Electrical inference heard thru power amps that are *not* connected to RCA...

[wappinghigh]

Is battery isolation of power amps the only way to stop ground loop and electrical interference noise> ?

 

I've got this problem in two of my amps.. Sounds like a wave of electrical noise coming thru in cycles of 30-60 seconds lasting 10-15 secs.. They are not connected to any source and it's still happening... I can't isolate the offending device/devices in my home.. what to do!!! ??

[Bear]

I have had similar issues - very frustrating. Does not sound like a ground loop as that is more of a consistent hummm if you may. Have you used these amps without issue before? Not being connected to a source could make the issue worse. My system is very sensitive to interference when in HT passby mode and I shut the processor off - in essence you then have an open line to the amps. If you have used these amps before I would start by trying to backtrack to a point where none of this happened and then go from there. Fans, refrigerators etc. can all be culprits. One of my issues turned out to be the computer - moved it further from system and changed power cord to upgraded version. Same on all other components. If you have cable box near by that is also a potential issue.

[wappinghigh]

Yes. Thanks. It will be impossible to find the source of the problem. Hifi has to live in the real world....

[sandyk]

Yes. Thanks. It will be impossible to find the source of the problem. Hifi has to live in the real world....

 

Wappinghigh

Do the power amplifiers use a 3 pin mains connection ? If so, is your mains supply earth bond in good condition?

Not being familiar with the U.S.A. mains supply, I would suggest sending "one and a half" a PM.

 

Regards

Alex

[wappinghigh]

^ Alex. Im here in Aus with ya man.... the land of the ground loop problems

 

How about the Thor power filter products? Worth a shot? Engineering Innovatitve Power Protection & Power Filtration Products

[One and a half]

^ Alex. Im here in Aus with ya man.... the land of the ground loop problems

 

How about the Thor power filter products? Worth a shot? Engineering Innovatitve Power Protection & Power Filtration Products

 

Are there 3pin plugs on each amp, and how far away are they from each other's 230V connection point? Thor won't do much except burn a hole in your pocket.

Grab a piece of 10AWG (4mm) cable and connect the two chassis of the amps together under a good metal screw, not under paint. Connecting the inputs to something helps.

[sandyk]

^ Alex. Im here in Aus with ya man.... the land of the ground loop problems

 

How about the Thor power filter products? Worth a shot? Engineering Innovatitve Power Protection & Power Filtration Products

 

O.K.

Most of my friends don't have anything like the problems that USA members have due to them having half the voltage and double the current. IME , it is very rare to get much more than occasional light switch noises ,with fridges cutting in and out more likely to cause problems. Being a problem here in Au., I would be inclined to first check out the mains earthing if you are able.

Years ago, in a rented house I used to get lots of nasty noises and breakthrough from a nearby CB operator on 27MHZ. and it turned out to be a corroded mains earth connection to a water pipe. Sometimes an additional earth connection from the amplifier case to an earth stake at the side of the house that is more damp can help too. This also helped with a TV masthead amplifier that was affected by the fridge cutting in and out with DTV in a low signal strength area (below a hill) in Sydney's northern suburbs.

 

Alex

[One and a half]

O.K.

 

Sometimes an additional earth connection from the amplifier case to an earth stake at the side of the house that is more damp can help too. This also helped with a TV masthead amplifier that was affected by the fridge cutting in and out with DTV in a low signal strength area (below a hill) in Sydney's northern suburbs.

 

Alex

 

An additional earth stake in the ground is OK, but it needs to be connected to the other main earth stake first. Many countries' regulations prohibit multiple grounding points in an installation to suit individual devices. The main reason is a fault current to earth can go through the appliance bypassing the protective device at the switchboard.

[sandyk]

An additional earth stake in the ground is OK, but it needs to be connected to the other main earth stake first. Many countries' regulations prohibit multiple grounding points in an installation to suit individual devices. The main reason is a fault current to earth can go through the appliance bypassing the protective device at the switchboard.

 

You are of course correct, however many older houses don't have ELCBs, especially outside of the major cities.

Things are changing here too in the earthing area due to use of plastic water pipes, and there was a recent earthing program inspection with this rented house checked by an Inspector too.

[StephenJK]

Is battery isolation of power amps the only way to stop ground loop and electrical interference noise> ?

 

I've got this problem in two of my amps.. Sounds like a wave of electrical noise coming thru in cycles of 30-60 seconds lasting 10-15 secs.. They are not connected to any source and it's still happening... I can't isolate the offending device/devices in my home.. what to do!!! ??

 

There is a systematic and logical path that you need to follow. It will take some time and some effort on your part, as there are no easy answers.

 

1. Remove all interconnects from all stereo components, and unplug all power cords except the amplifiers. Leave the speakers connected to the amplifiers. Turn on the amplifiers. Did the problem go away?

