EP1280134A1 - Apparatus for controlling an electroacoustic synthesizer for a guitar - Google Patents

Abstract

A guitar synthesiser control has optical transmitter receiver pairs (6, 22-20) above each string (5) to detect the start and end of a note by the plucking or stopping of a string with pitch set by the sum of voltages from the sensors and a resistance chain at the finger position fed from a current source (4). <??>Includes an INDEPENDENT claim for a version using pivoted switches instead of optical sensors.

Description

The invention which is the subject of this patent relates to the field of musical instruments, and more particularly relates to stringed instruments which the instrumentalist plays, either by direct action of the fingers on the strings, or by means of a pick. These instruments include guitars and so-called bass guitars.

Such instruments can be used for purely acoustic sound emission. But they are frequently used under the name of electric guitar, with amplification of their sound level by electroacoustic means.

The device then implemented in principle comprises a transducer element collecting the vibrations created by the strings and transforming them into electrical signals able to be amplified and emitted by a loudspeaker.

However, the sound produced by so-called bass guitars has never been satisfactory. This sound lacks definition in the attack phase and the sound spectrum is limited, especially in the extreme bass. This is why this register is often entrusted to electroacoustic synthesizers which allow the creation of more elaborate sounds. However, these synthesizers are controlled from a keypad whose expression is less fine than that which can be obtained with a string instrument. Indeed, where a synthesizer keyboard is content to press a key to produce a note, the string instrument completes and enriches the expression by allowing the modulation of the pitch of the note by glissando, vibrato, or all other actions of the fingers on the strings.

This is why research has been done to control these synthesizers directly from a guitar. Until now guitarists and bassists wishing to play the electroacoustic synthesizer with their guitar have at their disposal the solution of the converter of the acoustic signal of the string into digital code to MIDI standard. (Musical Instrument Digital Interface) to control the oscillators and envelopes of a synthesizer to this same standard. To do this, an electronic circuit analyzes the waveform generated by the pinching of the string during a wave cycle, before determining the pitch of the note delivered by said string. This reading time is correct for high frequencies, but becomes unacceptable for low frequencies. Indeed, the lowest string of a bass guitar (which is an E) vibrating at 40 Hertz / second, the analysis time of a wave cycle lasts 25 milliseconds. The synthesizer note will therefore only be generated after a delay of 25 ms, which is quite audible. To this delay must be added the delay for coding, serial transmission of MIDI data, as well as the response time of the MIDI synthesizer.

Another solution consists, according to the prior art, in locating the position of the finger on the neck of the guitar. On a stringed instrument, the height of a note produced by a string depends on its length determined by its support on the bridge and by its support on one of the frets embedded in the neck.

By connecting the frets to each other by a resistor, a chain of resistors of equal values is created. This resistance chain is supplied with constant current by a current source. Thus, when the guitarist's finger presses a string on a fret in order to obtain the desired note (in the acoustic field), the string captures the tension present on this fret. This tension being proportional to the pitch of the note, the position of the finger on the neck is thus known.

On the other hand, a synthesizer produces a note when it receives door information in two states: "open or" closed. The door information "open" triggers the start of said note, the door information "closed ", orders it to stop. According to known art, this door information is generated by detecting the peaks of the sound level of the string when it is pinched. Thus when said sound level reaches a certain threshold, the door information" open " This solution however has two major drawbacks: the rise time of said sound level not being instantaneous, it is necessary to take into account a certain time before said sound level reaches the triggering threshold. , when the string is played pianissimo, the low sound level obtained is insufficient to reach the threshold at the start of the note.

According to the invention, the door information is produced by a pair of sensor-optical transmitter, positioned above and parallel to the string, in the region where the finger or the middle finger pinches the string, in order to detect the play with the pick. or pizzicato, and over the whole extent of the neck, using a laser light emitter, to detect the finger when it strikes the string on the neck of the guitar.

