Hum FAQ - Page 4

im having a hum problem to.......i tried unpluging the 705,my tv, and my ps3 but the hum was still there,(says to try these things in the faq) i had my sub pluged in a surge protecter outlet that i got from bestbuy along with the tv and ps3, took it out from there and pluged it directly inside the wall socket but the hum is still there. and my hum turns on for awile and off awile. and i dont know if this happend because of the sub but last night the section where i have all my stuff hooked had a power outage. everything just cut off wile i was playing a game. everthing else in my room was still on except for that section.
everthing is back on now but from now on i just unpluge the sub when im not using it(its ok to leave it unpluged right?)
and by the way i dont have the 3 socket pluge i have the two.

and on my surgeprocter box both lights that say ground and surge are on what does that mean?.

Just a quick thanks for this sticky. Two days ago I got a Vizio LCD and an Onkyo SR605 to go with my Time Warner Samsung HD box. Well, I can't figure out a solution to the HDCP problem that's keeping me from running the cable HDMI through the Onkyo, but I can run it into the TV and run digital audio (coax) into the Onkyo. The Onkyo has an HDMI running into the TV also, for the DVD and other stuff.

So, that three-way dance caused a hum. After getting down to the bare minimum config and still having the hum, I called Onkyo and spent 40 minutes resetting everything and undoing all the speaker wires, and finally having the guy tell me to exchange it where I bought it. Hey, that thing weights 20 pounds easy and is one PITA to return. Plus, I really didn't think it was bad.

Then I looked here and read the sticky. Oh. Well, I still don't really know what the problem is, though I see lots of things to try, like post 64. Still, the critical thing for me so far was reading that optical doesn't cause this problem. I switched the box > onkyo from coax to optical and there went the problem. Happy happy joy joy. I'll look into the other stuff, but at least I can sleep tonight without cursing.

^ I second the thanks. I've just gone from clueless to somewhat informed by reading this and similar threads. The trigger? I just hooked up my new Onkyo 705 last weekend and entered the anoying world of ground loop hum. In my case, I think the problem is pretty clear. My Comcast cable is apparently at odds (ground wise) with the grounding prong in my PJ's 3-pronger. If I disconnect the cable from the cable box; dead silence. If I unplug the projector; also dead silence. Both hooked up (the two ends of the ground loop) and it hums away.

A side effect of these great new switching receivers, is that they are now in the middle of all connections, meaning any ground loop will pass through them and bring the hum. Prior to this, my old AVR was sitting on the side getting digital audio via coax for the cable box and optical for the HD-DVD. No opportunity in that setup for the cable ground vs. projector ground to show up in the AVR. I've got Comcast coming out to work on a better gound at the service entrance, but won't hesitate to buy the Jensen Isolator if need be. Like the last guy, I'm just glad I don't have to mess with returning the AVR, only to find that I still have the problem.

The only things that will stop the ground loops are if the cable is grounded to the grounding rod for the whole house or using a device like the Jensen Transformers cable isolator. The ground rod might be in the garage, or somewhere outside the house, probably close to the electric meter, or it may be in the basement near the location where the power feeds into the house from the meter. If the house is older, it may be relying on metal plumbing pipes for the ground which is NOT a good idea. The older the house is, the stranger and more oddly located the ground rod may be - or as noted, there may be no ground rod at all. The ground rod often looks similar to a piece of rebar (reinforcing bar used in cement) with a clamp on it and some electrical wiring being clamped to the bar. This bar may be protruding from concrete in the garage or basement, or it may be burried in the earth beside the home with the top sticking out of the ground. Protected locations (garage or basement) are preferred to minimize weathering effects on the electrical connections.

While all that is true (and useful ) for someone living back East, here in Arizona it's a different game. IIRC, the grounding rods for the houses in my neighborhood are buried beneath the slabs where there is at least a chance of some moisture in the ground. The service panel has nothing going into the ground other than the large conduit bringing in the underground electrical main. Plumbing is non-metallic. Of course, Comcast just slapped a metal clamp around the counduit and attached the ground wire from the cable box to it. I doubt the conduit extends into the soil more than a foot, and it is probably a poor electrical connection with the panel and the neutral/ground connections within. I'm giving Comcast a chance, since they charge so many $$$$ for everything. Worst case, I'll waste a half hour of my day off. Best case, they'll either improve the ground enough to eliminate the ground loop or supply an equivalent to the Jenson transformer. We'll see.....

