Ground Loops - Eliminating System Hum and Buzz

S

soundmagnet

Audiophyte
a hum form another source

I know where my hum is coming from. I tried connecting my PC to my system to play those hours of music uniterrupted. Works fine as long as the PC is running on battery. Plug in the power adapter and BUZZZZZZZZ.

Any ideas?

Thanks
soundmagnet
 
M

MeauxJeaux

Audiophyte
Wow that sounds complicated. Is there anywhere on the net where I can find more info.
 
R

rbeezey

Audiophyte
hello audioholics! 1st post, hope i am doing it right... sorry if not. been reading this forum (and MANY other sites) for a week now attempting to diagnose my humming problem. i have seen many similar problems but mine has a few differences that i have yet to have seen described. heres where it comes from:

numark TT1510 turntable w/ shure M25C cart
mitsubishi DA-G157 EQ
teac AG-V8050 receiver w/ phono input
pioneer CS-C403 big speakers

made from gifts, hand me downs, ebay scores... anyways, i am an entry level obsessive when it comes to this home system business so there ya have it. now, the problem:

hum. i have always been aware of a low end hum when listening to records. with the needle off the record, it was noticable at relatively high volume. with the needle down, the music was loud enough to cover it up. recently i added that mitsu EQ to the set up. now, with the EQ engaged, the hum is overwhelming and causing the (previously stable) turntable to feedback and "howl". i could go back to not using the EQ, but man, i didnt even get to play with it!

like i said, i've been researching this online for a while now and i keep getting led to "ground loop" discussions. i have performed many tests and here is what i end up with:

1: the hum never changes no matter what else i unplug in both the stereo's room and the neighboring room.
2: the hum is consistent even with the turntable unplugged from power.
3: the hum, although un-amplified, is present if i connect the turntable to a different input on the receiver.
4: both a CD deck and an iPod connected to the receiver do not hum.
5. the hum remains after connecting the system to nearly every outlet in my apartment.

so i am wondering now: problem with the turntable's internal wiring? do i take the table to a shop? buy a RIAA pre-amp? buy ground loop isolating RCA thingies? and yeah, i know i am working with fisher price "my first hi-fi"... there will be upgrades later; what can i do now?

thank you VERY much in advance! i am greatly looking forward to being a member of this forum!
 
R

rbeezey

Audiophyte
me again; i keep having these ideas right before i fall asleep.

recently i was fuc... uh, adjusting the head shell and cartridge for some reason that seemed good at the time. what would my table sound like if i re-wired the cart differently from the way its supposed to be? ie: switched the R and L and/or their grounds?
 
TLS Guy

TLS Guy

Audioholic Slumlord
me again; i keep having these ideas right before i fall asleep.

recently i was fuc... uh, adjusting the head shell and cartridge for some reason that seemed good at the time. what would my table sound like if i re-wired the cart differently from the way its supposed to be? ie: switched the R and L and/or their grounds?
A little hum is often present with turntables, however yours sounds excessive. It is not a ground loop. Do NOT change the cartridge wiring.

You need a multimeter or some means for checking electrical continuity.

Turntable grounding should be as follows.

The metal of the turntable arm should be grounded. There should be either continuity of the arm to the RCA plug grounds, or there should be a grounding tag on the base of the arm, under the mounting some place.

If the arm is mot grounded, you will have to install a grounding tag on the arm some place.

There should be a ground tag in the turntable itself. If not you will need to install one.

Now solder between the grounding tags to connect the pickup arm ground to the turntable ground. Now solder a wire from the turntable ground and attach a grounding spade to the other end of that wire. Attach the spade to the grounding terminal of your receiver.

The other issue is that you are using very excessive Eq, especially in the bass, and causing acoustic feedback between you pickup and speakers. This may well fry the woofer in your speakers. So don't use the Eq settings you have now, they obviously are way out there.
 
R

rbeezey

Audiophyte
thanks! i forgot to mention how and what i have done with grounding...

both turntable and receiver have ground tags and i have been wiring them together. the hum i experience barely changes when i disconnect the wire; only when i touch one free end.

so you are saying to solder another tag coming right off the outside metal of the turntable arm? and then the wiring goes from arm to table to receiver? i can manage that... any pictures out there of what something like that looks like ideally? i've never seen that, but i certainly believe you and am willing to try it. audioholics rule!
 
