Have you ever powered up your guitar rig and experienced a low frequency buzz or hum from your amplifier or speakers? Or perhaps a high pitched whine when connecting your effect pedals to your amplifier? If so, you are probably experiencing a ground loop or digital noise in your signal chain.
Ground Loops and Stereo Rigs
Grounding is an important part of your guitar rig. It’s used to protect you and your gear from dangerous voltages in the case there is a failure in your equipment. It’s also important in preventing any additional noise from entering your audio.
Ground loops can appear when there are two or more devices connected to a common ground and can sound like a low frequency hum, similar to touching the end of an instrument cable connected an amplifier. This typically happens when you are using a stereo guitar rig with two grounded amplifiers. The current that is flowing through these different ground connections can cause a 60Hz hum in your audio.
Some things to try when you experience a ground loop are:
- Plugging both amps into the same circuit or power strip.
- Lifting the ground on one of the amps. Some amps have a ground lift switch for this.
- You can also use a prong adapter that eliminates the ground prong for just the second amp.
- ***Make sure to remove this ground-lift adapter when using the amp by itself. Grounding is important for your safety and that of your equipment.***
- Cutting the ground/sleeve wire on the cable connecting the last pedal in your chain to the second amp.
- Getting a ground hum eliminator box between the pedal and one of the amps. Ebtech makes several products for this.
Avoiding Digital Noise
If you’re powering pedals with a non-isolated power supply, noise can creep into your signal. You can experience digital noise in your audio if you are using digital pedals that are being powered along with other pedals by a power supply that does not have isolated outputs to power each pedal.
This digital noise, which can sound like a high pitched whine, is filtered from the audio outputs of the digital pedal, but will leak into the audio signal of the other connected pedals through the shared, non-isolated power connection. The best remedy for this is to power the digital pedal with its own power supply, or use an isolated, multi-output power supply (like the Strymon Ojai or Zuma) to power up your effect pedals.
Another manner for noise to appear in your signal is due to the proximity of your pedals or your guitar pickups to other electronic devices.
Certain pedals, especially Wah pedals, when placed on top of or near external power supplies will add noise to your audio signal. You can also get noise if your your guitar pickups are near TVs, computer monitors, or even other pedals. The best way to avoid noise from any of these scenarios is to physically move these pedals or your guitar away from these electronic devices.
If you are experiencing a ground loop or other noises in your audio, please try out the suggestions above. If you are not sure or need further help with noise, we’d be happy to assist. Feel free to send us an email to [email protected].