us2089171 beauchamp electrical stringed musical instrument 1937

8/18/2019 US2089171 Beauchamp Electrical Stringed Musical Instrument 1937

1/8

A l l g - 1 0 , 1 9 3 7 ~ G .D .BEAUCHAMP 2 , 0 8 9 , 1 7 1ELECTRICALSTRINGEDMUSICALINSTRUMENT

ì Filed June 2, 1934 ’ 5 Sheets Sheet l

44

/ 4

4 . 4 , .f f , /l l / / f / l /


2/8

2 , 0 8 9 , 1 7 1ug. 1 0 , 1 9 3 7 . G . D . BEAUCHAMPELECTRICALSTRTNGEDMusïcAL INSTRUMENT

3 Sheets-Sheet 2i led June 2 , 1934

N


3/8

2 , 0 8 9 , 1 7 1ug. 1 0 , 1 9 3 7 . G . D .BEAUCHAMPELECTRICAL STRINGEDMUSICALINSTRUMENT

s s h e e t s - s h e e t 5i led June 2 , 1934

l y l 9


4/8

P a t e n t e dA u g . 1 o ,1 9 3 7

U N I T E DS T AT E S

2 , 0 8 9 , 1 7 1

P AT E N TO F F I C EELECTRICAL STRINGED MUSICAL

INSTRUMENTGeorge D. Beauchamp. Los A n g e l e s , l C a l i f . , a s l -'

s i g n o r t o E l e c t r o S t r i n g I n s t r u m e n t C o r p o r at i o n , L o s A n g e l e s ;C a l i f . ,a c o r p o r a t i o no f C a li f o r n i a

A p p l i c a t i o nJ u n e z , 1 9 3 4 , s e r i a l » 1 0 , 1 2 8 , 7 1 1

2 1 C l a i m s .T h i s i n v e n t i o n r e l a t e s t o m u s i c a l i n s t r u m e n t s

and i t i s a general o b j e c t o f the invention top r o v i d e a s i m p l e , p r a c t i c al and improved e l e ct r i c a ls t r i n g e d mu s i c a l 'i n s t r u m e n t .

5 I h i sa p p l i c a t i o n f o r L e t t e r s Patent i s a cont i n u a t i o n i n p a r t o f my a p p l i c a t i o n e n t i t l e dE l e c t r i c a l - s t r i n g e d m u s i c a li n s t r u m e n t ,S e r i a l N o .6 1 5 , 9 9 5 , ñled June 8 , 1 9 3 2 .

An . o b j e c t o f t h i s i n v e n t i o n i s t o p r o v i d e al 0 musical instrument i n which the v i b r a t i o n s o f

t h e sound producing e l e m e n t s o r s t r i n g s d i r ec t l yvary the r e l u c t a n c e o f a magnetic c i r c u i t t o i nduce an e l e c t r i c current i n a c o i l within the magn e t i c n e l d , which c u r r e n t i s s u i t a b l y a m p l i i l e d

l 5 yand t ransformed into sounds as true reproduct i o n s o i . 't h e sounds produced by t h e v i b r a t i o n so f t h e s t r i n g s . In t h e p r e s e n t i n v e n t i o n t h e t r u esound o f t h e v i b r a t o r y s t r i n g w i t h a l l i t s c h a r .a c t e r i s t i c s i s a c c u r a t e l y r e p r o d u c e dw i t h o u t t h e

2 0 e x t r a n e o u s sounds and v i b r a t i o n s produced byinstruments or devices in which a mechanicalp a r t i s made t o v i b r a t e through i t s mechanicala s s o c i a t i o n w i t h t h e v i b r a t o r y s t r i n g .

Another o b j e c t o f the i n v e n t i o n i s t o p r o v i d e2 ; , an e l e c t r i c a l musical instrument o f the character

mentioned i n c l u d i n ga n o v e l , s i m p l i f i e d and part i c u l a r l y e f f e c t i v e e l e c t r o - m a g n e t i cp i c k - u p u n i tf o r c o n v e r t i n g t h e v i b r a t i o n s o f t h e s t r i n g s ' i n t oan e l e c t r i c current having t h e c h a r a c te r i s t i c s o f

30 the string vibrations; , , fAnother o b j e c t o f t h e ‘i n v e n t i o n i s _ t op r o v i d ean e l e c t r i c a l m u s i c a l i n s t r u m e n t o i t h e charact e r mentioned i n c l u d i n g a s i n g l e e l e c t r o - m a gn e t i c p i c k - u p u n i t f o r transforming t h e v i b r a

3 5 t i o n s o f the s e v e r a l s t r i n g s ' o f the instrument i n t oan e l e c t r i c c u r r e n t . I n t h e d e v i c e x o f t h e p r e sent invention the v i b r a t i o n s of each of the sev

_ e r a l strings a f f e c t or v a r y the reluctance o i . ' themagnetic c i r c u i t o f a s i n g l e permanent magnet

4o unit to induce an e l e c t r i c current in a c o i l superf i m p o s e d o n the magnet , and the single unit i s not

s u b j e c t t o t h e v a r i a t i o n s ne c e s s a r i l y inherent i nd e v i c e s i n v o l v i n g a p l u r a l i t y o f e l e c t r o - m a g n e t i c

4 5 Another o b j e c t o f the i n v e n t i o n i s t o providean e l e c t r i c a l musical instrument that does notdepend upon a sound board, resonance box, or thel i l r e i nt h e p r o d u c t i o no r p r o p a g a t i o no f t h e soundo f t h e` \ d e s i r e d q u a l i t y , whereby the b o d y o f t h e

50~instrument may be.of s i m p l e , ' i n e x p en s i v econstruction ` .

Another . o b j e c t o f t h e i n v e n t i o n i s t o yp r o v i d ea musical instrument o f the character mentionedh a v i n g t e n s i o n e d l v i b r a t o r y s t r i n g s o f d i f f e r e n t

5 5 d i a m e t e r s and i n c l u d i n g a j s i n g l e e l e c t r o - m a g

f

( C _ l .84-1) . .n e t i c p i c k - u p u n i t c o n s t r u c t e d and d e s i g n e d t od e l i v e r an e l e c t r i c current t o a n a m p l i f i e r which_ c u r r e n t i s p r o p e r l y ‘ a n dt r u l y c h a r a c t e r i s t i c c i t h evibrations o i the s e v e r a l s t r i n g s . „

_ A n o t h e ro b j e c t o f t h e i n v e n t i o n i s t o p r o v i d ean e l e c t r i c a l s t r i n g e d musical instrument thati s adapted t o b e p l a y e d manually i n any t y p i c a lo r d e s i r e d manner and e l e c t r i c a l l y reproduce thesound or music at a remote p o i n t .

