How to find and fix hum in 3 easy steps
If your stereo or video system has a hum or buzz coming from the loudspeakers, there are several easy steps you can take to discover what the cause and cure will be.
If you need a more extensive procedure, click here for the extended version.
First, you should determine the type of hum you are dealing with. There are two basic types: 120Hz buzz, typically caused by ground loops, and 60Hz hum, typically a result of poor shielding, cable problems, or close proximity to strong magnetic fields.
To determine which of these you have, listen to the two examples.
60Hz hum caused by close proximity to other equipment or cables problems:
120Hz hum/buzz typical of ground loop problems.
Once you’ve identified which type of hum it is, the next three steps are to narrow down where the hum is coming from.
Step 1
Turn the volume control up and down.
Does the hum in your speakers go up and down with volume? Take note so we can come back to this answer.
Step 2
Select different inputs.
Does the hum go away? Is it only audible with one input selected, or all of them?
Step 3
Disconnect all inputs.
Remove the cables connecting the receiver, power amplifier, or device powering your speakers. Only the speaker cables, loudspeakers, and AC plug powering the unit should now be connected.
Does the hum go away?
Examine your answers
Yes, to Steps 1 and 2
If the answers are yes to questions one and two, it’s likely that one of your sources (like a CD player, turntable, video feed), is the source of hum. Remove that piece from the receiver, amplifier, or integrated and the system hum should now be gone.
Once determined you can either replace that piece of gear or read our extended hum fixing guide for further instructions.
Yes, to Step 3
If steps 1 and 2 were “no”, but removing all inputs eliminates the hum, it is likely you have what is called a ground loop.
Ground loops are common when video equipment is connected. In particular, a cable TV connection.
Reconnect each source again, one at a time and listen for the hum to return. The offending piece of equipment will show itself when you follow this procedure.
If it’s a ground loop
If the hum is caused from the cable TV connection, you can ask your cable company for an isolating transformer for the cable. You can also purchase a cable TV isolation transformers at most stores, or online here. They look like this.
If it is not a cable TV causing the problem, it may mean there’s a power ground loop between the two pieces of equipment. You can test for this by using an AC “cheater plug” that lifts the third wire ground from the AC receptacle. If this is the case, you can purchase a HUM X ground isolator that is safe and effective. These are available here.
It is not recommended to run your equipment ungrounded, for safety reasons.
Back
Thank you. Your cheater plug suggestion (the act of converting three prongs, to two prongs) allowed me to find the source of the audio hum in my Cable TV Receiver, TV, DVD recorder, Radio Amplifier configuration in seconds. I had spend hours trying to locate it following advice from other articles and YouTube video prior to reading this article. Again
Thank you,
Robert Ernster
FINALLY!! thank you, thank you. I had a humming noise coming from my TV speakers for a while, well really a long while. I have watched several videos and all a so complicated fix. Your clue of a bad connection, ground problem made me change the video and audio (the red, white and yellow cables) connections from my cable box to TV and….WHALA! no noise. Thank you so much for taking the time in shearing your knowledge. Wow what a difference. Again thank you so much.
I isolated the buzz to the passive am / fm antennas hooked up to the receiver. I disconnected everything except the antennas and the buzz continued. So just to rule out the antennas, I disconnected them and the problem was solved. Don’t know if it was the am / fm or both. The washing machine was on in an adjacent room and there was sort of a rhythmic pattern to the buzz, like it was picking up electrical pulses?? Any ideas? Thanks
Yes. Use an isolation transformer for the antenna and it should solve your problem.
I recently have a hum in my home stereo and I believe the source is my power amplifier. the hum increases with volume but it doesn’t go away even if I change the source. Tried to unplugged the tv and cable box, also tried to disconnect all source dvd, cd, etc. but the hum wont go away! pls help, thanx.
Disconnect everything from the amplifier so that only the speakers remain – no input cables at all. Does it still hum?
If the amp/receiver is the problem, then will a ground loop isolator not work as a fix? The amp, without anything plugged in, still creates a hum (sort of like an auto filter sound *thup thup thup thup thup) in both speakers, unaffected by volume control. Is the only solution to get the amp looked at or might a ground loop isolator between the amp and the speakers work? Thanks!
