Genelec 1029A noise problem when light switch on/off

[bouldersoundguy]

And as far as isolating ground - there are even extension cords that don't have grounding pins.

Ungrounded extensions are only suitable for ungrounded equipment. Defeating the ground on anything with a grounded plug is unsafe.

 

[bouldersoundguy]

At least go to the hardware store and get an adapter that has the ground lifted.

Those adapters have a ground tab that's you're supposed to attach with the wall plate mounting screw. If the tab is not attached or the screw is not actually grounded then it's unsafe.

 

[Seidy]

...At least go to the hardware store and get an adapter that has the ground lifted.

I am actually using these (and extensions without grounding )... Just sometimes you need a temporary solution and fast.

But yea, it's all cool. I hope I don't get killed someday by that.

 

[Lt. Bob]

Could be a grounding problem.

What kind of lights are they....some of the new "eco-friendly" fluorescent bulbs? They suck when it comes to audio...they can cause all kinds of noises.

he said it happens when the switch is switched either way ..... 'on' AND 'off' ...... so it has to do with the switch or the circuit and not the bulbs themselves.

 

[Lt. Bob]

we believe you, but it isn't safe and bad advice that could, under certain circumstances, lead to a trip to the hospital or the morgue.

You would also never want to remove the ground from the wall socket, because in order to put it back right, you would have to replace the socket. At least go to the hardware store and get an adapter that has the ground lifted.

an adapter is definitely the way to go rather than modding the wall outlet.

As for the danger ... it is extremely unlikely that anyone is gonna get harmed by this. I hear this all the time plus the usual one about people gonna get killed if they work on a tube amp. Do a google and see how many people have been killed by this ..... you won't find any. I looked hard for a couple days last year and I found exactly two. Out of the billions and billions of times people have fooled with amps and played thru them ungrounded that makes this much less likely than you choking to death on a sandwich or falling down and hitting your head while reading this.
Almost every house I've ever lived in has had two pronged outlets with no ground at all including the house I live in right now. And connecting that tab to the screw wouldn't ground it because there IS no ground. I'm not dead nor have I ever been shocked.
Also .... a LOT of amps and stereos have a ground-lift switch for this very purpose ....... they don't put that switch on there to kill you.

Lastly .... the OP isn't being very clear. He has repeatedly said he gets the spark sound when the switch is off so it could be just a transient that happens when that switch is thrown either way.
We really need a but more info on the sound and how long a duration it is.

 

[miroslav]

he said it happens when the switch is switched either way ..... 'on' AND 'off' ...... so it has to do with the switch or the circuit and not the bulbs themselves.

Since he mentioned lights and they ended up being the fluorescent type...I just figured it was easy enough to try removing them and see if it goes away. I had a lot of audio related noise caused by those screw-in "eco" bulbs meant to replace incandescents (I was trying to be eco-conscious )...and that's why I now don't use them anywhere at my house.
Even though I have dedicated lines to my studio, plus voltage regulators and serious line conditioners....the fluorescent bulbs were still a problem, causing obvious AC noise in my audio gear.

In his case, the "spark" sound may be something else altogether, but it's a bit coincidental that it's also related to.....flourescent bulbs.
They all have some kind of tranny/starter circuit...so maybe the on/off switching is just triggering that "spark" sound.

 

[ecc83]

First the grounding or "earthing" as it is known here, issue.

Electrical safety depends upon putting several obstacles in the way of a lethal shock. The first obstacle for audio gear is a double wound mains transformer that isolates the gear from mains. These are so good that you virtually never hear of a traff going primary to secondary short. However, other things are not so intrinsically safe, a metal kettle for instance has a heating element buried in metal oxide powder and these can and DO develop leaks! So, your gitamp might be perfectly fine on an unearthed outlet but make some tea and BAMM! Having the third ground wire means that for this once in a million event a breaker/fuse will trip.

Then, over here we have 230 (240 most often) mains volts on all domestic gear and that is four times as lethal as ~115volts and 230V breaks skin resistance down much better than 120!

