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!
9 thoughts on “6 simple and cheap ways to fix hum, buzz and ground loop noise issues”
I had some USB ground loop problems when using pedals/synths with USB midi and also a mixer (K-Mix) with USB on the same hub. I tried the beads, but it didn’t seem to help, but I had a lot of luck with some USB isolators from hifimediy that completely eliminated the problem. Had to use it on the synths/pedals though, rather than the K-Mix as that caused weird issues with connectivity.
Thank you for alerting me to the typo!
Nice article. My problem is with the new WiFi fibre optics. Sounds good but my apartment in clobbered with wattage and dBM from the closeness of cell phones, computers and bluetooth. All my systems shut down and I am one of few who hear the drone of audio carrying WiFi channels. Depending on day and busyness of internets. With all the electrical interference, these channels are picked up by my ear to the point I can hear the actual music and lyrics. These low level channels override any listening enjoyment of music, any quiet times and sleep. I am not a tech type person but I hear the same music threw out the city often and when I was in Puerto Vallarta recently same music as in Vancouver. I have been told that I must be hearing like hallucinations. Any suggestions for measuring this is hard because a recorder hardly would pick up the low level sound. Any thoughts you might have or explanations would be so appreciated. Thanks
Darrell Oakford frustrated.
Sorry no ideas, but perhaps one day someone reading this comment can help.
I came across some old recordings of me and friend which is on mono tape and I recently bought Mono Player that can convert to USB but because it isn’t in stereo there is an awful background noise almost like the missing speaker. Please can you suggest a way I can copy it safely onto another Device. It is more precious to me because I was very ill last year with SEPSIS and nearly died, I want to hear the music that I created with my friend, it is more than 40 years ago.
Thank you , Mary
Hi Mary, you need to establish if the noise is coming from the USB recorder or the tape itself. Try listening with a different machine. If it’s in the tape, you might be able to use software like RX7 from iZotope to clean it up. Be well!
Thank you for your help , yes it seems to be coming from the tape recorder , the original mono copy is pure but when copied on the stereo player to USB it carries the distortion.
I have seen some studios using an UPS (uninterruptible power supply) with single phase ‘true on-line’ output. From the wall outlet power enters the UPS through an inverter changing AC to DC which then goes through batteries and then inverts again DC to AC. This eliminates any noise carried from the electrical grid through your home and into your studio.
A connection using common mode chokes is a very good solution.
Another very cheap solution for audio application is to build a single channel (RCA / RCA) cable using a stereo cable and a small resistor (10 Ohms inside the RCA jack).
How it works? Under ideal conditions, the audio cable is only a voltage connection between the audio source and the power amplifier: this means that the current following the audio cable is negligible.
Unfortunately, some parasitics currents use the guard of the audio cable as a return path. Taking into account the cable losses, these currents create a voltage noise.
The suggested low cost solution is to use a stereo cable with a specific connection. The guard is connected to only 1 side of the cable to the RCA guard (it is a shield to avoid interference from the external electric fields. As it is connected at only 1 side there is no ground loop with the guard wire). The signal at left side is connected to the signal at the right side.
The second signal wire is used has a ground connection but using a small resistor in series (10 Ohms).
The ground connection between each side is in series with the 10 Ohms resistor. The parasitic current does not like the resistance of 10 Ohms and takes another path.
The input impedance of an audio amplifier is at least 600 Ohms, so the voltage drop of the 10 Ohm resistor is not significant on the audio level (you have lost less than 2% of the audio level).
This solution is efficient to remove 50Hz noise on a subwoofer.