Well, I'm not in the East, I'm in Colorado with very little rain or snow. And it's no different in AZ because garages are slabs, so are basements. When there's no basement the ground rod installation is the same as it would be if the rod was in the garage or basement... drive the rod several feet into the ground (how deep is established by state electrical code), compact the earth, lay a vapor barrier, install the rock layer, pour the cement.

Back east, most of the time the rods are inside the house (garage or basement), but I have seen them outside near the meter, probably the only variation you won't see in dry climates.

Sounds like I would be better off in Colorado.....

But seriously, I watched every step of my house being built and have lived in it for twelve years. There is no exposed ground rod anywhere. I vaguely remember them having routed the heavy copper cable inside the 8" wide stem wall that the service panel sits over. I have a raft foundation, so things may be different than the normal footer/slab or post-tension foundations.

I was right! I DID waste a half hour of my day off. Two techs were here and when I mentioned ground loop, they looked at each other with that revealing blank look. Then, I added to my wasted time by explaining that the ground of their incoming cable was at a slightly different potential than the ground of the single three-pronged device in the system (my PJ). I then demonstrated that if I unhooked the cable, the hum stopped; if I unplugged the PJ, the hum stopped. With both connected, the hum was very noticeable.

At that point, the more seasoned of the two pulled out his multimeter, checked the outlet my PJ was plugged into and proceeded to proclaim that the reason for my hum was that the outlet measured at 123 volts.

Needless to say, I wasted NO time in ordering one of the Jensen Isolators before they were even out of the neighborhood.

Cable company weasels - it's a wonder the "expert" knew how to measure the outlet voltage without electrocuting himself. To say these guys are "technicians" is like saying I'm a web page designer by adding my post to this thread.

You've got that right. I concluded that any time a Comcast tech decides that they have a customer with an "imagined" problem, they're advised to pull out the fancy meter and make some goofy recommendation designed to get the OCD customer's energy focused in some other direction. These guys didn't even do a convincing job at that.....

Hey all - First post.

I had the audio hum problem (ground loop) problem caused by coaxial cable. Both lines were previously grounded outside the house, but that didn't help with the hum. I had the same problem with my system with two different TV's. My original solution was to use one of those ground-breaking filters, but that degraded my picture quality to an unsatisfactory level.

I recently bought a new TV and it had a two coaxial hookups, one for cable/satellite and the other for an antenna. Those filters are quite expensive and as I said, they degraded the picture. I scratched my head for quite a while, but finally found a solution that worked well.

I bought a coaxial ground breaker and grounded it to my surge suppressor. Pretty simple and it completely eliminated the hum and there's no picture loss.

Here are the two pieces of equipment I used.

Paladin Tools - Dual port ground block

Panamax - Max 4400 20A surge suppressor.

(couldn't post links because of newbie status)

Many surge suppressors have grounding lugs and I would assume most people have invested in one. The ground breaker is only $3.50 and it works up to 3Ghz. I made two 1 ft. coaxial cables from the ground break to the TV and used a solid grounding wire.

In addition to the setup, I added a splitter for the OTA connection and used the second run for FM stereo. Sounds great and no degradation of video or audio. FYI my antenna amplifier is before the ground.

Perhaps this is a cheaper and easy solution for those not wanting to invest in those expensive filters.

Cheers!

Peter

Update: the Jensen Isolator is now installed. The thing works as advertised and I feel safe in strongly recommending it to everyone. There is no longer any trace of hum in my system, regardless of source.

I just got an Onkyo 705 and have a severe hum problem, audible in the main speakers as well as the sub.

I have no cable or satellite box and disconnecting the cable from the FM antenna didn't help.