Sounds like the amp has a problem a ground loop isolator won’t fix. The ground loop isolators are effective only by lowering interactions between equipment and uneven grounds. If a piece of gear struggles on its own it’s time for the repair shop.
Happy New Year! It’s rare to see a company doing what I can best describe as a public service – congratulations!
I also have a speaker plagued by hum – an active speaker (a Focal Solo6 Be). Only the right speaker has the problem, and it has it all the time, even when the XLR cable is removed – no changes when the volume is turned up or down, and no influence when I change the input. After I read your article, I physically removed the speaker from the current set-up, plugged just the power cord into a dedicated outlet (i.e. an outlet which was only serving this active speaker), and the hum was still there – please note that there was no XLR cable involved in this set-up. The hum can best be described like a faint diesel engine: doo boo, doo boo, doo boo, etc with white noise instead of a doo or a boo. Alternatively I can describe it as white noise (hiss) that happens 3 to 5 times a second.
Should I try the HUM X? Or should I take the speaker to be serviced?
It sounds to me like the speaker itself has a problem. I would get it serviced. Good luck!
I have a laptop and 2.1 speaker system both without ground wire but whenever I plug the speaker system to the laptop while the laptop is connected to the wall, I get humming speakers. It works just fine when the laptop is unplugged and running in battery. I tried different wall plug but no avail. Can you help me ?
Here’s a great example of when to use a 3-prong to 2-prong AC cheater plug on the laptop.
What are the power plugs on the back of amplifiers used for? I notice they are NOT grounded (3 prong).
Also, if the hum is indeed coming from the amp, is it typically the same source? Bad caps for instance?
I have a Plinius SA-100 MK III power amp plugged directly into the wall with an Audience Power Chord. I have a Plinius 12P preamp connected to the SA-100 with Audience Au24 Balanced XLR’s. The preamp is plugged in to a Monster power strip with ground, with a “regular” power cord. The only device plugged into the preamp is a Naim NDX DAC/streamer, with Morrow RCA cables, and a Morrow power cable into the Monster power strip. Incidentally, the Plinius gear has been totally reconditioned and upgraded with all new capacitors, etc. For two months in the new house, the system has worked flawlessly. After not using it for a few days, I turned it on and a huge hum was coming from the speakers. Nothing has changed in the house during that time. If I mute the preamp or turn it off, no hum. The hum is present if I switch inputs, or have nothing plugged in. I have tried plugging everything into the power strip, plugging the strip and the amp into the same outlet, plugging them into different outlets, turning off the Naim, nothing stops the hum. What can I do? I read that an isolation transformer will fix audio hum, but have also read that it cleans up dirty power but not ground loops. I have tried the floating ground on both the preamp and power amp but nothing works. Please help me, Obi-Wan Kenobi, you’re my only hope!
It sounds to me like there’s something wrong with your preamp. Follow the steps in our guide which are basically a process of elimination.
Start with the amp connected to the speakers but with no input cables connected to the preamp. Let’s assume no hum. Connect the preamp this time making sure the preamp hasn’t any source connected to it at all (mute doesn’t count). From what you said there would be hum. If not, keep going and add a source.
If the preamp has a low, deep, hum (not a buzz) just connected to the amp with no input then it’s likely it’s a problem preamp and needs repair.
Thanks Paul!
1. Amp connected to speakers without preamp = no hum
2. Amp with preamp connected but no sources connected to preamp = hum
3. Switching different inputs on the input sector knob = hum (but louder on Phono)
4. Plugging both Amp and Preamp into Power Strip = hum
5. Plugging both into same AC outlet = hum
6. Plugging into separate outlets = hum
As for the “tone” of the hum, my best unscientific guess is that the hum is in the 90-120 hertz range. It is a little like the hum that you might hear near one of those large transformer power stations, but obviously much louder.
I would hate to have to pack my preamp up and send it for repair, only to find out that there was something else outside of the preamp that I should have done, like an isolation transformer or the humX.
Is there anything else I should try before calling it and sending it to the hospital?