Another o b j e c t o f t h e i n v e n t i o n i s t o p r o v i d ean e l e c t r i c a l musical‘ instrumentvoi the charact e r mentioned t h a t may e e a s i l y and convenientl y a d j u s t e d b y t h e v m u s i c i a n ' o r p l a y e r t ov a r y t h evolume o f t h e music o r sound p r o d u c e d .

A n o t h e r o b j e c t o i t h e i n v e n t i o n i s t o p r o v i d ean improved e l e c t r o - m a g n e t i c p i c k u p u n i t ' c ap a b l e o f embodiment i n s t r i n g e d m u s i c a l i n s t r ume'nts o f various characters with l i t t l e or nomodiilcation .

A u r t h e r o b j e c t o f t h e i n v e n t i o n i s t o p r o v i d ean e l e c t r i c a l s t r i n g e d musical instrument o f thec h a r a c t e r ' m e n t i o n e dt h a t i s s m a l l and compact

Other o b j e c t s and f e a t u r e s o f t h e i n v e n t i o n w i l lb e b e t t e r and more f u l l y understood f rom t h ef o l l o w i n g d e t a i l e d d e s c r i p t i o n o f t y p i c a l formsa n d a p p l i c a t i o n s o ft h e i n v e n t i o n , t h r o u g h o u twhich d e s c r i p t i o n r e f e r e n c e may be h a d t o theaccompanying d r a w i n g s , i n w h i c h :

F i g . 1 i s / a top or plan view o f one t y p i c a lembodiment o f t h e p r e s e n t i n v e n t i o n . F i g . 2i s an e n l a r g e d , t r a n s v e r s e , d e t ai l e ds e c t i o n a l viewo f the p i c k u p r u n i t and b o d y taken a s i n d i c a t edb y l i n e 2 2 on F i g . 1 . F i g . 3 i s a n e n l a r g e ' dp l a n e l e v a t i o n o f t h e main p o r t i o n o f the bodywith the magnets i n c r o s s - s e c t i o n , being a viewtaken a s i n d i c a t e d b y l i n e 3--3 on F i g . 2 . ` F i g . 4i s a transverse detailed sectional view taken asi n d i c a t e d b y V l i n e4 4 on F i g . 3 . F i g . 51s an e n _l a r g e d f r a g m e n t a r ỳ d e t a i l e d s e c t i o n a l v i e w t a k e na s indicated b y l i n e 5 5 o n F i g . 1 .a fragmentary d e t a i l e d s e c t i o n a l view o f the b o d yshowing t h e s o c k e t and i l l u s t r a t i n g the p l u g i np o s i t i o n t o e n t e r the s o c k e t . F i g . ‘ 7 i s a W i r i n gdiagram o f the c i r c u i t i n v o l v e d i n the p r e s e n ti n v e n t i o n . F i g . 3 y i s -an e l e v a t i o n view o f thep r e s e n t i n v e n t i o n embodied i n a . s t r i n g e d music a l instrument having a wooden body. F i g . 9 i sa diagrammat ic view i l l u s t r a t i n g the non-unifo rm magnetic i i e l d s o f the p i c k up u n i t andF i g . l 0 i s an enlarged fragmentary diagrammaticView i l l u s t r a t i n g a . p o r t i o n o f one p o l e portion

F i g . 6 i s

2 0

25

30

35

40

45

5 0

of the magnet and a port ion of one core membertwith a s t r i n g p a s s i n g through t h e i l e l d providedt h e r e b y. 5 5


5/8

> 3 0

2

I h ei n s t r u m e n t p r o v i d e d by t h e p r e s e n t i nv e n t i o n i n c l u d e s , g e n e r a l l y , a . body I I l , a p l u r a l i t yo f sound propagating elements or tensloneds t r i n g s I I o n the b o d y I 0 , an e l e c t r i c magneticpickup u n i t I 2 o n the b o d y I 0 f o r t ransformingv i b r a t i o n s o f the s t r i n g s I l i n t o an induced e l e ct r i c c u r r e n t , and an amplifying unit o r system I 3f o r amplifying t h e ` pulsations in s a i d currentand convert ing them into sounds which are the

1 0 t r u e sounds o f the s t r i n g s I I .The body I l )may e v a r i e d c o n s i d e r a b l yi n s i z e .

shape and c o n s t r u c t i o n , and may b e constructedo f v a r i o u s materials without departing f rom thes p i r i t o f the i n v e n t i o n . In the l p a r t i c u l a r fo rm

l 5 o f the invention in F i g s . 1 t o 7 i n c l u s i v e , o f thed r a w i n g s ,t h e b o d y I I Ii s a s i m p l e i n t eg r a l c a s t i n gof metal, such as aluminum or the l i k e , andcompri ses a major or main portion I 4 and a neck

. I 5 . The main portion I l of the b o d y i s sub2 0 s t a n t i a l l y d i s c shaped, having f l a t upper and

C l

lower sides and a curved or cylindrical periphery. ‘

The neckI 5

p r o j e c t s r a d i a l l y with r e s p e c t t o thec e n t e r _ o f the p o r t i o n I 4 and i s o f g r a d u a l l ydiminishing c r o s s - s e c t i o n . The neck I 5 has a

with spaced f r e t s I 1 . The-underside o f the neckI 5 may b e convex or rounded as illustrated inF i g . 4 . The b o d y I I ) may b e h o l l o w - a sshown i nthe drawings t o b e l i g h t i n weight, i t being un-d e r s t o o d that i n some i n s t a n c e s i t may be des i r a b l e t o make the b o d y I 0 s o l i d . ` -

