JP2016206279A - Plucked string instrument body structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plucked string instrument structure for eliminating normal stress and achieving free vibration of a face plate by solving problems in which a plucked string instrument such as a classical guitar has a gap of a bridge (piece) and a saddle height between a string stretched over the saddle on a nut and a bridge (piece) and the face plate, and therefore the normal stress by the tension of the string acts on the face plate due to the gap to thereby prevent the free vibration of the face plate.SOLUTION: A face plate structure assuming a string position as an extended surface of a face plate surface is effective as a structure where normal stress may not act thereon. Consequently, the normal stress is eliminated by forming a central part from a neck attaching part to a bridge c of a face plate a in a concave structure, and mounting a neck h, a bridge and a saddle d to a recessed face plate g.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a surface plate structure for promoting vibration of a surface plate in a plucked musical instrument having a structure in which a string is fixed to a bridge (piece) fixed to the surface plate.

The conventional surface plate vibration is promoted by generating tension by a counter string to improve acoustic characteristics (Patent Document 1), and the string is fastened to a timber provided on the back surface of the surface plate to release vibration suppression (Patent Document 2). ) Has been proposed.

JP 7 — 95558 JP 2010-60963 A

The classical guitar shown in FIG. 1 has a bridge (c) c and a saddle d between a string i and a surface plate a stretched between a nut e and a saddle d on a bridge (c) c shown in the AA sectional view. There is a gap corresponding to the height of. The total height H of the bridge (piece) c and saddle d shown in the enlarged view of the bridge, FIG. 2, is about 13 mm. Due to this gap, the surface plate is subjected to vertical stress due to the tension of the string and free vibration of the surface plate. Is hindering.

In FIG. 3A-A cross-sectional view, the strength of normal stress acting on the surface plate is considered with ● as a fulcrum o. Since there is a gap H between the surface plate and the string, the tension of the string tries to pull up the surface plate in the direction indicated by the dotted line and generates vertical stress. In the vector diagram, in FIG. 4, the string tension is set to the left vector F, the stress of the same magnitude and the opposite direction is -F, the fulcrum o and the saddle d are connected at the upper end, -F component force is directed downward at right angles to F1 and F1 The component force of -F is defined as the normal stress F2. The angle between -F and F1 is Θ.
The tension of a typical classical guitar string is about 40 kg in total for the six strings, the string length L is 65 cm, and the gap between the top plate and the saddle top is about 13 mm. The fulcrum is at the same position as the center of the chord length of 65 cm, and the distance from the fulcrum to the upper end of the saddle is approximately 32.5 cm, which is half the chord length.
The normal stress acting on the surface plate is obtained from the above specifications.

Therefore, the normal stress F2 is as follows.

The tension of the string always pulls up the surface plate with a force of about 1.6 kg. In other words, the surface plate is sounded in a state where the vertical stress due to the pulling force is applied, and is not in a state where free vibration is possible.

In order to bring the surface plate into a free vibration state, the gap between the surface plate and the upper end of the saddle should be made as small as possible, that is, Θ = 0.
Specifically, as shown in the AA sectional view, BB sectional view, CC sectional view, and DD sectional view of FIG. 5, the string stretched between the nut e and the saddle d on the bridge (piece) c. The position may be the same as the extended surface of the surface plate a surface.
Therefore, a surface plate structure having a concave surface plate g in which the central portion of the surface plate a is lowered by about 13 mm from the neck h mounting portion to the bridge d is formed. Then, the bridge c and saddle d and the neck h shown in the plan view, AA sectional view, and DD sectional view of FIG. Same position. Due to the position of the string stretched on the extended surface of the surface plate a, the surface plate a is free from vertical stress and can vibrate freely.
Needless to say, this structure in which the string position is an extended surface of the surface plate can be applied to all repellent instruments (such as ukulele) that hold the string on the bridge on the surface plate, and free vibration of the surface plate can be expected.

The conventional type guitar shown in FIG. 1 has a thickness of about 2.5 mm so that the surface plate a is not deformed by the vertical stress due to the tension of the strings, and a plurality of timbers are arranged on the back surface. On the other hand, the surface plate structure guitar of FIG. 5 in which normal stress does not act does not deform the surface plate a even if the thickness of the surface plate a is thinned to about 1.5 mm, and the number of force trees on the back surface can be reduced. .
The thin and light surface plate a shown in FIG. 5 responds to the string vibration more sensitively and enables fast sounding. In addition, fine harmonic components such as overtones originally contained in string vibrations are fully reproduced, enabling mellow and glossy pronunciation.
The high-quality spruce material for musical instruments used for the surface plate is imported and expensive, so the musical instrument using it is also expensive, but if the thickness of the surface plate can be reduced, the amount of material used can be reduced. The price of the instrument itself can be reduced.
It should be noted that there is no influence on the musical instrument performance due to the structure change of the surface plate a, and it can be applied as it is without changing the conventional performance technique.