When playing pizzicato, the pair of sensor-optical transmitter detects, firstly, the moment preceding the plucking of a string, then in a second time, the plucking of said string. So when the guitarist prepares to pluck a string, he puts his finger on it. In doing so, said finger masks the light of the transmitter. The optical sensor, being masked, produces the "closed" door information. Then, when the finger or the pick picks the string, the optical sensor, lit by the transmitter, produces the "open" door information. said being an optical sensor made up of a phototransistor, the switching speed is very fast, of the order of a few microprobes.

The invention thus makes it possible to detect the action of the finger on a string, while preserving the spontaneous character essential for musical expression.

This device is particularly interesting for detecting finger play, called pizzicato play, played by bass players. By positioning the optical sensor slightly before the string is plucked, a note can be generated with a slight advance, thus anticipating the delay induced by the transmission of digital data which controls the synthesizers meeting the M.I.D.I.

However, when the guitarist or bass player plays pizzicato with the finger, the optical sensor must generate the "open" door information only when said finger plucks the string up and down towards the musician. For this purpose, a second pair of optical sensor-emitter, arranged parallel to the first but set back a few millimeters, is responsible for neutralizing the door information "open" when said finger passes in front of these two sensors, from bottom to top. A third optical sensor-emitter pair, arranged parallel to the previous ones, but a few millimeters lower, is responsible for detecting the finger between the strings. Finally, a key, the operation of which is identical to that of a key on the synthesizer keyboard, detects the finger at the end of the stroke. Each string is associated with such a set of sensors.

• La figure 1 représente, suivant une vue en perspective, une guitare équipée des couples émeteur-récepteur optiques positionnés entre le chevalet et la base du manche de la guitare, ainsi que les émetteurs de lumière laser placés sur la tête du manche
• La figure 2 représente, suivant une vue partielle en perspective, les couples émetteur-récepteur optiques montés entre les cordes d'une guitare.
• La figure 3 représente, suivant une vue en perspective, la réalisation d'un ensemble de trois couples émeteur-récepteur optiques, ainsi qu'une touche articulée dont la fonction est identique à celle d'une touche d'un clavier de synthétiseur. A chaque corde est associé un tel ensemble de capteurs.
• La figure 4 représente le parcours du médiator devant le capteur optique.
• La figure 5 représente le parcours du doigt devant trois capteurs optiques et l'action dudit doigt sur la touche.
• La figure 6 représente le parcours du doigt devant quatre capteurs optiques et l'action dudit doigt sur la touche.
• La figure 7 représente la réalisation du support d'un émetteur laser, et son réglage.
• La figure 8 représente la mise en oeuvre des capteurs optiques et des touches avec deux chaînes de résistances, afin de créer une tension capable de commander les ocsillateurs d'un synthétiseur électroacoustique.
• La figure 9 représente les différents modes de réglage des supports des couples émetteur-cateurs optiques.

The invention will be better understood with the aid of the description below, based on the appended figures in which:

• Figure 1 shows, in a perspective view, a guitar equipped with optical transceiver pairs positioned between the bridge and the base of the guitar neck, as well as the laser light emitters placed on the head of the neck
• Figure 2 shows, in a partial perspective view, the optical transmitter-receiver pairs mounted between the strings of a guitar.
• FIG. 3 represents, in a perspective view, the production of a set of three optical transceiver pairs, as well as an articulated key whose function is identical to that of a key of a synthesizer keyboard. Each string is associated with such a set of sensors.
• FIG. 4 represents the path of the pick in front of the optical sensor.
• FIG. 5 represents the path of the finger in front of three optical sensors and the action of said finger on the key.
• FIG. 6 represents the path of the finger in front of four optical sensors and the action of said finger on the key.
• FIG. 7 represents the production of the support of a laser transmitter, and its adjustment.
• FIG. 8 represents the implementation of the optical sensors and keys with two chains of resistances, in order to create a voltage capable of controlling the ocsillators of an electroacoustic synthesizer.
• FIG. 9 represents the various modes of adjustment of the supports of the optical emitter-cator pairs.

