Electrical Noise

[Dogoth]

I know this doesn't help but if it IS RF, maybe one of those tin foil hats over your gear would work (I think dboomer used to have one, maybe he'll loan it to you ;-). Sorry I'm just in one of those goofy moods :-).

[IanHey]

So it sounds like the steps I need to take are:

1. Set everything up without the UPS, see if the interference is happening

2. Assuming the interference is still there ... unplug everything on the input side and see if it continues.

3. Assuming the interference is still there .... add the UPS and see if it changes anything.

4. If I'm still getting interference then lift the ground.

5. If I'm still getting interference at this point then it is most likely RF?

 

What do you think?

[dboomer]

4. If I'm still getting interference then lift the ground.

 

From the signal, not the AC power.

 

5. If I'm still getting interference at this point then it is most likely RF?

 

Maybe but not necessarily. What you really need to do after step #1 is start from the back end of your system (speakers) and prove each piece moving from the back to the front and determine where the problem is getting into your system. Basic troubleshooting 101.

 

Did we ever determine that all of your system was plugged into the same AC source? I remember something about being 125' away. You could have pin 1 problems too. If you had a couple of 1:1 isolation transformers you could check that too.

[IanHey]

 

From the signal, not the AC power.

 

 

 

Maybe but not necessarily. What you really need to do after step #1 is start from the back end of your system (speakers) and prove each piece moving from the back to the front and determine where the problem is getting into your system. Basic troubleshooting 101.

 

Did we ever determine that all of your system was plugged into the same AC source? I remember something about being 125' away. You could have pin 1 problems too. If you had a couple of 1:1 isolation transformers you could check that too.

 

 

I'm not exactly sure what you mean, are you suggesting I unplug the mains / monitors as step 2 instead of the mics etc? I would have to use headphones to hear the noise.

 

I always try to use the same power source for everything and that is so in this case. I thought about an iso xfmr ... would that be a better idea than the UPS? I know it should isolate the ground as well.

 

[Pro Sound Guy]

By plugging your system into the same AC earth grounded source you eliminate a difference in ground potential

by using more then one AC earth grounded source. This can cause a ground loop or possible other issues.

Try one AC/Earth ground connection for all your gear. Honestly everything that has been posted is all the information

you need to figure this out. Lay back on the UPS idea and find the source of the issue.

[dboomer]

Yes... Unplug everything. Then start with your speaker all by itself. Hear any noise? No? Then plug in the speaker cable. Hear any noise? No? Then plug the speaker cable into your amp and turn your amp on with nothing plugged in. Hear any noise? No? Keep on going up the chain until you hear a problem.

[agedhorse]

Never isolate the power ground with an isolation transformer unless you derive an earth referenced ground on the secondary side, bonded so that can handle any fault current. That's a code reqt. for safety.

 

Follow Don's suggestions

[IanHey]

Never isolate the power ground with an isolation transformer unless you derive an earth referenced ground on the secondary side, bonded so that can handle any fault current. That's a code reqt. for safety.

 

Follow Don's suggestions

 

 

I was wondering about that. Every power transformer I've ever installed always had a bonded ground / neutral with some type of ground electrode system attached and yet I see these things being sold: http://www.tripplite.com/isolation-transformer-based-power-conditioner-500w-line-noise-reduction-spike-suppression~IS500/

 

I realize it's only 500W but that's plenty of fault current to kill or seriously hurt someone.

 

 

 

 

[agedhorse]

On a packaged unit like that, the secondary "neutral" is factory bonded to the primary's and secondary's safety ground, it is assumed that under normal operation the units will be used within reasonable proximity of the grounding electode(s). (see #4 below)

[h=4]Key Features[/h]

• Tripp Lite Isolator series isolation transformer-based power conditioners offer complete line isolation, continuous noise filtering and enhanced common mode surge suppression
• Supports combined loads up to 500 watts continuous/4.2A at 120V
  
• Isolation transformer with Faraday Shield offers 100% isolation from the input AC line
  
• Neutral to ground bonding at the secondary eliminates common mode noise and provides an isolated ground reference for sensitive equipment
  
• Isolation transformer design serves as an inexpensive alternative to the installation of dedicated circuits and site electrical upgrades
  
• Removes EMI/RFI noise, utility switching transients, background spikes and power problems generated by other on-site loads, utility grid-switching and lightning related surges
  
• Line isolation with additional surge suppression components offer continuous line filtering of a full range of power line noise in all modes
  
• Continuous transformer filtering with no wearable parts reduces surges in the worst of power environments to harmless levels
  
• Includes 4 widely-spaced NEMA5-15R output receptacles, 6 ft power cord, circuit breaker overload protection and lighted power switch
  
• Rugged all-metal housing ships ready for upright tower or wallmount installation
  

 

[IanHey]

Yes... Unplug everything. Then start with your speaker all by itself. Hear any noise? No? Then plug in the speaker cable. Hear any noise? No? Then plug the speaker cable into your amp and turn your amp on with nothing plugged in. Hear any noise? No? Keep on going up the chain until you hear a problem.

 

 

In an ideal situation with plenty of time that is what I would have done. Unfortunately, the problem is intermittent ... sometimes we hear short 1 to 5 second bursts that are just minutes apart but more often they're 20 to 30 minutes apart. I don't usually have too much time to figure things out .... we only get roughly an hour to load everything in and set up. Some times we don't hear any problems until after we start playing, other times we hear it before ... it's pretty random. We have played there about 6 times with this problem. All know for sure is: When I pull the mains down the noise goes away; When I pull the mics / inputs down nothing changes; When I switch to other outlets in the area nothing changes.

