Daktronics

Sportsound: Hum, humming or buzz noise on audio system, Check ground

Potential Symptoms

  • Low frequency noise is being emitted through Sportsound audio system, noticeable in the background of audio content being played.
  • Hum is only present when a laptop is plugged in.
  • Hum is only present when the DMP-8000 input is plugged in.

Environment

  • Product: Sports Sound Systems, Custom Audio
  • Component: 
  • Control System: 

Cause

  • Grounding of any audio connection at any point in the audio system.
    • Grounding of audio connection between any two points throughout the system.

Resolution

  • Isolate failure to the exact location and eliminate the improper termination/connection.
    • Check all XLR Cables/Connectors for proper shield connections and ensure the shield is properly connected/soldered.

For Temporary Operation

  • Install Ground Loop Isolator. 
  • The last resort workaround is to disconnect the shield ( typically pin1 XLR or TRS) on the receiving piece of equipment. It should be carefully connected/disconnected while playing audio to test if this is a fix. Note: this "fix" may allow for RF interference in the signal such as AM radio stations.
  • When connecting a computer/laptop using an LTIBLOX 1/8" headphone jack to XLR adapter a hum may be present. When using this adapter it is recommended to "lift" the shield (pin1) on the XLR female that plugs into the mixer. This can be a "fix" due to the differences in grounding practices between the computer manufacturer and the professional audio equipment. The cable that has been modified for the ground "lift" must be labeled for its specific purpose/connection as it will no longer function properly when used with other equipment.

Related Resource

Sound System Interconnection by Rane Technical Staff

KB ID: DD3156030

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