How to Prevent and Eliminate Audio Ground Loop Hum in Live Broadcasts

Introduction

When it comes to audio issues in a live production, one of the most common will be what is known as “ground loop hum”. If you’ve ever listened to audio and heard a low buzzing or humming sound that’s ground loop hum. It typically will present itself when you’ve connected multiple devices as opposed to just a singular one. We’ll go over what causes this issue as well as how to fix it in your broadcast!

What a Ground Loop Is

So what exactly is a ground loop? Well it’s caused by having more than one device connected that are grounded at different reference points. So when these devices share an audio connection, the difference in the electrical potential will create a current that is then interpreted by us as noise! This becomes exceedingly common in setups where power is drawn from several locations or if you have a mixture of balanced and unbalanced audio connections. 

How to Identify Ground Loop Hum

Thankfully ground loops are very distinct and easy to notice:

• A low-frequency buzz, usually around 50 Hz or 60 Hz depending on the region.
• Noise that increases when powering up additional devices.
• More noticeable when using long cable runs or unbalanced connections like RCA or 3.5 mm.
• Noise that disappears when disconnecting a specific device or cable.

If the noise changes when you plug or unplug equipment, then most likely a grounding issue is causing it.

Common Causes in Broadcast Setups

Ground loops can appear pretty easily in environments that have:

• Devices powered from different AC circuits
• Mixed balanced and unbalanced audio systems
• Long cable runs between cameras and mixers
• Audio extraction from HDMI or SDI converters
• USB capture cards connected to grounded computers
• Equipment racks with inconsistent power

How to Eliminate Ground Loop Hum

1. Use Ground Loop Isolators

You can grab an inline isolation transformer which is an effective way to break a loop without altering a signal. Thankfully these are commonly available in almost all standard audio connection types. 

2. Switch to Balanced Audio Connections

Balanced XLR or TRS cables reject interference and eliminate many grounding issues. If your equipment supports balanced I/O, using it will significantly reduce hum.

3. Ensure All Devices Share the Same Power Source

Plugging mixers, cameras, converters, and computers into the same power strip or conditioner helps unify the grounding reference.

4. Use DI Boxes for Long Runs

A direct injection (DI) box allows long audio runs to remain balanced and isolated. Many DI boxes include ground lift switches that can eliminate hum instantly.

5. Add a Power Conditioner

Power conditioners stabilize the AC supply and help minimize noise caused by fluctuating power conditions or improper building wiring.

6. Avoid Ground Lift Adapters

While sometimes effective, ground lift adapters can create safety risks. Always choose transformer-based isolation rather than removing the ground pin from power plugs.

Preventing Hum in Future Broadcasts

In order to prevent these issues from cropping up again and again try some of these:

• Keep all audio connections balanced whenever possible.
• Use high-quality cables and avoid unnecessary adapters.
• Place power and signal cables separately to reduce interference.
• Test each device independently before the broadcast begins.
• Maintain consistent power distribution for all components.

Conclusion

Ground loops can be very frustrating to deal with as it’s such an easy problem to run into, but thankfully that also makes it one of the easiest to identify and fix! Just make sure to follow proper grounding practices and use the right tools for the job and you’ll be on your way to a clean broadcast!