AC power Speaker buzz with no audio connections

[Speedskater]

Well it's not a ground loop, a ground loop requires multiple cable paths. It could be an interference problem or more likely and AC power line problem of asymmetry or DC off-set. Does it happen 24 hours by 7? Have you tried turning of all your electrical appliances?

[vince @ speck]

Try connecting the speakers to a source... something with a balanced output. Turn the speakers and the source on. By doing this you are terminating the inputs. Noise still there?

The KRK's have unterminated XL inputs. Some gear does not like sitting idle without a termination.

[Bill@WelcomeHome]

Originally Posted by vince @ speck

The KRK's have unterminated XL inputs. Some gear does not like sitting idle without a termination.

My thought, too.

[weltact]

This is happening whether I have my balanced xlr plugged in them or not. And it's also there when I plug my speaker in the power socket in the kitchen, without any other electrical appliances. And it's 24/7.

[cavemusic]

Originally Posted by weltact

Hello gearslutz

I have an issue that's very confusing, and would really appreciate some advice.

I have KRK VXT6 monitors and I've used them in two different flats before and they were fine.

I just moved to this new flat and as soon as I plug the power in they start buzzing. It's a horrible high pitched electrical buzz type. But I don't think it's coming from a transformer or anything because when they are plugged in to the wall but the on/off switch is OFF they don't make this noise. It's only when they are plugged in the wall and switch turned to ON. And this is without any audio connections, just power plugged into a wall socket. I tried them in different rooms as well, without anything else being plugged in the same socket, and it's still the same.

So I concluded this must be something with AC power in this flat. I suppose this is not a ground loop in that case and I don't know if buying any of those ground loop eliminators like this Behringer HD400 would do anything for me, because they are all put in the middle of audio connections, connected with TRS. My problem is definitely coming from the AC power, so I would need something that would go between the power socket and the speaker.

I saw this Ebtech hum X that could possibly solve my problem, but they only make them for american plugs and I'm in the UK. Although I don't really know if this would work for me because as far as I know this is not a ground loop as such, or maybe it is I don't know.

Could someone please give me some advice on this issue, and suggest some possible routes to fix this problem (involving no DIY because I'm pretty uncomfortable doing this to my speakers).

Any help much appreciated.

Thanks

The Ebtech won't work if it's not a ground loop issue. There was a similar problem, with a filter solution (although it's a bit of a DIY - sorry), discussed in the following thread:

Monitor noise

[Ike Zimbel]

Originally Posted by weltact

Hello gearslutz

I have an issue that's very confusing, and would really appreciate some advice.

I have KRK VXT6 monitors and I've used them in two different flats before and they were fine.

I just moved to this new flat and as soon as I plug the power in they start buzzing. It's a horrible high pitched electrical buzz type. But I don't think it's coming from a transformer or anything because when they are plugged in to the wall but the on/off switch is OFF they don't make this noise. It's only when they are plugged in the wall and switch turned to ON. And this is without any audio connections, just power plugged into a wall socket. I tried them in different rooms as well, without anything else being plugged in the same socket, and it's still the same.

So I concluded this must be something with AC power in this flat. I suppose this is not a ground loop in that case and I don't know if buying any of those ground loop eliminators like this Behringer HD400 would do anything for me, because they are all put in the middle of audio connections, connected with TRS. My problem is definitely coming from the AC power, so I would need something that would go between the power socket and the speaker.

I saw this Ebtech hum X that could possibly solve my problem, but they only make them for american plugs and I'm in the UK. Although I don't really know if this would work for me because as far as I know this is not a ground loop as such, or maybe it is I don't know.

Could someone please give me some advice on this issue, and suggest some possible routes to fix this problem (involving no DIY because I'm pretty uncomfortable doing this to my speakers).

Any help much appreciated.

Thanks

I would have a qualified electrician test your electrical system ASAP. It sounds like crappy power to me. The trick is you have to find someone who is more knowledgeable than just a "plugged a lamp in and it lit up" kind of guy. Could be poor ground connections at the panel, or even at the service entrance (where the power comes into the building).
Best,
Ike

[weltact]

Oh my god, this sounds like it's going to be a long journey for me. I think it would cost me serious money to have a professional electrician check my mains.

I'm gonna check out that topic posted earlier about filter solution.

Do you guys know if those power conditioners could possiby give me a quick fix?
Maybe something like this Lindy mains conditioner

[Speedskater]

First go you have friendly neighbors that would let you try your equipment in their homes? It might be a neighborhood power problem. Cam you borrow an other brand of equipment from a friend?

Without diagnosing the problem, it's hard to say what will cure it.

[sandersd]

Sounds like you may have 2 ground paths in your electrical service. I'm not familiar with the specifics of wiring in the UK, but in the US with a three-wire system, there is a hot, a neutral, and a ground. The ground is a safety (redundant) ground that is connected to a ground rod or similar earthed item. If there are two paths to separate earthed items a ground loop can occur. Also if electrical devices are connected to different circuits (i.e. different paths to same ground) a ground loop can occur. This can happen if one device is plugged into one outlet and another is plugged into a different outlet and the two are on different circuits back to the main panel.

Hope this helps.

[cavemusic]

Originally Posted by weltact

Oh my god, this sounds like it's going to be a long journey for me. I think it would cost me serious money to have a professional electrician check my mains.

I'm gonna check out that topic posted earlier about filter solution.

Do you guys know if those power conditioners could possiby give me a quick fix?
Maybe something like this Lindy mains conditioner

If the noise filter in that "power conditioner" is decent, it might work. Perhaps it's worth the money to try it, and maybe you can return it if it doesn't perform. I have a Furman power conditioner (PL-8C) that does help reduce mains noise in some situations.

