500 BRIJ. SYSTFM TECHNICAL JOURNAL 



hiid been arranged in such a manner that the relative loudness of the 

 various parts had been balanced correctly, it was found that the whole 

 selection was either too loud or too weak. This usually meant a com- 

 plete rearrangement of the players. With the flexibility introduced by 

 the use of electrical apparatus including amplifiers, the control of loud- 

 ness is obtained by simple manipulation of the amplifier system and is 

 in no way related to the difficulties of the relative loudness of one in- 

 strument to another. The only problem for the studio director in this 

 case is to obtain the proper balance among the various musical instru- 

 ments and artists. The advantages derived from this added ease of 

 control are also made manifest in that it is much easier and less tire- 

 some for the artists and it is usually possible to make more records in a 

 given time. 



Mechanical Versus Electrical Reproducing 



Where the question of reproduction is concerned, the same two alter- 

 natives mentioned for recording present themselves, namely, direct use 

 of power derived from the record itself versus the use of electrome- 

 chanical equipment with an amplifier. In this case, however, the situa- 

 tion is a little different as the power which can be drawn directly from 

 the record is more than sufficient for home use. Since any method of 

 reproducing from mechanical records by electrical means involves the 

 use of a mechanical device for transforming from mechanical to elec- 

 trical power and a second such device for transforming from electrical 

 back to mechanical power, that is, sound, it is necessary to use two 

 mechanical systems, one at each end of an electrical system. Where 

 the power which can be supplied by the record, is sufficient to produce 

 the necessary sound intensity, as in the case of home use, it is in general 

 simpler to design one single mechanical transmission system than it is 

 to add the unnecessary complications of amplifiers, power supply and 

 associated circuits. In cases where music is to be reproduced in large 

 auditoriums, the power which can be drawn from the record may be 

 insufficient and some form of electric reproduction using amplifiers be- 

 comes necessary. 



Brief Description of Recording System 



The system used for recording consists of a condenser transmitter, a 

 high quality vacuum tube amplifier and an electromagnetic recorder. 

 Fig. 2 shows the calibration of the condenser transmitter and the asso- 

 ciated amplifiers. The condenser transmitter and amplifiers are so de- 

 signed that the current delivered to the recorder circuit is essentially 

 proportional to the sound pressure at the transmitter diaphragm. The 



