Question for the Electrical Gurus (RE: circuits)

[adamlloyd]

Howdy Folks,

I just moved my project studio to a new building and as usual the production equipment is all on it's own dedicated circuit. I have an air filter that I use to control dust in the equipment room and it's plugged into an outlet from a different circuit. For some reason when I turn it on or off it's causing a pop through the audio system---on the dedicated circuit. Can someone tell me what's going on?

Granted this isn't a huge problem because if need be I'll just avoid turning it on when the gear is all fired up... I'm just baffled and would like to know the science behind what's goin on.

Thanks!!

[ktf]

All circuits are common at the breaker box - a dedicated circuit just means that it's got it's own circuit breaker with nothing else hooked up to it. Motors can make the transformer on the pole brown out momentarily. Every circuit in my house dims when the AC kicks in. To have a true dedicated circuit you would have to have Edison install a dedicated transformer and a new drop line. So you should probably just do your best to work around it. Maybe a big AC cap on the motor line will help with a pop.

[adamlloyd]

Originally Posted by ktf

All circuits are common at the breaker box - a dedicated circuit just means that it's got it's own circuit breaker with nothing else hooked up to it. Motors can make the transformer on the pole brown out momentarily. Every circuit in my house dims when the AC kicks in. To have a true dedicated circuit you would have to have Edison install a dedicated transformer and a new drop line. So you should probably just do your best to work around it. Maybe a big AC cap on the motor line will help with a pop.

Hey, thanks for the info. I will do some research on here, but do you know about how much it costs to have the dedicated transformer and drop line installed? I live in condo so it might be a realistic option if it will make my life a lot easier.

Also.. Just curious, but I'm running all my production stuff from an on-line UPS that only uses the wall power to charge the batteries, then the batteries run everything... therefore I wouldn't think brownouts or the like from a motor going on/off somewhere in the circuit should even affect the equipment because the UPS makes up for all that.. Any reason why I'd still be having pops through the UPS?

[ulysses]

It's possible that the pop from the air filter is coupling electromagnetically through space rather than coming in on your power wiring. I doubt it's causing a pop in every piece of gear you have though. You should be able to figure out which piece(s) of gear are sensitive to that noise by trying it with and without various pieces of gear powered up. Start with nothing but your monitors and amps, and see what you get. Then add one piece of upstream gear at a time until you hear the pop. Once you know which piece of gear is responsible, then you can investigate it more closely to find out if it's coupling through air or through copper. How far away from the equipment is your air cleaner?
But like you said, it's pretty easy to just not switch the air cleaner while you're recording.

[adamlloyd]

Originally Posted by ulysses

It's possible that the pop from the air filter is coupling electromagnetically through space rather than coming in on your power wiring. I doubt it's causing a pop in every piece of gear you have though. You should be able to figure out which piece(s) of gear are sensitive to that noise by trying it with and without various pieces of gear powered up. Start with nothing but your monitors and amps, and see what you get. Then add one piece of upstream gear at a time until you hear the pop. Once you know which piece of gear is responsible, then you can investigate it more closely to find out if it's coupling through air or through copper. How far away from the equipment is your air cleaner?
But like you said, it's pretty easy to just not switch the air cleaner while you're recording.

Haha, whoa, trippy..."through space"...Thank you though, that is a good thing to try this weekend. The air cleaner is pretty close to everything (like 6 feet or so). I find it helps counter-act the dust attracting tendency of all the electronics.

[nosebleedaudio]

Make sure ALL 3 wires for your dedicated circuit go NOWHERE But back to the panel, also make sure the ground wire is a home run, not a ground via the conduit...
And use the Isolated ground outlets...

[dale116dot7]

If an arc or surge is big enough, it'll travel as a radio wave does - through air, or even down a single conductor, through the ground wire only. So does the pop get quiet if you move the filter away from the gear then turn it on? If if does, that's a clue.

[nosebleedaudio]

Originally Posted by dale116dot7

If an arc or surge is big enough, it'll travel as a radio wave does - through air, or even down a single conductor, through the ground wire only. So does the pop get quiet if you move the filter away from the gear then turn it on? If if does, that's a clue.

I have to disagree regarding the ground only, spikes will be on BOTH conductors...
And yes move it as far as you can as see if the pop reduces.

[amorris]

how dedicated is this circuit? do the indidiviual grounds for every plug go directly to the breaker box? or are the chained along from one to another? (like all electricians will do with out FORCING them to do otherwise) does this ground chain touch ANYTHING metal on its way to the breaker box? the wrong answer anywhere here WILL cause exactly what you are describing. so dedicated circuit is probably not so dedicated as you think. I have to literally be in the room as the electrician is wiring to make sure they dont cut these corners. and they will. they just dont know what we are going for. when I do, the rooms are SILENT and have had issues for years.

[Ethan Winer]

Originally Posted by adamlloyd83

I have an air filter ... when I turn it on or off it's causing a pop through the audio system

This is a common problem, and the most likely solution is a power line filter. These can be had for under $30. More info here:

Hum and Buzz, Clicks and Pops

--Ethan

[nosebleedaudio]

Originally Posted by Ethan Winer

This is a common problem, and the most likely solution is a power line filter. These can be had for under $30. More info here:

Hum and Buzz, Clicks and Pops

--Ethan

Depending on levels a Conditioner will NOT eliminate all pops ect...