TLS Guy

TLS Guy

Audioholic Slumlord
thanks! i forgot to mention how and what i have done with grounding...

both turntable and receiver have ground tags and i have been wiring them together. the hum i experience barely changes when i disconnect the wire; only when i touch one free end.

so you are saying to solder another tag coming right off the outside metal of the turntable arm? and then the wiring goes from arm to table to receiver? i can manage that... any pictures out there of what something like that looks like ideally? i've never seen that, but i certainly believe you and am willing to try it. audioholics rule!
You need to check whether there is continuity to the arm to the RCA Jacks, or to the turntable ground or both. If there is no ground continuity to the arm, then I would link the arm to the turntable ground. I have a suspicion your arm is not grounded.

I'm leaving for Benedict now, and I will try and get some pictures underneath my turntables this weekend. It is really pretty simple. You do need a meter though to know what you are doing.
 
SWHouston

SWHouston

Enthusiast
Turntable Humm

rbreezy,

I know you said you cnecked everything but....

I had a very similar problem with my Turntable,
Had to run a separate Ground wire from the chassis
of the Turnbable, to the chassis of the main Amp
to get to stop.

Try using an Ohm meter to verify your ground between
the two pieces, or run a separate wire.

Have a good Day ! :)
S.W.
 
highfigh

highfigh

Audioholic Overlord
I'm having a video hum problem. (Probably audio hum as well, though the video hum is unmistakable.)

I have a new Panansonic HTIB (http://reviews.cnet.com/Panasonic_SC-HT920/4505-6740_7-30895706.html) that I just hooked up to my system, which includes TV, VCR, and DirecTV satellite receiver. The HTIB main unit (DVD player) is connected to a powered subwoofer (active subwoofer). The video hum is only present when watching DVD's, not when watching the satellite.

The satelitte box has a 3-prong power cable, while the powered subwoofer has a 2-prong power cable. (The TV and VCR also have 2-prong power cables; the DVD player is powered by the subwoofer.) What I've found is that unplugging the satellite box eliminates the video hum.

I've tried plugging the satellite box into another power recepticle, including in another room, but the hum is still present in varying degrees. (I should mention at this point that my house is 80 years old, for what it's worth.) As a test, and using an extension cord with a ground recepticle, I plugged the satellite power cord ground (third) prong ONLY into the extension cord's ground recepticle, leaving the other two prongs unplugged. The hum came back. This leads me to believe that it is indeed a ground loop issue.

After reading many articles and posting on the site about eliminating ground loops and interference, I decided to try using an isolation transformer. I purchased this one:



...since I figured the Jensen was a bit expensive and I didn't even know if that would solve my problem. It did not solve my problem. I'm not even sure if it helped at all as I didn't see any noticeable reduction in hum. I tried connecting it at the wall outlet for the satellite cable, at the satellite receiver, at the point where the satellite receiver connects with the VCR... pretty much everywhere I could. No luck. Then I read somewhere--maybe on the Jensen site--that satellite receivers may not be affected by an isolation transformer. I'm certainly not sure.

Any guidance would be much appreciated. I'm guessing that something is not grounded properly but I really have no idea how to fix it.
An 80 year old house can be expected to have electrical service that may be fine for lights and motors, but resistance in the neutral path will cause all kinds of issues, like yours. Also, if the stereo is on one circuit and the display is on another that uses the other Hot cable, while it's supposed to be sharing the neutral, it won't be the ideal situation, as far as the power supplies are concerned. Try to connect everything to the same circuit and see if some, if not all, of the noises go away.

You may have a ground loop on the audio cables, too. If you're using a digital coax, the ground is still connecting the two pieces and if your hum goes away when you unplug the coax, try using an optical cable.

If you can, run a new power feed to the equipment. The 80 year old wiring undoubtedly has more than a few connecting points and they won't necessarily make sense. Half of your house may have the neutrals combined in a box for a ceiling light, like mine did. Of course, I didn't know this when half of my recepticals went dead after I removed a ceiling fixture but I found it while searching for whatever could be disconnected.

