Troubleshoot and Eliminate AC Hum on Sound System

Visit www.alectrosystems.com to learn more. This video explains common causes and troubleshooting and eliminating techniques for AC Hum on Sound Systems.

[@menimus]

This video is about to be 9 years old and still providing so much information. Thank you very much, sir.

[@winataatmaja3457]

11 now

[@marcofernandoruizorrego6037]

​@@winataatmaja3457😢

[@tomridge7772]

This video just helped me with a year long problem in my guitar setup. I had been chasing the problem, not getting results, and about ready to move out of my house because that had to be the problem thinking i had tried everything else. Thank you so very very very much. I added a studio monitor to my sound about a year ago and plugged it into an outlet on the other side of the room. Today I changed it to match where my amp is powered. Thank you so very much.

[@Dreweful]

for a layman in audio engineering but an active musician, this is amazingly clear and understandable. thank you for the explanation

[@Coneman3]

If only all teachers at school were this good.

[@RainDancerVideo]

I've been looking for a good explanation of ground hum for years. This video was very well done. Thank You.

[@USSBARBEL]

Slightly above my head, but I got most of it. Thanks for putting this together.

[@hereonmars]

This video is so amazing. 30 plus years in as a gigging musician and I learned a lot. I will def buy something from you all.

[@capitalist38]

Very knowledgeable description of my buzz/hum. The solution might be beyond my budget. Thank you for sharing your expertise. Based upon your explanation I tested a couple things. Unplugged all devices, mouse, external hard drive from the usb ports and unplugged AC too. When I move the AC cable close to its import connector or my computer the buzz grows. I'll have to record without it being plugged in. Thanks again for your help.

[@QoraxAudio]

Nice explanation. This is exactly why a ground lift switch on DACs with an USB input is a very useful feature, but often overlooked.

[@S1ph3r]

I loved this break down especially with the graphs. it helped a lot to understand what is 'actually' happening.

[@yrot1123]

love your explanation, clear, crisp and correct.. as an electrical engineer, I appreciate the way you explain the balance signal with differentiate amp to eliminate noise while producing 2X the signal.. I'm hoping your next video is going to be about eliminating feedback with home entertaining system .. singing karaoke at home produced a lot of feedback, and I bought a few feedback destroyer devices, but none of them seem to help.. Thks..

[@anarovsky1]

very easy to understand with all the animations and clear voice. Thanks.

[@robhend8948]

Thankyou for the info. It makes me crazy hearing that buzz. In my case it was Coming from a computer. You nailed it.

[@seenbelow]

Best video I've seen yet on this topic.

[@djsranger]

Great explanation - best I have seen on this important topic for anyone working in audio engineering!

[@johngil2848]

A good video. In sound systems, howling, hum noise, ground noise, and oscillation (higher frequency instability) are big problems and each one has its own ways of being eliminated or attenuated. Oscillations sometimes have to do with amplifiers with very high feedback loops or with output and input lines to close to each other. Ground noise has to do with the so called ground loops while hum noise has to do with micro lines peaking up harmonics of line frequency that propagated by air or by AC lines to close to audio lines. Howling has to do with microphone and loudspeaker closed to each other or resonances in the space where the system is used. To attenuate this trouble we have to reduce sound level, reposition micro and speakers, use frequency shifters and/or equalisers. The PCB ground line is normally connected to the chassis somewhere and it is the main source of ground hum.This hum can be attenuated if we cut this direct connection (it is a short circuit) and connect both grounds through a wire wound resistor of about 10 Kohms having in parallel wit it a 2 MF ceramic, polyester, etc, capacitor.

[@JamesFishwick1980]

Best explanation I've found on youtube!

[@djchur-bro6856]

Thanks for this tutorial has help me to understand how I should set my system up and what type of speakers leads I need use or devices to accompany as an option.

[@eresperro222]

Thank you so much! Your video helped me a lot.

[@richb313]

I worked in the ROV industry. We sent control signals and video over umbilicals 1000 Meters or more in length. Ground loops and noise were serious issues as well as the risk of fatal electrical shocks. First we had our power supplied by an Ungrounded Delta Wired Generator. This eliminates a power return to ground making operations much safer for personnel and equipment and while this option really does not apply with sound equipment I supplied it to show sometimes the problems can be caused by normal safe practices. We eliminated or mostly got rid of our ground loop problems by isolating chassis or electrical ground from any signal ground or signal path or return. In some systems we could have as many as four different isolated grounds. The bad news is that signal voltages could float above normal electrical ground but there was no path for current to flow. I would like to see the professional audio and sound operators and manufacturers adopt this philosophy by using totally isolated signal paths eliminating ground loops by doing so.