Figure 1 shows , in a perspective view, a guitar equipped with optical transceiver pairs (6) positioned between the bridge (8) and the base of the neck (1) of the guitar, above each string (5) and parallel to these, as well as the laser light emitters (22), positioned on the head of the neck of said guitar, pointing its beam of light towards the sensors (20).

2 shows , in a partial perspective view, the sets of three optical transceiver pairs (6) mounted between the strings (5) of a guitar, between the base of the neck (1), and the bridge (8 ). These sensors are arranged in such a way that when a finger pinches a cord, said finger successively masks the optical sensors and finishes its course by exerting a pressure on an articulated key (7) whose operation is identical to that of a key d '' a synthesizer keyboard.

FIG. 3 represents, in a perspective view, the production of a set of three optical transmitter-receiver pairs (6), equipped with the button (7). Each string is associated with such a set of sensors.

Each optical sensor (36) consists of a phototransistor (37) with a diameter of 3 mm. This phototransistor is included and glued in a 4 mm tube (38) with a length of approximately 3 cm, the opening of which is reduced to 2 mm or 1 mm in order to reduce the visual field and the sensitivity. A version with two phototransistors is produced with two optical fibers (43) inserted in a 4 mm diameter tube (42). This phototransistor-tube assembly is slid into a support tube with a diameter of 5mm (40b) and of the same length secured to the support (33). Facing it by illuminating it, is placed a light emitting diode (39) emitting either in the infrared or in the visible spectrum. This diode, with a diameter of 3mm, is itself included in a 4mm tube (41) whose opening is not reduced, then is slid into the support tube (40a), with a diameter of 5mm which is integral with the support (33). An articulated key (7) identical to a synthesizer keyboard key operating according to the prior art, is placed on the support (33) of the optical sensors. Each string is associated with such a set of sensors

FIG. 4 represents the path of the pick in front of the optical sensor. When the guitarist prepares to pluck a string (5), by blocking it with the pick (M), it masks the light of the transmitter. The optical sensor (1) in the "blocking" state, creates the "closed" door information. If a note has been played previously, it is stopped. When the pick picks the string, the optical sensor is lit by the transmitter, and as it passes, creates the "open" door information.

• figure 5 b : L' information de porte "fermé" est créée quand les capteurs optiques c1 et c2 sont masqués par un doigt. Une note a été jouée précédemment est stoppée.
• figure 5 c : L'information de porte "ouvert"est créée quand le capteur optique c1 est éclairé et le capteur optique c2 masqué. Si le capteur c2 est éclairé, le capteur c1 est neutralisé afin d'empêcher ce capteur c1 de crée l'information de porte "ouvert" quand le doigt passe devant c1 de bas en haut. Autrement dit, le capteur c1 est neutralisé quand le capteur c2 est éclairé avant le capteur c1. Le capteur c3 neutralise, quand il est masqué, les capteurs c1 et c2 de la corde adjacente inférieure afin d'éviter ces mêmes capteurs de créer l'information de porte "fermé".
• figure 5 d : La touche 7, par le contact c4, crée l'information de porte "ouvert" si les capteurs c1 et c2 sont masqués . En effet le jeu pizzicato se jouant avec l'index et le majeur, en alternance, il peut arriver, dans certaines conditions, que l'action du doigt qui pince la corde soit masquée, vis à vis des capteurs c1 et c2 par l'autre doigt qui prépare cette même action. Dans ce cas, la touche 7 crée l'information de porte "ouvert" quand les capteurs c1 et c2 sont masqués.

