Audio Setup

Ground Loop Hum: How to Find and Fix Audio Buzz

By HyFa Published · Updated

A persistent 60 Hz hum (50 Hz in Europe) that comes through your speakers or headphones is almost always a ground loop. It is the most common audio problem and the most fixable. Here is how to diagnose and eliminate it.

Ground Loop Hum: How to Find and Fix Audio Buzz

What Causes Ground Loop Hum

A ground loop occurs when two or more devices in your audio chain are connected to different electrical grounds. The slight voltage difference between these grounds causes current to flow through the audio cable’s ground conductor, which produces an audible hum at the AC mains frequency (60 Hz in North America, 50 Hz elsewhere).

Common scenarios: computer connected to a DAC via USB while both plug into different outlets. Turntable connected to a preamp with different ground potentials. TV connected to a soundbar with the TV grounded through a cable box.

Diagnosis

  1. Disconnect all sources from your amplifier. If the hum stops, the problem is in a source connection.
  2. Reconnect one source at a time. The source that re-introduces the hum is the problem path.
  3. Touch the RCA connector shell of the problem cable. If the hum changes, it confirms a ground issue.

Solutions (Cheapest to Most Expensive)

1. Plug Everything into the Same Power Strip ($10)

The simplest fix. When all audio equipment shares the same electrical outlet, the ground potential difference is eliminated. Use a quality power strip, not a cheap extension cord.

2. Use a Ground Loop Isolator ($10-$20)

A small transformer that breaks the galvanic connection between devices. Insert it on the RCA cable between the problem source and your amplifier. Brands like Mpow and PAC make effective units for under $20.

Trade-off: a cheap ground loop isolator can slightly degrade bass response and add minor distortion. Quality units minimize this.

3. Switch to Optical Connection ($10)

If your DAC and source both support optical (TOSLINK), this eliminates the ground path entirely. Optical cables carry light, not electricity, so ground loops are physically impossible. See [INTERNAL: dac-amp-setup-guide-beginners] for digital connection options.

4. Use Balanced Cables ($15-$30)

XLR (balanced) connections reject common-mode noise including ground loop hum. If your DAC and amplifier have balanced inputs/outputs, switching from RCA to XLR often eliminates hum.

5. Install a Hum Destroyer ($50-$100)

Ebtech Hum Eliminators use isolation transformers on multiple channels. They are the professional solution for persistent ground loops in studio and home theater systems.

Turntable-Specific Hum

Turntables are particularly susceptible because the phono signal is extremely low-level (millivolts). Ensure the turntable’s dedicated ground wire is connected to the ground terminal on your phono preamp or amplifier. A disconnected ground wire is the number one cause of turntable hum.

For turntable grounding details, see [INTERNAL: turntable-setup-guide].

Key Takeaways

  • Ground loop hum is caused by different ground potentials between connected equipment
  • Plugging all audio gear into the same outlet is the simplest fix
  • Optical connections and balanced cables physically prevent ground loops
  • Turntable ground wires must be connected to the preamp

Next Steps

For complete audio system wiring, see [INTERNAL: dac-amp-setup-guide-beginners]. For cable truth and myths, read [INTERNAL: audio-cables-truth-vs-myth].