In this paper we describe a new guitar-like musical controller. The ’GXtar’ is an instrument which takes as a starting point a guitar but his role is to bring different and new musical possibilities while preserving the spirit and techniques of guitar. Therefore, it was conceived and carried out starting from the body of an electric guitar. The fingerboard of this guitar was equipped with two lines of sensors: linear position sensors, and tactile pressure sensors. These two lines of sensors are used as two virtual strings. Their two ends are the bridge and the nut of the guitar. The design of the instrument is made in a way that the position of a finger, on one of these virtual strings, corresponds to the note, which would have been played on a real and vibrating string. On the soundboard of the guitar, a controller, with 3 degrees of freedom, allows to drive other synthesis parameters. We then describe how this interface is integrated in a musical audio system and serves as a musical instrument.