The s t r i n g s I I a r e the sound v i b r a t i o n producing elements o f the instrument and are adaptedl t obe manually p l u c k e d o r o t h e r w i s e manipulatedt o produce the d e s i r e d v i b r a t i o n s . The s t r i n g sI l extend d i a m e t r i c a l l y a c r o s s the top o i thebody p o r t i o n I l and o v e r the f i n g e r b o a r d I B t ot h e o u t e r end o f the n e c k . In t h e ‘ p a r t i c u l a r i nstrument i l l u s t r a t e d t h e r e a r e s i x spaced s t r i n g sI l i n a s u b s t a n t i a l l y p a r a l l e l s e r i e s . The p l u r a li t y o f s t r i n g s I I p r e f e r a b l y l i e i n t h e same p l a n e ,that i s , t h e i r c e n t r a l longitudinal axes are i nor adjacent a common plane. ' I ' h e s t r i n g s I Ipass over a bridge I 8 o n the main portion I lo f the b o d y and over a s i m i l a r bridge I 9 o n theo u t e r p o r t i o n o f the neck I 5 . The inner endso f the s t r i n g s are s u i t a b l e secured i n openings

40

45

20 adjacent the » b r i d g e I 8 and the s t r i n g s havet h e i r o u t e r ends engaged b y s e c u r i n g and t e ns i o n i n g k e y s 2 I . The p o r t i o n s o f t h e s t r i n g s I Iextending between the b r i d g e s I 8 and I a r eunder various degrees o f t e n s i l e s t r a i n and are

f r e e t o v i b r a t e i n the production o f recognizedmusical t o n e s . I t i s t o be noted that the oppo5 5 s i t e ends o f the s t r i n g s I I are r i g i d l y and u n

y l e l d i n g l y connected t o t h e r i g i d metallicbodyI l s o that t h e i r major p o r t i o n s may have longp e r i o d s o f v i b r a t i o n with no dampening a c t i o ndue t o t h e a b s o r p t i o no f t h e v i b r a t i o n s b y wooden

6 0 b o d y parts or the l i k e a t the ends of the s t r i n g s .In accordance with the usual p r a c t i c e i n i n

` struments o f the c l a s s i l l u s t r a t e d the strings I Iare graduated i n diameter. The s t r i n g s I I areformed wholly o r i n part o f conducting material

6 5 or magnetic material having a d i f f e r e n t degreeo f magneticpermeability than t h e surrounding

50

air to proper ly influence o r an'ect the reluctanceo f the magnetic f i e l d i n the u n i t I 2 .

, T h e pick-up unit I 2 i s a magnetic o r e l e c t r o7 0 magnetic d e v i c e f o r converting the a c t u a l tone

producing v i b r a t i o n s o f the s t r i n g s I I i n t o ani n d u c e d e l e c t r i c c u r r e n t . The f r e q u e n c i e s andt h e o t h e r c h a r a c t e r i s t i c s ' o f t h e v i b r a t i o n s o f thes t r i n g s I I which maybe termed t h e p h y s i c a l

7 5p r o p e r t i e s o r t h e s o u n d p r o d u c e db y t h e s t r i n g s

f i a t upper s i d e forming a fingerboard I B p r o v i d e d A

2 , 0 8 9 ,17 .

are represented in the e l e c t r i c al c i r c u i t i n a proportional or d e i i n i t e manner with r e l a t i o n t o thea c t u a l p h y s i c a l v i b r a t i o n s o f the s t r i n g s s o t h a tthe amplifying unit I 3 i s actuated b y o r i n f l uenced b y the p h y s i c a l p r o p e r t i e s o f the sound t of a i t h f u l l y and a c c u r a t e l y r e p r o du c e 't h e s o u n d .The pick-up u n i t I 2 comprises a magnet which,in practice, may b e a of l i k e opposed permanent magne t s 2 2 . The magne t s are U-shaped oro f horse-shoe design and are attached t o a supp o r t i n g p l a t e 2 3 . T ' h e opposed lower o r i n n e rarms A f the magnets 2 2 have t h e i r lower s i d e sresting on the plate 23 and the a rms A are a ttached t o the p l a t e b y s u i t a b l e screws 2 4 . Inaccordance with the invention the ends o f themagnets 2 2 are in opposed r e l a t i o n with t h e i rp o l e s north t o nor th and south t o s o u t h , yas i n d icated in the drawings. This provides a continuous p o l a r i t y a t the o p p o s i t e s i d e s o f the magneto r magne t u n i t . In the ‘ p r e f e r r e d constructionthe confronting or oppo sed ends o f the magnets 2 2are in spaced relation. - '

An opening 2 5 i s provi ded in the top o r uppers i d e o f the body p o r t i o n I l t o r e c e i v e the pickupu n i t I 2 . The p l a t e 2 3 carrying the magnets 2 2i s i n s e r t e d i n the opening 25 and studs or b o l t s2 6 p r o j e c t upwardly from t h e o p p o s i t e ends o fthe p l a t e t o extend through openings i n p l a t e s21 o n the body. The p l a t e s 2 1 may carry s l e e v e s2 8 f o r r e c e i v i n g the b o l t s 2 i . I t i s p r e f e r r e d t omountor support the unit I 2 so that i t may b eadjusted and a c c u r a t e l y s e t with r e l a t i o n t o thes t r i n g s I I . Nuts 29 are threaded o n the outerends o f the b o l t s 26 and bear against the outers i d e s o f the p l a t e s 2 1 . The nuts 2 5 may be t i g h tened down t o adjust or s h i f t _ t h e unit l 2 out~

wardly. Springs I I I surround the b o l t s 2 E and a r earranged under compression between t h e p l a t e2 3 and the p l a t es 2 1 t o normally urge the u n i tinwardly and hold i t a g a i n s t movement.

Wi t h the unit I 2 mounted or supported a s ~ j u s tdescribed the pair - o f opposed -magnets 2 2 a r ed i s p o s e d t r a n s v e r s e l y o f the s e r i e s o f s t r i n g s I Iand their upper o r outer arms B r e spaced abov ethe top s u r f a c e o f the b o d y . ' The s t r i n g s I l passunder the mag net a rms B with considerable c l e a ra n c e . A ' T h e s t r i n g s I l pass through the magneticf i e l d o f the magnets 2 2 . The outer a rms B o f

10

20

25

30

40

the magne t s may e s l i g h t l y inclined t oward their `opposing ends t o compensate f o r the widenedmagnetic f i e l d a t t h e i r p o l e s or e n d s . The abovedescribed i n c l i n a t i o n of the magnetic a r m s B ssuch that the spaces between the a rms and t r i n g svary s u b s t a n t i a l l y - i n p r o p o r t i o n t o t h e i n t e n s i t yo f th magnetism o f s a id arms. _ l

