APPARATUS FOR ALTERING THE TUNING CONFIGURATION OF A STRINGED INSTRUMENT

Abstract: Apparatus for altering the tuning configuration of a stringed instrument comprising a body (3), a neck (4), a nut (5) and a plurality of strings (26). The strings are tensioned between a first contact point (8) adjacent the apparatus and a second contact point (9) adjacent the nut. The apparatus comprises a base member (27) secured to the instrument and provided with a string securing means (29) for each string, said string securing means arranged adjacent the first contact point (8), and an adjustable tensioning mechanism (16, 11, 10) connected to each of the string securing means (29). In each of a number of positions the string securing means (29) applies a predetermined tension to the strings (26). The first contact point (8) is provided on an element (30) displaceable in relation to the string securing means (29) and connected with the adjustable tensioning mechanism (16, 11, 10).

Description: Title: Apparatus for altering the tuning configuration of a stringed instrument- Technical Field The invention relates to an apparatus for altering the tuning configuration of a stringed instrument, such as a bass guitar comprising a body, a neck, a nut, and a plurality of strings being tensioned between a first contact point adjacent the apparatus and a second contact point adjacent the nut, said apparatus comprising a base member adapted to be secured to the instrument and being provided with a string securing means for each string, said string securing means arranged adjacent the first contact point and outside the area between the contact points, and an adjustable tensioning mechanism connected to each of the string securing means and adjustable in a number of positions in which the string securing means applies a predetermined tension to each string, whereby a change in the position of the tensioning mechanism effects a change in the tuning configuration of the stringed instrument. An apparatus of the above type forms the bridge assembly on the stringed instrument and is used by musicians to alter the tuning configuration of the instrument in a quick and easy manner by altering the tension of each string such that it - when struck in an "open" state (an open string is a string which is not pressed down on the finger board) - produces a different note. The apparatus renders tuning of the instrument in the usual manner by means of the tuning pegs of each string superfluous. The apparatus is advantageous, if the musician wishes to alter the tuning configuration between two pieces of music during a concert and is particularly advantageous, if the musician wishes to alter the tuning configuration in the middle of a piece of music. Background Art Several patents for instance WO 95/01631 disclose a tuning apparatus for mounting on a guitar, said apparatus providing each string with several predetermined tensions. By activating an operating means the guitar may be quickly changed to another tuning configuration. However in practice it has been found that by altering the tuning configuration by means of such an apparatus, the instrument becomes out of tune at the frets for the reasons stated below: The term "out of tune at the frets" in a stringed instrument means that the exactly correct note is not produced, when the strings at the individual frets are pressed down. The higher up the finger board the strings are pressed down, the higher deviation from the correct note. Basically, the vibration frequencies of a string depend on the following factors: The length (ie the distance between the two contact points): The vibration frequency of a string is inversely proportional to the length of the string. If the length is doubled, the vibration frequency of the keynote is halved, ie the pitch is lowered by an octave. Tension: The vibration frequency of the string increases proportionally to the square root of the tension, for which reason the tension has to be multiplied by four in order to raise the pitch by two octaves. Mass per unit of length (or the diameter): At a given length and tension, the vibration frequency decreases proportionally to the mass of the string per unit of length. Rigidity: A string vibrates under the influence of two different types of forces deriving from the tension in the string and from the rigidity of the string, respectively. The rigidity increases the vibration frequency slightly and its influence increases with increasing mass per unit of length and decreasing length of the string. The adjustment of the position of the bridge assembly on an electric bass guitar or on other stringed instruments having a finger board is based on a mid-positioning of the 12th fret of the finger board between the contact point adjacent the nut and the contact point adjacent the bridge assembly. During play the strings are pressed down on the finger board, whereby the tension is increased slightly as the total length of the strings are slightly increased. In addition hereto the influence of the rigidity