The Korg GT-3 is a dedicated guitar and bass tuner aimed toward the entry-level user. Only standard tuning is supported, six strings for guitar and four for bass. It is simple to operate, having the advantage of easy-to-read light-emitting diodes (LEDs) that are useful in dark stage conditions. This feature makes the GT-3 attractive to advanced players who use only standard tuning under performance conditions. Though no longer manufactured or supported by Korg, the GT-3 is easy to find in the used equipment market.
Use the internal microphone to tune acoustic guitars. Pluck a string and the tuner will automatically switch to the nearest note, indicating sharpness with LEDs to the right of centre and flatness with LEDs to the left. Turn the mechanical tuning peg on your guitar to bring the lit LED to the centre. Repeat for the remainder of the strings on the guitar.
Connect an electric guitar or bass using a 1/4-inch phone plug guitar cable to the input on the GT-3, which is indicated by a left-pointing arrow on the tuner. Tune your instrument the same way as described for acoustic guitars.
Connect the output of the GT-3 to the input of an effects pedal or pedal board. The output is indicated by a right-pointing arrow, and uses a 1/4-inch phone plug connection as well. This keeps the tuner in the guitar signal path for performance use.
You may get better results by plugging into the GT-3 as ambient noise no longer enters the built-in microphone to influence tuning results. Generally, a bridge pickup will give more fundamental tone information from a guitar string and so works better for tuning on guitars with more than one pickup.
Be careful not to overtighten a string that is not indicating proper tuning on the GT-3. Guitar strings work under tension and may snap if tuned higher than specification.