Through experimentation while on the stage and in the studio, revelations both sonically and as they pertain to design have allowed me and the gifted team at MM to update and improve the features of the JP over the years. The 13 marks the first time a preamp circuit has been introduced in this guitar along with a solo boost conveniently accessed from the volume knob. The enhanced tonal range and openness is noticeable and welcomed from the moment you plug it in. - John Petrucci