The banging lamp: Change the switch! Often these have burned and cratered contacts and arc when making and breaking. Fit the highest rated switch you can find. Lighting switches (UK) are 5A rating but a 16A one will probably do a better job. Fit an X or Y rated capacitor across the load side of the switch. Live to neutral..NOT live to ground! I bet the wires to the light fitting do NOT carry an earth to the lamp casing? Fit one if possible.

But the noise is radiated. Betcha, betacha and so the quality of the balanced feed to the speakers must be questioned? replace the cables with stuff with better shielding or maybe star quad? I would guess that the Genlec's input balance is superb but the mixer's output? Fit a pair of GOOD transformers, the Art Cleanbox 2 has a good rep.

Lastly. I agree the "lethal stored charge" in valve amps is OTT but it IS possible it could stop a heart or kill a pacemaker! We have a potential audience of billions worldwide, somebody, somewhere, sometime, WILL fuckup! It behoves us all IMO not to give even slightly misleading or unsafe advice.

Dave.

 

[hydroflare]

It sounds like a spark across the switch contacts, which causes a spike to travel back down the mains wiring to any locally connected equipment. This is fairly common when switching an inductive load or an smps with large capacitors. Usually a piece of equipment that is in dange of doing this at switch on/off will have MOVs and filters to suppress and limit the spike, however this is not the case with fluorescent tubs/lamps that can have a ballast (inductor) or smps (compact fluoro). The arcing across the switch will cause contact damage over time, which can make the problem worse. The first solution would be to change the light bulb with a better quality one, however finding a decent one amongst the many crappy Chinese ones is difficult. Otherwise replace it with a LED bulb if you can find one that suits. The other solution is to filter the mains before it goes into your amplifier, using a reasonable filter with surge suppression included. This will help ensure that sparks and noises are filtered and suppressed before ending up at the amplifier (which should also have internal mains conditioning if it is any good).

Lastly, never remove the safety earth from an appliance. It is there for a reason and in some jurisdictions it is unlawful to do so and usually a practice performed by uninformed fools.

 

[bouldersoundguy]

Only about 400 people die per year in the US of electrocution. Because of safety precautions like proper grounding.

 

[Divinit]

You've tried everything but this....

Hi,

If you have a regular lamp (non-fluorescent), plug that into an extension cord and run it into your recording room as a light source. Turn OFF your fluorescents. Turn ON your incandescent lamp. Recheck to see if you have problems. If not, you've narrowed the problem down somewhat. Now plug the incandescent lamp into power that is IN your recording room. If you STILL have no noise, the Fluorescent lamp ballasts are emitting electromagnetic interference (EMI) and that isn't going to go away until you replace your light source. Not as bad as having to put in a new circuit though. Besides, there are some pretty cool lights out there now for your studio!

good luck!!!!

 

[ecc83]

Only about 400 people die per year in the US of electrocution. Because of safety precautions like proper grounding.

Which means my guess of a live chassis accident was worse than I indicated and is more like one in 500,000?

The figures are only that low because people do not as a rule lift earths!....Not so funny story:
A good few years ago now a politician's relative (daughter I think) was killed in a tragic but, AFAIK, freak electrical accident. The result was that a totally draconian set of electrical installation regs were kneejerked into action and this put many perfectly good and safe electricians out of work.

Leave us ALL be sqeaky clean, to the book and careful in what we say.

Dave.

 

[Lt. Bob]

Which means my guess of a live chassis accident was worse than I indicated and is more like one in 500,000?