FIG. 5 represents the path of the finger in front of three optical sensors, and the action of said finger on the key: the pizzicato game being played with the index and middle fingers, alternately, the first optical sensor (c 1 ) does not generate l door information "open" only when the finger plucks the string up and down towards the musician. The "open" door information is therefore neutralized when said finger passes in front of this sensor in the opposite direction, from bottom to top. For this purpose, a second optical sensor-emitter pair (c2) is arranged parallel to the first but set back a few millimeters. A third optical sensor-emitter pair (c3) is also arranged parallel to the previous ones, but a few millimeters lower, in order to detect the finger between the strings. Finally, a key (7) whose operation is identical to that of a synthesizer keyboard key is responsible for detecting the finger at the end of the stroke. The signals from the sensors are processed through logic circuits in such a way that:

• figure 5 b : The "closed" door information is created when the optical sensors c1 and c2 are masked by a finger. A note previously played is stopped.
• Figure 5 c : The "open" door information is created when the optical sensor c 1 is lit and the optical sensor c 2 hidden. If the sensor c 2 is lit, the sensor c 1 is neutralized in order to prevent this sensor c 1 from creating the "open" door information when the finger passes in front of c 1 from bottom to top. In other words, the sensor c 1 is neutralized when the sensor c 2 is lit before the sensor c1. The sensor c 3 neutralizes, when it is hidden, the sensors c 1 and c 2 of the adjacent lower cord in order to avoid these same sensors from creating the "closed" door information.
• Figure 5 d : The key 7 , through the contact c 4 , creates the door information "open" if the sensors c 1 and c 2 are hidden. Indeed, the pizzicato game is played with the index and middle fingers, alternately, it may happen, under certain conditions, that the action of the finger which plucks the string is masked, with respect to the sensors c 1 and c 2 by the other finger which prepares this same action. In this case, key 7 creates the "open" door information when the sensors c 1 and c 2 are hidden.

FIG. 6 represents the path of the finger in front of four optical sensors and the action of said finger on the key. These sensors make it possible to know the speed of the finger before the attack on the note. The acquired value is assigned, when the note is attacked, to the level control of an amplifier, or to the velocity. Velocity is a parameter of the MIDI standard. (Musical Interface for Digital Instrument) which controls the sound level of the synthesizer: the value 127 produces the highest sound level, the value 1 produces the lowest level. The value 0 stops the note. This device makes it possible to follow the nuances of dynamics of the musician's game.

• figure 6 b : En jouant pizzicato, le doigt pince la corde (5)vers le musicien. Ce faisant, les capteurs optiques c1a et c1b sont exposés à la lumière l'un après l'autre. Lorsque le capteur optique c1a est éclairé, il déclenche le départ d'un décompteur numérique. Le décompte étant sur 7 bits, il débute à 127 et décompte jusqu'à 1 en une fraction de seconde. Le décompte est stoppé et mémorisé quand le capteur optique c1b est exposé à la lumière, lequel capteur crée l'information de porte "ouvert". Le résultat du décompte est attribué au message M.I.D.I. vélocité. En effet, il y a un rapport direct entre la vitesse et la puissance du pincement de la corde. Plus le temps écoulé entre l'éclairement des capteurs c1a et c1b est court, plus le chiffre du décompte est élevé et plus le niveau sonore du synthétiseur est élevé. Le capteur optique c1b n'est opérant que si le décompteur est enclenché. Cette caractéristique empêche c1b de créer l'information de porte "ouvert" quand le doigt passe devant ce même capteur c1b avant le capteur c1a, de bas en haut.
• figure 6 a : L'information de porte "fermé"est généré quand les capteurs c1b et c2 sont masqués. Le décompteur est également mis à zéro. En langage M.I.D.I., si la vélocité égale 0 , la note est stoppée. Le capteur c3 neutralise, quand il est masqué, les capteurs c1a, c1b et c2 de la corde adjacente inférieure, masqués par le doigt en fin de course. L'information de porte "fermé" non désirée est ainsi évitée.
• figure 6 d: Les contacts c4a et c4b de la touche 7 opèrent comme les capteurs c1a et c1b. Le contact c4a déclenche le décompteur, lequel décompteur est stoppée quand le contact c4b est établi, lequel déclenche l'information de porte "ouvert". Les contacts c4a et c4b opèrent uniquement si les capteurs c1b et c2 sont masqués par un doigt. En effet, tel que dit précédemment, le jeux pizzicato se jouant avec l'index et le majeur en alternance, il se peut que l'action du doigt qui pince la corde soit masqué, vis à vis des capteurs optiques c1b et c2 par l'autre doigt qui prépare cette même action. Dans ce cas, les contacts c4a et c4b sont opérants .

