically adjust. This feature helps to avoid feedback and other distortion. Proposed Changes Staff contacted the CBC who is familiar with this system as well as has experience with Council Chamber audio systems. The Contractor concurred with Staff. analysis that a "lavaliere" style microphone would be the best way to assure the speaker remained within the "Window of Acceptance". The curved layout of the Council Chamber dais, and the frequent occurrence where persons speak to individuals to the side, would make it difficult for any other style to improve the amplification. Attached as Exhibit 2 is a catalog description of the proposed microphone. This is still part of the Shure AMS line. Since the microphone would be worn by the speaker it should capture their voice without regard to the direction they are facing. In order to install the new microphones the Contractor has proposed to install an audio jack, which will automatically disengage the pedestal microphones when the "lavaliere" microphone is plugged in. The lighted mute button would continue to operate in the same manner as the current system. In addition to this work, Staff has requested that the Contractor tune the system and provide a brief on-site overview of the operation of the system for appropriate maintenance and City Staff. Staff has also requested an estimate to modify one of the wall mounted microphone jacks to an audio output jack. The purpose of this modification would be to allow Community Television a direct access point to the audio system. The exact mechanics of this change have not been fully detailed. However, Staff has discussed the conceptual operation with CTV and the Contractor and it appears that it is a feasible option. QW The purchase of the 11 new "lavaliere" microphones is estimated at $2,640. The manufacturing of the switches, installation, system tuning, and CTV modification is anticipated not to exceed $2,360. This results in a total project cost not to exceed $5,000. Staff has identified that funds are available in the Building Management Department Budget and the modifications could be completed prior to June 30, 1995. Staff would request City Council authorization to authorize Coast Business Communications, Inc. to proceed with the modifications as outlined in this report. ITEMNO.-8.Z COPIES TO: CITY CLERK FILE~ . e " '1 Ac..c.~pTAt.\c.. e. S\(.(TC. ~ Aff\S " . "\.\ . ~ ,.., - W:s::.N~O~ 0 . fI' \ e\'"o rho C'\.e.> , T ,\~e. ,." BASIC SETUP: THE MICROPHONES o @ AMS26 MICROPHONE f('o\ot,. @ WHAT TO DO ", 6. In general, place the talker within the front acceptance angla of the microphone. 7A. If the chairs are 3 feet or less from each other, use one microphone between eech pair of seats. 78. If chairs are more than 3 feet from each other, use one microphone per seat. 8. Remove any objects immediately behind the microphones that may reflect sound. \..ow ~C'ot.le. AMS22 MICROPHONE II "'f'V~d. LECTERN AMS24 MICROPHONE \.1 ~ OO$C."e.yr... HOW TO DO IT 6. Sound sources outside the shaded acceptance angle will not tum on the microphone. See diagrams 6A through 60. 7 A. Place each.microphona a foot and a half from the table edge, halMay between the two seats, 78. Place each microphone a foot and a half from the table edge, directly in front of the talker 8. The grille of en AMS26 [probe) or AMS24 [gooseneck] microphone should be at least 8 inches above any table- top. [The A26X Extension Tube inserted between the swivel adf,lpter and desk stand will raise the AMS26 en additional 3".) Remove objects behind AMS22 micro- phones. . EXHIBIT 1- r't"IUI\l1;: .;II cU til:lb-f:jl:lUU . L!\tJU: ~"lI..JHrIVIlL.HU I.