Lift the ground pin (using a "cheater " plug) on all 3-prong power cords except the preamp. That should get rid of the hum.
Then remove the cheater plugs one by one until the hum returns. That's the one giving you the ground loop. |
My Avantgarde woofers hum very slightly and the hum goes very slightly louder when I power up the rest of the system. I think this issue was solved in the latest sub amp. I'm not sure if it similar to the DB99 set up, but the symptoms seem similar. I have tried every solution including the one suggested above to no avail. The hum is so slight i've decided to ignore it. I can't hear it during music. I hope you can solve yours with cheaters.
Good luck |
Have your utility check your voltage, your lites shouldn't flicker. I had a similar problem with low voltage from an undersize old power transformer. I am curious about the dedicated lines. Are they all on the same phase(side) of your panel? this can cause noise problems. |
If you plugged everything into one outlet, then ground loops are not the problem. It is most likely caused by either external RF/EMI interference or power line noise which may be in the power coming into the house (yes, the power company xfmr can radiate the noise). Only an isolation transformer can solve this problem. If there are RF sources, then the long Romex runs pick up the noise. One method to solve this may be to put the romex into metallic tubing and ground the tubing by bonding it at the panel.
A second source of the problem could be if you have cable TV service and the incoming cable is not grounded to the house electrical ground or is not connected at all. This can cause ground loops within the house wiring from the CATV equipment.
Another problem could be the second ground. Try disconnecting the water pipe ground and see if there's a problem with just the ground rod connected. Then try the disconnecting only the ground rod. If either of these is the problem, get an electrician to confirm that they have been reconnected properly. Usually, two ground connections result in a voltage differences throughout the grounding system making it more likey to pick up stray currents. |
If you plugged everything into one oulet, you have ground loops galore!! You may not have a ground loop thru the in-wall ground wire(s) but so what? Trace the path: from AC ground to component to interconnects to next component and back to AC ground, and so on and so on and so on with each source component thru the preamp thru the amp and thru any powered speakers/subs.
Lift all ground plugs except the preamp so you have a single path from all equipment back to ground. |
Hi,
Thanks for all the info and ideas. Although I'm pretty sure I had already tried lifting the grounds on everything but the preamp, I tried it again, but the hum persists. Considering that the speaker will hum even if it is not connected to anything, only plugged in to the wall to power the subamp, it seems unlikely/impossible to be a ground loop associated with the rest of the equipment.
I have been researching the subpanel/isolation transformer idea for a month or two now and managed to pick up a 5Kva Topaz transformer on the cheap, so I'll probably go this route at some point in the near future.
I suppose I'll need to call the utility co. and ask them to replace the transformer leading to my house. Is this something I'm likely to meet resistance with?
With respect to Gs5556's response, What does EMI/RFI sound like? Kind of naive question I guess, but does it sound like 60Hz hum? What differentiates it? Second, I do have cable and I remember the installation guys hooking up some kind of grounding to my electrical panel, but I think it's mounted to the outside of the box. There is no cable hooked up to any part of the stereo however. And last, I did actually disconnect the water pipe ground a while back to see if it would make any difference, but it didn't. I never tried disconnecting the other ground though while leaving the water pipe connected so I'll give that a try.
I really appreciate everybody's help!
Matt |
Call your power company and have them test the transformer and install a data recorder at your meter if the CATV and phone grounds are not the problem. CATV and phone must be connected to the same ground rod as the service grounding conductor. Most power companies are required to provide clean power to the service. If you have a well, the ground rod or rods are your ground and the water pipes are not. The pipes are bonded to the ground for saftey. Never ever disconnect the ground wire of the service with the main breaker on. Turn off the main breaker before disconnecting the service grounding conductor. You could get electricuted if you dont. Your lights will dim for 1-3 seconds no matter what the size of the transformer when you AC starts. What you are hearing is probably a 60Hz hum. The hum could be coming in through the neutral from the transformer. If you lift (remove) grounds on your equipment with metal housings, you have a small chance of getting killed. If the power company will not help you do this. Hire an electrician and ask him to connect an outlet directly to the line (street)side of the meter socket. Plug your subwoofer or you whole system into that outlet. If it still hums, complain to your power company about bad power and have them fix it.
