Resolving Tube Amp Hum, Buzz, or Hiss
In this guide, we will show you how to diagnose and remove unwanted noise (buzz or hum) from tube amplifiers. We recommend temporarily removing any pedals or effects from your rig so that only the guitar is connected directly to the amplifier. Testing your amp this way limits how many variables there are to consider. Follow each of the sections below to get started.
Tube Amps: Noise and Volume
While it’s perfectly normal for a tube amplifier to produce fairly significant amounts of noise (especially when compared to a solid state amp) there are several reasons an amp can produce extraneous noise. The difficult part is determining which is which and how much is too much.
Electronic Noise, Tube Noise, and Noise Floor
It’s important to note that most tube amps are made completely from analog components and each component, to varying degrees, contributes to the amp’s analog noise floor, or self-noise. If your amp is working normally, it should seem like the noise floor disappears as soon as you start playing.
Hissing Sound
The “hissing” sound your amp makes normally won’t drown out the sound of your playing. If this is the case, it might be time for new tubes. Learn more about replacing tubes in our Tube Amp FAQ.
Gain, Volume, and Self-Noise
The amplifier’s power rating (wattage) can impact the noise floor level. If you have a 100-watt tube amp, it’s probably going to make more noise than a 15-watt tube amp. Also, if your amp is designed for high gain settings, it will most definitely make more noise than an amp designed to run cleaner.
The higher you crank up the gain on your amp, the more noise it’s going to make. If you want more distortion or overdrive, then noise is an inherent part of obtaining that sound. To get a louder clean tone, try turning down the gain and turning up the master volume.
Tube Amp Troubleshooting
Tubes will make a myriad of strange and seemingly inexplicable sounds. The one thing they won’t do is hum. It can, however, seem that way if one or more power tubes go out. When this happens, the natural hum from your power transformer is no longer being phase canceled by the tube that just died. This makes it seem like a bad tube is humming, but in reality, it just isn’t silencing the hum anymore. That’s pretty rare, but if it does happen you’ll need to replace the power tubes. More often than not, when your amp is making a humming sound, it’s caused by dirty power, a bad ground connection, or fluorescent lighting. Below are a few things to consider when dealing with this pesky hum.
Isolate the Sound or Noise
The fastest way to solve humming issues in a tube amp is to figure out what is causing the hum. Is it coming from the amp or somewhere else? To find out, disconnect all cable(s) connected to the amp’s inputs and listen to see if the hum goes away. If the hum is no longer present, then it may be caused by either a ground loop or cable/pedal placed before the input or in an effects loop. From here you may decide to replace a power cable or use different configuration(s) to power your rig until the hum goes away.
Electrical Hum or Buzz Sounds
Cellular devices and fluorescent lighting will introduce extra noise when located too close to an amp or guitar. To test this, try moving the phone away from the amp, or the amp further away from the light(s). If the noise lessens or disappears, you’ve found the culprit.
Power Conditioners
A power conditioner is an invaluable tool for preventing extra noise introduced by dirty power. Some conditioners have noise filtering technologies to ensure a noise-free power supply regardless of the location.
Ground Lift Switches
Some devices have built-in ground lift switches, like DI boxes and some amplifiers, and are your first line of defense for identifying and removing ground loop hum. If after safely lifting the ground you still hear humming, the problem is likely at another point in the setup. If the buzz or hum persists, a ground loop hum adapter can be used to identify a ground loop. The cheap three-prong to two-prong plugs remove the center pin, or ground, and are not safe for general operation. While they are a quick way to identify a ground loop, they are in no way a proper solution. We recommend a safer way, like using the Hum X Ground Loop Hum Exterminator or CleanBOX II 2-Channel Hum Eliminator.
Guitar Pickup Feedback
Since tube amps are made of transformers and other electromagnetic susceptible components, live guitar pickups should not get too close to an amplifier. When you want to change settings and walk up to your amp, the magnetic pickups are now close enough to all the humming parts within your amp to pick them up, too. The effect is a feedback loop produced by the amp feeding the guitar, which feeds the amp, which then feeds the guitar again, and so forth. Your amp will amplify not only the guitar but also any of the extra noise present in its electronics.
Humbucking and noiseless pickups
Moving away from the amplifier will help a ton, but the type of pickup matters, too. Humbuckers are designed to reduce the amount of noise transferred to the amplifier by using two coils with opposite polarity (this cancels or bucks the hum). They aren’t perfect but do essentially cancel out any noise that may come through. Single coil pickups, on the other hand, only have one coil (hence the name) and are much more susceptible to additional noise interference.
Related Content
- Tube Amp FAQ
- Tube Amp Troubleshooting Guide
- How to Replace Tubes in Your Guitar Amp
- Amp Anatomy: How Power Tubes Affect Your Tone
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