advertisement


What are ground loops?

P

Phil Bishop

pfm Member
I have an issue with buzz from an Audio Technica LP5X turntable which is driving me nuts. I thought I had it sorted but somehow I seem to have lost the fix (no idea how) and it has returned. Tried all sorts of things, grounding to phono pre-amp, grounding to mains earth, grounding to both. I can reduce it but it never seems to fully go away.....well, it did but like I say I seem to have lost that fix.

One thing I keep on hearing is "avoid ground loops". Can someone explain to me in layman's language what these are and how to avoid them?

Any advice appreciated.
 
A ground loop occurs when there are multiple paths to ground in an electrical system, causing a difference in potential between the grounds. This can lead to unwanted currents flowing through interconnected equipment, resulting in noise, interference, or even equipment damage in some cases.
 
Also keep in mind that there is more than one ground. You have electrical ground as well as signal ground.
I am no expert but try to keep it as simple as possible. Plug all items into same outlet (or one power strip into one outlet to start). Only plug in amp and turntable at first (no streamer, CD player etc. power or interconnects). Get yourself a piece of wire to run as a separate ground wire to use to experiment with the signal ground. You might connect this from tonearm ground to hifi rack, or chassis of amp etc, just play around till something changes.
 
Are you using an integrated amp? Have you run a separate ground from the turntable to this amplifier? (it’s on the back of the turntable, next to the RCAs.)

If you have and you still have a hum, it sounds like you may have an rca ground fail from the turntable, the hum is then introduced as it is finding its route to ground another way, and introduces the hum.

Check the RCAs you’re using from turntable to amp are shielded (grounded) by putting a multimeter continuity tester on the end of each rcas ground end and check continuity, if no continuity then your RCAs are the problem.
 
simon g said:
Perhaps this product might help?

ifi-audio.com

GND Defender by iFi audio - Eliminates ground loops that often cause audible speaker hum.

GND Control The GND Defender (Ground) eliminates ground loops in your audio set-up that often cause audible speaker hum.
ifi-audio.com ifi-audio.com
Click to expand...
That worked for me (not currently in use, as it went away with a change or two in boxes). I tried it on almost every component, and it only solved the issue in one specific location, so some trial and error may be needed. I note that their was some discussion on whether or not it complied in certain countries, with no real conclusion as far as I could deduce. I lived to tell the tale anyway.
 
chartz said:
It would be nice to see what’s inside. Nothing I guess?
Click to expand...

See below from a review site that google just told me about. I wouldn't be brave enough to suggest their was nothing inside, as that would imply ground lifting only, which would definitely be illegal (and perhaps libelous).

https://positive-feedback.com/reviews/hardware-reviews/gnd-defender-and-the-dc-blocker/
The iFi GND Defender is not just some stupid overpriced cheater plug. The inner circuitry is "intelligent," automatically lifting the ground on the attached device, but…also automatically reinstating the ground connection to pass current if a fault is detected. So it meets code! The results with the Dynamo far exceeded what I might expect from any other $99 investment I can think of. If a ground loop plagues your setup, this iFixer is a no-brainer.
 
As I said, probably not much inside.
John Phillips said:
I don't know but I have always assumed product like that uses the circuit (or similar) from figure 5 on this page which goes into the subject of ground loops.
Click to expand...
As I said, probably not much inside, and a real profit maker for the manufacturer.
Could anybody here have theirs open for inspection?
 
Although written for music production audiences, I found Sound On Sound's articles on the matter to be very educational.

Ground Loops Explained

Few things can be more frustrating than having a recording system plagued by hum. Paul White explains the causes of hum-inducing ground loops, and offers practical advice on how to avoid them.
www.soundonsound.com www.soundonsound.com

Understanding & Solving Ground Loops

Suffering from mysterious hums and buzzes in your studio? This down‑to‑earth explanation will help you identify and solve the problems — or hopefully avoid them in the first place!
www.soundonsound.com www.soundonsound.com
 
I just pulled a back cove off my Ifi GND, but couldn't get any further without destroying it, as it is filled with an epoxy-like substance.
 
gustav_errata said:

Understanding & Solving Ground Loops

Suffering from mysterious hums and buzzes in your studio? This down‑to‑earth explanation will help you identify and solve the problems — or hopefully avoid them in the first place!
www.soundonsound.com www.soundonsound.com
Click to expand...
I have always used the mains powering approach in diagrams 3 and 5. I doubt that here at home there is as much difference in ground potential as there might be in a well-equipped studio so I suspect it is not really needed. But I still regard it as good practice. EDIT: and it should normally avoid the need for the iFi product.

It isn't the only issue that where a ground loop can cause audible problems but it may help in some situations.
 
John Phillips said:
I have always used the mains powering approach in diagrams 3 and 5. I doubt that here at home there is as much difference in ground potential as there might be in a well-equipped studio so I suspect it is not really needed. But I still regard it as good practice. EDIT: and it should normally avoid the need for the iFi product.

It isn't the only issue that where a ground loop can cause audible problems but it may help in some situations.
Click to expand...
They are a nice clear diagrams that even I can understand. I'll have to think a bit more about it when their is half a dozen mains plugs and more interconnects in the mix.
 
Thanks for all your replies chaps, I'll digest in due course. However, I think I may be on to something.

I had solved the issue but then I ordered a mains plug with just a earth pin and a new turntable ground cable. I replaced my temporary set up and the buzz came back, no matter how I connected things it was there at some level. I could not work out what was going on!

So, sleeping on it overnight it occurred to me the turntable has a built in phono stage so I could at least take my external phono stage out of the equation. I did and the buzz reduced but did not go away. I then tried a different ground lead and HEY the buzz went. I then reverted to my new ground lead and the buzz came back. I snipped off the spade connectors from the new ground lead and just bared the wires and it now works fine, no buzz. Could it be as simple as the spade connectors were not fitted properly or just adding to the issue? It is a cheapo eBay lead.

Not sure I'm totally out of the woods yet but I think it may just be as simple as the new ground wire was faulty.
 
paulfromcamden said:
Could be something as simple as an iffy ground cable. I had a Numark turntable where the attachment to the spade connector on the ground cable had failed.
Click to expand...
I think that may be it. It's funny how you can run round in circles and miss the obvious. Not sure I'm totally out of the woods yet but at the moment I'm buzz free. Just need to set up permanently with ideally my external phono stage and achieve the same outcome.
 
Phil Bishop said:
Thanks for all your replies chaps, I'll digest in due course. However, I think I may be on to something.

I had solved the issue but then I ordered a mains plug with just a earth pin and a new turntable ground cable. I replaced my temporary set up and the buzz came back, no matter how I connected things it was there at some level. I could not work out what was going on!

So, sleeping on it overnight it occurred to me the turntable has a built in phono stage so I could at least take my external phono stage out of the equation. I did and the buzz reduced but did not go away. I then tried a different ground lead and HEY the buzz went. I then reverted to my new ground lead and the buzz came back. I snipped off the spade connectors from the new ground lead and just bared the wires and it now works fine, no buzz. Could it be as simple as the spade connectors were not fitted properly or just adding to the issue? It is a cheapo eBay lead.

Not sure I'm totally out of the woods yet but I think it may just be as simple as the new ground wire was faulty.
Click to expand...
Yes, that would be it.
 
You must log in or register to reply here.


advertisement


Back
Top