Sat systems don't always have the same causes of hums and noise bars, but some are more than similar and coincidental. One cause is that the cable may not be very good or the terminations may be less than correctly installed. When the feed runs parallel to power wires, it's easy to pick up EMI. If they must be in the same place, cross them at a right angle and separate them by at least 12", more is better.

Cable, phone and satellite feeds are required to be grounded at the point of demarcation for the building, by the National Electrical Code. If they aren't grounded outside of the building, they are required to be grounded as close to that point inside of the building to the electrical panel or a cold water pipe that has no breaks between that point and the ground outside. The problem with this is that most of the cable and satellite installers either don't know this, or don't care. They're paid on a per-job basis and if they have to spend more time at one job, one or more jobs won't be done and they lose money. That's too bad. I want my house to be wired by the provider as well as I do for my customers and when they don't ground it, I call them back whether it's for my place or for a customer. I don't want to have a call-back, because some schmuck didn't think this was necessary.

Cable has a different cause, usually. They try to squeeze as many customers onto one amplifier and at some point, their ground's integrity is compromised. This causes voltage to be present on the shield and the resulting noise. A cheap RF isolator can work well but in some cases, the Jensen is needed. I was working on a job a couple of weeks ago and when we fired up the Cable TV, it hummed like crazy. We estimated that it had close to 60VAC on the cable, so we used a cheap isolator, since we weren't expecting any noise. Worked like a charm and the video quality was great, most likely because of the short distance. My cable had over 15VAC and I measured it after getting a good jolt when I connected it with one hand, behind the equipment. I saw a spark, too. I had to do the same for a customer last year when the new system hummed and that was all the time, not jsut when cable was on.

The way way to check for this it by making a short coax jumper that has no connection to the shield. If the noise is gone when this cable is used, isolation is needed.

DO NOT TOUCH THE SHIELD FROM THE CABLE BOX WITH ONE HAND AND GROUND YOUR OTHER HAND.
 
TLS Guy

TLS Guy

Audioholic Slumlord
This is an old thread, But I have reviewed it, and it seems a lot of misunderstanding has got into this thread about ground loops and grounding!

First of all, a ground loop has one and only one causation. It is a voltage potential between grounds. This way currents flow along your audio cables between the grounds, and it does not take much to induce hum. That is the cause, and the ONLY cause.

So ground loop problems are solved by removing and interrupting grounds, and NOT adding them.

Ideally the whole system should have ONE good ground. Often this is not possible, because a cable system brings in a ground at a different potential to the outlet you are using. In that case a ground MUST be interrupted. So the use of a quality device like the Jensen mentioned is indispensable.

These problems occur in new and old houses.

To solve your ground loops have a clear idea what the problem is and then use logic to solve it.

People make this issue so complicated. It is not, it is a straightforward problem.
 
A

audiomadman

Audiophyte
Wow that sounds complicated. Is there anywhere on the net where I can find more info.
All i can think of is an isolating transformer and maybe an inductor clamps around the power cables
 
TLS Guy

TLS Guy

Audioholic Slumlord
All i can think of is an isolating transformer and maybe an inductor clamps around the power cables
It is not complicated it is simple! It is not the power or power cables. Those have NOTHING to do with this issue. The issue is solely due to potential (voltage) between grounds. That issue is ALL that you have to focus on when sorting out ground loops.
 
ratso

ratso

Full Audioholic
jensen-transformers.com has been mentioned a lot in this thread. i might point people that are having trouble should go to that site's "white pages" - there is an excellent paper there called 'trouble shooting your system' or something to that effect. it gives a step by step method for finding exactly where the problem lies in your system. the shorting plugs that it talks about can either be made (they give you instructions) or bought from them for cheap.

all this having been said, why isn't there specialist in this field that you could pay to assist you (is there?). couldn't you just have someone come over to your house, diagnose your system, and fix it (really fix it, not just plug in few cheater plugs and call it a day). are most HT installers trained in this? (sorry i'm a 2 channel guy).
 