 

[soundguruman]

One of the venues we play quite often has an intermittent noise issue coming from the house electrical system. I'm sure it's not our gear, we only hear this problem when we play this particular venue and another band that was just finishing told us they had the same issue. I've been doing this for quite some time and it's the first time I've heard anything like this. It only seems to affect the PA, we hear bursts of noise through the fronts and monitors lasting from a split second to sometimes 5 or 6 seconds. The bursts seem to be completely intermittent ranging from 5 to 20 minutes apart. I could best describe it as a crackling buzz? The stage, (it's a small outdoor venue), has it's own sub panel with a dedicated 20A GFI quad outlet. I chased around the facility trying various different outlets and it made no difference so I suspect it is system wide issue. At first I through maybe it was a pump or motor but the more I thought about it I think it's some kind of arcing issue in their electrical system.

 

Our system is a Mackie Onyx 1620 board feeding four RCF 312's with a graphic EQ for the monitors and and old midiverb for effects. I always power the entire PA system from a single 120V source to prevent any loop issues. My thinking to resolve the issue on our end is to use a UPS system as a line conditioner on at least the rack and mixer, (I know the electrical noise isn't directly affecting the cabs). Does any one have experience with this? Any issues or problems I might not foresee?

 

Thanks.

 

It really seems more like a defect connection in the main power feed or on the power pole. When these connections oxidize or burn, they have to be replaced. There is no gadget that stops it...It can be a defective main breaker, or a loose wire that feeds the power panel.

aside from running the equipment from batteries on a UPS system, as you mentioned. That might do it.

 

An electrician should go through the entire thing. The utility will check the connections on the poles.

Also check the power meter socket, if the terminals are burned or oxidized.

You can hook a chart recorder to the power, to help narrow down the vicinity of the defect.

You really need to document this stuff over time, to find the actual source of the problems. That's why a chart recorder is the standard method.

 

No, a "line conditioner" is not going to solve that one.

Might be a bad insulator on the power pole, that's intermittently arcing.

 

It don't seem like RF at all, I would doubt it. Many people blame "RF" for noise, but often they are mistaken.

If it really IS RF, this is a good place to start:

http://palomar-engineers.com/rfi-kits

However, I doubt that it's RF. It really sounds like you have a defect connection in a power panel...fried main breaker, bad connect on the power pole...

 

[IanHey]

On a packaged unit like that, the secondary "neutral" is factory bonded to the primary's and secondary's safety ground, it is assumed that under normal operation the units will be used within reasonable proximity of the grounding electode(s). (see #4 below)

[h=4]Key Features[/h]

• Tripp Lite Isolator series isolation transformer-based power conditioners offer complete line isolation, continuous noise filtering and enhanced common mode surge suppression
  
• Supports combined loads up to 500 watts continuous/4.2A at 120V
  
• Isolation transformer with Faraday Shield offers 100% isolation from the input AC line
  
• Neutral to ground bonding at the secondary eliminates common mode noise and provides an isolated ground reference for sensitive equipment
  
• Isolation transformer design serves as an inexpensive alternative to the installation of dedicated circuits and site electrical upgrades
  
• Removes EMI/RFI noise, utility switching transients, background spikes and power problems generated by other on-site loads, utility grid-switching and lightning related surges
  
• Line isolation with additional surge suppression components offer continuous line filtering of a full range of power line noise in all modes
  
• Continuous transformer filtering with no wearable parts reduces surges in the worst of power environments to harmless levels
  
• Includes 4 widely-spaced NEMA5-15R output receptacles, 6 ft power cord, circuit breaker overload protection and lighted power switch
  
• Rugged all-metal housing ships ready for upright tower or wallmount installation
  

 

 

That makes sense. I'm guessing there is limit where they can factory bond and not require a ground electrode system. Something like a 1000VA? I'll have to check NEC.

 

 

[IanHey]

 

It really seems more like a defect connection in the main power feed or on the power pole. When these connections oxidize or burn, they have to be replaced. There is no gadget that stops it...It can be a defective main breaker, or a loose wire that feeds the power panel.

aside from running the equipment from batteries on a UPS system, as you mentioned. That might do it.

 

An electrician should go through the entire thing. The utility will check the connections on the poles.

Also check the power meter socket, if the terminals are burned or oxidized.

You can hook a chart recorder to the power, to help narrow down the vicinity of the defect.

You really need to document this stuff over time, to find the actual source of the problems. That's why a chart recorder is the standard method.

 

No, a "line conditioner" is not going to solve that one.

Might be a bad insulator on the power pole, that's intermittently arcing.

 

It don't seem like RF at all, I would doubt it. Many people blame "RF" for noise, but often they are mistaken.

If it really IS RF, this is a good place to start:

http://palomar-engineers.com/rfi-kits

However, I doubt that it's RF. It really sounds like you have a defect connection in a power panel...fried main breaker, bad connect on the power pole...

 

 

That was my first thought ... a bad breaker or connection that arcs for a few seconds when a load kicks in. We've talked to the venue staff about it and they don't seem particularly interested in hiring an electrician to go through their system because it doesn't seem to affect any other part of their operation. I'd just as soon tell them to call us when they have it fixed and we'll be back but it's a great venue for us ... a lot of our friends / followers like to see us there. I'm going to try a UPS on the mixer / rack, I have a sneaky feeling that will probably resolve the issue for us.

 

[agedhorse]

Electrical arcing generates RF, this is why I suggested determining if it's due to conducted or radiated RF (IF it's even RF at all). Conducted radiation is usually (though not always) generated either from a connected load or from a defect in the wiring system that allows arcing to occur. This kind of noise can travel quite a distance but not like high level radiated RF.