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Ground issue? Humming Noise from Speakers.


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Im sure this topic has been covered before but I will ask the question anyway. I recently acquired a different 2 channel amplifier, and said goodbye to the Emotiva 2 channel amplifier for good. This is my concern and my question. Once getting the amp hooked up and powering it on I received a humming sound coming out from the front channel speakers, (Cornwalls). I immediately double checked all of my connections and found that everything was installed properly. I began to try and figure out what the issue was, I pulled the rca connections off from the back of the amp and noticed that the humming sound stopped, so I started to replace my rca cables thinking this was the issue but once again I plugged different types of rca cables into the amp and noticed that the humming noise had come back. I read a post about pulling the third prong off of the power cable in which I did and when I plugged the amp back in suprisingly enough the humming noise has stopped. Alright here is the question, what are my potential hazards for removing the third prong from which I understand is the ground connection of the plug, to myself, my other audio equipment in the rack or anything else? The amplifier does plug into a Belfin PF-60 power console. If I was to replace the power cord with an identical cord meaning another cord with the third prong again and I was to purchase direction rca cables would this eliminate the humming noise also? Any type of input would be appreciated, thanks.

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Okay JJ this is definetly not an edjucated response. This is a solid state amp. Acurus A150 2 channel power amplifier. I have it plugged into a Belkin PF-60 power console. It is driving a pair of Cornwalls. Im using banana plugs as connectors and some high end rca cables.

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OK, so you have identified 1/2 of the ground loop. I would hunt for the other half and see if that is where you might want to "snip" the ground. Add all other electrical devices to the same power outlet block/conditioner can fix it. Also an antenna's ground can cause the loop. They sell isolators for that.

A ground loop can occur anytime your audio equipment has two grounded items. An antenna can also do it. It's these two or more grounds that make up the loop.

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Do you have a CATV coax connection to your system? I found that the ground from the CATV and power ground in my house were at different potentials and raised hell with one of my power amps. The introduction of a Jensen VRD-1FF ground loop isolator fixed the problem.

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When you hook up a unit that initiates a ground loop that unit's power supply is improperly designed (not isolated). Don't care if it costs 10 grand. It will cause you problems in the future and more headaches.

JJK

If a ground loop is present in the system and one piece of equipment reacts to it and one doesn't is it really a measure of the quality of the item? I'm not sure?

I argued with Bryston regarding their 2B-LP in this regard to this. I have 3 power amps and it is the only one that exhibits the problem I have had with hum and CATV.

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Is this amp tube or solid state? Removing the safety ground (third prong) is not a good idea. It affords protection in case of a powerline short to the chassis, and also provides a ground reference for the amp. Please post what amp it is, what is connected to it, etc.

This is entirely wrong!!!!!!!!!!!!!!!!!!!!!!!!!!

First of all it does not matter whether the component is a tube or transistor product.

Second, you will increase the potential shock hazzard by having multiple ground connections. The ground should be allowed to seek its own level and this can only be done by allowing a single path to ground.

In the case of a powerline short there should be other more prodigiuous measures in place such as fuse or circuit breakers. Simply leaving the ground connected is not necessarily going to protect you from this.

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Alright here is the question, what are my potential hazards for removing the third prong from which I understand is the ground connection of the plug, to myself, my other audio equipment in the rack or anything else?

The amplifier does plug into a Belfin PF-60 power console. If I was to replace the power cord with an identical cord meaning another cord with the third prong again and I was to purchase direction rca cables would this eliminate the humming noise also? Any type of input would be appreciated, thanks.

First of all you must make sure the power outlet you have everything connected to is connected properly. Get yourself a ground fault tester such as this:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=391-150&FTR=gfi%20tester&CFID=13025&CFTOKEN=15970921

If you are using Belkin PF-60 power console as your "power source" which distributes power to all of the other components, then this is the ONLY component that should be grounded to the power outlet with a three-prong plug. Everything else that is plugged into the Belkin PF-60 should have the ground lifted via a 3-2 prong plug adaptor.

You will find that some components are more susceptible to ground loop issues than others. In other words, everything may have been fine, and then, you change something, like the Emotiva vs. whatever you recently swithced from, and all of a sudden there's a problem noticed.

Plug polarity can sometimes also be an issue, especially with older components where plug polarity is not designated. And then, not everything is made properly - people/manufacturers can and do make mistakes.

By grounding the entire system at one point, and letting the ground find its own best level, through cables, equipment racks, whatever, you will avoid ground loop problems, and avoid the associated shock hazzards as well.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=391-150&FTR=gfi%20tester&CFID=13025&CFTOKEN=15970921'>
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When you hook up a unit that initiates a ground loop that unit's power supply is improperly designed (not isolated). Don't care if it costs 10 grand. It will cause you problems in the future and more headaches.

JJK

While this may indeed be the case, it is rare. Virtually all grounding noise and ground loop problems can be traced to an improperly wired power outlet, multiple ground loops (connections) between system components, and/or improper polarity.