The signals from the sensors are processed through logic circuits in such a way that:

• figure 6 b : While playing pizzicato, the finger plucks the string (5) towards the musician. In doing so, the optical sensors c 1a and c 1b are exposed to light one after the other. When the optical sensor c 1a is lit, it triggers the start of a digital down-counter. The count being on 7 bits, it starts at 127 and counts down to 1 in a fraction of a second. The countdown is stopped and memorized when the optical sensor c1b is exposed to light, which sensor creates the "open" door information. The count result is assigned to the MIDI velocity message . In fact, there is a direct relationship between the speed and the power of the chuckle. The shorter the time between the illumination of sensors c1a and c1b , the higher the counting number and the higher the sound level of the synthesizer. The optical sensor c1b only operates if the down-counter is activated. This characteristic prevents c1b from creating "open" door information when the finger passes in front of this same sensor c1b before the sensor c1a, from bottom to top.
• Figure 6 a : The "closed" door information is generated when the sensors c1b and c2 are hidden. The down counter is also set to zero. In MIDI language, if the velocity equals 0, the note is stopped. The sensor c3 neutralizes, when it is masked, the sensors c1a , c1b and c2 of the lower adjacent cord , masked by the finger at the end of the stroke. Unwanted "closed" door information is thus avoided.
• Figure 6 d : The contacts c4a and c4b of the button 7 operate like the sensors c1a and c1b . The contact c4a triggers the down-counter, which down-counter is stopped when the contact c4b is established, which triggers the door information "open". The contacts c4a and c4b operate only if the sensors c1b and c2 are hidden by a finger. Indeed, as said previously, the pizzicato games being played with the index and middle fingers alternately, it may be that the action of the finger which pinches the rope is masked, vis-à-vis optical sensors c1b and c2 by the other finger which prepares this same action. In this case, the contacts c4a and c4b are operational.

Figure 7 shows the realization of the support of a laser transmitter.

The purpose of these laser light sensors is to detect the action of the finger when it strikes the string on the neck of the guitar.

Figure 7a : Above each string and parallel to it, between the bridge (8) and the head of the neck (1) of the guitar is scattered a beam of laser light. Each laser light emitter (22) is positioned on the head of the handle, in the axis of the cord which corresponds to it.

The sensor, which faces each laser transmitter, consists of an optical fiber (20), guiding the laser light towards a phototransistor (21). Each optical fiber is inserted into a tube with an inside diameter of 2mm, attached alongside the other sensors, above each cord. Thus, each support (33) of the optical assemblies described above makes it possible to point each optical firearm perfectly towards the laser transmitter.

Figure 7b : The laser beam deflects, by design, at an angle of about 2 or 3 degrees relative to an x axis, parallel to the cylindrical housing (22) containing the laser diode. By rolling this box on itself, the laser beam describes a circle c in space.

FIG. 7c : by positioning the laser beam, by rotation on itself, at point X overhanging the optical sensor, it suffices to lower the laser beam to make this laser beam coincide with the optical sensor (20).

Figure 7d shows the embodiment of the support of the laser housing: said cylindrical housing (22) containing the laser diode, is inserted into a metal tube (23) whose inner diameter is 0.5mm smaller than the outer diameter of said housing. This tube is split in the longitudinal direction and has a certain elasticity making it possible to insert and maintain therein said housing firmly, while leaving it the possibility of turning on itself.