- e; ;~~P~ONE~;~~D ~~~~~~~; ~~~~ONENTS . I 1 .. I - ~_ rr ~lU.rll JUJfl I .,~/..J(~~'" ~~t"'V*lI~. MODEL AMS28 11II1 JIILlH.11l1f U_111l,,"~ I I:!... ... .b.....LL I 'hllll1Il1f r. I IIIIIlIIlI JI''1l' [ IvqV ~ I LAVALlEA MICROPHONE FOR SHURE AUiOMATIC MICROPHONE SYSTEM rhe Model AMS28 Condenser Microphone Is design. ed for use only with the Shure Automatic Mlorophone System (AMS). a unique and highly efficient method of turning microphones on only when and If they are need. ed. When used with Shure AMS mixers such as th~~ AM$4000 and AMSaOOO, this microphone provides ex. cellent performance, versatility and ease of use In multi. microphone Installations such as oonferenoe tooms, legislatures, churohes, courtrooms, broadcast studios, and panel discussions. The AMS28 Is a lavaller unit. designed for chest.worn operation, and supplied With a matching lavaller assembly. Unlike conventional microphones, the AMS26 con talns electronic: circuitry and a novel transducer con. figuration to make It compatible with Shure AMS mix. ers. Note that the AMS28 should not be conneoted to standard phantom- (simplex.) or non-phantom.powefsd microphone Inputs; It will not function properlY. AMS microphones, In conjunction with the lifJ!:Icial circuitry in the AM$ mIxers, uniquely discriminate be- tween desired sounds that originate within their 120" front acceptance angle and all other sounds. Sounds from the front of a microphone are detected and caU$O It to be gated on. transmitting 115 signal to the mixer Oul. put. Sounds outside the acceptance angle will not galu . the microphone on, When an AMS28 Is gated on. it operates like a unidirectional (cardioid) microphone, Each AMS microphone operates completely ill. dependently In analyzing Its own sound field and deoldlng whether or not a sound source Is within the front acceptance angle. The microphone connector Is a standard tlHue-pin professional audio type (XLR). Under most clr. cumstances, lengths of 150 meters (500 ft) Ot more of gOOd.quallty two.conduotor shielded microphone cable oan be used as an extension between AMS microphones and AMS mixer Inputs. Note that the same conductor must be wired to the same numbered. pin at both endS of the cable to enSll(e proper functioning of Copy"Ut,1 1985. !IhU'tl BrOlhe's Inc. 27A 19141EI) :2e-d ~H I I'JI...IO~ 8831'-.1 I 8na: the units. The shield must be connected to pin 1 at both ends of the cable. Good practice dictates that microphone and extension oables be grounded only to Itle AMS mIxer chassis. Features . Microphone only turns on for weare('s speech and nol for other talkers . Low vibration and hum sensitivity . Unidirectional design minImizes background noise . Wide frequency response, especially tailored for voice clarity . A(:oustlcally optimized for lavalier operation . Extremely flexible long.llfe cable . l.ow handling and clothing noise INSTAllATION The lavaller assembly provided with the AMS28 Is llesigned to keep the microphone fl(mly In plaoe durIng use. The microphone, clip a.nd cord can be engaged ad. jU$ted and removed quickly and easily. I WII!) the AM$2S held by the rubber ring ot the lavaller f:l$s(~mbly, place the lavaller oord around the user's neck and secure the free end of the oord In the slot at the side of the assembly (see Figure 1). Fasten the clip to the \J5~r's shirt or blouse, and pull the oord through the slot until the stack Is taken up. If desired. the ollp can be rotated for left or right fastening, or It can be removed by turning It to the vertical position and pulling straight out. Adjust the cord length so that the AMS28 Is 200 to 250 mm (8 to 10 In.) belOW the user's mouth. IMPOR. TANT: For proper operation, the AMS28 must be at least 76 mm (3 In,) from any solid surface (table top or Eldge). ro rfllTlQve thE!! microphone, first disengage the clip. With the microphone In one hand, pull the end of ihe cord with the other hand to remove It from the lavaller (l:,;sernbly slot; a qulok. steady movement will release It Elasily. ,/\ LAVALIER ASSEMBLY FIGU RE 1 Print/ill In U.S.A [ ~ \-\ i: ~:J:T S-IV~14'4eO'442 6. e":-'2;-''f-.--a3 1"1 ~ 6. - ~3 l _.-::;::I;"W J..8~O~