Violin completely losing tension. A violin in which the tuning pegs are slipping needs to be repaired by a luthier or violin repairperson. Peg dope or peg compound, used regularly, can delay the onset of such wear, while allowing the pegs to turn smoothly. The tuning G–D–A–E is used for most violin music, both in Classical music, jazz and folk music. Other tunings are occasionally employed; the G string, for example, can be tuned up to A. The use of nonstandard tunings in classical music is known as "scordatura"; in some folk styles, it is called "cross tuning". One famous example
Electric violin to an independent MIDI channel. Most recently, Keith McMillen of Keith McMillen Instruments, a founder of Zeta Music, announced the StringPort polyphonic string-to-USB 2.0 converter for the Zeta polyphonic pickup and other modern polyphonic violin systems. Whilst no other dedicated violin-to-MIDI systems have been manufactured, more generic pitch-to-MIDI systems like those from Roland, and Yamaha can be adapted to use standard electric violin output. Most systems allow only monophonic operation—only one pitch can be detected and digitised at a time—but through the use of proprietary pickups, some limited MIDI polyphony can be achieved. Some pitch to MIDI interfaces from Axon/TerraTec