The pickup u n i t I 2 i n c l u d e s a c o i l C arrangedo n or superimposed o n the permanent magnet .The c o i l C s supported o n the inner a r m s A ofthe pair o f magnets 2 2 and i s t o r e c e i v e an i nd u c e d , e l e c t r i c c u r r e n t when the r e l u c t a n c e o f

Y the f i e l d of the magnet or magnet unit i s varied.The o i l C includes a c o i l f o r m or spool 3 i havingspaced upper and lower f l a n g e s 3 2 . A winding3 3 o f s u i t a b l e enameled w i r e i s provided o n thes p o o l ) I between the f l a n g e s 3 2 . The s p o o l 3 |i s fo rmed o f a s u i t a b l e i n s u l a t i n g m a t er i a l . Thenumber o f turns I n the winding 2 3 and the gaugeo f the wire o f the c o i l depends upon the p a r t i cu l a r amplifying u n i t I 3 with which the i n s t r ument i s t o be u s e d . In accordance with the i nvention the c o i l C i s p o s i t i o n e d between thenorth and south p o l e s o f the magnet and i sr e l a t e d to the s t r i n g s I I . t o be i n f l u e n c e d o r a ff e c t e d by t h e i r v i b r a t i o n i n t h e ' m a g n e t i c f i e l d .

50

55

65

7 0


6/8

2 5 0 8 9 ,1 7lThe o u t e r s i d e o f t h e s p o o l 3 I i s spaced below t h eser ies o f s t r i n g s Il. _ „

' I ' h e invention includes a p l u r a l i t y of core memb e r s 3 5 f o r c o n c e n t r a t i n g t h e magnetic f o r c e o fthe magnet i n non-uniform f i e l d s l i n k e d withthe c o i l . ` The members 35 may e in the f o r m ofp l a t e s . However, i t has been found p r a c t i c a l t omake the members 35 in the f o r m of posts or pi ns

1 5

25

30

3 5

as i l l u s t r a t e d throughout the drawings. Thelower ends o f the pins r e s t o n or engage the lowerarms A f the magnetswhile the upper ends o ft h e p i n s p r o j e c t from t h e s p o o l 3 I . I h eupperends o f the c o r e pins 3 5 are spaced d i r e c t l y belowt h e s t r i n g s I I a s c l e a r l y i l l u s t r a t e d i n F i g s . 2 and3 o f the d r a w i n g s . In o r d e r t o p r o p e r l y compens a t e f o r d i f f e r e n c e s i n the extent o r degree o fv a r i a t i o n o f the magnetic r e l u c t a n c e i n thespaces between the outer ends o f the members 3 5and the adjacent arms o f the magnet due t o _ t h ed i f f e r e n c e s i n t h e diameter o f t h e s t r i n g s I I ,the spaces between the upper ends o f the - p i n s3 5 and the s t r i n g s I I a r e graduated s u b s t a n t i a l l yi n proportion t o the graduation i n the diameterof the strings. ~

To e l i m i n a t e t h e n e c e s s i t y o f ag round l e a df r o m the c o i l C one or both o f the end pins 3 5p r o j e c t f rom t h e s u r f a c e o f t h e s p o o l 3 I and a r ev e n g a g e dby t h e i n n e r w i n d i n g s 3 3 which havethe enamel removed therefrom t o e l e c t r i c a l l y cont a c t o r connect with the p i n s . -The p i n s 3 5 thuse l e c t r i c a l l y connected with the i n n e r winding o rwindings o f t h e c o i l Care grounded t o t h e bodyI 0 through t h e magnet arms A , t h e p l a t e 2 3 ,b o l t s 2 5 and p l a t e s 2 1 . By t h u s grounding t h ec o i lw i n d i n g t o t h e body t h r o u g h t h e magnetsthe sounds or n o i s e s that are c h a r a c t e r i s t i c s o _ fthe o i l and magnets are eliminated or avoided. I t ,i s believed that i t w i l l b e apparent how the nuts <

v 2 9 may b e employed t o s e t o r p o s i t i o n t h e u n i t

4 5 .

50

55

60

65

7 5

where the pins 3 5 are related t o the s t r i n g s I I t o ,p r o v i d e f o r t h e d e s i r e d o p e r a t i o n o f t h e pickupu n i t I 2 . The p i n s 3 5 i n extendinginto the c o i l Co p e r a t e t o c o n c e n t r a t e t h e magnetic f o r c e . i nspaced zones or f i e l d s i n the spaces between t h e i ro u t e r ends and the adjacent a rms o f the magnetand carry the magnetic f o r c e i n t o the center o f` t h e f i e l d o f t h e c o i l . The s t r i n g s p a s s i n g between t h e ends o f t h e p i n s 3 5 and t h e l magneta r m s B vary the reluctance o f the magnetic f i e l dwhen vibrated and thus induce a n e l e c t r i c current in the c o i l C. ~

The c o i l C s e l e c t r i c a l l y connected t o a s u i t a b l ea m p l i f i e r and s p e a k e r u n i t I 3 whereby t h e v a r i at i o n s i n t h e r e l u c t a n c e o f t h e magnetic c i r c u i t

imposed o n the c o i l are converted i n t o sound. The.sound thus produced i s a true reproduction o fthe sounds o r t o n e s produced b y the _ s t r i n g s I I .The p a r t i c u l a r a m p l i f y i n gu n i t I 3 i l l u s t r a t e d i n .the drawings i s a one stage audiofrequency amp l i f y i n g c i r c u i t and i s merely t y p i c a l of the va- <r i o u s amplifying systems that may be employed.Means i s p r o v i d e d f o r c o n v e n i e n t l y c o n n e c t i n gt h e c o i l C with t h e amplifying u n i t I 3 . In theform-of the invention being described a socket orj a c k 4 0 i s p r o v i d e d i n t h e body I I I and i s e l e ct r i c a l l y c o n n e c t e dwith t h e c o i lC b y a conductorI l . The s o c k e t 4 0 i s adapted t o removably r ec e i v e a plug o n the end of a f l e x i b l e two-cond u c t o r c o r d 4 2 e x t e n d i n g from t h e a m p l i f y i n g

u n i t I 3 . Means i si n t e r p o s e d

between thec o i l

C and t h e a m p l i f y i n g u n i t I 3 f o r v a r y i n g t h ea m p l i f i c a t i o n c i s o u n d . . The volume c o n t r o li s p r e f e r a b l y provided on t h e instrument propert o be c o n v e n i e n t l y a c c e s s i b l e t o the p l a y e r . Int h e drawings I have shown a typicalvariabiere

3s i s t a n c e element 4 3 connected b etween t h e s o c k e t40 and the c o i l C and i n c l u d i n g a c o n t r o l o rr e g u l a t i n g knob I 4 p r o j e c t i n g f rom t h e upper Is u r f a c e o f t h e b o d y .

