How to Tune Using a Line 6 Spider IV 15

By Simon Foden
Adjust the tuning keys in response to the LED display.

The Line 6 Spider IV 15 is a modeling amplifier for the electric guitar. A modeling amplifier has integrated digital effects that emulate the sound of other amplifiers. This makes for a versatile “Jack of all trades” type of amplifier, capable of creating a wide range of usable sounds but lacking a distinctive tone of its own. As well as a range of digital effects, the Spider IV has an on-board tuner. When the tuner is engaged, the LED display that indicates the settings converts into an LED tuner display.

Plug a 1/4-inch jack instrument cable into the input on the amplifier. Connect the other end of the instrument cable into your guitar output jack.

Turn the volume dial down to zero and turn the amplifier on. Gradually increase the volume to a moderate level. The volume level doesn’t influence the tuner directly, but its always smart to start with the volume at zero when turning on your amp. This way there are no unexpected bursts of sound.

Turn the guitar volume dial up to maximum. This ensures that the tuner receives the strongest possible signal from the guitar.

Press and hold the “Tap Tempo” button, located between the “Phaser” and “Tape Echo” dial. The “Tap Tempo” has a dual function. Press it once for the tempo function and hold it to convert the LED display on the dials either side into a visual tuner. Once the tuner is engaged, the amplifier is muted.

Play your bottom E string. The tuner detects the pitch of your string and matches it to the closest open string guitar pitch. For example, if your D string is one step sharp it creates a D sharp note. The tuner detects that the nearest open guitar string note to that pitch is D and subsequently indicates the sharpness.

Monitor the combination of LED lights on the amplifier. If the LED lights next to “Crunch” and “Metal” light up together, the string is in tune. If either “Crunch” or “Clean” are lit up on their own, the string is flat. If the “Metal” or “Insane” LED lights are lit, the string is sharp. The degree of sharpness or flatness is indicated by the distance of the illuminated LED from the tuner button. Since “Insane” is furthest right from the tuner, that indicates a string that is further out of tune than if the “Metal” LED is illuminated.

Relax the tension of sharp strings by turning the tuning key. To determine the correct turning direction, pluck the string and rotate the tuning key half way. If the note increases in pitch when you turn it, turn it in the other direction. If it decreases in pitch when you turn it, continue turning until the “Crunch” and “Metal” lights illuminate together to indicate the string is in tune. For flat notes, increase the pitch of the string by tightening the string. Turn the tuning key in the opposite direction from that which you used to correct sharp notes.


If your strings are constantly going out of tune, replace them with a lighter gauge set.


Turn the tuning key smoothly. Turning too fast can snap the string.

About the Author

Simon Foden has been a freelance writer and editor since 1999. He began his writing career after graduating with a Bachelors of Arts degree in music from Salford University. He has contributed to and written for various magazines including "K9 Magazine" and "Pet Friendly Magazine." He has also written for