This tube (23) is integral with a support (24) which pivots, along an axis, in a cradle (26) screwed on the head of the neck of the guitar by two screws (28). The pivot is provided by a screw (25) which passes through said cradle and is screwed into the support (24). The action on the support (24) of two screws (27) screwed into the bottom of said cradle and located on either side of the y axis, allows the laser beam to go up or down. In feedback, the two screws (27) and the screw (25) block the support (24) of the laser housing once the setting found. Thus the action on the x and y axes allows the laser beam to coincide perfectly with its optical sensor.

So when the guitarist strikes a string on the neck of the guitar, he cuts the laser beam. Its optical receiver (20) being masked, creates the "open" door information. Conversely, said receiver creates "closed" door information when it is lit.

Thanks to these laser sensors, it is also possible to know the speed of the finger between the moment when said finger cuts the laser beam, and the moment when this same finger touches a hoop. As explained below, the frets are traversed by a constant current. So when the string picks up the tension produced by the hoop, the door information is produced with speed information.

FIG. 8 represents the device for implementing the optical sensors and keys with the aim of creating a control voltage, which controls the oscillators controlled by a voltage of an electroacoustic synthesizer. At the same time, said sensors create "open" or "closed" door information, which information controls the beginning or the end of the note created by this same electroacoustic synthesizer.

• 1) L'information de porte produite par chaque ensembles de capteurs (6), commande une des voies d'un organe connecteur (14) dont chacune des voies est reliée aux bornes des résistances d'un pont de résistance d'égales valeurs (15), alimentée en courant constant par une source de courant (16). Lorsqu'un doigt ou un médiator sollicite un des ensemble de capteurs, ces mêmes capteurs commandent l'ouverture ou la fermeture de la voie correspondante de l'organe connecteur. La tension collectée à la borne de chaque résistance est proportionnelle à la hauteur de la corde correspondante, et définit une tension vB. Une guitare étant accordée en quarte, le passage vers une corde accordée cinq demi-tons plus haut élève la fréquence de l'oscillateur commandé en tension dudit synthétiseur de cinq demi-tons.
• 2) La deuxième chaîne de résistance d'égales valeurs est réalisée en reliant chaque frette (2) du manche de la guitare par une résistance (3), laquelle chaîne de résistance est alimentée en courant constant par une source de courant (4). Chaque progression d'un demi-ton sur le manche de la guitare module l'oscillateur d'un demi-ton. Seule la frette la plus haute est prise en compte. Ainsi, lorsque le doigt appuie une corde (5) sur une frette (2), pour obtenir une note dans le domaine acoustique, la corde capte la tension présente sur ladite frette. Cette tension, prélevée sur la corde, définit une tension vA . L'addition des deux tensions vA et vB commande la hauteur des oscillateurs, commandés par une tension, dudit synthétiseur. Parallèlement, cette tension est convertie au travers d'un convertisseur volt -> message M.I.D.I., afin de commander un synthétiseur répondant à la norme M.I.D.I. Dans le même temps, l'information de porte "ouvert" ou "fermé" produite par les capteurs commande les enveloppes de ce même synthétiseur, lesquelles enveloppes commandent le départ ou la fin de la note par l'intermédiaire de divers modules de synthèse tels qu'un amplificateur ou un filtre.

To create the control voltage, there are two chains of resistors of equal value:

