Audio equipment setups can get pretty involved. You might have several playback devices, computers and codecs all converging at your mixing board. And now you find there is a mysterious “hum” or “buzz” that wasn’t there before.

First, determine if the hum is being “heard” by a mic, and is simply being passed through the system as part of a valid audio signal. If it’s not part of the audio signal, hum is often caused by differences in the ground circuit on the various AC outlets you may have in use. Or perhaps that un-grounded power supply that runs your laptop computer. What’s the solution?

ART, Rolls, and Ebtech offer products (cleverly called “hum eliminators”) that will stop the offending hum without having any negative effect on audio quality. Once you have identified which device is creating the noise, simply connect its line level audio output cables to the hum eliminator, and from the other end of the hum eliminator to the original destination. The hum or buzz is now gone, because the internal transformers in the hum eliminator have isolated the electrical grounding discrepancy.

Hum eliminators won’t get rid of a hum that is actually part of the audio signal. They will only work on hum that is a result of an external problem, like the grounding issue mentioned above.

Hum eliminators are passive devices… no power is necessary. Most use 1/4″ TRS jacks for input and output. Some have a combination of RCA, XLR, and TRS jacks available. They are 2-channel units, so you can isolate a stereo device, or a couple of mono devices.

For larger setups, Ebtech makes a couple of rack-mounted models that give 8 channels of hum isolation: HE8 (1/4″ TRS), and HE8XLR (XLR). ART’s T8 has XLR, TRS, and RCA.

Stop that noise! I mean it!

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