Making a Talking Machine 



A simple construction within the scope of the amateur 

 B\' Charles Horton 



THE talking machine herein described is 

 of the well-known so-called "hornless" 

 type in which the horn is of rectangular 

 cross-section instead of circular, and is con- 

 cealed within the base of the instrument. 



Details of the turntable and the location 

 of the electric motor for driving it 



Contrary to general opinion among experi- 

 menters the talking machine is a very simple 

 instrument and not difficult to make, pro- 

 vided the underlying principles are under- 

 stood and correctly applied. 



The chief difficulty, of course, is in making 

 the spring motor. 



Sound is understood as that disturbance 

 in the air body which is capable of causing 

 vibration of the ear drum with consequent 

 typical sensation. There are various kinds 

 of sounds, which may be roughly divided 

 into two classes — noises and musical sounds. 

 Noises are unsymmetrical groups of sound 

 waves. Musical sounds, on the other hand, 

 are symmetrical groups of sound waves. 

 A musical note is a group of sound waves 

 occurring in perfect rhythmical order. The 

 rapidity of \'ibration of any sound wave is 

 called the "pitch," and the quality due to 

 the overtones is called the "timber." 



The talking machine is a machine for 

 reproducing sounds from permanent me- 

 chanical records of original sounds. The 

 record is made by allowing the original 



sounds to impinge on a flexible diaphragm 

 the resultant movements of this diaphragm 

 being arranged to cause a needle point to 

 trace in a soft substance in motion a wavy 

 line characteristic of the impinging sounds. 

 The reproduction is accomplished by prac- 

 tically the reverse of this process and the 

 tones are amplified by allowing them to 

 pass through a resonant chamber. 



From the above it will be readily under- 

 stood why the phonograph is imperfect in 

 its reproduction ; for while it is easy enough 

 to record and reproduce the fundamental 

 notes, some of the complex overtones are of 

 very high pitch and also of very small 

 magnitude and are consequently lost, either 

 not being recorded at all, or not being 

 reproduced, or being lost in the reproducer 

 and resonant chamber. Furthermore, since 

 the pitch of a musical note determines the 

 note, even the slightest variation of the 

 speed of the record changes the pitch of the 

 music. Also the resonant chamber some- 

 times adds typical overtones to the music. 

 Thus the two principal problems to be 

 solved in making a talking machine are, 



FIG.2 



The top plan shows the tiomtable with 

 location of the arm and two needle tills 



first, to secure a good reproducer and, 

 second, to secure perfectly uniform speed 

 of the turntable. 



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