[dale116dot7]

Originally Posted by nosebleedaudio

I have to disagree regarding the ground only, spikes will be on BOTH conductors... And yes move it as far as you can as see if the pop reduces.

Of course it would be on all conductors simultaneously, but it treats all of the wires in the power cables as if they were a single wire - it's common mode and the 'return path' has to do more with antennas than electricity. That's why common mode chokes work.

[Ethan Winer]

Originally Posted by nosebleedaudio

Depending on levels a Conditioner will NOT eliminate all pops ect...

Right you are Mike. If the pop is caused by a direct lightning spike, it will probably get into your system anyway.

But for typical motor switching pops that travel through the AC line, as the OP noted, a good LC filter like the kind in my article usually does the trick. At least it's always worked for me.

--Ethan

[nosebleedaudio]

Originally Posted by Ethan Winer

Right you are Mike. If the pop is caused by a direct lightning spike, it will probably get into your system anyway.

But for typical motor switching pops that travel through the AC line, as the OP noted, a good LC filter like the kind in my article usually does the trick. At least it's always worked for me.

--Ethan

Not talking about a lightning hit, for example my soldering station pops my amp on my bench EVERY time I turn it on/off, a conditioner makes NO difference, they are designed for higher voltage spikes and surges...

[Ethan Winer]

Okay, could be. I have no idea what sort of conditioner you mean. Not a power strip with a surge thingie in it, right? Regardless, for $30 (raw filter) it's not an expensive thing for the OP to buy to test.

--Ethan

[ulysses]

Yes, an EMI filter will help if the pop is coming over the power line. If it's coming through the air, the EMI filter won't help (unless it's radiating from the power wiring as opposed to from the motor itself).

This is not a ground issue. Whether or not the ground wire is isolated likely has nothing to do with it. If the pop is coming over the power wiring, it's because the portion of the mains wiring that is common to the air cleaner and the audio gear has enough impedance so that the startup current in the motor produces a significant voltage drop. Significant in this case means audible in the audio gear.

But well-designed audio gear should not couple power line noise into the audio path. Either you've got a crappy piece of gear there someplace, or this pop is electromagnetically coupled.

[drtechno]

what has to be done is softening of the counter-EMF of the inductive load.

you need to solder a mov and a .01 snubbing cap across the power switch inside the air cleaner:

assuming its a 120 VAC:

mouser electronics numbers:

650-ROV05-391K-S-2 250V MOV
871-B81123C1103M .01uf/w series resitor

[nosebleedaudio]

Originally Posted by drtechno

what has to be done is softening of the counter-EMF of the inductive load.

you need to solder a mov and a .01 snubbing cap across the power switch inside the air cleaner:

assuming its a 120 VAC:

mouser electronics numbers:

650-ROV05-391K-S-2 250V MOV
871-B81123C1103M .01uf/w series resitor

MOV's are kinda slow, if it's a fast spike it will not help much.
A .1uf would be better, or both...

[drtechno]

its just topology

the cap has a 30 to 100 ohm series resistor built inside. common to snubbing relay contacts

the value of the can cap will vary from .01 to .33 depending on inductance and required in-rush current. Hand selecting part will give the best result.

and the mov can be a 170v to 200 v that is in pararrel to the rc cap and
mov and switch contacts...

[Time Tech]

It could be that the Dedicated audio CKT is on the same phase leg as the Air Cleaner.

I would try to move the air cleaner to another wall plug that is on the other phase leg of the incoming power.

The audio ckt should be on an I.G. outlet and the ground wire tied to a ground spike. I would not trust the old school method of attaching the ground to a "cold water pipe" as these days chances are good that somewhere in that line it becomes a piece of PVC.

Perhaps a small isolation transformer on the air cleaner may help as well.

cheers,

Bruce Maddocks
cups 'n strings

CUPS 'N STRINGS are experts in digitizing, restoration and preservation of audio recordings. audio analog to digital transfer specialists, Los Angeles

[ulysses]

Originally Posted by Time Tech

The audio ckt should be on an I.G. outlet and the ground wire tied to a ground spike.

The ONLY place you should drive a "ground spike" (copper rod) is at the service entrance, where the ground and neutral conductors of all the circuits in the building get tied together. INCLUDING your dedicated audio circuit. Not connecting the safety ground of your audio circuit at this location would be illegal, dangerous, stupid, and will not reduce noise in your studio (unless it kills a guitar player).

[nosebleedaudio]

I think most people who are not around electrical much, and this includes some electricians, they think an isolated ground circuit MEANS the ground is isolated from the main AC ground, which IS NOT correct, it means its isolated from other grounds BEFORE it connects at the main AC, NO multiple paths..
For example: it does NOT connect to the metal conduit, it is an insulated ground wire that is a home run back to the main AC ground point, where ALL grounds are tied (Bonded) together...
NEC 250.50

Just one more point; I have seen many times where the ground is obtained(allowed) via the metal conduit, which its connection is dependent on several EMT connectors, couplings for its ground path and that WAS NOT, because those connectors/couplings had come loose, so NO ground connection...IF it had been a dedicated ground wire run with the circuit wires it WOULD NOT have been a problem, at least it would have still been grounded..