[@kutilkol]

Amazing, thanks for lecture. So useful. Best found so far.

[@BritishSoundboardPranks]

What a great video. My set up is as follows - Macbook, connected to a wall powered mixing desk via a USB insert - in that mixing desk I have an XLR condenser mic connected, using another wall powered compression unit, connected through an insert on the same channel as the mic. No problems, no ground loop. The problem began when I tried to do something very simple, which was add a 3.5mm TRS to Dual 1/4" TS cable between the mixer and my DSLR camera,, so that the mic runs through the camera (for better lip sync on live stream/conferencing). Instant ground loop and very loud hum and buzz and I couldn't work out why. Now I know why. I'm using my DSLR camera as a webcam, which is also wall powered with a dummy continous battery - when connected to the mixer, this means I have two different wall powered devices running through it (the compressor and camera) which is obviously causing the loop (with the USB connected wall powered Macbook which may or may not be adding fuel to the fire). I've ordered one of those decoupling boxes and will expect that this will work, when connected between the camera and mixing desk. Fingers crossed.

[@ChrisHogg777]

Trying to figure out the hum in our church live stream setup, and this explanation helped a lot - thank you!

[@jayford669]

Massive thank you, very clear and solved the issue in a matter of seconds...

[@nasanction]

Very informative! Thanks!

[@aubreyholman1951]

Thanks for the "balanced input". it was very well "received".

[@cainbradley8697]

Hi I know this video is a lil old but thank you so much for explaining this properly, you explained this better than my tutor

[@9Tensai9]

Wow... this is an ad and.. you are teaching us stuff... how cool is that? I'd happily buy after this

[@ehhhhhhhhhh]

Nice algebraic explanation of balanced cables at 8:12!

[@Craig_34]

Very good and detailed explanation. Super helpful, thank you!!

[@bakayarouotaku3298]

Excellent video, thank you. Wish I had this knowledge years ago.

[@alibehrouz9833]

I understand very well thanks for your help.

[@prodigalus]

thank you so much for making this video available. you would not BEE LIEVE what people at music stores do _not_ know.

[@DaveZiffer]

Thanks for a really great video!

[@CazYung]

thanks for making this! no more humming...

[@knickknacks8594]

very educational! Thanks!

[@gabrielkashbenitez]

Very good video!!! thanks

[@chrismcdade8283]

Actually, this video helped me tangentially. It prompted me to look at the many connections in my modest shack and reconnect some of the AC feeds. This provided a modest improvement, so it seems that I am on the right track. It's still humming, since I couldn't pull the rascal out of the multi-tap feed. It's funny though, the problem of humming just suddenly appeared. It's freezing here ... nothing works ... time to call Ghostbusters.

[@TonyHarrod]

....thanx ....reinforced my understanding of ground loops and ac hum...

[@cchong8585]

Thanks very much for the explanation. I have a few questions as follow: 1. If possible, please explain more of the differences between passive DI box and Active DI Box, which one is better and why? 2. I noticed at both active and passive DI box settings there is a button call GROUND LIFT, which one should we choose ("GND" or "Lift") in order to eliminate the ground loop noise? 3. In the DI box, may I know what is that "Attenuator/Attenuation" all about? And which setting should we choose (i.e. 0, -20 or -40?) 3. Can I simply use DI box for all ground loop problems instead of AGDC2? (because in my location I see only DI box available in all the music shops, never seen one like the AGDC2, never even heard it before.)

[@DANWRIGHTITIS]

excellent video!! I live on 4th floor in a 120 year old block of flats in Madrid. The 240 juice fluctuates on a daily basis . i dont think the earth cables get all the way to the bottom!! Thiis presentation was very informative . THANKS

[@KingGrio]

Thanks ! That video was very basic, but very useful !

[@PipCritten]

Really helpful, many thanks.

[@n00baTr00pa]

Good informative video; thanks!

[@prabhakaran5419]

innovative information thank u for the videos

[@darkstar218]

Really appreciate this video. Was never a physics guy in school, but you made it all very easy to understand.

[@JordanMetro]

this is my favorite video on youtube. thank you

[@luoyisishimisi470]

Thank you. This was extremely informative.