F i g . 8 o f t h e d r a w i n g s i l l u s t r a t e s t h e i n v e nt i o n embodied i n an instrument i n the fo rm o f ag u i t a r having a wooden body I I I . The body I I I I ahas the u s u a l resonance - b o x I 4 * and t h e neckI 5 ‘ . The s t r i n g s I I a extend a c r o s s the uppers u r f a c e o f t h e body and are maintained undert h e r e q u i r e d t e n s i o n by k e y s 2 l i . The e l e c t r omagnetic pickup u n i t I 2 “ i s s u p p o r t e don t h e body

. I t ’ a so that the strings Il pass under i t s outer`magnet a rms A 1 . I h es t r i n g s I I * ipass betweenthe magne t arms A1 andthe c o i l o f the u n i t .The unit I 2 a operates i n the same manner as the v

' . unit I 2 and s u i t a b l e conductors extend f rom thec o i l o f the u n i t t o connect with an amplifyingu n i t o r system. A volume c o n t r o l element 4 3 S li sarranged i n the c i r c u i t - o f the c o i l . In the i nstrument i l l u s t r a t e d i n F i g . 8 o f t h e drawingswhere the body I b i i s o f w o o da ground conductori s connected with the c o i l o f the u n i t I 2 ß .

I t i s b e l i e v e d t h a t t h e o p e r a t i o n o f the i n s t r ument p r o v i d e d b y the p r e s e n t i n v e n t i o n w i l l b er e a d i l y u n d e r s t o o d from t h e f o r e g o i n g d e t a i l e dd e s c r i p t i o n . In p l a y i n g t h e i n s t r u m e n t ' t h es t r i n g s I I are plucked or otherwise vibrated a sd e s i r e d a n d Am a y b e engaged a l o n g l t h e f i n g e r' b o a r d I 6 by t h e f i n g e r s o f t h e p l a y e r o r by a s t e e lo r p l a y i n g y b a r h e l d i n t h e - p l a y e r ’ s hand.

Asbes t i l l u s t r a t e d i n F i g s . 9 and 1 0 o f t h ed r a w i n g s . t h e magnetic f l u x p a s s e s between t h eupper or outer a rms of the magnets 2 2 and themembers > 3 5i n concentrated non-uniform f i e l d sF . That i s , the l i n e s of magnetic f o r c e a s v i l l u st r a t e d d i a g r a m m a t i c a l l yby t h e s p a c e d l i n e s Li n F i g s . 9 and 1 0 are r e l a t i v e l y concentrated i nt h e s p a c e s o r f i e l d s F between the o u t e r arms o f` t h emagnets and t h e e x p o s e d -e n d s o f t h e p o l emembers 3 5 and converge t d o r i i a r e outwardlyfrom r i e r e l a t i v e l y l i m i t e d s u r f a c e sp r e s e n t e d b yends o f the members 3 5 .ing i n F i g s . 9 and 1 0 a r e not intended t o i l l u st r a t e the t o t a l l i n e s o f ' m a g n e t i c f o r c e i n t h ef i e l d s F and merely i l l u s t r a t e t h e g e n e r a l groupi n g and t h e g e n e r a l d i r e c t i o n o f t h e l i n e s o ff o r c e i n the f i e l d s when the s t r i n g s I l a r e i nt h e i r normal p o s i t i o n s . The v i b r a t o r y s t r i n g sI I o f magnetic m a t e r i a l p a s s through t h e s econcentrated non-uniform ñ e l d s F nd when theyare stationary or unmoved there i s a fixed orstable condition of magnetic f l u x and reluctancei n the f i e l d s F . Movement or vibration o f as t r i n g I I i n any d i r e c t i o n a l t e r s t h i s f i x e d cond i t i o n o f the f i e l d F t h r o u g h Wh‘ch i t p a s s e svarying the reluctance i n the space or f i e l d F .I ‘ h ev a r i a t i o n i n the r e l u c t a n c e o f the f i e l d F

induces a current in the c o i l C. The current i nduced i n the c o i l C has c h a r a c t e r i s t i c s proport i o n a l t o the c h a r a c t e r i s t i c s o f the movement o fthe s t r i n g s I I . As t h e f i e l d s F r e non-uniformo r composed o f f i a r i n g o r converging l i n e s L o fmagnetic f o r c e , movement-or v i b r a t i o n o f t h es t r i n g s I I i n t h e d i r e c t i o n ‘ o f the l o n g i t u d i n a laxes o f the members 35 and movement o f thes t r i n g s I I i n a d i r e c t i o n t r a n s v e r s e o f s a i d axesboth vary the r e l u c t a n c e s o f the f i e l d s F and thusinduce a currentin t h e c o i l . However, l t h et o n eo r the character o f the tone produced by t h ea m p l i f i e r I 3 r e s u l t i n g from t h e c u r r e n t » i n d u c e di n the c o i l C b y variation i n the reluctance o f ag i v e n f i e l d F caused b y movement o r v i b r a t i o no f the s t r i n g I I therein i n va d i r e c t i o n substant i a l l y t r a n s v e r s e ofthe l o n g i t u d i n a l ax i s o f t h e

The lines L appcar

20

30

40

45;

55

60

7 0

7 5


7/8

4a d j a c e n t member8 5 i s d i f f e r e n t from t h a t r e s u l ti n g f rom v i b r a t i o n o f the s t r i n g in a d i r e c t i o ns u b s t a n t i a l l y a x i a l l y o f s a i d a x i s . Assuming t h a ta s t r i n g I i i s vibrated t o move s u b s t a n t i a l l y