.

not a chance ...... I bet every single one of those 400 are from all sorts of causes other than fooling with an amp and getting bit by a live chassis. That figure's gonna include people who sawed thru their power cords while working with a saw or people running stuff outside and working when it's wet and every sort of possible cause. he said it's 400 a year from electrocution ..... NOT from working on or playing with amps.
The odds of dying from something guitar amp related are extremely low .... lower than getting hit by lightning ..... lower than falling down your stairs

 

[ecc83]

not a chance ...... I bet every single one of those 400 are from all sorts of causes other than fooling with an amp and getting bit by a live chassis. That figure's gonna include people who sawed thru their power cords while working with a saw or people running stuff outside and working when it's wet and every sort of possible cause. he said it's 400 a year from electrocution ..... NOT from working on or playing with amps.
The odds of dying from something guitar amp related are extremely low .... lower than getting hit by lightning ..... lower than falling down your stairs

Yes Bob, agreed it will be a mixed bag. But one thing is for sure. If the conductor that killed them had been bonded to earth sufficiently to carry the fault current and trip a breaker they would not have died. My guess would be that only one...maybe, of those deaths was a complete "accident". The other 399 were rank stupidity. No Old Bold electricians!

My point is simple that we should not ever advise people to remove mains earths...EVEN for tests because if they knew enough to do that safely they would not be asking. Sure more people get killed by lightning but you would not advise anyone to fly a kite in a storm!

Dave.

 

[bouldersoundguy]

The fact that the fatalities are that low is not because of an inherent lack of danger but BECAUSE OF THE SAFETY FACTORS DESIGNED INTO ELECTRICAL SYSTEMS AND PRODUCTS. Telling people to defeat the power safety ground can only increase the number of fatalities.

The first thing the OP should do is make the connection with a proper balanced cable. If that doesn't solve it then making changes to "user serviceable" parts would be next. After that having a qualified electrician correct the wiring might be in order.

 

[Lt. Bob]

The fact that the fatalities are that low is not because of an inherent lack of danger but BECAUSE OF THE SAFETY FACTORS DESIGNED INTO ELECTRICAL SYSTEMS AND PRODUCTS. Telling people to defeat the power safety ground can only increase the number of fatalities.

The first thing the OP should do is make the connection with a proper balanced cable. If that doesn't solve it then making changes to "user serviceable" parts would be next. After that having a qualified electrician correct the wiring might be in order.

and so I ask, there are LOTS of amps and stereo gear that have ground lift switches on them for the purpose of selectively defeating the ground .... do they increase the number of fatalities?

 

[witzendoz]

and so I ask, there are LOTS of amps and stereo gear that have ground lift switches on them for the purpose of selectively defeating the ground .... do they increase the number of fatalities?

Some have an audio ground lift, I don't think you will find that any modern gear has a mains ground lift. In the 1970's I had a bass amp that had a mains ground lift switch, it was modified not to work. When I asked a tech he said that some US gear had mains ground lifts, when the amp was imported into Australia it did not comply to the regs and the switch had to be modded not to work. I would think that a mains earth lift is legal anywhere in the world now.

DO NOT REMOVE MAINS GROUND WIRES. If you do and someone dies, guess who is going to jail, unless it's you who dies.

Alan.

 

[bouldersoundguy]

and so I ask, there are LOTS of amps and stereo gear that have ground lift switches on them for the purpose of selectively defeating the ground .... do they increase the number of fatalities?

Do whatever you want with audio ground as long as the power ground is connected.

 

[Lt. Bob]

Do whatever you want with audio ground as long as the power ground is connected.

and once again .... my house doesn't HAVE a ground.
I bet you any amount of money you want that I never get electrocuted.

 

[ecc83]

and once again .... my house doesn't HAVE a ground.
I bet you any amount of money you want that I never get electrocuted.

Then you must have a floating supply? These are "intrinsically safe" from live to ground shock (get across it and 120 will still spoil your day. Our mansized 240 will stop ya ticker) .

I have heard of earth free mains sytems in Asia but not the States?

It is of course VERY dangerous to other people on the supply to ground any of your equipment.

Dave.

 

[bouldersoundguy]

and once again .... my house doesn't HAVE a ground.
I bet you any amount of money you want that I never get electrocuted.

You mean your outlets don't have grounds. If the wall box is grounded then you might be able to use one of those adapters with the wall plate screw going through the tab and have proper protection. Otherwise the "correct" thing to do is have the wiring updated to modern standards. I do understand the resistance to spending money, but in this context I can only recommend doing it right.

So, if you did get electrocuted how would I collect?