A system to reproduce the sound of a stringed instrument comprising hammers striking strings, said system comprising: - speed detection means to be coupled with each hammer to detect the percussion velocity on the string, - a plurality of note modules, equal to the number of hammers, receiving in input from the speed detection means a signal representative of the hammer velocity and generating a force signal ( F tot) representative of all the partial components of the string vibration, and - a soundboard-instrument body module receiving in input said force signal representative of all the partial components ( F tot) from each note module and generating two electrical signals ( left, right) adapted to power two electroacoustic transducers for sound emission; wherein said note module comprises: - a hammer module receiving in input said signal representative of the hammer velocity and generating a force signal ( F h) reproducing the evolution across time of the force with which the hammer strikes the strings of the key when playing ff "fortissimo" dynamics and a resonance impulse signal ( F h,res) reproducing the evolution across time of the force transmitted to the strings by the hammer when playing ff "fortissimo" dynamics, both the force signal ( F n) and the resonance impulse signal ( F h,res) in function of the hammer impact velocity, - a primary and longitudinal resonator module receiving in input said force signal ( F h) from the hammer module and generating a force signal ( F prim+quad) representative of the linear and quadratic primary component of the string vibration and a force signal ( F long) representative of the longitudinal component of the string vibration, - a secondary resonator module receiving in input said force signal ( F h) from the hammer module and an active note signal ( F c) obtained from the sum of said resonance impulse signals ( F h,res) and said force signals representative of linear and quadratic primary component ( F prim+quad) of all the note modules and generating a force signal ( F sec) representative of the secondary component of the string vibration, and - a duplex resonator module receiving in input a force signal ( F c, duplex) obtained from the sum of said resonance impulse signals ( F h,res) of all the note modules and generating a force signal ( F duplex) representative of the duplex oscillatory component of the string vibration, said force signal representative of linear and quadratic primary component force signal representative of longitudinal component ( F long), force signal representative of secondary component ( F sec) and force signal representative of duplex component ( F duprex) being summed in each note module in such manner to obtain said signal representative of all the partial components ( F tot) to be sent to said soundboard-instrument body module. - speed detection means to be coupled with each hammer to detect the percussion velocity on the string, - a plurality of note modules, equal to the number of hammers, receiving in input from the speed detection means a signal representative of the hammer velocity and generating a force signal ( F tot) representative of all the partial components of the string vibration, and - a soundboard-instrument body module receiving in input said force signal representative of all the partial components ( F tot) from each note module and generating two electrical signals ( left, right) adapted to power two electroacoustic transducers for sound emission; - a hammer module receiving in input said signal representative of the hammer velocity and generating a force signal ( F h) reproducing the evolution across time of the force with which the hammer strikes the strings of the key when playing ff "fortissimo" dynamics and a resonance impulse signal ( F h,res) reproducing the evolution across time of the force transmitted to the strings by the hammer when playing ff "fortissimo" dynamics, both the force signal ( F n) and the resonance impulse signal ( F h,res) in function of the hammer impact velocity, - a primary and longitudinal resonator module receiving in input said force signal ( F h) from the hammer module and generating a force signal ( F prim+quad) representative of the linear and quadratic primary component of the string vibration and a force signal ( F long) representative of the longitudinal component of the string vibration, - a secondary resonator module receiving in input said force signal ( F h) from the hammer module and an active note signal ( F c) obtained from the sum of said resonance impulse signals ( F h,res) and said force signals representative of linear and quadratic primary component ( F prim+quad) of all the note modules and generating a force signal ( F sec) representative of the secondary component of the string vibration, and - a duplex resonator module receiving in input a force signal ( F c, duplex) obtained from the sum of said resonance impulse signals ( F h,res) of all the note modules and generating a force signal ( F duplex) representative of the duplex oscillatory component of the string vibration,