Whether you just bought your first tube amp or you’re a valve veteran, it always seems as if there is more to learn about tubes. Below are a few things to consider if you encounter unwanted noise in your tube amp.
First, 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. While it’s perfectly normal for a tube amplifier to produce fairly significant amounts of noise when compared to a solid state amp, there are a lot of things can cause an amp to produce too much noise. Because each amp is a little different, it can be difficult to determine how much noise is too much. An way easy way to know if your amp is producing an abnormal amount of noise is listen for the amp’s noise floor. If your amp is working normally, it should seem like the noise floor disappears as soon as you start playing. The “hissing” sound that your amp makes normally should never drown out the sound of your playing -that would be too much noise. If you are able to hear a hissing sound when you play, it might be time for new tubes. Click here for a video that will show you the how, when, and why of changing tubes.
Tubes will do a myriad of strange and seemingly inexplicable things but the one thing they won’t do is hum. If your amp is making a humming sound, it is probably dirty power, a bad ground connection, or florescent lighting. The fastest way to solve a hum problems in a tube amp is to start by figuring out if the hum is coming from inside or outside the amp. First, disconnect your cable(s) from the input of the amp. This will rule out everything on the input side. If the hum persists try a ground lift adapter. These little adapter attach to the end of your amp’s power cable and will essentially remove the center (ground) pin. While they’re not a permanent solution, they will rule out any hum that might be coming in through the power. If your amp is still humming, it’s coming from the amp itself.
Even though they won’t prevent ground loops, a power conditioner can be an invaluable tool for keeping hiss that is present in the building’s power from entering the amp.
When a tube amp is close to florescent lighting it will often make a buzzing or clicking sound. The easiest solution is to turn off the lights but since you need light to see, moving the amp as far as possible from the lights is usually the better option.
Another thing to think about is the interaction between your guitar and your amplifier. Tube amps use transformers and other components that both produce and are susceptible to interference form electromagnetic fields. Now consider the pickups in your guitar. They’re magnets. When you walk up to your amplifier to change settings, you’re bringing the magnetic pickups closer to all those humming parts within your amp. By doing this, the pickups are going to “pick up” any noise those components are making. If the volume of your guitar is turned up, the noise is going to be amplified by the amplifier you’re plugged into. The type of pickup makes a difference as well. Humbuckers are designed to reduce the amount of noise that gets transferred to the amplifier by using two coils with opposite polarity. They aren’t perfect, but this essentially cancels out any noise that may come through. Single coil pickups, on the other hand, only have one coil (hence the name) and these pickups are going to be much more susceptible to noise.
One last thing to consider is power and gain. 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’re trying to turn up the volume, try turning down the gain and turning up the master volume. If you want more distortion and overdrive, then noise is an inherent part of obtaining that sound.