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ELECTRICAL IUS ICAL IN STRUIEN'I'

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~ Patented Apr; 24,

1,956,350

UNITED STATES PATENT > OFFICE" /

1,956,350 ‘ ’

ELECTRICAL MUSICAL INSTRUMENT Laurens Hammond, Chicago, Ill. ,

1934, Serial No. 707,280 I ‘ Application January 19,

74 Claims.

duced by synthesis of’ the fundamental tone with J various proportions of its harmonics. '

I am aware that various ‘attempts have been made in the past to produce an instrument of this '

but as‘ far as I have knowledge, none / of these attempts accomplish the desired result

10. because of

'~ will hereinafter be more fully discussed. 16 I It is a well known fact that any sustained mu *‘ sical soundcan be analyzed into sine wave‘com

plitude and various amplitudes of different har 20» monies of the fundamental. It has been found

' that in most musical tones the predominant har . monies are those of the lower frequencies, and that harmonics above the eighth have very little effect in characterizing the tone, especially in the middle‘ and upper registers of a higher order would lie above the range of audibility. . ~

Thus most musical tones ‘may be produced by de?nite combinations of\ the fundamental tone

30 with various proportions of» the ?rst eight har _ s ' monies} - I ‘ _

riihe instrument of my invention employs the tempered musical scale not only in the produc tion of the fundamentals but in the production of the various harmonics.v As a result any de sired chords may be played

= ble beats. _

‘ ‘It is thus the primary object of my invention A0 to provide an electrical instrument for the pro ‘ duetion of musical tones upon which any desired

‘musical composition may be played. Incident to

my

this broad object of my invention. are numerous . other objects, the attainment of which contrib

45 utes materially to the'achievement of the pri-—‘ mary object.‘ These objects appear more fully in the_accompanying speci?cation, and include the following: J - ~ _ .

(l) vTo provide an improved means for gen e'i) crating a plurality ‘of ‘currents of'di?’erent'fre

vquencies capable of being translated into musil ~cal sounds. ;. ‘ ' __

‘ l2) To provide. improved’ means for driving such generators at a constant speed. _ > A

515'. ('3) To provide improved circuits by which cup

where harmonics}

without causing audi- Y

(01.

rents from various or synthesized.

84-—1)

generators may be combined

(4) To provide improved means for eliminating the ing the

(5) To provide

noise produced upon completing and break the various circuits, sometimes referred to as' “key thump” or “key click" noise.

an improved electrical circuit

60

wherein a plurality of currents from dl?erent sources may be combined additively without ap preciable cancellation or subtraction.

(6) To provide an electrical circuit in which selected proportions of electrical energy derived from sources 0 bined. '

different frequencies may be com

I . (7) To provide selective means for changing ('70 the quality of the tones produced by the instru m'ent.

(8) To provide selective means for changing the drawn relative proportions of the electrical energy

from the generators of the fundamental 75 and the various harmonics thereof.

(9) To provide selective means for simulta- ~ neously determining the quality of all of the tones. produced upon depression of the keys of a manual.

(10) T0

of a plurality of preselected qualities. (11) To provide means for easily changing

said preselected qualities of tone. (12) To provide

rents produced by for

due (14) To provide

ing

means for adjusting the cur the generators to compensate

unavoidable defects in the means ultilized to _.translate the currents into sound.

(13) To provide ‘of generators of different frequencies which re

an arrangement of a plurality

to es inductive coupling between the generators. an improved means for driv

the generators at the different speeds re quired for the generation of the currents of dif ferent frequency. ' (15) To provide if Ll improved means for producing tremolo effects. ‘

(16) To provide improved methods of wirmg the duetors resi

(17) To provide whi

(18)‘ To provide ‘her

changing the quality of the tones produced by ‘playing upon the

instrument wherein a number of the con serve‘ as a means for introducing thigh

stances into the circuit.- '

an instrument of the type ch is relatively light in weight and is portable.

an instrument having a num of-‘key manuals with improved meansfor 105

100

different manuals. (19) To produce similar generators for a plu

rality of different frequencies-in which compen .- sati on may readily be made to cause the currents 11o

2 produced by the generators when translated into sound to be of equal volume.

(20) To provide a plurality of generators of currents of different frequencies in which a single' countershaft comprising a plurality of articulated sections is utilized for driving all of the gen erators. - l . '

(21) To provide a bank of generators for cur rents of different frequencies in a plurality of ?exibly connected units, eachunit including a plurality of generators of frequencies which are exact multiples of one another and each unit being shielded from the remaining units.

(22)To provide a plurality _of_' generators for producingcurrents of different frequencies, made up of av plurality of similar units 'in which the rotor shafts of successive units are staggered rela tive to one another so that the rotor shafts of adjacent units may have a bearing in common.