is increased in relation to that of the tension, as the vibrating portion of the string (ie the distance between the frets on which the finger presses the string down, and the first contact point) is shorter than the open string. In order to compensate for this situation, the contact point adjacent the bridge assembly is moved rearwards, ie the distance between the contact point adjacent the bridge assembly and the 12th fret is increased in relation the distance between the contact point adjacent the nut and the 12th fret. Provided this compensation is carried out correctly, when pressing the string down on the 12th fret, the struck string produces a note which is exactly one octave higher than the note produced when striking an open string. As the thicker strings often are further spaced apart from the finger board than the thinner strings, the change in the tension is higher when the thicker strings are pressed down than when the thinner strings are pressed down, for which reason a higher degree of compensation is needed for these strings. Accordingly, on a four-stringed bass guitar the contact point of the thick E string is positioned further to the rear on the body than the contact point of the thinner G string. It should however be noted that in practice it is rarely obtained that the instrument is perfectly in tune - even at a correct adjustment. As the frequency depends on both the rigidity and the tension and as the neck of the instrument yields when the strings are loosened, a quite complicated situation exists, this being the reason why an instrument can only be adjusted in an optimum manner to a certain tuning configuration. If the tension is altered, the distance between the first and the second contact point also has to be altered, if the instrument is to remain in tune. Brief Description of the Invention The object of the invention is to provide an apparatus by means of which the musician may alternate between several predetermined settings of the tension of the strings in a quick and simple manner and wherein it at the same time is ensured that the instrument retains in tune at a change between said settings. The apparatus according to the invention is characterised in that the first contact point may be provided on an element displaceable in relation to the string securing means and connected with the adjustable tensioning mechanism in such a manner that by changing of the position of the latter, the contact point is displaced in the longitudinal direction of the string. As a result the stringed instrument remains in tune when changed to another tuning configuration. According to an embodiment by changing the position of the tensioning mechanism, the string securing means may be displaced in the longitudinal direction of the strings, whereby the pretension of each string is adjusted in a simple manner. According to yet another embodiment the tensioning mechanism may comprise a first transmission adapted so as to separately displace each string securing means when the position of the tensioning mechanism is changed. A more accurate adjustment of the length of each string in relation to the tension is thereby obtained. The apparatus according to the invention may further comprise an additional transmission for each string being adapted so as to separately displace the individual displaceable elements in relation to the string securing means of the respective string when the position of the tensioning mechanism is changed. Consequently an optimum setting of the length and the tension of each string is ensured such that all the strings of the instrument remain in tune. According to a preferred embodiment the displaceable element may comprise a further element provided with the first contact point and connected to the displaceable element by means allowing for an adjustment of the distance of the element to the base member and its position in the longitudinal direction of the string in relation to the displaceable element. It is thus possible to fine-adjust the length of the string and to fine-adjust the height of the strings above the body of the instrument. According to the invention the tensioning mechanism may comprise an operating handle adapted to be operated manually, whereby the musician may change to another tuning configuration in a quick and simple manner. The first transmission may according to an embodiment of the invention be a gear transmission. Such a gear transmission is reliable and comparatively easy to manufacture. Optionally, the first transmission may be a worm gearing, whereby a more compact structure and a different position of the operating handle are obtained. According to a preferred embodiment the additional transmission may be formed of a threaded rod having a first threaded portion engaging a threaded hole in the string securing means, and a second threaded portion engaging a threaded hole in the displaceable element, the thread pitch of the first threaded portion differing from the thread pitch of the second threaded portion. A simple and