. The Bell System technical journal . nce talking or a close talking transmitter isto be used, or whether the speeches are brought in over a telephoneline, and secondly, the size of the space in which the amplified sounds PUBLIC ADDRESS SYSTEMS 129 are to be delivered to the audience. It was found that four unitswould provide for all the conditions occurring in practise, two ofthese being speech input or transmitter amplifiers with different gainsand two being power amplifiers of different power ratings. Theseunits and other equipment used with the system, are made up inpanels, of uniform widt
. The Bell System technical journal . nce talking or a close talking transmitter isto be used, or whether the speeches are brought in over a telephoneline, and secondly, the size of the space in which the amplified sounds PUBLIC ADDRESS SYSTEMS 129 are to be delivered to the audience. It was found that four unitswould provide for all the conditions occurring in practise, two ofthese being speech input or transmitter amplifiers with different gainsand two being power amplifiers of different power ratings. Theseunits and other equipment used with the system, are made up inpanels, of uniform width, in order that the proper equipment for anyinstallation may be assembled on two vertical angle iron racks ar-ranged to be fastened to the control room floor. Speech Input Amplifier—First Type The first of the speech input amplifiers is shown schematically inthe upper part of Fig. 8. It is a three-stage amplifier. Two po- SPEECH INPUT AMPLIFIER For Distant Talking Transmitter To Medium or High c=r« «2L x-g ;Pt2? o^,,™,.™,,^^. To LongLines Connected for 350 V. Long LineTransmitter Receivin8 Control Panel 12V. 9Supply SPEECH INPUT AMPLIFIER To Medium orHigh For Close Speaker Transmitter High and Low Power Amplifier ~^Or Long Lines Receiving Gain Switch
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