[@valentinfedorovici2476]

Excellent presentation + clearest explanations. --- I have never found an explanation for similar problems in a 2 wire (AC) 220V European circuits, though. Are those boxes identical in construction and use? Is AC filtering done the same way, since they don't have 3d prong for ground? I thing that Alectro is the place to get answers and... to shop. Bravo!

[@pradeep-rajnanavatijain752]

I've gone through the content along with conceivable way of explanation on subject & pattern of elaboration of issues & there causes & solutions. Big thanks for the same!!! It would more useful , if available in Hindi (Hinglish) language retaining of technical terms in English!!

[@IamkjEZ]

thank you very much for this video. i'm wondering if the DI box capabilities of audio interfaces can suffice or should a separate DI box be used because i still get nasty hum out of my electric guitar when i connect it to my audio interface to my laptop.

[@ManojJohn]

This is so perfect.. Thanks a lot to make it such simple....

[@arleneyates2540]

Perfect Presentation!

[@AnilKumar-zo2eu]

Thank you so much sir for your packaged information.

[@dillipphunbar7924]

very helpful, thankyou.

[@tedlahm5740]

Wonderful explanation. Clear video .

[@Usernamebutwhy]

Thankyou for this amazing video

[@ChrysanthoFantastikoFiloi]

thank you, very helpful!!! :)

[@seshachary5580]

very educative. Thank you regards

[@ChrisRickardTM]

Thanks so much.

[@Calvinp106]

I have the Shure Wireless MIcs using XLR cable to connected BMB karaoke mixer input. It works fine, but want to add the compressor of BEHRINGER MULTICOM PRO-XL MDX4600. After connect them all together. IT have the hum sounds. So I think I need the DI box? if so, do I need just 1 DI box or 2 boxes since I currently have 2 mics? Thx

[@Roy-sw7dd]

Thanks for the information

[@williamyancey90]

VERY HELPFUL

[@SOUL-ry2ds]

This video is a Godsend

[@brady0630]

this video put me onto the right track to resolving my sound issues. my desktop had a major hiss, my laptop on battery power did not. thank you so much for this very informative video.

[@Mgenis1]

So, my chain looks like this: guitar->usb audio interface -> pc(running guitar rig/bias/etc). In this case there is a lot of hum,but some noisegates can handle with it, but when i add a preamp beetween guitar and audio interface no gate can help. Now,the question is - if it's the groundloop conflict and if a dibox may help solving this issue? Many thanks anyways

[@bethstrain7442]

Thank you!

[@company-income]

thanks a lot for this video :)

[@mindofown]

Very Helpful

[@ArntPetterAndersen]

Very informative video - but I am buffeled... I am using this connection: Instrument -> Mixer -> [via USB] -> PC and the sound out from the PC speakers. When I am going into my DAW (Cubase 8 LE) and bring up the amp/fx plugins to start recording it screams like HELL :-O I've tried several sollutions, but I can't get rid of the hum/squealing sound. -Are there a option to get a ground loop filter on the USB cable wich goes from the mixer to the PC? - Hope that someone have a sollution for me. -tnx! -Arnt Petter in Norway

[@AngelAndTheWolf]

I solved my hum. I used two channels of my Mixer/Amp, plugged the left and right RCA cords from my laptop into separate RCA to 1/4 inch phono jacks, one in each channel.

[@shawnf_ltd9937]

Wonderful explanation

[@xmanxmansyr3147]

Beautiful.

[@danielsimpson8929]

After 10 or so hours of trouble shooting/investigating/self educating, this video made everything clear. We're going to take an old set of balanced trs cables and remove the ground pin on the trs connectors on the monitor ends. This will be our ground lift point for the two monitors. Configuration we have is computer tower - usb to interface - interface output via 1/4 inch trs to each monitor. Each monitor is self powered/grounded, so we have a ground loop between the monitors via the interface. Ground lift on the trs cables on the monitor ends should fix our hum/hiss/pops

[@jamesanthony8438]

I was having this problem a few months ago with our PS3 when I connected it to one of our stereos. Tried using grounded adapters for the outlet plug like someone on a forum had recommended, but that didn't work. Figured out that the AV cable was sitting on top of the power cable from the unit. I simply cut a small 3" length of pipe insulation (which I already had) and placed the AV cable inside of it, then let it rest atop the power cable, instead. Hum immediately went away and hasn't been back. Wish I had thought to do that, first; would've saved me a few bucks on something I don't use. :)

[@randinonsense7360]

May I ask what kind of pipe you used?

