recording studio

[normbac]

Anyone know if putting outlets on a seperate dedicated panelboard would reduce any interference with equipment. Owner wants eight dedicated 20a circuits in a studio, with Iso ground on each circuit. Am worried about problems after all work is complete and they complain about an interference while recording. (With my luck after 10 days of unpaid troubleshooting the noise will mysteriously stop) Any ideas would be helpful. TIA

 

[mdshunk]

Owner wants eight dedicated 20a circuits in a studio, with Iso ground on each circuit.

What the owner wants, the owner gets. That's my motto. Unless he's willing to hire an engineer, I'm generally unwilling to guess-engineer a solution myself.

 

[480sparky]

Last time I worked with any sound equipment of any consequence, they sound guys said they wanted all the gear on the same phase. Not the same circuit, but all on the same phase.

I didn't ask why. Like md said, what they want is what they get.

 

[normbac]

Last time I worked with any sound equipment of any consequence, they sound guys said they wanted all the gear on the same phase. Not the same circuit, but all on the same phase.

Anybody have an idea why

 

[brian john]

Yes most of thought for these designs are based on HOO DOO VOO DOO, What the customer wants as long as it is NEC legal go for it. But IMO and expierence a properly installed electrical distribution system will not have interference problems.

 

[dereckbc]

If the customer really wants professional electrical system they would not use IGR. They would use balanced power which is basically an isolation transformer with no grounded circuit conductors on either the input or output. It is what the NEC call 120/60 Sensitive Electronic Equipment covered in article 647. He/She can buy the complete system in a black box or rack system and all you have to do is run a single 240 VAC 30, 40 or 50 amp circuit with appropriate receptacle. By using the black box or rack mount system you can completely bypass the NEC because it is plug-n-cord.

http://www.equitech.com/products/products.html

 

[LarryFine]

Last time I worked with any sound equipment of any consequence, they sound guys said they wanted all the gear on the same phase. Not the same circuit, but all on the same phase.

Anybody have an idea why

Yes, to minimize ground-loops which might induce noise because of shielded audio cables interconnecting separate equipment enclosures.

 

[iwire]

Yes, to minimize ground-loops which might induce noise because of shielded audio cables interconnecting separate equipment enclosures.

Larry how does that have anything to do with placing all the circuits on one phase?

 

[RayS]

Larry how does that have anything to do with placing all the circuits on one phase?

I think this is to keep the inevitable leakage currents at the same potential, which would tend to keep them from circulating on the enclosures and thru the shields

 

[electrimate]

I'm an electrician. And I am a musician. I have a home studio. It's small enough that all of my recording equipment is on one circuit. My house is old, built in 1966. I tried using some of the wall circuits, and got ground loop noise, it's a real problem. Once I went to a single dedicated circuit, the problem was solved. With modern digital recording, you can hear the slightest noise, and ground loops can be a huge problem.
I think the idea of having a separate IG panel all on the same phase is a good one. I would drop a ground rod as close as possible to the panel for the isolated ground. You didn't state if the wiring was in conduit or not, but that is a good idea as well, even if it's not neccessary by code.

 

[don_resqcapt19]

electrimate,

I would drop a ground rod as close as possible to the panel for the isolated ground.

What do you mean by "isolated ground"?
Don

 

[zbang]

On the one hand, most recording and other sound engineers have absoloutely no idea why they want things like isolated grounds or single-phase power, they just know they have to have them. OTOH, a few are actually clueful on this. Those few generally use things like proper isolation transformers and/or balanced power rigs, nothing special at all, or just run on batteries.

Drawing from a single phase? I suppose if the designer wants it, but it might still have HVAC or other noisy loads on it. I suspect concept this is an extention of drawing from a single outlet and proper star grounding.

Large systems on a single phase? Maybe in a studio, but any decent size sound reenforcement rig pulls from all three. Sometimes from multiple sources if it's big enough (say, a stadium show w/ multiple generators).

 

[electrimate]

The original poster said that the client wanted an iso ground. Isolated ground. It is an insulated separate ground buss, separate from the system ground. Those are common for telecom systems, it's an orange receptacle. The idea is that the equipment ground is separate, and should not pick up any interference from other electrical equipment on the other panels.
In a recording studio, the power requirements are not that large, but clean power is neccessary. UPS systems are a good idea, and are effective isolation, but inverters can be noisy, so the unit must be of high quality. Just about all recording equipment runs on low voltage DC, and just about every piece of equipment has an onboard power supply. The ground loop problems come into play when equipment is fed from different sources. A lot of recording equipment has a ground lift switch for that reason. Usually that switch ungrounds the seconary of the power supply so that the ground loop is eliminated. That doesn't always work.
The best way to do it on a new building is to feed a separate panel from a transformer and use both an isolated neutral and an isolated ground.
Another consideration is the separation of the power wiring and the audio wiring. Most recording engineers know better, but that can be a problem as well. If the audio lines do have to cross the power, crossing at right angles should prevent inductive inteference.

 

[don_resqcapt19]

electrimate,

It is an insulated separate ground buss, separate from the system ground. Those are common for telecom systems, it's an orange receptacle.

That ground is not permitted to be separate from the system ground. It would be a very dangerous installation if it were. Under the NEC isolated ground only means it is isolated back to the point of the main or system bonding jumper. At that point it is required to be connected to the sytem ground.
Don

 

[steve66]

Last time I worked with any sound equipment of any consequence, they sound guys said they wanted all the gear on the same phase. Not the same circuit, but all on the same phase.

Anybody have an idea why

Its common mode noise vs. differential mode. If you use the same phase, the same noise is on all the supply lines. Common mode is a lot less noticable, and tends to cancel itself out.

Steve

 

[dbuckley]

You dont need an isolated ground, and it is conceivable it may make matters worse, but to keep the noise down, using the PANI order of wires in the ground bar will help.

 

[dereckbc]

The Isolated ground. It is an insulated separate ground buss, separate from the system ground. Those are common for telecom systems, it's an orange receptacle.

Beg your pardon but I have designed Telephone Office Protective Grounding Systems for about 30-years, and that is far from the truth. I have also done a little recording studio work and you are speaking of is extremely dangerous if I understand you correctly. What you shuggest is not only dangerouse, but in all likelyhood would make the problem much worse.

All professional recording studios I have ever seen use one of two methods with a common technique.

1, The majority use just a plain ole isolation transformer and SG circuits.
2. Modern studios use Balanced Power 120/60 which is just another form of an isolation transformer.

I have heard of some using a UPS, but it does the same thing as an isolation transformer. Isolation transformers or other such forms of SDS are the only way you can remove Common Mode Noise. No IGR circuit is capable of removing any noise what so ever. There only use is a possible means to keep noise out and the results can be no effect, desired effect, or make the problem worse.

 

[brian john]

ELECTRIMATE:

If you have excessive hum/noise from utilizing seperate circuits you need to locate the wiring issues in your house.

 

[tonyou812]

Hey normbac im sure if you Google EMF chokes you will find something that you are looking for. Isolating the ground will not solve this. Ever wonder why your radio sounds crappy when a charger is plugged in and how you dont get this effect if you are using a Dewalt radio with built in charger? The Dewalt radio has a built in choke that reduces the noise or emf noise. If these people have a recording studio in their home than im sure they also have dimmers,low volt transformers, central vacs, intercom systems, you will have a though go at it trying to eliminate the noise. Good luck.

 

[brantmacga]

putting the console on a dedicated circuit w/ no shared neutral usually helps too, if they haven't already done so. i've seen this work many times.