reliable additional transmission is thus provided. According to the invention the further element may comprise a shaft on which a roller determining the first contact point is rotatably mounted. The friction between the string and the first contact point is thus minimised such that the strings slide more readily over the contact point at a change to a different tuning configuration. According to a preferred embodiment of the invention the apparatus may comprise a nut element determining the second contact point and provided with means for retaining the string in its longitudinal direction. This ensures the function of the apparatus, as the portion of the string positioned between the nut element and the tuning pegs does not affect the tension in the string between the first and second contact points. The nut element may according to the invention comprise means for adjusting the height of the second contact point in relation to the finger board. Jointly with the height adjustment means of the apparatus this feature enables adjustment of the strings in an optimum height above the finger board in the entire length thereof. The nut element may according to the invention further comprise means for fine-adjusting the tension of the string, whereby it is possible to fine-adjust the tension of the string in a simple and quick manner independently of the apparatus on the body of the instrument. The invention also relates to a stringed instrument provided with an apparatus according to the invention. Brief Description of the Drawings The invention will be explained in detail below by means of a preferred embodiment illustrated on the drawings, in which Fig. 1 is a diagrammatic top view of a bass guitar provided with an apparatus according to the invention, Fig. 2 is a detailed top view of the apparatus according to Fig. 1, Fig. 3 is a sectional view of the apparatus in Fig. 2 along the line III-III in Fig. 2, Fig. 4 illustrates a nut element for retaining the strings adjacent the second contact point, Fig. 5 is a diagrammatic view of a gear transmission in the apparatus according to Fig. 2, and Fig. 6 is a diagrammatic view of a worm gearing according to another embodiment. Best Mode for Carrying Out the Invention The bass guitar shown in Fig. 1 comprises a body 3, a neck with a finger board 4, a nut 5, a headstock 54 with tuning pegs 55, strings 26 and an apparatus 1 according to the invention mounted on the body. The apparatus 1 forms the bridge assembly of the instrument. The apparatus 1 , which is shown in detail in Figs. 2 and 3, basically comprises a base member 27 fixedly mounted on the body 3 of the instrument, four string securing means 29, four displaceable elements 30 and a tensioning mechanism 16, 11 ,10. The tensioning mechanism 16,11,10 comprises four threaded rods 16, a gear box provided with a first transmission 11 , and an operating handle 10. The gear box 36 comprises an operating means in form of an operating handle 10 rotatably arranged in the gear box by means of a bearing 40. The handle 10 is connected with a drive pinion 37 meshing with a crown wheel 42. The crown wheel 42 is secured to a gear wheel 68 by means of a bolt 43 (confer Fig. 5), whereby the gear wheel 68 rotates when the operating handle 10 is turned. As illustrated in Fig. 5, which is a diagrammatic view of the gear transmission of the gear box, the gear wheel 68 meshes with additional gear wheels 48, 49, 50, 51, 52, 53. Each of the gear wheels 48, 50, 51, 53 is directly connected to a threaded rod 16 engaging the string securing means 29 and the displaceable element 30. As a result of this gear transmission 11, a turning of the operating handle 10 allow for a separate turning of each threaded rod 16. The string securing means 29 is slidably arranged on the base member 27 and is provided with a threaded hole 56 engaging a first threaded portion 17 on the threaded rod 16. The displaceable element 30 is slidably arranged in a groove 58 in the string securing means 29 and provided with a threaded hole 57 engaging a second threaded portion 18 on the threaded rod 16. In this embodiment the threaded rod 16 is formed of two separate threaded rods 16a, 16b joined by threads in the portion 34. The threaded portions 17,18 have differing pitches. At turning of the threaded rod 16, the string securing means 29 and the displaceable element 30 are thus displaced differently in the longitudinal direction. A further element 31 is connected to the displaceable element 30 by means of a cross-headed screw 13 extending through a slit in a vertical wall section of the displaceable element 30. A compression spring 33 attached to the screw 13 spaces the further element 31 apart from the vertical wall portion of the displaceable element 30. The further element 31 is provided with a roller 20 rotatably arranged on a shaft 21. A string 26 provided with a cylindrical body 43 at one end is received in a vertical and cross-sectionally semicircular slit 35 in a vertical wall portion of the string securing means 29 (confer Fig. 2). From the