Cross section of conventional guitar Expanded sectional view of bridge c and saddle d Schematic diagram for explaining normal stress acting on the surface plate of a conventional type guitar String tension and stress vector illustration Cross section of a guitar according to the present invention Rise waveform diagram of the guitar according to the present invention (upper) and the conventional type guitar (lower) of one open string Rise waveform diagram of guitar according to the present invention (upper) and conventional type guitar (lower) of two open strings Rising waveform diagram of the guitar according to the present invention (upper) and the conventional type guitar (lower) of the three-string open string Rise waveform diagram of guitar according to the present invention (top) and conventional type guitar (bottom) 4-string open string Rising waveform of the guitar according to the present invention (upper) and the conventional type guitar (lower) of the 5th open string Rising waveform of the guitar according to the present invention (upper) and the conventional type guitar (lower) of 6 strings open string Frequency characteristics diagram of guitar according to the present invention (upper) and conventional type guitar (lower) 1 string open string Frequency characteristics diagram of the guitar according to the present invention (top) and the conventional type guitar (bottom) of two open strings Frequency characteristics diagram of guitar according to the present invention (top) and conventional type guitar (bottom) 3 strings open string Frequency characteristics diagram of guitar according to the present invention (upper) and conventional type guitar (lower) 4-string open string Frequency characteristics diagram of guitar according to the present invention (upper) and conventional type guitar (lower) 5 strings open string Frequency characteristics diagram of guitar according to the present invention (upper) and conventional type guitar (lower) 6 strings open string A photograph of a guitar in which the surface plate of the guitar according to the present invention and the conventional type guitar is attached to one sounding drum Enlarged photo of the guitar plane and concave surface plate, bridge (piece), saddle, neck, string of the guitar according to the present invention

Hereinafter, embodiments will be described with reference to the drawings.

In the waveform recording described below, the surface plate of the guitar according to the present invention produced on the one side of the sound drum as shown in the photograph of FIG. A guitar with a conventional type guitar face plate and neck attached to the opposite side was created and used.
FIG. 19 is a plan view (top) of a guitar according to the present invention and an enlarged view (bottom) of a neck, a bridge (piece) c saddle d and a string i installed on the concave surface plate g.
The open strings from 1 to 6 of this guitar are stringed by the apoyande method, and the pronunciation is recorded by the waveform analysis software Sound Engine. The rising waveforms are shown in FIGS.
Incidentally, the upper part of each figure shows the waveform of the guitar according to the present invention, and the lower part shows the waveform of the conventional type guitar.
It was impossible to play the string with the same strength because it was played with a finger, but the string was played so that the maximum amplitude was as much as possible plus or minus -6 dB centering on the vertical scale 1ch-lnfdB. The horizontal axis is time and the unit is second. All strings were tuned based on the pitch of the 1st string in which the 5th fret of the 1st string was matched to a tuning fork with a pitch of 440Hz.
When observing the rise of the waveform of the first string in FIG. 6, the guitar according to the present invention observes the amplitude P1 aligned with the maximum amplitude in one cycle from the sound generation. On the other hand, in the conventional type guitar, the amplitude P2 of one cycle is about 2/3 of the maximum amplitude from the sound generation, and the rise is slow. Thereafter, it can be determined that the 2nd string in FIG. 7 to the 4th string in FIG. 9 and the 6th string in FIG. Musical instruments that rise quickly are clearly pronounced and are preferred by performers.
As for the 5th string in FIG. 10, the conventional type guitar is faster, because of the characteristic that the 5th string open string (sound name tone) of the conventional type guitar strongly resonates with the sound drum. The characteristic that a five-string open string resonates more strongly than other strings and the volume is increased is often observed in commercially available guitars, but the performance of the performer is not good as an instrument with a poor volume balance of each string.

FIGS. 12 to 17 are frequency characteristic diagrams, and the waveforms recorded in FIGS. 6 to 11 are displayed by a spectrum analyzer of the waveform analysis software Sound Engine.
The frequency characteristic diagram is a characteristic around the horizontal axis of 0.1 seconds (black vertical line). The upper part of each figure shows the characteristics of the guitar according to the present invention, and the lower part shows the characteristics of the conventional type guitar.
When observing the frequency characteristics of the 1st string in FIG. 12, the guitar according to the present invention has a higher harmonic level in the vicinity of 1 kHz to 2 kHz than that of the conventional type guitar, and the pronunciation sounds mellow and glossy. Thereafter, similar characteristics can be observed from the 2nd string in FIG. 13 to the 4th string in FIG. 15 and the 6th string in FIG. 17, and a mellow tone can be discriminated in terms of audibility. Musicians with a mellow and glossy sound are preferred by performers.
FIG. 16 shows the frequency characteristics of the five strings, but the conventional type guitar has a higher harmonic level from 1 kHz to 2 kHz. This is because, as described above, the five-string open string (sound name sound) of the conventional type guitar strongly resonates with the sound drum. Many of the characteristics of the five-string open string resonating with the sound cylinder more strongly than other strings are observed on commercial guitars, but the performance of the strings is not good by the performer as an instrument with a poor sound quality balance.

a Surface plate b Side plate c Bridge (piece)
d Saddle e Nut f Sound hole g Recessed surface plate h Neck i String o Support point F Total tension from 1st string to 6th string-Stress to F F1-F component force connecting fulcrum o and upper end of saddle d F2 F1 perpendicular to F1 -F downward component force (normal stress)
H Total height of bridge c and saddle d L String length Θ -An angle formed by F and F1

Claims (2)

A plucked instrument body structure characterized in that the vertical stress due to the tension of the strings does not act on the face plate in a plucked string instrument with a structure in which the string is fastened to a bridge (piece) fixed to the face plate. 2. A surface plate in which a neck and a bridge saddle are installed on a concave surface plate installed in the center of a surface plate bonded to a side plate of a musical instrument in the plucked string instrument of claim 1, and a string position is bonded to the side plate. Surface plate structure characterized by promoting the vibration of the surface plate with the same structure as the extended surface of the surface plate.