F

fractile

Junior Audioholic
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><A href="http://www.audioholics.com/techtips/setup/avhardware/groundloopcableTV.php"><IMG style="WIDTH: 73px; HEIGHT: 100px" alt=[productsshot] hspace=10 src="http://www.audioholics.com/news/thumbs/productsshot_th.jpg" align=left border=0></A>You’ve just connected your system and there’s a buzz or hum that won’t go away. You’re running your gear through power conditioners and you’re beating your head against the wall trying to figure out what’s up. Congratulations - you've just entered <EM>The Ground Loop Zone...<?XML:NAMESPACE PREFIX = O /><O:p></O:p></EM></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><O:p></O:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Several weeks ago I was pulling my hair out after I installed a new component into Reference System 3 for review. It was an amplifier that came with a three-prong power cable. Immediately after placing the amp in my system a very noticeable 60Hz hum starting pouring from my speakers.<O:p></O:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><O:p></O:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">If this has happened to you the chances are it’s a ground loop between your Cable TV and another component in your system (like an amplifier or powered subwoofer). Now, how do you solve it?<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>Check out this article for a surprisingly helpful way to combat this common problem.</SPAN></P>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">[Read About Combatting Ground Loops]</SPAN></P>
I don't even know if it's related, but a while back I was hearing hum from the self-powered sub-woofer when there was no signal and before it auto-shutoff. That instigated my purchase of the Furman IT-20 Balanced Power Conditioner. Meanwhile, the problem went away. No, that's not a $2.98 fix.
 
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F

fractile

Junior Audioholic
My take on the problem is that in standard ulitity wiring, the neutral wire is clamped to ground and any noise gets put there as well. Electronic equipment can do a lot of that, as if Ground is a free dumpsite.
 
F

fractile

Junior Audioholic
This is an old thread, But I have reviewed it, and it seems a lot of misunderstanding has got into this thread about ground loops and grounding!

First of all, a ground loop has one and only one causation. It is a voltage potential between grounds. This way currents flow along your audio cables between the grounds, and it does not take much to induce hum. That is the cause, and the ONLY cause.

So ground loop problems are solved by removing and interrupting grounds, and NOT adding them.

Ideally the whole system should have ONE good ground. Often this is not possible, because a cable system brings in a ground at a different potential to the outlet you are using. In that case a ground MUST be interrupted. So the use of a quality device like the Jensen mentioned is indispensable.

These problems occur in new and old houses.

To solve your ground loops have a clear idea what the problem is and then use logic to solve it.

People make this issue so complicated. It is not, it is a straightforward problem.
I see it as not just a ground problem, but a neutral clamped to ground problem, since, for one, the powered sub-woofer has no ground pin, but had hum.
 
highfigh

highfigh

Audioholic Overlord
...all this having been said, why isn't there specialist in this field that you could pay to assist you (is there?). couldn't you just have someone come over to your house, diagnose your system, and fix it (really fix it, not just plug in few cheater plugs and call it a day). are most HT installers trained in this? (sorry i'm a 2 channel guy).
You seem to think most dealers actually provide training for their installers. That's not the case, unfortunately and because it falls under the Low Voltage umbrella, it's not required, but because of the bad business practices of many non-storefront dealer/installers (and the fact that it would provide income to the local government), more cities are requiring that anyone who wants to do this legally will need to be licensed.

CEDIA is an attempt to do for home theater and residential electronic equipment installation what MECP did for car audio, which is increase the average level of knowledge and skill for installers. The problem is that installers don't see it as a long-term career, so they don't really care to know more. They often think that they know it all anyway, so it's not worth their time and sometimes, money. Dealers often don't see the benefit in sending their installers to training because they want to see dollars, not certificates, hats and patches that are sewn onto a shirt. The irony is in the fact that they have more trouble calls and repairs to bad terminations/improper wiring. If an installer can't terminate Cat-5e or coax, don't expect them to know anything or care about high voltage unless that's what they did before low voltage.