string securing means 29 the string extends over the roller 20 forming the first contact point 8. The further element 31 and thus the roller 20 is adjustable in the longitudinal direction of the string by means of the screw 13 and in its height above the base member 27 and thus the body 3 by means of two height adjustment screws 14. As illustrated in Fig. 2, the operating handle 10 is provided with notches 19 forming fixed stop means. Two opposing notches 19 engage the right-angled edge 59 of the gear box 36, when the operating handle is not activated by the user. By means of a blind hole 60 the operating handle 10 engages a shaft portion 61 provided with the drive pinion 37. The shaft portion 61 and the hole 60 may for instance be hexagonal in cross-section to prevent mutual rotation thereof. The shaft portion 61 is provided with a blind hole, one end of a tension spring 38 being secured to the bottom of the said hole. The other end of the tension spring is attached to a screw 41 extending through two slits 69 in the shaft portion 61 and through the hole 60 in the operating handle 10. As long as the operating handle 10 is not activated by a user, two of the notches 19 of the operating handle 10 engage the edge 59 of the gear box and the drive pinion 37 meshes with the crown wheel 42. If a user pulls the operating handle upwards against the force of the spring 38, the notches 19 are pulled out of engagement with the edge 59 of the gear box 36, and if the handle is subsequently let go, it engages the edge 59 by means of a second pair of notches 19. An optional even number of notches are provided along the circumference of the operating handle 10. Suitable thread pitches for the threaded portions 17,18 combined with a suitable gear transmission 11 allow for any desired pretension and longitudinal displacement of the first contact points 8 of the individual strings by a single activation of the operating handle 10. The apparatus thus ensures that the tuning configuration of the instrument can be changed in a quick and simple manner while all of the strings in the frets remain in tune. Fig. 4 illustrates a nut element 22 mounted at the end of the finger board 4 opposite the bridge assembly. The nut element has three functions. Firstly, it determines the second contact point 9 of each string, secondly it retains the individual string in the longitudinal direction, and thirdly, it enables fine-adjustment of the tension in each string. The height of the second contact point 9, ie the distance to the finger board 4, is adjustable by means of a hexagon socket screw 24. A wrench for this screw may be inserted through a hole 62 from above for engagement with the screw 24. On the opposite side of the nut element, the string is retained in the longitudinal direction by means of a screw 23 securing the string in a hole 63 in the nut element. A thumb screw 25 is screwed into a threaded hole 64, the end of the screw abutting the upper face of the string 26. When the screw 25 has been screwed in, the string is pressed downwards, whereby tension of the string is increased. It is thus possible to fine-adjust the tension of the strings quickly and easily independently of the apparatus on the body of the instrument. According to another embodiment the first transmission 11 provided in the gear box 36 may be in form of a worm gearing instead of a gear transmission. Such a worm gearing is diagrammatically shown in Fig. 6. By turning the operating handle 10 a worm 46 is turned, which in turn causes a turning of the worm wheels 47, 65, 66, 67 corresponding to the gear wheels 48, 50, 51, 53 in Fig. 5. A worm gearing may be more compact than a gear transmission and allow for a more advantageous position of the operating handle 10, viz on the side and not at the end of the gear box 36. The worm 46 may optionally comprise four separate worm portions with different pitches, each worm portion optionally arranged on separate worm parts joined in the same manner as the threaded rods 16a, 16b. The design options of the individual worm wheels 65, 66, 67 as regards diameters and teeth are increased. The invention has been explained by means of two embodiments, but is not limited to said embodiments. For each string the gear box may for instance be provided with disengaging means adapted to disengage and retain the gear wheel/worm wheel of the string such that the pretension and length of the string is not altered when the operating handle is activated. The apparatus may thus be set to activate only some of the strings. The tensioning mechanism may also be provided with a pedal device by means of which the musician with his foot may change to another tuning configuration. The apparatus according to the invention may also be provided with an indicator, eg in form of an electronic display, displaying the chosen tuning configuration. The invention has been described in connection with a four-stringed electric bass guitar, but may just as well be used in connection with another stringed instrument such as an electric guitar.