(23) To provide an improved resilient driving 6 connection between the synchronous motor and

25

40

60

the generators. (24) To provide an improved gearing arrange

,ment for driving the rotors of the generators at the required speed.

(25) To provide an instrument in which chords may be played and in which all of the electrical current of the same frequency. whether utilized in the various tones as fundamentals or as har~ monies is derived from a common source.

(26) To provide an instrument in which di minution of the output derived from a given gen erator is obtained by a method which decreases the impedance of the output circuit.

(2'7) To provide an instrument having a plu rality of keyboards in which there is a duplica tion of tone range and in which tones of dif ferent quality may be controlled by the different keyboards, in such manner that the depression of corresponding keys on two or more keyboards will result in a true combination of ‘the individual tones produced thereby, without substantial energy loss.

- (28) To provide an instrument having a plu rality of alternating current generators of differ ent frequency capable of generating relatively strong currents and by suitable resistances de creasing the actual currents utilized to a relatively small percentage of the possible output of the generators, combining the currents produced by various selected generators in predetermined relative proportions, and amplifying the com posite current and translating it into sound.

(29) To provide means for compensating for the differences in the energy of the currents pro duced by the generators of different frequencies. Other objects are the provision of an elec

trical musical instrument which may be eco nomically produced in large quantities, in which there is a relatively small number of parts, in which the various elements may be readily as sembled, and which will be durable.

Further objects will appear from the follow ing description, reference being had to the ac companying drawings, in which:

Fig. 1 is a plan view of the instrument; Fig. 2 is a horizontal sectional view showing

the pedal keyboard and swell pedal; Fig. 3 is a vertical cross-sectional view of the

upper and lower manuals and the generator as sembly; -

Fig. 4 is an enlarged vertical sectional view > of the assembly of the generators;

Figs. 5, 5a and 5b together constitute a plan viewof the assembly of generators and the syn

1,956,850 chronous motor for driving the same, various . parts thereof being shown in fragmentary sec tion better to illustrate details;

Fig. 6 is an enlarged vertical cross-sectional view of the synchronous motor and its driving connections; '

Fig. 7 is a vertical sectional view taken on the line '7—7 of Fig. 6; ,

Fig. 8 is a greatly enlarged vertical sectional view showing the mounting of the generator rotors; I .

Fig. 9 is a central vertical sectional view show ing the bearing construction for the countershaft

80

85

sections and the ?exible coupling connecting the ' countershaft sections;

Fig. 10 is a fragmentary sectional view taken on the line 10-10 of Fig. 8; . .

Fig. 11 is a right side elevation of the synchro nous motor, various parts associated therewith' being broken away to show detail, the view being taken substantially on the plane of line 11-—1l of Fig. 6; _ ' _

Fig. 12 is a vertical sectional view-of the syn

95

chronous motor taken on the line 1‘2-12- of ‘ Fig. 6;

Fig. 13 is a fragmentary plan view of a sec tion of multiple contact switches, parts thereof \ being shown in fragmentary section;

14 is a fragmentary vertical sectional view taken on, the line 14-14 of Fig. 13; ‘

Fig. 15 is a fragmentary sectional view illus trating the method by vwhich the switch con tact members are mounted;

Fig. 16 is ‘a fragmentary sectional view taken on the line 16--16 of Fig. 13, illustrating the means by which the switch actuator is connected to the switch contact members; '

Fig. 17 is a transverse sectional view taken on the line 17-17 of Fig. 13; _

Fig. 18 is a vertical sectional view of the timbre selector mechanism;_

Fig. 19 is a sectional ~view taken on the line 19-19 of Fig. l8;' ~

Fig. 20 is a vertical sectional view of the pedal keyboard taken on the line 20--20 of Fig. 2; ’

Fig. 21 is a plan view of a portion of the pedal keyboard with the pedals removed;

Fig. 22 is a vertical sectional view of the swell pedal and associated mechanism taken on the line 22-22 of Fig. 23; . > “

Fig. 23 is a vertical sectional view of the swell pedal mechanism taken on'the line 23-28 of Fig. 22; '

Fig. 24 is a vertical sectional view of the stop 'key operated pre-set combination selector;

Fig. 25 is a fragmentary plan view of the mechanism shown in Fig. 24,- various parts be- ing broken away to show the details of con struction; - '

Fig. 26 is a vertical sectional view of the in strument taken just inside the right-hand side wall and showing the general arrangement of

v the mechanism ;

Figs. 27' and 27a, together ‘constitute a sche matic wiring diagTBJn of the instrument; and

Figs. 28 and 28a constitute a chart usable in conjunction with the wiring diagram to indicate the connections not shown in the diagram and setting forth the numbers of teeth, etc., in the various gearing utilized to drive-the generators.

General description

The‘ detailed description of the instrument of my invention will, I believe, be more readily un derstood if it’ is read with a previous general

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