314 



ARCHITECTURAL ACOUSTICS 



STUDIO 



ACOUSTICS OF STUDIO 



MICROPHONES 



AMPLIFIERS 

 MIXERS 



AMPLIFIER 



ATTENUATOR 



AMPLIFIER 



ISOLATING 

 AMPLIFIER 



TRANSMITTER 



EQUALIZER 



LIMITING 

 AMPLIFIER 



ATTENUATOR 

 AMPLIFIER 

 MODULATOR 

 OSCILLATOR 



MONITOR 



ACOUSTICS OF 

 MONITORING ROOM 



LOUD SPEAKER 



ATTENUATOR 

 EQUALIZER 



LINE 



ISOLATING 

 AMPLIFIER 

 REPEATER 

 ; TO TRANSMITTER 

 REPEATER 



REPEATER 

 ■ TO TRANSMITTER 



E. Radio Sound Reproducing System. — A complete radio broadcasting 

 and receiving system is shown in Fig. 12.21. The factors which influence the 

 collection of sound in a broadcasting studio have been discussed in Sec. 12.3. 

 The mixers and attenuators are used in the same manner as in the case of 



the sound motion picture sys- 

 tem. The monitoring system 

 and mixer console are located in 

 the control room. A sound- 

 proof glass wall partition which 

 separates the studio and control 

 room gives the engineer full 

 view of the action in the studio. 

 The output of the studio am- 

 plifier feeds the isolating ampli- 

 fiers and the monitoring system. 

 Isolating amplifiers feed the 

 wire lines to the various trans- 

 mitters. In the case of the 

 local transmitter, repeaters are 

 not needed and the output of 

 the isolating amplifier is fed 

 directly to the equalizer and 

 limiting amplifier. The equal- 

 izer compensates for the fre- 

 quency discrimination in the 

 line. The limiting amplifier is 

 of the compressor type in which 

 the peak volume levels are re- 

 duced. The limiting amplifier 

 is followed by an attenuator for 

 controlling the input to the 

 transmitter amplifier. The 

 amplifier is followed by the modulator and radio frequency oscillator. 

 The output of the oscillator feeds the antenna. The monitoring system 

 at the transmitter consists of a detector coupled to the output of the 

 transmitter and followed by an attenuator, amplifier and loud speaker. 



A very small portion of the radio frequency energy radiated by the trans- 

 mitter antenna is picked up by the receiving antenna. A typical super- 

 heterodyne receiver is shown in Fig. 12.21. The output of the antenna is 

 amplified in the radio frequency stages and combined with an intermediate 



HOME 



ACOUSTICS OF ROOM 

 LOUD SPEAKER 



AF AMPLIFIER 



ATTENUATOR 



2ND DETECTOR 



IF AMPLIFIER 



1ST DETECTOR 

 OSCILLATOR 

 RF AMPLIFIER 

 ANTENNA 



Fig. 12.21. 



Complete radio broadcasting and 

 receiving system. 