Claims: Claims 1. Apparatus ( 1 ) for altering the tuning configuration of a stringed instrument such as a bass guitar (2) comprising a body (3), a neck (4), a nut (5), and a plurality of strings (26) being tensioned between a first contact point (8) adjacent the apparatus and a second contact point (9) adjacent the nut, said apparatus comprising a base member (27) adapted to be secured to the instrument and being provided with a string securing means (29) for each string, said string securing means arranged adjacent the first contact point (8) and outside the area between the contact points (8,9), and an adjustable tensioning mechanism (16,11,10) connected to each of the sting securing means and adjustable in a number of positions, in which the string securing means (29) applies a predetermined tension to each string (26), whereby a change in the position of the tensioning mechanism (16,11,10) effects a change in the tuning configuration of the stringed instrument characterised in that the first contact point (8) is provided on an element (30) displaceable in relation to the string securing means (29) and connected with the adjustable tensioning mechanism (16, 11 , 10) in such a manner that by changing of the position of the latter the contact point (8) is displaced in the longitudinal direction of the string. 2. Apparatus according to claim 1, characterised in that by changing the position of the tensioning mechanism (16,11,10) the string securing means (29) are displaced in the longitudinal direction of the strings. 3. Apparatus according to claim 1 or 2, characterised in that the tensioning mechanism (16,11,10) comprises a first transmission (11) adapted so as to separately displace each string securing means (29) when the position of the tensioning mechanism (16,11,10) is changed. 4. Apparatus according to one of the claims 1-3, characterised in that it comprises an additional transmission (12) for each string being adapted so as to separately displace the individual displaceable elements (30) in relation to the string securing means (29) of the respective string when the position of the tensioning mechanism (16,11,10) is changed. 5. Apparatus according to claim 1-4, c h a ra c te r i s e d in that the displaceable element (30) comprises a further element (31) provided with the first contact point (8) and connected to the displaceable element (30) by means (14,32,33) allowing for an adjustment of the distance of the element (31) to the base member (27) and its position in the longitudinal direction of the string in relation to the displaceable element (30). 6. Apparatus according to claim 1-5, characterised in that the tensioning mechanism (16,11,10) comprises an operating handle (10) adapted to be operated manually. 7. Apparatus according to claim 1-6, characterised in that the first transmission is a gear transmission. 8. Apparatus according to claim 1-6, characterised in that the first transmission is a worm gearing. 9. Apparatus according to claim 1-8, characterised in that the additional transmission is formed of a threaded rod (16) having a first threaded portion (17) engaging a threaded hole (56) in the string securing means (29), and a second threaded portion ( 18) engaging a threaded hole (57) in the displaceable element (30) , the thread pitch of the first threaded portion differing from the thread pitch of the second threaded portion. 10 Apparatus according to claim 1-9, characterised in that the further element (31) comprises a shaft (21) on which a roller (20) determining the first contact point (8) is rotatably mounted. 11. Apparatus according to claim 1-10, characterised in that it comprises a nut element (22) determining the second contact point (9) and provided with means (23) for retaining the string in its longitudinal direction. 12. Apparams according to claim 11, characterised in that the nut element (22) comprises means (24) for adjusting the height of the second contact point (9) above the finger board (4). 13. Apparatus according to claim 11, characterised in that the nut element (22) comprises means (25) for fine-adjusting the tension of the string. 14. Stringed instrument (2) provided with an apparams (1) according to one of the claims 1-13.

Inventors: PETERSEN LASSE, PETERSEN, LASSE
Applicants: PETERSEN LASSE, PETERSEN, LASSE
Application year: 1999
Main classification: G10D
IPC codes: G10D1, G10D3