. |
Matt, a lot of subs have a very faint 60 cycle hum/buzz when plugged in alone with no other connections. Something in those class D amps they use. You might want to check with the manufacturer though. |
Nsgarch,
It's actually a 300W Class A/B solid state amp. If it was only the sub amp then the midrange and tweeter shouldn't be effected according to Kevin at VSA. We'll see...
Matt |
Noisy power poles are a longtime nemesis for ham radio operators whose sensitive receivers try to pull weak signals from the ether. An arcing insulator on the 12KV lines atop most residential and rural neighborhood power poles can spew RFI across hundreds of Mhz.
Depending on what mode you listen in (AM, FM, SSB) it sounds like a grinding buzz, or your basic 60-cycle hum. There's a pole 2-300 yards from our house that has been causing me no end of grief, and the local power company doesn't give a rat's ass about it. Last year I complained formally and after 7-months they dispatched a truck to "rebuild" the entire top of the pole. The parts all looked the same when I got home from work that day, and of course, the noise was still there.
Use a portable AM radio tuned to an empty spot on the AM band. Walk down your street from power pole to power pole noting if static/hum increases as you approach/depart each pole. If a pole has guy wires, twang the wires and listen for noise (it shouldn't cause any). Bring a pad of paper and pen as you'll need to note the pole ID numbers to lodge your formal complaint. Some utilities are pretty good about fixing these things; others, like PG&E here in NorCal, are not.
If you end up finding a noisy pole and file a formal complaint, I strongly recommend you log each and every contact you make with your utility as you may need it later when the issue has dragged on longer than you ever imagined possible.
I have a hum problem on my newly assembled high-end system and I'm hoping it's something *inside* my house and not something *outside* in PG&E's domain. |
The power company made it out today and although they couldn't find a voltage problem they installed a data recorder and said they'd be back in a few days. They agreed that the transformer was very old and possibly undersized as well. He said they would turn in a work order to replace it after they finished recording it's activity. Fairly positive visit, but we'll see how it turns out. Sometime next week my electrician is going to come over and install the iso transformer as well so pretty soon I should have an answer. Thanks for your help so far and I'll let you know how things work out. |
The electric company let me down. They said that, although my voltage did drop below 120V when the A/C turned on, it was otherwise operating normally. They also said that noise on the line was not their problem and they weren't willing to use their resources to track it down. They suggested getting a "Starter Kit" for my A/C, but I know nothing about these so I'll have to do some research. They offered no real help with the hum. I'm going to try and schedule some time with the electrician to install the Iso tranny and see if that helps. After that I'll try and run the Romex thru metallic tubing that I ground to the subpanel. Eventually, I may solve this:-). |
A heavy duty starter kit is a good thing to have on your A/C anyway (though I don't think it will solve your noise problem) It's an especially good thing to have if you've got children who play with the thermostat! |
I'm hoping the isolation transformer will help with the noise. The electrician is coming over Thursday night to do a test hook-up and see what happens. The starter kit is something I know nothing about, but if it will stop my lights from dimming I'm all for it. Before I start the search do you have any suggestions/explanations that could point me in the right direction? |
Well, we hooked up the Isolation Transformer today and the hum was still present. I guess the only thing I haven't been able to try yet is ruling out RFI. Is there any way to check for this without spending a lot of money? |
Did you test the power at the meter yet? Is the hum still present before the power enters your dwelling? |
No, I did not get that done. The city however has told me they will not do anything about the hum problem as I do not have a voltage problem as far as they're concerned. I thought the iso tranny would help kill any noise coming from the main transformer? Any ideas? |
I guess I could use some help clearing my head:-). What should I do next? The iso tranny didn't work, the electric company seems to think there is nothing wrong with the transformer, no amount of Quietlines or Enacom filters seem to have any effect. How do I stop this hum??? It's driving me freakin' nuts. The electrician will not hook up an outlet in the manner Nerspellsner describes because he says it would be against the law, a felony I believe. Granted it would only be for a few minutes but he's not going to do it. I really don't know what else to do. Any help to offer? |