• 1) The door information produced by each set of sensors (6), controls one of the channels of a connector member (14) each of which channels is connected to the terminals of the resistors of a resistance bridge of equal values ( 15), supplied with constant current by a current source (16). When a finger or an pick picks up one of the set of sensors, these same sensors control the opening or closing of the corresponding channel of the connector member. The voltage collected at the terminal of each resistor is proportional to the height of the corresponding string, and defines a voltage vB. A guitar being tuned in fourth, the passage towards a chord tuned five semitones higher raises the frequency of the oscillator controlled in tension of said synthesizer by five semitones.
• 2) The second resistance chain of equal values is produced by connecting each fret (2) of the neck of the guitar by a resistance (3), which resistance chain is supplied with constant current by a current source (4). Each semitone progression on the guitar neck modulates the semitone oscillator. Only the highest fret is taken into account. Thus, when the finger presses a string (5) on a hoop (2), to obtain a note in the acoustic field, the string picks up the tension present on said hoop. This voltage, taken from the string, defines a voltage vA . The addition of the two voltages vA and vB controls the height of the oscillators, controlled by a voltage, of said synthesizer. At the same time, this voltage is converted through a volt -> MIDI message converter, in order to control a synthesizer meeting the MIDI standard. At the same time, the "open" or "closed" door information produced by the command sensors the envelopes of this same synthesizer, which envelopes control the start or the end of the note via various synthesis modules such as an amplifier or a filter.

FIG. 9 represents the various modes of adjustment of the supports of the optical transmitter-sensor pairs. The sensor support settings are made along two axes: Let an x axis perpendicular to the body of the guitar and a y axis parallel to the body of this same guitar, and perpendicular to the x axis. The support (33) of the optical sensor (36), movable along the y axis, is fixed to a rail (35) by a bolt (32). This rail is adjustable in height along the x axis by the action of the two round head hexagon screws (30) taking support under the rail and screwed onto the plate (34). These screws are adjusted from above. This rail is slightly milled opposite the round heads of the hexagon screws in order to maintain its alignment along the y axis. A screw (31) blocks the adjustment of the screws (30) by pressing on the rail (35) and by screwing on the plate (34).

Claims (9)

Electroacoustic synthesizer control device for guitar, said synthesizer being controlled, to produce the beginning or the end of a note, by "open" or "closed" door information created by sensors, characterized in that said sensors, attached to a guitar and associated with each string, are sensitive to movement of the fingers or the pick on said string. Synthesizer control device according to R.1, characterized in that said sensors are pairs of optical transmitter-sensors (6) fixed on the guitar, above each string (5), and parallel to them, between the easel (8) and the base of the handle (1). Synthesizer control device according to R.2, characterized in that said sensors are three pairs of optical emitter-sensors positioned parallel one after the other, on the path that the finger takes when pinching the string, in order to '' evaluate the speed and the direction of passage of the finger in front of said sensors. Synthesizer control device according to R.1, characterized in that said sensors are articulated keys (7), the operation of which is identical to that of a synthesizer keyboard key, said keys being placed between the strings (5 ), parallel to these, between the bridge (8) and the base of the neck (1), in order to deliver the information of note pitch, start and end of note, pressing speed, and pressure of said key. Synthesizer control device according to R.1 characterized in that each sensor assembly (6), associated with a cord (5), controls one of the channels of a connector member (14) each input of which is connected to the terminals of the resistors of a resistance chain of equal values (15), supplied with constant current by a current source (16), said connector member having as many channels as there are strings Synthesizer control device according to R.5 characterized by the addition to the voltage collected at the outlet of said connector member (14), of a voltage sensed by the string (5) on the frets (2), said frets being connected one by one by a resistor (3), thus forming a chain of resistors of equal values, supplied with constant current by a current source (4). Synthesizer control device according to R.1, characterized in that each sensor assembly associated with a string controls the contacts of a key on a synthesizer keyboard. Synthesizer control device according to R.1, characterized in that the sensors are optical sensors (20) located above each string, each being illuminated by a beam of laser light, produced by a laser diode (22), diffused over the entire extent of the neck of the guitar, above each string and parallel to them, in order to assess the speed d '' a finger between the rupture of said laser beam by said finger, and the contact of the string with the frets of said guitar neck, said frets being supplied with constant current by a current source (4), said strings being metallic and insulated electrically between them. guitar, characterized in that it is provided with a control device according to any one of the preceding claims.

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