[@Hakucho64]

@@randinonsense7360 pipe insulation, it's a foam rubber sleeve like a pool noodle. I think it worked for him because it physically separated the two cables enough that the AV cable didn't pick up any EM radiation from the power cable.

[@tigros999]

i was looking into ferrite noise filters or maybe toroids, is that the main ingredient in some of these boxes? toroids can be expensive it looks like.

[@justinfarrar4019]

Wow this was very helpful

[@kevinbeckenham3872]

Excellent lecture on ground loops in P.A or HiFi systems.

[@charlescandelario]

Thank you...

[@That1_K1ng]

A lot of great tutorials. I have an issue that two “Professionals” could not fix. Do you make house calls?

[@donf3877]

I used to work on sound systems for churches and my own church drove me insane with hum. Had to do many crazy things to get it down and quiet. What do you have going on???

[@silverskull5725]

ok so if I'm connecting a hifi amp to a roland tri-capture (input moniter) then i need the agdc2?

[@mw9558]

Cutting signal wire ground could introduce RF noise due to antenna effects. However, these effects are (almost) non-existent in audio systems due to the cable and wavelength. Unless the system is >6km (λ/f) Cutting the signal ground but leaving the shield intact is the safest budget solution.

[@HajraSiddique]

Very Informative

[@geoffkennard7001]

thanks very much!!!

[@ozb8337]

Great video! Do voltage regulators help? My system also has a hum but only Ribbon Microphones bring it out clearly. As you described in the video, my 50ft. snake amplifies the hum signal very well. So I wonder if I plug all my equipment into a single Voltage regulator such as the APC LE1200, would that get rid of the hum?

[@ozb8337]

+OZ B Just realized that I may need a Power Conditioner - not a regulator! Going to try the Furman M-8X2. Anyone else try that unit to eliminate hum and hiss?

[@Dreadonator]

thanks!

[@ivanalfonsocorderogutierre7498]

Hi, if I connect the guitar amp with a trs balanced cable into the console need a direct box?

[@roarproductionsstudio]

a million thanks

[@mitchminimal6942]

Thank you 🙂

[@rich1051414]

So, I currently have an odd setup, so perhaps you can let me know a better way to deal with it. I have 2 different dacs feeding two different audio sources, when either is used individually, the ground noise is essentially zero, but when the two sources are merged, there is a horrible buzz. The signal is sent stereo via 3 wire, and I assume the problem is the shared 0v ground aren't the same on the two sources. One of the dacs is grounded to earth, but the other takes DC in and isn't ground referenced at all, i assume it functions on virtual ground. How would I mix together these two sources without the grounds clashing then causing hum? Basically, I am attempting to have two different audio sources play on the same set of speakers, without buzzing occurring when more than one source is hooked up at the same time. Currently my solution is use a 2 way toggle switch that I have to flip manually to switch between the sources grounds, but I hate this solution.

[@Variable1000]

thanks a lot

[@mindofown]

How can I but a agdc2 and do they work in Australia's 240 Volt network?

[@GianVelPal]

excellent

[@iandoesallthethings]

This sounds familiar. We had a problem for a while in our rehearsal space where I would get shocked if I touched my guitar strings and the cage of an SM58 at the same time. I assumed it was a ground loop between the mixer and my amp, so I just started mixing and matching outlets throughout the room, and found that as long as my amp was on the same power strip as the mixer, I could plug my pedal board (about 6 analog pedals daisy chained on a 9 volt power supply) into an outlet on a different breaker and avoid getting shocked. So I'm not sure exactly where the loop was, but I broke it somehow!

[@den2dizon758]

How many di box shoulf i use if i have 3 guitar amp unbalance?

[@MrFlint51]

DI boxes will operate with any signal level from guitar up to loudspeaker terminals, thanks to attenuators.

[@MrFlint51]

Passive DI boxes (transformer type) can be used "backwards" to convert balanced back to unbalanced

[@dumindavidanagamarachchige9631]

good lesson

[@ZethesTheGamer]

Heard the intro. exited.

[@metalmyke1]

Can I use a audio interface to achive this?

[@braveclyde]

At 14:05, if the laptop's input is stereo (unbalanced) and I'll send signal to it from an unbalanced aux-send, how would you make the connection balanced? Thanks!