Symptoms
- Low hum from speakers even at zero volume
- Buzz that changes with dimmer switches or other devices nearby
- Hum only through certain inputs, not others
- Hum gets worse when a phone charger or laptop is plugged in nearby
Likely causes
- CommonGround loop between components on different outletsDevices plugged into different circuits with different ground potentials create a hum through shared cables.
- CommonLoose speaker or interconnect cable connectionA partially seated connector can introduce noise.
- PossibleCable TV or antenna ground loopA coax connection can introduce hum if not properly grounded.
- PossibleNearby dimmer switches, fluorescent lights, or chargersThese can radiate electrical noise picked up by audio cables.
- Less commonFaulty cable or failing componentA damaged interconnect cable or an aging capacitor in the receiver.
What to do
- Plug all components (TV, receiver, cable box, etc.) into the same outlet or power strip to equalize grounding.
- Reseat every speaker wire and RCA/HDMI cable at both ends.
- Temporarily unplug one component at a time (source by source) to identify which one introduces the hum.
- Move audio cables away from power cables and dimmer switches if they run parallel to each other.
- Try a ground loop isolator on the suspect cable if the hum is tied to a cable/satellite box.
- Test with only the receiver and one speaker connected, no other sources, to isolate a receiver-side issue.
Tools and parts
- Ground loop isolator (if needed)
Ground loop isolatorSearch: “audio ground loop isolator”
When to call a pro
If a ground loop isolator and reseating cables don't fix persistent hum, have a technician check the receiver's internal grounding or power supply.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.