You dont have to (steal) power to do this test. I will describe the legal way to test your power. This has to be done by a licenced electrician. Open your meter socket.Leave the meter in the socket and disconnect the feeder wires at the load side of the meter socket.As long as the meter is in place, you are not stealing power. Connect a fused or circuit breaker protected outlet attached to an extension cord long enough to reach your equipment. You have to find out if the hum is from the street or is coming from your house somewhere before you try to fix it. |
A few more questions. Do you have only one main electrical panel or do you also have a sub panel installed. Is your main circuit breaker in the panel or in the meter socket? On to another subject. There is a chance that somewhere in the house, a bare ground wire is touching the neutral terminal of an outlet. This problem would not be indicated with a plug in outlet tester. If the ground touches the neutral, current will be flowing through the ground wire and produce a hum. I hate to say this but the only way to find out is to remove every outlet in the house and visually inspect each one. Sometimes you can see the problem by just removing the cover plate. Turn off the circuit breakers before you do this. You can wrap the outlets with high grade electrical tape to cover the screw terminals to prevent the ground from touching the neutral screw. This problem could also happen in light fixtures or switches or even a screw or nail going through the cable but much less common than the outlets. Before spending time doing this, find out if the hum is originating from the street or your house by using the method described in my previous post. Good Luck. |
Thanks Nerspellsner! I didn't understand clearly before what you meant. I will ask my electrician about it and hopefully get him to come out and give it a try. |
Forgot to answer your questions...I have only one main panel. When we hooked up the transformer we used a subpanel in a temporary arrangement, but I wanted to try it before permanently installing it. The main breaker is in the panel, not the meter socket. |
This is a great product for surge protection and power enhancement that installs at your main panel. This is whats inside of the old Seakay Linerover line conditioners. It will not help with the hum problem. http://www.usesmfg.com/ |
I ruled out the speakers today. Borrowed a friends and they hummed too. Next step is to find out if it's the city or the house. |
RFI is not the prob. Does the hum have a bit of a buzzing component to it? Two types;60&120hz. 120 has this really anoying buzzing to it,60 is rather bassey of course. A mic and a o-scope, sure would be handy. Dumb question,is a TV,or some other electronic device near the speaker, and was it also near your test speaker? |
No TV or cable anywhere near the system or connected to it in any way. I couldn't tell you whether it's 60Hz or 120Hz. I've listened to it pretty carefully and would swear there is a rythm to it of about 4 beats per second, but other than that I don't know. A mic and scope would be nice, but unlikely I can find one to borrow. What would the difference be as far as what's wrong if it's 120Hz vs. 60Hz? |
This may be totally off track, but I was a technician and was troubleshooting a problem at a customers home. I found no problem at the home, but with an RF meter, walked down the street and found a neighbor had installed an invisible fence for his dogs. He had the gain turned up to the max and this was affecting their TV, appliances and garage door opener. Their tv had lines and a hum. This may not be your issue, but worth a look. The man turned the gain down and the problem went away.
Good luck! |
Do you have any halogen lites? I had a hum problem that none of my friends who are also into this hobby could solve. Turned out it was the halogen bulbs in my listening room's pot lites. Changed all of them and the hum was gone.Although we live in different places it seems as if the"power company" plays by it's own set of rules.In my case they lost when they read the weekends power read out and installed a new transformer on the outside pole.Of course I did mention that they would be liable if my AC and refridgerator motors burnt out. |
I sypathize. I am having very similar issues. So far, the only thing that has helped is plugging my amp into the richard gray 4000pro and having that run into the pole pig. I am going to see if it helps with the second amp and external crossover. I have been suffering with my hum for close to a year now and since I live in the virgin islands, if you think your power company is bad.........
; |
120hz would be the ripple component frequency of a rectified power supply. Trying to determine if it's an electrical or electronics problem. The PS unit should have isolated the equipment from AC, since it regenerates it's own. Did you try it with every thing hooked up to it, and all grounds floating? Also, does the Topaz offer 240/120 stepdown? You could try this and establish a good ground at the secondary, or float it. Doing this may determine if you have a problem with an unbalanced service transformer. Another thing, how about light dimmers? The triacs used in them have been known to cause problems. Floresence fixtures? |
Hifi57,
The topaz can step 240 down to 120 as far as I know. I believe we hooked it up that way at one point. We tried various connections, even wiring it for balanced output. What/How would grounding, or floating the ground, on the output side tell us about the service transformer?