I’ve added some recordings of both types of hum. https://www.psaudio.com/ps_how/how-to-find-and-fix-hum/
Let me know which of these more closely resembles yours.
Thanks but neither sample will play. I don’t know if its a javascript setting or what. I have tried listening to 60 and 120 samples but they all sound different. :(
Paul, although I was unable to get the samples to play, probably due to various script and ad blockers that I have running, I listened to some samples on YouTube and the hum is definitely closer to the 120hz sound than the 60 hz sound . . .
That sure sounds like a ground loop then. So, the preamp and amp together hum if nothing is plugged in or touching the preamp but the amp? And this didn’t happen before? Are you certain?
Positive, worked perfectly until a few days ago! I ordered two HumX things that arrive Thursday to see if that makes any difference, not sure if there’s anything else I can do,,,
Hi Paul i broke out my vintage Yamaha RX-995 receiver and Yamaha yp-701 turntable. I’m getting a lot of feedback from my turntable thru the speakers. I can just tap the turntable base and hear it thru the speaker or whenever the arm moves i get loud feedback. I do have the tt ground connected to the receiver. I have moved the tt to a different location and plugged the power into different outlets. and no help. Do you concur that i probably have a mag. cart. connection that’s bad (shure type V15-III), a bad ground or bad cable from the tt? Any help would be appreciated.
This sounds more like an acoustic problem than an electric one. I am guessing you’re in need of a new table?
Hi Paul, I had an issue with my Kenwood series 21,its a vintage system about 20 years old. It developed a hum on all inputs. After unpugging everything from the control centre it was the graphic equaliser at fault. I swapped it for another one I have as spare and the hum is gone. However graphic equalisers for this system are quite rare and I want to keep it in case of problems in the future, what I want to know is does the G.E need to be looked at by a specialist or will fitting an RCA ground loop isolator to the G.E outputs resolve the issue. Buy the way I’m in the U.K so running at 220 volts 50 Hz if that’s relevant.
Cheers Nigel
Good question and I am not sure of the answer. If you listen to the two example tones is it closer to the high frequency one or the lower frequency? If the latter then likely you need a new set of power supply capos, if the former, it might be solved with ground loop isolation.
It was closer to the 120Hz hum given that I cant hear the 60Hz one either on here or as a test signal on a couple of you tube channels though it was of a lower frequency than the one at the top of the page.
Not sure if its relevant but the G.E with the hum is a recent acquisition ( last 2 weeks ), I changed it out for the G.E I already had to make sure everything was working fine, which it was. On Friday last week I changed the single tape deck for the optional twin tape deck which I had acquired as brand new old stock from Italy ( same voltage same frequency as UK ) and changed the plug to a UK one. The hum started about 2 days later, the G.E is an optional extra and connects via the tape inputs in the receiver the tape deck then connects through the G.E in that configuration.
Howdy. Just recently upgraded my A/V receiver. I use the pre-outs to power my front speakers. I get a hum from them in every situation I’ve tried so far. I think I’ve found the problem but want to double check before I call the cable company or have to buy a fix. When I disconnect the coax cable coming into the house (Comcast) the hum disappears. I’m assuming that I need an isolating transformer for that cable connection. Is that correct? Thanks in advance!
That is correct. An isolating CATV connector will do the trick. Good detective work!
I have a similiar issue. It is when I add a rca over cat5 balun between an amp and a preamp. The preamp is a nuvo grand concerto to a nuvo 2 channel amp. Even if I have the 2 pieces of equipment connected with a very short cat5 or a long one like in the wall I get a very loud hum. If I connect via rca no hum. As soon as the cat5 and balun is introduced hum. I tried different cat5 lengths cause I thought it was the inwall wiring too long or bad. Same hum. Tonight I connected a solid copper from the amp to the preamp using screws on the chassis and the hum decreased but it is still there. If I stand 5 feet Tom the speaker I hear it with the volume all the way down. If I turn the vol up I obviously don’t hear it. But with speaker vol all the way down it’s coming from the speaker. So again only when the balun and cat5 are introduced it it there and copper ground to amp and preamp decrease it but not completely.
Thanks!
Jim