172 BELL SYSTEM TECHNICAL JOURNAL 



practically eliminated and hence there is an even greater reduction 

 from the maximum impedance which occurred in the earlier reproducer 

 at resonance. Both needles and records have a relatively long life 

 with the later type pickup, which has been in commercial use for 

 some months. As is seen, the higher frequencies are reproduced in 

 considerably better fashion. A third curve is given in Fig. 12. This 

 was obtained with a more recent experimental model in which a 

 further large reduction in the needle point impedance had been 

 effected and in which, in addition, a very much more rigid, though a 

 lighter structure served to connect the needle point with the armature. 

 This model shows further reduction in wear and tear on the record 

 and very greatly improved reproduction at the high frequency end 

 of the scale. 



The application of the processes of sound recording on "wax" to 

 the synchronized film has involved meeting a number of conditions 

 not previously encountered in the phonograph field. One of the 

 most important of these relates to editing, cutting and rearranging 

 of the picture. Various methods have long been used to copy or 

 "dub" a disc record. The prime requirement is that there be no 

 sacrifice in quality. To attain this end records have sometimes 

 been copied at very low speed. This method appears unnecessarily 

 laborious and slow and the results obtained are not altogether satis- 

 factory in the light of possibilities presented by pickups and recorders 

 of the characteristics shown above. Rearrangement of material on 

 records is entirely practicable, portions may be deleted or new portions 

 added either as a whole or the new sounds added to those already on a 

 record — in fact any changes of this type may be made which can be 

 made in the picture. 



The detailed technique of "dubbing" appears to offer no serious 

 technical difficulties. The refinement reached and the extent of its 

 future use may be expected to be governed by the demand in the 

 synchronized motion picture field. 



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