Have you ever hooked up a new piece of gear into your setup and suddenly heard a horrible noise you weren’t expecting? Or just had an unbearable noise find its way into your recording without you noticing in the heat of the moment? The cause may be a ground loop, some other interference, or even loud air-conditioning. Here are a few ways to solve this problem:
Use one outlet
If a ground loop is the problem – Plugging everything you’re using into the same outlet will probably solve it – most noise or hum issues coming from ground loops are a result of having your setup plugged into more than one wall socket in your studio. I’ve seen people recommend removing the ground pin or using a ground lift plug on one but not both of your sockets – I’m no electrician but that doesn’t seem safe to me – and the only reason I’m mentioning it is because that’s something I think you shouldn’t do.
If you’re like me and just don’t want to run wires so that everything is plugged into one place, use balanced, or XLR or TRS cables across your setup – while these cables may look like stereo cables they’re actually used to carry one mono signal, so you’d need two to carry stereo audio. However, your audio interface or other gear may not support balanced outputs, so plugging a balanced cable into it won’t help…which brings us to solution number three…
Use a ground loop isolator
A favorite of mine is a simple and cheap ground loop isolator – just pass your audio through it and magically the annoying ground loop noise will disappear. One thing I have noticed this do is invert the audio’s phase, which is probably not a big deal unless there’s a particular case where this is a problem for you.
Another option that may work for you is Ferrite beads or a ferrite choke. You can either buy a transformer or cable with a built in choke, or buy a separate ferrite bead and install it on your cable. Ferrite beads aren’t designed for audio rate noise – rather, for things like network or USB cables.
If you’ve already recorded your audio with ground noise, and re-recording isn’t practical, you may be able to fix it in post with a filter or plugin. If the noise happens to be at a particular frequency, you can use a precise notch filter at that frequency. For example, I recently recorded a long audio clip and only after recording the whole thing noticed a relatively quiet but nasty high pitch noise at 8khz, that for some reason I missed during recording. By applying a sharp notch filter to that particular frequency, I was able to completely remove the noise without any noticeable change to the audio overall. Notch filters are typically free with most audio and video editing software – and certainly with the fantastic open source Audacity software. If the noise or hum are located in the high or low portion of the spectrum and your audio isn’t, a high or low pass filter might do the trick without doing to much damage to the audio you intended to record.
Advanced repair tools
If it’s a nastier hum, or broader frequency noise like an air-conditioner hum or just an overall noise coming in through your mic, the methods mentioned above won’t work. In that case you might need to use an advanced noise removal algorithm. A free solution that might work for you is audacity’s noise removal algorithm, where you can use a few seconds of your audio that contain the problematic audio you’re trying to get rid of, and then apply noise reduction to your entire clip.
If its too big of a problem to fix with free tools try out Noise Remover from Accusonus or RX7 by Isotope, though those are no longer in the cheap category – if you’re stuck with bad audio, they’re may still be cheaper than a going back and rerecording your audio, and there are demos or rent to own options for those which help lower costs or try them out for free.
Got any other ideas? Please leave a comment below, and if you want other electronic music ideas, tips and tricks check out my ever growing book on Patreon!