A healthy amp is likely to make some sort of noise when idle. The amount varies depending on the voicing and design of the amp in question. Hiss is caused by high volume settings, high gain settings or bright EQ settings. Sadly there’s no way to avoid this if you choose to play in this way.
Poor quality pedal boards, FX units or even guitars will feed noise into the amp that will be exponentially amplified. If the AC supply is poor or your outlet is not earthed well enough then it can create a humming or buzzing sound.
Your amp is also susceptible to Radio Frequency Interference which is worse in areas that are close to radio towers.
How can I get rid of unwanted noise from my amp?
You may not be able to completely get rid of unwanted noise but here are some things to take into consideration:
Cables: Avoid using defective, cheap or poorly shielded cables
Instrument: Try using another guitar or bass
Earthing: Speak to your instrument repair person to ensure your instrument is properly earthed and discuss the possible benefits of lining it’s control cavity.
Single Coil Pickups: Unfortunately these pickups commonly produce a hum due to the way they are designed. If your guitar is equipped with three single-coils and a 5-way selector switch, set the switch to position 2 or 4. This should hopefully cancel out the hum.
Active Pickups: When the battery supplying these pickups starts to die, it can induce distortion.
AC Supply: Try using your amp in another AC outlet, another room or even another building.
External FX: Try disconnecting your FX units. These can be problematic when they are not functioning correctly.
Lights: Neon lights, fluorescent lights and dimmer switches cause a buzz through the power supply.
Preamp Valves: You may need to replace the preamp valves to resolve unwanted sounds. If this doesn’t work then the output valves may need replacing. We recommend that all valve replacements are carried out by a qualified engineer.
If you’re still struggling with unwanted noise then you may need to consider having your amp fully investigated by a qualified engineer.
Why does my amplifier squeal when I play in my bedroom?
The distance between your guitar pickups and your amplifier is responsible for the squealing noise you hear. The louder you set your amplifier, the greater this distance needs to be. If you plan to use your amplifier at higher volumes then move as far away from it as possible.