Matt |
After reading all these, (and you didn't specify what the borrowed speakers were) I'd *really* suspect your power amp.
Followed by the speaker cables. One of the two; doesn't matter the order. |
That wouldn't make any sense because when the power amp and speaker cables are disconnected, and only the speaker is plugged into the wall, it will hum. You should re-read some of the above posts, as I'm sure they are confusing. At this point, I'm sure it's coming from the electricity and not my equipment. I still need to find whether it's coming to me from the city, or something that happens after it arrives in my house. Hopefully soon, I'll have some more answers. |
The ideal ground would be at 0v DC, 0hz to light AC, to earth. All voltages are ultimatly referenced to ground. If you have trash on the ground it can couple to your system. |
Sorry, I missed that line in your original post.
Your friend's speakers(unamed, but let's assume the same as yours) hummed at your place. You've gone only half way; do yours hum at his place? Do his hum at his place? That's all the matrix you need to try.
Both hum, both places = design or production fault w/ both speaks.
Both hum, only your place = wiring problem, your place.
His don't, your's do hum, your place = defect in your speaks. |
It's been a while now Mab33. Did you ever get the hum issue rectified? |
Hi Sherod,
Well, yes, but not in the way I thought I would. I can't count the number of times I had my friend Terry, who is an electrician, over to the house to try whatever I had read about in an effort to kill the noise. In the end, it never made any difference, well, that I could tell at least.
Then, I replaced my preamp and phono stage with Raul's Essential 3150 Phono/Line preamp, and all the noise went away. Actually, not all of it, if I put my ear within a few inches of the driver I can still hear a tiny bit of noise, but I think that's fairly normal and it definitely doesn't bother me or become audible from the listening position.
I have to tell you that this makes no sense to me. In the posts above I described unplugging everything in the system and disconnenting the speaker cables so that I could effectively isolate one speaker. I then plugged in the sub amp of just the one speaker with nothing else attached. This still resulted in the same amount of noise, but only thru the woofer, because the mid and tweeter were not recieving any signal/power. Since this, I presumed, meant it wasn't any of the other equipment, or a typical ground loop problem, I focused my attention on the electrical power coming to/thru the house. Nothing I tried, however, worked.
So, I have no idea why changing to the Essential fixed the problem, but it did and I can only tell you that I popped one of my best bottles of wine that night and sat there alone listening to the silence between songs in total amazement/relief/bewilderment until I was not thinking clearly anymore and called it a night:-).
The Essential does run fully balanced and now everything in the system, except the CD player, runs balanced connections as well, including my tonearm, so perhaps that has something to do with it. The power supply on the Essential is a fairly sophisticated beast and very well could be responsible, but ultimately I have given up trying to figure out why and have happily accepted the result.
There are a couple of threads in the Analog forum that discuss the Essential 3150 if you're interested. Mine is not the only system that got quieter after installing it according to at least one post. Needless to say I'm very happy with it!
Matt |
I have given up trying to figure out why and have happily accepted the result. Noise is probably coming from the mains and the pre has a serious grounding scheme on it (finally!). Balanced helps with common mode rejection. I had a similar problem and solved it with a symmetrical double filter (for AC). |
Can you tell us more about the filter you are using? |
Mab33 -- I haven't seen the schematics, I'm afraid, so there is little I can actually say about the circuit.
It was made by an acquiaintance and its intended use is for medical diagnostic equip -- not hi-fi.
The net result is to lower the noise floor considerably in my system; it also eliminated the usual buzz & hum. Strangely, the sonic improvement was remarkably clear even on my cdp which, purportedly, already has an AC "filter" of sorts... |
I am still not at the bottom of my hum problem but I think I finally have a line on it. With the speakers connected to the amp and the pre disconnected I have hum on the right channnel only. With pre connected hum is in both speakers. I put my older amp in and the speakers are silent, thus I have concluded that it has to be in the amp. I am going to take the amp to another house and connect it to the speakers and if I still hear the hum it is definately the amp. I have many hours of trouble shooting this problem. I have tried cheater plugs, different interconnects and power cords you name it and I have tried it. Should know for sure this weekend. |
Elsneb, very good thinking, man! Moreover, you just may have saved the "Woofer" from gettin" blown!! |