I shorted the outer shell of the 705's HDMI output connector to the 705 chassis ground screw; didn't help.

As soon as I disconnect the 35' HDMI cable that runs to my projector, it goes away.

All devices with 3-prong plugs are properly grounded, eventually, to ground rods at the main service entrance and subpanel.

Any suggestions?

Do you have any light dimmers on the same circuit? Does your HDMI cable run along any AC house wiring and/or power cords?

"Do you have any light dimmers on the same circuit? Does your HDMI cable run along any AC house wiring and/or power cords?"

No to both.

Thanks.

35' That's a long cable run. Have your tried moving the projector close to the receiver and using a shorter HDMI cable to see if the noise is still there? Might be a big hassle if you already have it mounted.

Sure would be; it's behind the back wall.

I'll try a cheater plug on the pj and see what happens.

The cheater plug on the pj got rid of the hum, so I ordered a Hum X. Hope it works.

I have a 10' SVS box sub, which I love. I changed receivers a few days ago, and since then have been having a bad hum whenever the new receiver is off. When I tried to trouble shoot this I discovered a few things, all of which make me confused:

1) The BASH amp in the sub doesn't have a grounded power plug, so, even though I bought a cheater plug to test, there's no ground to lift. Everything I've read says that an ungrounded sub should only be a temporary condition, but this doesn't even have the option. Why?

2) I bought a cheap isolator from Radio Shack today to test that, but in the course of testing it discovered that if I plug it into the line in on the Sub and then touch either the post or ring of the matching RCA jack I get a hum, like my finger has enough current to drive the amp, the volume of the hum does respond to the gain control. This effect is independent of the Isolator, I tested it with a regular cable. I assume it's related to my finger creating a ground condition with my feet and the house and that's what I'm hearing.

3) What's happening here, and is there anyway to fix it?

NO CHEATER PLUGS... EVER! PLEASE! People have been killed by products plugged in with cheater plugs. DON'T DO IT!

There's a 99.9% chance your hum will disappear if you get a decent 35' AC extension cord (get one for power tools like saws or compressors) and plug it in to the same outlet or power conditioner as the AVR.

You have a ground loop that's being caused by the projector ground and AVR ground not being at the same potential. The cheater plug will probably stop the hum - but you will be putting yourself in danger. You can try the cheater plug briefly to see if the hum goes away... if it does (and it probably will), remove the cheater plug right away, then get the nice grounded extension cord and use that to power the projector instead of the outlet it's plugged into now.

I’ve made a few changes to the surround channel arrays or the amplifiers that they drive, which has now induced the elusive mains humming sound transmitted though one of many electrical items.

So far I’ve isolated but one amplifier Marantz 1050 that runs the centre HF and centre back surrounds.

Now here is the funny the humming that is being produced on the sidewall surrounds driven by the Marantz 1030 only occurs when I turn on the second Marantz 1050, I have two of them. Now if I turn on the other Marantz 1050 the hum is induced over to the Marantz 1030, weird but true. Now if I undo the RCA phone leads leading to the Marantz 1030 the hum goes away, but that’s not going to help because I need to here the sidewall surrounds, don’t I.

I’ve checked the earth leads connected to them and even undone one or two to see if that clears it, as its worked in the past.

I’ve even tried attaching some wire to the (outside chassis casing) and attached the wire to several electrical items to see if that clears it. So far this has been a fighting challenge to solve the (elusive humming) does something give here for Pete shakes!

Anyways I don’t like giving up and I’ll keep go at it, until I track down the curse of the (elusive mains humming gremlin).

Oh, last time it took me 24 hours around the clock to find main hum that was induced by the new, well old, but it was new to me, TV and all I had to do was undone a sodden earth lead on an active crossover network.

In response to myself:

I fixed the problem by replacing the subcable, which used to be a very poorly insulated RCA run with a length of R6 Coax terminated in RCA connectors. It works great now, but I left the isolator off the linkage since it was inducing hum itself (the leads on the Rat Shack Isolator are very thin and poorly shielded too). I don't know if that means that there's some major interference source in the room or what, but since the problem is gone I've stopped caring.

maxdb,

"NO CHEATER PLUGS... EVER! PLEASE! People have been killed by products plugged in with cheater plugs. DON'T DO IT!"