5 t r a n s v e r s e l y through i t s ñ e l d F r e l a t i v e to thegeneral d i r e c t i o n o f the l i n e s o f f o r c e L , the magn e t i c path through t h e s t r i n g i l i s l o n g e r v o rg r e a t e r when t h e s t r i n g i s i n the end p o s i t i o n so i i t s v i b r a t o r y motion than when the s t r i n g i sl 0 i n t h e i n t e r m e d i a t e p o s i t i o n o f s u c h 'motion. Ther e l u c t a n c e o f thespace or f i e l d F therefore i sg r e a t e r w i t h t h e s t r i n g I l k i nt h e end p o s i t i o n so f -i t s v i b r a to r y m o t i o n "than with t h e s t r i n g i n t h eintermediate p o s i t i o n o f i t s movement . ' I ‘ h u s

l » v i b r a t i o n o f the s t r i n g I l ? h o r l z o n t a l l y or subs t a n t i a l l y t r a n s v e r s e o f t h e l o n g i t u d i n a l a x i s o fthe member l 5 induces a current i n the c o i l V Cwhich i s ‘ c o n v e r t e d b y the a m p l i f i e r I l i n t o at o n e i n which t h e second harmonic o f the noteofthe s t r i n g p r e d o m i n a t e s . Assuming t h a t t h eabove-mentioned s t r i n g I l i s vibrated i n a gene r a l v e r t i c a l direction or in a direction substan

20

t i a l l y p a r a l l e l with or a x i a l l y o f the longitudinal

a x i s o f the member 3 5 , t h e e f f e c t o f the s t r i n g i nreducing t h e r e l u c t a n c e o f t h e i l e l d F s g r e a t e rwhen a t t h e end o f i t s vibratory t r a v e l nearestthe member l 5 than when t the end o f i t s t r a v e ln e a r e s t the a r m o i ’ t h e , m̀agnet 2 2 . This i s duet o t h i s ' p a r t i c u l a r movement o f the s t r i n g I l i n

3 0 the non-uniform - o r s u b s t a n t i a l l y fan shaped. f i e l d F made up o f the l i n e s L of force converg

i n g . t o o r f l a r i n g f rom the end o f t h e member 3 5 .Vibration o f the s t r i n g I I i n a s u b s t a n t i a l l y vert i c a l d i r e c t i o n or in a d i r e c t i o n substantially a x i a lo f the member I I induces a current i n the c o i l Cw h i c h a c t ' u a t e s t h e a m p l l i l e r t o produce a tonewhich ‘ s s t r o n g l y t h a t o f t h e fundamental . n o t eo f t h e s t r i n g . While i t may not be p r a c t i c a l t ov i b r a t e t h e s t r i n g s I l i n t r u l y v e r t i c a l o r t r u l y

4 0 ' h o r i a o n t a l d i r e c t i o n st h e vp l a y e r o r musician maya t w i l l r e a d i l y vary and c o n t r o l the character o f

25

35

t h e t o n e s produced e l e c t r i c a l l y by t h e i n s t r u m e n t .by p l u c l r i n g o r o t h e r w i s ev i b r a t i n g t h e s t r i n g s I lt o vibrate i n a generally v e r t i c a l direction or a

4 5 g e n e r a l l y h o r i z o n t a l d i r e c t i o n . The soundproduced by the'system or unit I 3 t h e r e f o r e has a l lthe t o n a l » q u a l i t i e s o f the sound which r e s u l t sfrom t h e p h y s i c a l v i b r a t i o n o f t h e s t r i n g s i l .I h eelement ` I l may be employed t o c o n t r o l or

5 0 v a r y « t h e volume o f t h e sound produced b y t h euniti) and s c o n v e n i e n t l ya c c e s s i b l e t o the hando f the player or musician employed to pluck orv i b r a t e t h e s t r i n g s . The sound i s reproducedw i t h o u t the mechanical v i b r a t i o n o f any part a t

5 5 t h e pickup u n i t l 2 y o t h e r than the ' s t r i n g s I i .The r e s u l t a n t music or sound accordingly doesnot have any extraneous vibrations or unwantedqualities . -

Having d e s c r i b e d o n l y t y p i c a l p r e f e r r e d formsa 0 and a p p l i c a t i o n s o f Amy n v e n t i o n I do n o t > wish

t o be l i m i t e d or r e s t r i c t e d t o the s p e c i i i c formsand a p p l i c a t i o n s herein s e t f o r t h , but wish t o res e r v e to myself any modiilcations or variationsthat may ppear t o those s k i l l e d i n the a r t or f a l l

6 5 withi n the scope o f 4 v t h ef o l l o w i n gc l a i m s .Having d e s c r i b e d my n v e n t i o n , I c l a i m :l ; A pick up u n i t f o r use with the vibratory

s t r i n g s o f a musical instrument, i n c l u d i n g apermanent magnet, a c o i l supported b y the mag

7 0 n e t between i t s p o l e s , means mounting themagnet t o have thestrings pass between one o f i t sp o l e s and the c o i l ,and c o r e members within thec o i l each having anend f a c i n g a s t r i n g . l

2 . In c o m b i n a t i o n ,a s e r i e s o f t e n s i o n e d s t r i n g s7 5 o f magnetic m a t e r i a l o f d i f f e r e n t d i a m e t e r s , a

2 , 0 8 9 , 1 7 1s i n g l e magnet hav ing i t s pole portions a t oppos i t e s i d e s o f the s e r i e s o f s t r i n g s , a c o i l betweent h e p o l e p o r t i o n s o f t h e magnet, a n d Amagneticcore members extending f r o m one o f the poleP o r t i o n s toward t h e o t h e r and t e r m i n a t i n g t oform s t r i n g , s p a c e s which vary i n _ s i z ewith,thes t r i n g s .

l 3 . In combina t ion , a plurality of spaced v i b r at o r y s t r i n g s o f magnetic m a t e r i a l , and a p i c k upunit i n c l u d i n g , a p a i r , o f permanent mag nets arranged t o surround t h e s t r i n g s with t h e i r c o r r esponding p o l e s o p p o s e d ,a c o i l within the f i e l d o ft h e magnets, and means s u p p o r t i n gt h e magnetsand o i l for adjustment y r e l a t i v e to the s t r i n g s .

