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Humming and Hissing

How to Eliminate Humming and Hissing

Humming and Hissing

You love your electric guitar system with its awesome effects pedals, powerful amplifier and expensive speakers; yet instead of crisp, cool sound you get a hum and a hiss. Before pulling out all of your hair, there are quite a few things you can do to reduce this background noise to an acceptable level - some are easy, and some can be expensive. Your budget, knowledge, and patience will dictate how far you can go.

A noise suppressor will sometimes help, but you also lose some signal quality in the process. The best approach is to eliminate the noise generators entirely.

Noise Generators

There are many noise generators and the most common ones are:

1. Ground loops
2. Power-line noise
3. Electro-magnetic interference
4. Electronic/electrical equipment

Ground Loops

Ground loops occur when there are multiple electrical paths to ground. When several pieces of electronic equipment are connected together, each equipment may have its own path to ground yielding possibilities to form ground loops. Even though these grounds are connected, due to wire resistence and imperfect connections, voltage differences may exist between the grounds of two equipment. This voltage difference will add to the signal causing noise.

If you connect your electric guitar to several pedals and then to the amplifier, the amplifier has a ground connection and each pedal will have a potential ground connection. The number of potential ground loops is 1/2*N*(N-1) where N is the number of equipment. If you have an amplifier and 3 pedals, N is 4 and the number of potential ground loops is 6.

The best way to eliminate ground loops is to have one common ground for all your equipment and make sure the wire connections are firm and solid. This would eliminate voltage differences between equipment grounds.

Isolation transformers can also be used to break ground loops.

Voltz uses battery to drive the pedals and there is no connection to the ground - except the one at the amplifier. There is no ground loop.

Power-line Noise

Noises can also be injected by other equipment connected to the pwer line. Examples are light dimmers, miswired outlets, bad safety grounds, motorized appliances (e.g. refrigerator), and lightning.

Find out and remove the source. For example, if you have a light dimmer, disconnect the light dimmer and see if there is any improvement.

Under certain situations, a surge protector or power-line isolation transformer would help.

Voltz uses battery power and is unaffected by power-line noise. Furthermore, each milliVoltz has a isolation transformer which further reduces interferences among pedals.

Electro-magnetic interference

Strong radiation from radio, TV, power line and other sources can cause problems. Normally their effects are secondary and quality shielded cables will reduce the interference down to a negligible level.

Electronic/electrical equipment

Old, defective or low-quality equipment can give sub-par performance. The only hope for such equipment is to upgrade your system.