Sometimes a desktop or notebook computer can generate unwanted noise on the external speakers. This is typically described as a humming noise from the speakers. Most commonly this is caused when the speakers (like computer speakers) are powered by a transformer that introduces interference. Devices such as cell phones, or an iPhone, when placed close to speakers may cause audible interference.
Some external computer speakers can be powered by battery or an AC power adapter (power supply or transformer). When using batteries, the speakers would typically have no humming noise. When powered by an AC adapter, the speakers might make a humming noise. The same problem may occur with a notebook computer. When the notebook computer is powered by batteries, it will most likely not produce a humming noise. When the notebook computer is plugged into AC power, it may make a humming noise.
Here are some things to consider:
- The humming noise may be a result of a defective or poorly designed power adapter. Try using another power adapter, such as those available from Belkin, Kensington, iGo, and Targus.
- It may be that the notebook will generate a humming noise regardless of the external power source. However, to test this, try using the above mentioned power adapter in a car, drawing power from the car’s battery while the car is turned off to ensure that the engine and electronics of the car do not introduce any interference. Or, alternatively, use a 12-volt battery to power the transformer. If the power adapter still causes the computer to have noise when powered from a clean 12-volt source, then the power supply is at fault.
- The humming noise may be caused by some appliance that is plugged in on the same circuit. Try a different circuit.
- There may be something in the house that is causing a house-wide interference problem. Try using an uninterruptible power supply (UPS) or similar device to “clean” the power.