4 . A musical instrument comprising, a b o d y t obe h e l d b y t h e p l a y e r , a p l u r a l i t y o f spaced v i b r at o r y s t r i n g s o f magnetic m a t e r i a l a t t h e e x t e r i o ro f the b o d y having p o r t i o n s a c c e s s i b l e t o be eng a g e d b y t h e p l a y e r , a permanent magnet h a vi n g a p o l a r p a r t extending o v e r t h e s t r i n g s t ocover the same adjacent s a i d portions and fo rma gua rd therefor and a r e s t f o r the operator, a n da c o i l within the i l e l d of the magnet sensitive to .

dis turbances therein.5 . A musical instrument comprising, a b o d y t obe held b y the p l a y e r , a p l u r a l i t y o f spaced v i b r at o r y s t r i n g s o f magnet m a t e r i a l a t the e x t e r i o r 4o f the b o d y having p o r t i o n s a c c e s s i b l e t o be engaged by t h e p l a y e r , a . permanent magnet having i t s polar parts spaced abov e and below thel s t r i n g s whereby the s t r i n g s p a s s through a densep o r t i o n o f t h e f i e l do f t h e magnet, t h e upper p o l a rp a r t s extending over the s t r i n g s adjacent s a i dportions t o cover the same and f o r m a gua rd i o rthe s t r i n g s and a hand r e s t f o r ' t h e p l a y e r , anda c o i l i n ~ s a i d f i e l d s e n s i t i v e t o disturbancestherein ` ‘

25

30

> 6 . A us ica l instrument compr i s ing , a plural- ‘i t y o f spaced v i b r a t o r y s t r i n g s o f magnetic mat e r i a l , a magnet n i t p o s i t i o n e dso that the s t r i n g spass through i t s t i e l d ,a c o i l a s s o c i a t e d with themagnet“ unit t o have a current induced thereinhaving the c h a r a c te r i s t i c s o f t h e v i b r a t i o n s o i t h es t r i n g , and means supporting t h e magnet u n i t a t> s p a c e d p o i n t s f o r i n d i v i d u a l adjustment a t s a i dp o i n t s r e l a t i v e t o t h e V Vs t r i n g s t ‘ oe i i ‘ e c tt u n i n g o ithe pick up means _ ,

7 . A ick up unit f o r use in combination w i t h a .p l u r a l i t y o f spaced s t r i n g s o i a musical i n s t r ument, s a i d p i c k up u n i t c o m p r i s i n g ,an e l o n g a t emagnet u n i t d i s p o s e d t r a n s v e r s e l y o f t h e s t r i n g sto have a polar par t a b o v e the s t r i n g s , a c o i l carr i e d b y the magne t t o r e c e i v e an i n d u c e d l current f rom i t s f i e l d , and means f o r s h i f t i n g themagnet f rom e i t h e r ‘ e n d t o move i t r e l a t i v e t 0the s t r i n g s t o tune t h e p i c k up u n i t .

8 . A " pick up unit f o r use in combination with

40

the vibratory s t r i n g o f an instrument i n c l u d i n g , -a magnet h a v i n g spaced polar parts, an induc- „

I t i o n c o i l p o s i t i o n e d between the s a i d polar p a r t s ,and means i o r supporting the magnet and c o i ls o t h a t t h e s t r i n g p a s s e s through t h e s p a c e ' between the c o i l and one o f s a i d p a r t s whereby v ib r a t i o n o f t h e s t r i n g v a r i e s t h e r e l u c t a n c e o f t h esaid space t o induce a current in the c o i l . ` .

9 . A ick up means o r use i n combination witha musical instrument having- a v i b r a t o r y s t r i n go f .magnetic m a t e r i a l , s a i d p i c kup means i n c l u di n g , > a magne t havi ng spaced polar p a r t s , a c o i l „

p o s i t i o n e dbetween t h e s a i d p a r t s , t h e magnet andc o i l being p o s i t i o n e d s o t h a t the s t r i n g vp a s s e st h rough the space between the c o i l and one ofs a i d p a r t s whereby v i b r a t i o n o i t h e s t r i n g v a r i e sthe reluctance o f a r e l a t i v e l y dense portion o ft h e magnetic i l e l dt o i n d u c e a c u r r e n t i n t h e c o i l ,

65

7 0

7 5


8/8

U l

v 1 0

20

30

2 , 0 8 9 , 1 7 1and means c a r r y i n g t h e magnet and c o i l f o r adjustment r e l a t i v e t o t h e s t r i n g .

1 0 . In combination, a s e r i e s o f v i b r a t o r y s t r i n g so f magnetic m a t e r i a l o f d i f f e r e n t d i a m e t e r s , amagnet,»a c o i l i n the f i e l d o f the magnet, the magn e t b e i n g p o s i t i o n e d s o t h a t the s t r i n g s passthrough t s f i e l d ,magnetic c o r e members extending f rom one p o l e portion o f the magnet and passi n g through t h e c o i ltoward t h e o t h e r p o l e p o r t i o no f t h e mag net and t e r m i n a t i n g a t p o i n t s s p a c e df rom the s a i d o t h e r p o l e p o r t i o n t o l e a v e spacesthrough which the s t r i n g s p a s s , and means f o rs h i f t i n g the magnet t o vary t h e r e l a t i o n betweenthe s t r ings and s a i d s p a c es . ì ì

1 1 . A musical instrument compr i s ing a bodyt o be held b y the p l a y e r , a p l u r a l i t y o f v i b r a t o r ys t r i n g s o f magnetic material extending a c r o s s anexterior face o f the b o d y in spaced relation there-t o , a permanent magnet on the body h a v i ng ap o l a r p a r t r e l a t e d t o the s t r i n g s _ t o cover thes t r i n g s and fo rm a guard therefor and a h a n d

> r e s t f o r t h e p l a y e r , and a c o i l _ i nthe f i e l d o f t h emagnet s e n s i t i v e t o d i s t u r b a n c e s t h e r e i n .

1 2 . In a musical instrument, a s e r i e s o f spacedv i b r a t o r y s t r i n g s o f magnetic m a t e r i a l , an c i o n -gate magne t unit d i s p o s e d . transversely o f thes t r i n g s where t h e s t r i n g s p a s s through i t s f i e l d ,ac o i l c a r r i e d b y the magne t unit t o r e c e i v e an i nduced current f rom the magneticñeld, and meansf o r s h i f t i n g t h e magnet f rom e i t h e r end t o a d ju s ti t relative to the strings. -

1 3 . In a musical instrument, a s e r i e s of spacedV i b r a t o r y s t r i n g s o f magnetic m a t e r i a l , an e l o n

_ gate magne t unit disposed transversely o f the

40

45

60

s t r i n g s where t h e s t r i n g s p a s s through i t s f i e l d ,a c o i l i n the magnetic f i e l d o f the unit t o r e c e i v ea n induced current therefrom, and means forr o c k i n g t h e magnet u n i t i n a p l a n e s u b s t a n t i a l l y >

t r a n s v e r s e o f the s t r i n g s t o adjust i t r e l a t i v e t othe strings. V '

1 4 . In a musical instrument, a s e r i e s o f spacedv i b r a t o r y s t r i n g s o f magnetic m a t e r i a l , an e l o ng a t e magnet u n i t d i s p o s e d t r a n s v e r s e l y o f t h es t r i n g s where t h e s t r i n g s p a s s through t s f i e l d ,ac o i l i n the magnetic f i e l d o f the u n i t t o r e c e i v e aninduced current therefrom, and means f o r t i l t i n gt h e magnet u n i t i n a p l a n e s u b s t a n t i a l l y ' t r a n sv e r s e o f the s t r i n g s , s a i d means including supp o r t s f o r t h e magnet u n i t a t p o i n t s a t o p p o s i t es i d e s o f t h e s e r i e s o f s t r i n g s .

