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Tech Tip Of The Day: Using EQ To Conquer Hum

Is there any way to remove the hum from bad power using just EQ?

Provided by Sweetwater.

 
Q: I recently made a very mediocre recording (I’m very ashamed, really) on location which has some serious issues.

The problem is that while most bands just end up taking their “live recording” home and never listening to it again, my client would like to clean it up and put out a live release.

This is all well and good because I’m happy to have the work, however I wish I’d know the greater plan going into the gig because I would have planned.

So, I’m now saddled with “cleaning up” this recording, which really is just riddled with hum from bad power.

I know there are specialized plug-ins which can do the job, but is there any way to accomplish this using just EQ?

A: Sorry to hear about your recording woes!

By nature, hum-causing electricity in the United States has a fundamental frequency of 60Hz (hence the name 60-cycle hum) and harmonics of different volume at 60Hz intervals such as 120Hz, 180Hz, etc., running throughout the frequency spectrum.

EQ set to any harmonic frequency of 60Hz can be used to filter out offending frequencies.

It should be noted that the narrowest Q possible should be used in order to cause as the least amount of damage to the overall sound quality of the audio.

Using a high-pass filter dialed in to 60Hz or 120Hz you can effectively reduce a good portion of the hum. Of course, on bass-heavy instruments, the high-pass filter could remove crucial low frequencies, and must be used cautiously.

On a single-coil equipped electric bass, setting the high-pass filter to 120Hz would pull a substantial amount of the low end out, causing a weaker bass sound.

But since it’s not uncommon to cut the bass at around 50Hz, a cut a 60Hz would probably handle any hum issues with little impact on the overall integrity of the tone.

On the other hand, with an electric guitar equipped with single-coil pickups, the high pass filter could be set to 120Hz without causing substantial damage to the sound.

Your best bet would be to try these various EQ techniques and then if it seems as though there is more hum to remove, consider third party plug-ins.

As always, we welcome input from the PSW community and would love to know how you would handle this situation. Feel free to let us know in the comments below.

For more tech tips go to Sweetwater.com

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