Noisy guitar pedals can really make you sound bad. All parts of your signal chain should be silent when not in use. Depending on the problem, guitar pedals can emit a low hum, a loud crackle or a high pitched squeal. Typically, the problem is related to the wiring or the potentiometers in the pedal. Low battery life can also cause your pedals to become noisy, so it’s smart to invest in some 9-volt power supplies so that you can eliminate this problem.
Troubleshoot your entire signal chain. Your cables and connecting patch leads can cause sounds that are similar to those caused by noisy guitar pedals. Plug into your amp with each cable in turn to ensure that these aren’t the source of the noise. Replace any noisy pedals for new ones. Check each pedal individually. Remove all other pedals from the signal chain and play each one as you normally would. Set aside any pedals that make noise for further examination.
Turn each dial on the pedal. A common source of noise is dirty potentiometers, or pots as they are often called. The pot is the interior part of the dial that controls the amount of current that passes through the circuit. Dirty pots typically create a crackling sound. If the dial is the source of the noise clean the pot.
Unplug and unscrew the front of your pedal. Use a shaving brush to get rid of any dust on the interior. Spray a plastic-safe contact cleaner on to each pot. Plug the pedal back in and check the pedal again.
Inspect the wiring. Loose wiring is another source of crackling and hissing. If you find a loose wire, melt the connection with your soldering iron. Get rid of the solder residue with the shaving brush and solder the wire back to the same terminal. Check the pedal again. If reconnecting the wire hasn’t worked, replace it. Melt the solder connection at each end. Strip a half-inch of the insulation from the ends of the new wire. Solder the new wire in place.
Examine the printed circuit board. If you have previously modified the pedal and used a soldering iron, check the board for solder blobs where the iron might have dripped. Solder blobs cause bridges in the circuitry that diverts the audio signal from its intended location. It happens with amplifiers, too. This can cause intermittent squeaking, low level hum or intermittent loss of sound. If you spot a blob, melt it with your soldering iron and brush away the residue.
Check the tubes. If you have a tube-powered pedal, such as the Electro Harmonix White Finger compressor pedal, dying tubes might be making the pedal noisy. Replace any tubes that have a brown tint on the glass. Brown discoloration is a sign that the tube has blown out.
Test your guitar rig at a different property than yours. Poor electrical wiring can amplify the more subtle noises that pedals make, creating the illusion that they are overly noisy.
Always unplug the input and output cable from your pedals. Not doing so will drain the battery. It also increase the risk of damage when the pedals are in transit.