Why Does Your Guitar Amp Hum When Not Touching Strings?

Unwanted noises from your amp are one of the most common and annoying problems guitarists can experience. As with any electric instrument, making an electric guitar sound the way you want can be challenging. Actually, it can sound quite bad if you experience a humming or buzzing issue.

The guitar amp hum when not touching strings can have many reasons, but the most common cause is grounding issues. When the amp is not adequately earthed, the player’s hand acts as the grounding connection with the contact between the hand and the strings. This grounds the electric flow, stopping the hum.

The grounding issue can be caused by the amp, cable, pedals, or the electric outlet if the grounding of any of these parts is broken. Also, interference and shielding problems can cause the guitar to buzz.

Luckily, grounding problems are pretty easy to fix. So read on if you want to learn more about the guitar amp hum and ways to fix it!

Why Does Guitar Amp Hum Happen?

The main reason behind the guitar amp humming is the grounding problems, which can be caused by the earthing problems on the amp, cable, pedals, or electric outlet. When you touch the strings, your body acts as the grounding, which silences the hum.

The guitar amp hum happens because the low voltage in the electric signal does not get grounded. So, when the main electric signal goes through a transformer, the transformer’s low voltage side does not get grounded and floats through the signal. As a result, the 0Vdc side of the rectifier, which is actually the part that is plugged into the guitar, floats at the main current flow. 

This is not a problem for the amp’s circuit, as all the rectifier voltages flow together in the amp. However, it is a problem for the metal parts of the guitar, as they will have a flow in potential at a harmonic of the main frequency. This is the technical reason behind the guitar amp hum. If the grounding works properly, this current gets grounded, not reaching the metalwork of the guitar, preventing any unwanted noise.

How to Fix The Guitar Amp Hum?

Change The Cable

The easiest thing you can do is to check if the cable is the source of the problem. You can basically try playing with a different cable and see if the hum is still there or not. If not, your cable’s grounding wire was broken, and that was the cause of the hum. If the hum is still there, you have to check other parts in your signal chain.

Check The Amp

Sometimes, the grounding wire of the amps gets loose, causing the hum in the guitar. If you are moving your amp a lot or traveling with it, it is more likely that you will encounter this problem. If you find out that your amp is the cause of the hum, you will have to take it to a professional to fix it.

To find out if your amp is having this problem, you can try your guitar and setup with another amp to see if they work properly. Any guitar shop will allow you to test your gear, or you can also borrow from a friend if you don’t have another amp in your house.

Check The Pedals

Another reason could be the pedals in your setup as well as your power supplies. Using a power supply for multiple pedals can cause a grounding issue. Try to plug your guitar directly into the amp to see if the hum is still occurring or not.

Then, you can start to take your pedals one by one to figure out which pedal is the source. Also, you can try to power your pedals with batteries to see if the problem is with the power supply.

Check Your Guitar

If the problem is not with your amp, cable, pedals, or the power supply, you should check the grounding wire of your guitar. Every electric guitar has a grounding wire for the metal parts of the instrument. Sometimes, this wire gets broken or loosened, which creates a humming sound.

Some guitars have the grounding wire on the backside of the body where the tremolo strings are located. With these guitars, it is easy to check the wiring. However, some guitars, like Fender Stratocasters, have them inside the body, which means you will have to remove the strings and the pickguard. Check clearly if the wires are well connected to the pots and ends.

Check The Power Outlet

Although rarely, the problem is with the power outlet. You can plug your setup into another power outlet to see if the problem persists or to be sure, you can go to a friend’s house and use the sockets there to see if anything changes.

So, if you find out that using another power outlet solves the problem, you will have to call an electrician to fix the power outlets in your house. There might be a problem with one of the sockets in your house, or it could be a general problem with your house’s circuit.

Other Reasons for Guitar Amp Hum

Shielding

Another reason for guitar hum is shielding issues. If the hum occurs when you touch the strings but gets silenced when you play a note, it is likely a shielding issue you face. Putting adhesive copper tapes to electronic cavities will solve the problem. 

60 Cycle Hum

60-cycle hum or mains hum is created by single coil pickups, as they are like antennas and pick up more noise compared to humbuckers. The mains hum is always apparent and does not disappear when you touch the strings or play a note.

The solution is to change your single coils with better pickups that pick up less noise. You can go for noiseless single-coil pickups specially designed to prevent this issue.

Fret Buzz

A different kind of noise annoying for guitarists is the fret buzz. The reason is that the strings are located too close to the frets and hit the frets when they vibrate. The nut, the guitar action, and the truss rod adjustment are the usual suspects of fret buzz issues.

Conclusion

So, the main reason behind the guitar amp hum is the grounding problems that can be caused by your cable, amp, pedals, power supply, guitar, or power outlet. You might have to check these elements one by one to figure out the cause of the problem. And when you do, it is pretty easy to solve it either by yourself or with a technician.