 

2. No? Then there's a problem with an amplifier. Or go to step 6.

 

3. Yes? Then you need to start plugging in components one at a time, including the component power cord and interconnect.

 

4. At some point, the problem will either reoccur or it won't. What you hope for is that it will, and once you identify the component that's giving you problems you can tell us what you did and we can move on from there.

 

5. An intermittent fault is the most difficult and frustrating to find. If something is faulty and broken, and stays that way, you can and will find it.

 

I had a Luxman amplifier many years ago that would pump 60 Hz hum through the speakers on an irregular basis. I fought that for close to a year, sending the amplifier back to the shop by friggin' bus at least four times. The last time, I took it in myself and talked to the service manager. The problem was a loose ground connection on one of the amplifier heat sinks. Hopefully, that won't be your issue.

 

6. Do consider that there may be something in your house such as a freezer or refrigerator or air conditioner compressor start up that's creating electrical noise. In that case there might not be an amplifier problem, but exactly that, interference.

[sandyk]

6. Do consider that there may be something in your house such as a freezer or refrigerator or air conditioner compressor start up that's creating electrical noise. In that case there might not be an amplifier problem, but exactly that, interference.

 

Especially with a poor mains earth, the problem may even be coming from adjoining premises. Are there any workshops etc .nearby ?

[Tony Lauck]

Especially with a poor mains earth, the problem may even be coming from adjoining premises. Are there any workshops etc .nearby ?

 

If I were the OP, I would start by pulling all the breakers in my electrical panel except for the one needed for the audio equipment. If this did not eliminate the noise I would then unplug all the audio equipment on this circuit except for the amplifier. If the noise persisted then I would then pull the breakers on all the neighbors' electrical power. (No, don't ask me if I have done this. :=) I will neither confirm or deny doing something like this... Note, I do not suggest doing this unless your neighbors are often out of town, unless you are sure that they don't have vicious dogs or guns and unless you have access to the necessary circuit breakers or know how to work safely on live power wires... Just saying. YMMV)

 

If there were still noise then I would replace the amplifier. If the problem persisted with a new amplifier then I would contact an electrician.

[Speedskater]

Some of the things that can cause intermittent interference:

a] water pumps

b] sewerage pumps

c] refrigerators/freezers

d] fish tank pumps

e] water heaters

f] deicing heaters

Defective units with thermal overload switches:

a] parking lot & street lights

b] CFL bulbs that you think are turned-off

c] door-bell transformers. Most people don't even know that they have a door-bell transformer.

 

and the list goes on.

 

As a side note:

That stake in the garden has nothing to do with this kind of problem.

[sandyk]

As a side note:

That stake in the garden has nothing to do with this kind of problem.

 

A heavy gauge earth wire to a stake in the side of the house, when connected to the metal case of a 2 way TV splitter DID cure fridge interference to DTV where a varistor across the powerpoint where the fridge was plugged in did very little.

The OP is from Australia where these kinds of problems are rarely severe, unlike the huge numbers of reports, especially with Hi Fi , that seem to come from the U.S. with it's half the voltage and double the current 60HZ supply.

[Flinx]

My guess would a device that is doing some sort of communication check. Someone earlier in the thread referenced a computer being too close-----could be that device pinging the internet (notice your modem lights are constantly going), or even interference caused by the hard drive spinning. Ever been on a conference call and you can hear an intermittent buzz when someone's mobile phone is just checking the airwaves (I know, not the right term)? Something of this regularity makes me think communication check vs something cycling (refrigerator, A/C, etc.).

 

If you are using surge protectors, try putting the Amps on one by themselves if everything is already on one surge protector. That is really just a shot in the dark because as someone else also pointed out, your issue doesn't sound like a ground-loop hum. Is there such a thing as an intermittent ground-loop hum? If you can isolate stuff like modems, routers, switches, and your computer, maybe that will help. I would think isolating the amps would fix this if that is the case.

 

 

Is battery isolation of power amps the only way to stop ground loop and electrical interference noise> ?

 

I've got this problem in two of my amps.. Sounds like a wave of electrical noise coming thru in cycles of 30-60 seconds lasting 10-15 secs.. They are not connected to any source and it's still happening... I can't isolate the offending device/devices in my home.. what to do!!! ??

[cjf]

Not sure how old the OP's amps are but I use to fight with a similar buzz with no interconnects attached to an old PASS Labs X250 amp I used to own. Tried a bunch of stuff with no luck.

 

The fix was building new amps known for low noise and with care taken on the ground wiring. Now I have zero buzz or peep of any kind with ear an inch away from speaker and volume at full tilt (no track playing of course). I use no power conditioning of any kind either.

 

Moral of the story is to see if you can borrow an amp and connect it to the same circuit as your current amp. If noise goes away then you have your answer.