Electric Guitar 'String Ground'
What Is A "String Ground Wire"
In electronics, “ground” is the term used to refer to the common return path of an electric circuit. Ground connections are an essential aspect of your instruments wiring. They are required for the proper functionality and safety of your guitar and amplifier.
The design of most electric guitar pickups are by definition “electromagnets”. As electromagnets, they are prone to something called electromagnetic interference or EMI. Potential sources of EMI are all around us: cell phones, radios, computers, and fluorescent lights are just a handful of common sources. To compound the issue, the human body is a natural antenna for electromagnetic interference.
When near the guitar, the human body naturally increases interference in the circuit. We may hear this as hiss and noise through the amplifier.
To eliminate the EMI that a player inherently adds to the signal, a wire is attached in such a way as to connect the guitar strings to the instrument’s electronic ground.
While the player touches the strings, this wire effectively cancels out the noise that their body adds to the signal by giving it a path to ground. This crucial length of wire is known as the “String Ground Wire”.
If touching the strings of your guitar makes the instrument quieter, your guitars string ground is functioning properly.
In the example above, a wire is connected to the “tremolo claw” of a Fender Stratocaster. The attached springs connect to the tremolo block at the bottom of the photo, which in-turn holds the ball-end of the guitar strings. Since all of these metal pieces are electrically conductive, the ground wire is effectively connected to the strings and therefore the player as they touch them during use. When the player removes their hands from the strings, their body is no longer connected to the electronics ground, therefore additional noise may return. This is perfectly normal and in keeping with the circuits design.
'String Ground' Installation on an Archtop Guitar
This Peerless Imperial model guitar is fitted with electronics reminiscent of those used during the golden age of archtop guitars from makers such as D’Angelico and D’Aquisto. It features a “floating pickup” mounted at the end of the fingerboard, with volume and tone controls attached to the pickguard, wired to a side mounted output jack.
Since guitars of this ilk were primarily designed to be acoustic instruments, the electronics are set away from the guitars top. This allows it to vibrate unobstructed by the added weight and sound dampening properties that could occur with other methods of installation.
One important feature this particular model lacks is a string ground wire.
In electronics, “continuity” means that there is a link between two given points; they are electronically connected to one another. To test for continuity, we use a multimeter with one lead clipped to a guitar string and the other lead grounded. In the photo, the meter shows “open lead”, indicating that there is no continuity; the string is not connected to ground. This means there is no string ground wire!
After talking with the client, and confirming that he often found the instrument to be noisy, we got approval to modify the electronics for quieter operation.
Since most metals conduct electricity, instruments with a metal bridge or tailpiece can be grounded by simply attaching a length of wire from either component to the electronic ground. As explained above, this will create continuity to the metal strings which are in contact with it.
Since wood does not conduct electricity, it is a bit more complicated to wire a string ground on this instrument on account of the floating bridge’s wooden base and the tailpiece’s largely wooden body.
Fortunately, we were able to modify the tailpiece by attaching a wire underneath the metal string plate on the top side, then running it underneath to the metal mounting bracket. We used some copper tape to hold it in position. True to the manufacturers aesthetic, once installed, the wire is out sight and free from the top.
After connecting the mounting bracket of the modified tailpiece to ground, the multimeter now shows a reading, indicating that there is continuity. The string ground is functioning properly.
Having retrofitted this important piece, the guitar should be much quieter during use. Touching the strings will now ground the player and cut down on unwanted noise.
My Guitar Has A String Ground, But It Still Buzzes!
A string ground wire is just one tool in the kit of reducing unwanted noise in your guitars signal path. In extremely EMI intensive environments, shielding the instruments control cavities can provide additional noise relief.
Neither a string ground, nor shielding, will eliminate the 60-cycle hum that is inherent to single coil pickup designs. Nor will it eliminate noise from sources further down the signal chain such as bad cabling, effect pedals, pedalboard power supplies, amplifiers, etc. In these cases, further troubleshooting may be necessary to isolate the cause of the noise!
About Guitar Repair Long Island
Guitar Repair Long Island is the area’s premier destination for fretted musical instrument care and maintenance. Led by owner/head technician Erik Salomon, the shop is dedicated to providing quick, honest, and reliable service. Our vast experience in all aspects of instrument repair ensures that we can help with whatever your needs are. Contact us with any questions or book your appointment today.