Just for a couple of days, I promise.

I don't see the danger, as the pj has a plastic case.

"There's a 99.9% chance your hum will disappear if you get a decent 35' AC extension cord (get one for power tools like saws or compressors) and plug it in to the same outlet or power conditioner as the AVR.

You have a ground loop that's being caused by the projector ground and AVR ground not being at the same potential. "

All of the ground wires are connected together via the electrical system, it's just a question of the length/resistance of each conductor.

What's to keep the ground wire in the long extension cord from also causing hum?

In any case, because I have no attic and am on a slab, the only way to do that is another conduit run on the roof; not gonna happen.

As long as the long extension cord has a large enough wire gauge to read very close to 0 ohms from end to end, it will not induce a loop. The whole point of plugging it into the same outlet or power conditioner as the AVR/processor is to put the projector ground and AVR/processor ground at the same potential - which they will be if the extension cord is a good one (for use with saws and other high-current tools). I wasn't advocating installing it in the wall, floor, or ceiling. I was thinking you'd just run it around the perimeter of the room... from where the AVR/processor is plugged in to where it needs to be to plug in the projector.

Certainly the bottom of the projector has exposed metal? Any exposed metal part on the projector can be at 120VAC if you use a cheater plug... touch the wrong spot and your heart can be stopped. It doesn't happen often... but it does happen. Connectors usually have metal around them...those could be raised to 120VAC when using a cheater plug also. There has to be a component failure in the "cheated" product for this to happen - but it can happen.

HELPP!!!!!!!

I've got a VERY LOUD ground hum that just started after someone decided it would save alot of time to install a fan light fixture without cutting the power to the line before working. After alot of sparks I developed a very loud ground hum. It is present on alot of outlets in that area of the house I plug the sub into. If i run an extension cord to some different outlets in the room or other places in the house it isn't evident at all.

I've tried removing the switch that got zapped and still have the humm. I tried a plug with the ground pole removed(cheater plug?) and its still there and still loud.

Can this be a problem at the individual breaker? How can I find the source.

Sounds like the fan is not wired properly or that you're pulling too much juice from the circuit.

You are in very dangerous territory right now. It does not sound like you have the knowledge or skill with electrical wiring and electricity to safely diagnose what is going on. Doing the wrong thing, like using a cheater plug which you already tried, can put your life at risk. This is something for a knowledgeable professional - and I don't mean Joe Electrician who runs wires and hooks up outlets or fans. Something is fundamentally messing with your wiring and until it is fixed, I would not even operate my system on that power.

It might be something completely safe, but troublesome, but it could also be something that could burn your house down or damage your equipment. I would not take chances.

GROUND-LOOPING PROBLEM

I have read a lot of forums on this, but for me, all the solutions given have not worked for me. I keep getting oud buzzing noise in my right speakers. Here is my scenario. I have a Macintosh Powerbook.

The audio out of the laptop goes into an M-Audio MobilePre (Audio Interface)

From there, White/Red RCA output cables WITH a ground-loop isolator connect to my Onkyo receiver.

From there the Onkyo receiver connects to 2-sets of speakers. Speaker set A and B.

Both my laptop and receiver have 2-prong un-grounded plugs that go into the same power strip that then goes into the wall (using a 3 to 2 prong adapter for the power strip does not help at all).

Also disconnecting any TV or Antennas from the receiver doesn’t help either.

There is only one solution that clears the noise from the speakers…disconnect the power to my laptop and run on battery. But my computer is slower and I typically leave my computer on for 8-10 hours at a time so that solution is not practical.

So my question becomes what other (affordable) solutions can I try? I really don’t want to spend $100 dollars on one of those expensive surge protectors that eliminates all hum on any appliance. So what else can I try?

Any suggestions would be much appreciated.

You could spend $100 bucks on an airport express, but that only works with iTunes. Have you tried a different miniplug to rca cable? Also, contact M-Audio support for answers.