1 5 . In combination, a v i b r a t o r y s t r i n g o f magn e t i c m a t e r i a l , a magnet having p o l e p o r t i o n s a to p p o s i t e s i d e s o f the s t r i n g , a c o i l between thep o l e p o r t i o n s o f the magnet, a .magnetic c o r emember extending from one o f t h e p o l e p o r t i o n stoward t h e o t h e r p o l e v p o r t i o n and t e r m i n a t i n ga t a p o i n t spaced therefrom t o forma s p a c e ' _through which t h e s t r i n g p a s s e s , and means f o r

‘ _ s h i f t i n g the magnet to v a r y the positions of thec o r e memberand t h e s a i d o t h e r p o l e p o r t i o n withr e l a t i o n to the s t r ing . ' ‘

1 6 . A usical instrument comprising a body, a >

5p l u r a l i t y o f e x p o s e d v i b r a t o r y s t r i n g s e x t e n d i n ga c r o s s a f a c e o f the b o d y n spaced r e l a t i o n theret o ,a p a i r o f o p p o s e dmagnets on t h e body havingp o l a r p o r t i o n s d i s p o s e dt r a n s v e r s e l y o ft h e s t r i n g sand r e l a t e d t o t h e s t r i n g s t o form a guard t h e r e

f o r , s a i d guard e x t e n d i n g o v e r t h e s t r i n g s t oc o v e r t h e same, and a c o i l i n t h e f i e l d o f the p a i ro f magnets s e n s i t i v e t o d i s t u r b a n c e s t h e r e i n .

1 7 . In a p i c k up u n i t , v i b r a t o r y s t r i n g s o f magn e t i c m at e r i a l , a magnet having s p a c e d p o l e p o rt i o n s and p o s i t i o n e d s o that the s t r i n g s pass between s a i d p o l e p o r t i o n s ,a p l u r a l i t y o f magneticp o l e members on one o f s a i d p o l e p o r t i o n s , eachmember having a l i m i t e d s u r f a c e o f magnetica t t r a c t i o n a d j a c e n t one s t r i n g whereby t h es t r i n g s a c t i n zones wherein the l i n e s o f magneticf o r c e f l a r e i n w a r d l y t o s a i d l i m i t e d s u r f a c e a v a n d

V a c o i ls u r r o u n d i n gt h e p o l e members.1 8 . In a pick up _ n i t ,v i b r a t o r y s t r i n g s o f mag

n e t i c m a t e r i a l , a s i n g l e permanent mag net h a ving a s e r i e s o f p r o j e c t i n g p o l e p a r t s o f l i k e pol a r i t y , each p o l e p a r t p r e s e n t i n g a l i m i t e d s u rf a c e adjacent a s t r i n g whereby the l i n e s o f magn e t i c f o r c e f l a r e outwardly f rom s a i d s u r f a c e sabout the t r i n g s , and an induction c o i l surroundi n g s a i d s e r i e s o f p a r t s .

1 9 . In a p i c k up u n i t , a p l u r a l i t y o f v i b r a t o r ys t r i n g s o f magnetic m a t e r i a l , a magnet havings p a c e d ‘ p o l e po r t i o n s p o s i t i o n e ds o t h a t t h e s t r i n g spass between the p o l e p o r t i o n s i n c l o s e r proxi m i t y t o one than the o t h e r , magnetic p o s t s extending f rom s a i d o t h e r , p o l e p o r t i o n and eachhaving a surface o f l i m i t e d extent adjacent as t r i n g and opposing t h e f i r s tmentioned p o l e port i o n whereby the s t r i n g s v i b r a t e i n a zone wherethe l i n e s o f magnetic force converge t o said surf a c e s , and a c o i l i n the f i e l d o f the magnet.

2 0 . In a p i c k up u n i t , a p l u r a l i t y o f v i b r a t o r y

s t r i n g s o f magnetic m a t e r i a l having t h e i r axesi n a common l a n e , a‘magnet having a p o l e port i o n adjacent the s t r i n g s a n d ` i n c l i n e d with r es p e c t t o s a i d plane s o that the s p a c e s between> s a i dp o r t i o n and t h e s t r i n g s v a r y s u b s t a n t i a l l y i np r o p o r t i o n t o t h e i n t e n s i t y o f t h e magnetism o fs a i d p o l e p o r t i o n , and a c o i l i n the f i e l d o f themagnet ` ,

2 1 . In a p i c k up u n i t , a p l u r a l i t y o f v i b r a t o r ys t r i n g s o f magnetic m a t e r i a l having t h e i r axes i na common-plane, a magnet having a p o l e p o r t i o na d j a c e n t t h e s t r i n g s and i n c l i n e d with r e s p e c tl t o s a i d plane s o t h a t the spaces between s a i dp o r t i o n and t h e ‘ s t r i n g s v a r y s u b s t a n ti a l l y i n p r op o r t i o n t o t h e i n t e n s i t y o f t h e magnetism o f s a i dp o l e p o r t i o n , t h e magnet having a second p o l ep o r t i o n , magnetic p o s t s on s a i d second p o l e po;t i o n h a v i n g l i m i t e d s u r f a c e s y a d j a c e n t t h es t r i n g sand o p p o s i n g t h e ñ r s t mentioned p o l e p o r t i o nwhereby t h e v i b r a t o r y s t r i n g s a c t i n i l e l d s wherethe l i n e s o f magnetic f o r c e converge t o . s a i d l imi t e d s u r f a c e s , and a c o i l i nthe ñeld o f the magnet ‘ ‘

GEORGED . BEÁUCHAMP.

, 1 5

y 3 0

40

6 0

us2089171 beauchamp electrical stringed musical instrument 1937

Documents