Do you or neighbours have dimmer switches on the lights? You could try turning them off and on to see if it makes a difference. Try turning off other electrical devices to see if something you have is a source of noise. Like speedskater said, some experimentation will help to diagnose.

[weltact]

I've tried plugging them in in different sockets in different rooms, with no other appliances being on and the noise is still there. We don't have dimmers installed anywhere. There is one thing that might be related: we have some weird rule in our contract that due to the electrical wiring in this block of flats we can't use any light bulbs more powerful than 35w and they have to be specific energy saving type, that have to be changed by the porter and we shouldn't do it on our own. I thought that was a bit weird, but it's very hard to find out more without getting a professional electrician to test it.

I'lll try to ask one of my neighbours to plug it in their flat.

And I think I'll get one of those Lindy power conditioners in the mean time, they have good reviews, they might do something.


On that note, I noticed that Furman power conditioner, like all those other £100+ conditioners seem to have these ports

and not standard AC power plug sockets like this

It might be a bit of a silly question but why is that?

[Speedskater]

High efficiency lighting required. Are these brand new flats? Or did they refurbish the electrical wiring for the whole block? Are the light bulbs a special type of LED or CFL lamp?
If only one power cord is connected and no audio interconnects to other equipment, it can't be a ground loop.

[weltact]

They are standard 35w energy saving light bulbs. The flats are probably a decade or two old but refurbished to a good standard. I don't know. Something is a bit fishy there but I would probably have to focus on the situation in my flats electrics because I can't really change anything about the building's power situation even if I find out the reasons behind their policy...

[cavemusic]

Originally Posted by weltact

I've tried plugging them in in different sockets in different rooms, with no other appliances being on and the noise is still there. We don't have dimmers installed anywhere. There is one thing that might be related: we have some weird rule in our contract that due to the electrical wiring in this block of flats we can't use any light bulbs more powerful than 35w and they have to be specific energy saving type, that have to be changed by the porter and we shouldn't do it on our own. I thought that was a bit weird, but it's very hard to find out more without getting a professional electrician to test it.

I'lll try to ask one of my neighbours to plug it in their flat.

And I think I'll get one of those Lindy power conditioners in the mean time, they have good reviews, they might do something.


On that note, I noticed that Furman power conditioner, like all those other £100+ conditioners seem to have these ports

and not standard AC power plug sockets like this

It might be a bit of a silly question but why is that?

It's a pretty standard plug in North America. It can be adapted to UK connections:

FurmanSound.com - 220-240V International Home Theater Product - Adaptor Cords

Better check with Furman's tech support before buying anything for your location.

[weltact]

I didn't have high hopes but I bought this tacima power conditioner
It did absolutely nothing.

When I plug just the speakers in the conditioner, with nothing else, there is still that same electrical buzz coming through the speakers. Equally loud, equally infuriating.

I think I might have to splash out on an electrician to give me some answers here.

Anyone know a cheap electrician in east london?

[Matt Syson]

Hi
I would suspect the 'low energy' lighting as they create a fair amount of HF 'noise' often around 50KHz. You can't hear them directly of course but 2 nearby will 'heterodyne' and give you sum and difference frequencies that you probably will hear. Eg, 50KHz and 51KHz will give 1KHz and the 'carriers' are badly smoothed mains so you get some of that too.
Another good source of noise is the inverter for solar power installations. These distort the existing mains supply at powerline frequency and usually have a strong 'high' frequency, in my case either 9KHz or 17KHz. When I am testing gear I often have to turn the flourescent striplights off as they 'squeak' at 35KHz.
The monitors you mention may not have particularly good 'RF' rejection capabilities either.
You could get some ferrite filters to put around both mains and audio wiring into the monitors (doing what should have been done internally). There are many threads about this look under 'RF/radio noises'.
Matt S

[Speedskater]

I think that the items that need to be investigated are:

a] Do these monitors have the same problem at other locations (both nearby and far).
b] Do other monitors have this problem at this location.
c] Is the problem HF or RF noise/interference.
d] Is the problem line or other Low Frequency noise/interference.
e] Is the problem power line borne.
f] Is the problem air borne.

[Matt Syson]

Hi
If you say you are in 'flats' then it could well be your neighbours 'creating' the noise or if there are CFL lamps in communal hallways for example that could be it.
I would suspect 'HF' energy being 'conducted' into the monitors almost like water which will run down a piece of string held at 45 degrees, not 'full conduction' (as water would be through a pipe) but more strongly than 'wireless'.
Double check your monitors for being 'quiet' at another house (you said they were fine and they probably are) which then puts the problem back into your flat.
You need to be talking to all or at least some neignbours to find out any other electrical using activity that goes on nearby within say a couple of hundred metres.
Apart from getting some ferrite rings, rods or whatever (Maplin?) I would not buy anything else yet. These ferrite things are typically seen on the cables used for computer monitors, switchmode power supplies and so on. They are the cylindrical 'lump' near the end of the cable. Typically a couple of quid each. If your flat has such bad radiation of 'noise' goping on, you may well need loads of them for your other gear!
Matt S

[weltact]

Thanks for comprehensive replies guys, you've been very helpful.
It seems that this low energy lighting scenario is very likely, I didn't know that they can create RFI, this is completely new to me, but it makes sense, because I never had this problem elsewhere.

I tried two different speakers in my flat as well, KRK rockit and some small genelecs, no RFI whatsoever.

So it seems that VXTs have a really bad RFI isolation, which is very dissapointing for monitors that cost this much. I think I'm on the verge of ditching them for this reason, and going for monitors that don't have RFI problems.

In the meantime I'll get some ferrite rings as advised, hopefully they can fix this temporarily.