An instrument cable connects a guitar, bass, keyboard, or other electronic instrument to an amplifier or preamp that’s intended for direct connection of an instrument. Instrument cables are designed to carry low-voltage instrument signals, and most often have 1/4" phone plug connectors. Depending on the location of the output jack on your instrument, you may want a male jack with a straight or right-angle connector. In deciding how long a cable to buy, keep in mind that longer cable runs are more prone to picking up interference.