Most people who do low voltage installation see high voltage as three wires and want easy solutions to their system problems. Ground lift adapters and isolation transformers are easy fixes, but not all transformers are created equal. I saw a whole house rack filled with 36 channels of Bryston amps and IIRC, I counted a dozen Radio Shack ground loop isolators, which sell for about $15. I was not impressed.

Best case, the neutral is grounded properly in the service panel, the receptacles are decent, the wire nuts are tight/clean and there's nothing that causes resistance from one equipment location to another. Worst case, the circuit is being pushed close to its limit, the receptacles were back-stabbed, the wire nuts aren't tight and some weekend warrior added all kinds of switches, lights and receptacles to the legs, usually between the amp(s) and sources, sub or TV.
 
ratso

ratso

Full Audioholic
You seem to think most dealers actually provide training for their installers.
no actually i figured (thanx for the post BTW) that most don't. i just think maybe some SHOULD. i know jensen transformers gives seminars, it would be nice if there was some sort or certification offered. and i would think at least in major urban areas (i live by chicago) that there would be some profit to be made if a HT/stereo specialty store that already does in home service could add "humbusting" to their services offered. some places seem to be finding some profit in ISF certification, i'm thinking something like that?
 
highfigh

highfigh

Audioholic Overlord
no actually i figured (thanx for the post BTW) that most don't. i just think maybe some SHOULD. i know jensen transformers gives seminars, it would be nice if there was some sort or certification offered. and i would think at least in major urban areas (i live by chicago) that there would be some profit to be made if a HT/stereo specialty store that already does in home service could add "humbusting" to their services offered. some places seem to be finding some profit in ISF certification, i'm thinking something like that?
I have never had a single person ask if I have any kind of certification. I could wear my CEDIA patch or put their logo on my business cards but if nobody knows about it, it doesn't seem to be worth much. The problem with being the "go to guy" for this kind of thing is that to legally do high voltage work, the person has to be licensed for that. To go to school to be an electrician would mean that I would have to go through the apprentice program, which I wouldn't complete until I'm over 60 years old. Apprentices make approximately squat and thanks to all of the financial BS, that's not even close to being an option. Also, residential electricians aren't at the top of the heap when it comes to skills, unless they are the type who want to be the best at that and not use it to advance to industrial/commercial work. This means that in addition to the HV technical info and training, they would have to learn about all of the low voltage technicalities that electricians seldom care about. Most of the ones I've dealt with look at me like a dog watching TV when I tell them that I want the receptacle for the TV to be fed from the same circuit as the rest of the system and that I want the leg from the feed to the TV and the rest to be the same length.

The problem with all of this is that most owners of companies that do sales, integration and installation don't want to pay for highly trained people, in a lot of cases. It doesn't make sense from the standpoint of wanting to do everything right but you need to realize that people don't want to pay the price a local dealer needs to make in order to survive, let alone adding the installation, parts, programming, additional equipment and custom work. Even people who have so much money their grandchildren would have a hard time spending it all can be incredibly cheap. People would rather buy this stuff online because they don't want to pay retail, yet they want a local guy to come in and fix their installation problems, tell them that they bought all the right stuff and smooth everything out when it looks or sounds like crap. Shopping the local stores and buying mail order isn't a new thing, but it's a serious PITA to those of us trying to make a buck.
 
highfigh

highfigh

Audioholic Overlord
no actually i figured (thanx for the post BTW) that most don't. i just think maybe some SHOULD. i know jensen transformers gives seminars, it would be nice if there was some sort or certification offered. and i would think at least in major urban areas (i live by chicago) that there would be some profit to be made if a HT/stereo specialty store that already does in home service could add "humbusting" to their services offered. some places seem to be finding some profit in ISF certification, i'm thinking something like that?
I saw the noise busting seminars by Bill (from Jensen) when I did 12V audio and again in '05 when I worked for a large integrator. He basically did the same presentation, because the basics don't change. The guys I went with were pretty lost, but since I have had more training, it was a re-hash for me. Still, it's always good to go back to refresh when that much time has passed between sessions.

As I posted- high voltage work requires a license unless the company has a licensed electrician on staff, which isn't an option for the vast majority of dealers, although it makes complete sense, to me, that all dealers should hire one.
 

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