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The unit I had was an MDR-200 HDV Tuner which did the same thing that the autor stated. I used an isolation plug and it worked ok for a while then burned up. My Guru buddy had TWC install their cable package and they said his TV was causing a ground loop and they would not install their stuff untill the tv was fixed. He installed an isolation plug and it was ok but then his X-Box wouldn't work with the TV. Don't know what the final solution was. I think he used an isolation transformer for the X-Box.

JJK

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Is this amp tube or solid state? Removing the safety ground (third prong) is not a good idea. It affords protection in case of a powerline short to the chassis, and also provides a ground reference for the amp. Please post what amp it is, what is connected to it, etc.

This is entirely wrong!!!!!!!!!!!!!!!!!!!!!!!!!!

First of all it does not matter whether the component is a tube or transistor product.

Second, you will increase the potential shock hazzard by having multiple ground connections. The ground should be allowed to seek its own level and this can only be done by allowing a single path to ground.

In the case of a powerline short there should be other more prodigiuous measures in place such as fuse or circuit breakers. Simply leaving the ground connected is not necessarily going to protect you from this.

Actually, it can make a difference regarding tube vs. solid state in the context of my reply. Many vintage tube amps ran a capacitor from each side of the AC line to the chassis to filter RF and other "nasties" from the power transformer primary. Those caps were notorious for leakage, especially if they took a number of power line surges. In that case hum often resulted which was not present when using an amp not affected by that problem. Further, if the cap connected to the "hot" side of the AC line showed enough leakage, or shorted, the chassis could now have 120 VAC on it. Having the third prong connnected to the chassis would/should cause the breaker in the entrance panel to trip................

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Virtually all grounding noise and ground loop problems can be traced to an improperly wired power outlet, multiple ground loops (connections) between system components, and/or improper polarity.

By grounding the entire system at one point, and letting the ground find its own best level, through cables, equipment racks, whatever, you will avoid ground loop problems, and avoid the associated shock hazzards as well.

I had a pair of Mark Levinson SS monoblocs (ML-2's) for many years, which produced a very loud hum on one side unless both monoblocs were plugged into house outlets with 2-prong cheaters. If I did that, the hum completely disappeared. No problems ever resulted from using cheater plugs on those two very high-quality amps.

No one could ever explain the cause or solve the hum. The amps were connected only to the speakers and different preamps at different times -- no TV, cable, or HT interconnections. Of course I had the house and outlet wiring checked, and everything checked out OK. I believed it was a ground loop that required that only the preamp be grounded through a 3-pin plug. And isn't everything already "grounded" through the neutral wire and prong of every power cord and outlet? Obviously I don't understand what was going on.

I think the bottom line is "whatever works" if you've exhausted all other possibilities.

A Mark Levinson power supply should have a very adequate design, although I never had the factory check them out.

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After hours and I mean hours of posting my first thread on this topic I have finally figured this issue out. First let me tell you that I realize the importance of having high end rca cables, im a believer of directional rca cables. Anyway I started my process of elimination by pulling out all of the HDMI cables from the back of the receiver, powered the amplifier back up amazingly no hum. I had my system set up where the receiver was doing the upconverting, hdmi from the cable box into the receiver input and then output to the tv. HDMI for the blu ray player straight into the receiver. I plug the HDMI cable back in for the PS3 no hum coming out of the amplifier. I plug the HDMI cable back in for the cable box turn on the amp and bang there is the hum. Im thinking maybe a bad HDMI cable so I replace the cable, now this HDMI cable I was taking it out from the back of the cable box and then plugging it back in. So basically at this point all I was doing was pulling the HDMI cable in and out from the output of the cable box, unplug it no hum, plug it back in there is the hum. Changed HDMI cables, replaced ALL rca cables with a decent cable, at least they seem descent to me and was within my price range or should I say Michelle's price range, $80.00 dollars for a pair of spider directional rca cables x3. I had a friend of mine over (William Land) and he hooked the system up like this, ran the HDMI cable straight from the cable box into the tv and then ran a fiber optic digital cable from the cable box into the receiver, turned on the amp and I could not believe it the hum was gone, however the issue of the hum was not dealt with. Though I sort of like having my system set up the way Bill set it, the only issue is now my receiver will do no upconverting hooked up this way even though the Onkyo TX-SR 806 really does not upconvert that well. Anyway I could not leave well enough alone until I figured out this issue and then it freaken hit me like a ton of bricks, the cable line coming in from the wall it was the only thing left at this point that I could check or at least my mind could handle. I went to the local hardware store and purchased a cable ground loop isolator filter, I literally flew home and hooked this filter up and BAM I knocked the hum out. Thanks for all the posts, I would not of been able to figure this out without the help of the members of this forum.

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The most common, and easiest, solution is to add a Cable TV ground isolator. Jensen Transformers has been around for over 30 years and makes one of the best (MSRP $59.95) as it has a flat frequency response from 2MHz - 1300 MHz, spanning the VHF/FM/UHF/CATV spectrum. Why is this important? Well for starters if you plan on using digital cable, a cable modem, or on-demand services you better not get a cheap RF filter from the local electronics store as it will most likely filter out more than you bargained for. In addition, we respect a company who measures their products and is willing to post a frequency response performance graph to back up their claims. Getting a flat frequency response from 2MHz - 1300MHz ensures no loss of signal quality and a great result.

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