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Balanced power, grounding etc...
Old 6th January 2005
  #1
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Balanced power, grounding etc...

My goal = I would like to have the cleanest power and least amount of noise possible in my signals.
I have heard of people using wood rack rails or even grounding their rack rails, has anyone heard of this?

I have heard of people grounding there patch bays too.

While we are on the clean signal / low noise subject, I would like to ask some questions about balanced power. Can anyone shed some light on this subject?

I was wondering how much of a difference balanced power makes?
Equi-tech said if I go with their balanced power units that I don’t have to star ground.

Another idea, I was thinking about saving some serious money and using flectchers balanced power trick
(Kind of worried about blowing up some gear).

Does balanced power really lower your noise floor? If you run all your audio gear through equitechs balanced power units does it really break all the ground loops and make star grounding unnecessary or it star ground and balanced power both, the best things to do.

I’m building my 1st studio and I don’t want anything to go wrong.

One last thing, I’m in Hawaii and the power out here is notoriously dirty.

Any info would be great!
Old 1st October 2005
  #2
Here for the gear
 

Balanced power is normally a good suggestion but you need very big transformers which can slow down the power.
Furthermore bridge rectifiers are normally used in all kind of gear which means that it´s already balanced in every power supply.
Therefore I would suggest you a real power conditioner (if you want to make it perfect), which generates a new sinus with 50 or 60 Hz at one stable voltage and you can buy them as an UPS system as well which can bridge a break for 5 or 10 minutes (depends on batteries) for a whole studio.
You should use some special cables for your different equipment and filters for digital gear.
The only reason why the balancing units break ground loops is that the power is galvanic isolated and the ground is on the middle of the power but if you connect the real ground again it can make the same crab again.
If you don´t connect the ground you have to ground the frame of the console that the whole circuits have a shielding.
If you have more questions contact me.

Good luck
Old 1st October 2005
  #3
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I have always wondered how the Furman units perform. Maybe it's worth the extra cash???


http://www.furmansound.com/products/.../balanced1.php
Old 1st October 2005
  #4
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In thirty years of audio work I have never seen a hum, "ground problem" or a "bad AC" problem that was not remedied by simple and sound electrical practice.

I have worked in, built and re-wired studios for thirty years.
I have set up, mixed on, and built live sound systems for equally as long.
I always use an AC distro system that I have built myself.
I NEVER HAVE HUM OR NOISE.
I can almost always eliminate hum from a rig.

Hare are some points to digest:

I have seen ground rods cause more problems than they ever eleviate.
The biggest reason is that if any device that derives it's GND from anything other than the ground rod is entered into the system there will be ground loop. EVERYTHING including the wall outlets in a studio where GTR amps are plugged into must be on the ground rod or it doesn't work. A ground rod actually opens up the possibilty of a ground loop because everything else in the building is on the AC service's ground.

I have seen a situation where the soffit mounted TV monitor for a SSL console's automation caused hum since it also had a feed from the cable TV. The cable system had a different GND and hence there was a loop!

I have seen a situation where a multiroom facilty had a new room wired with a dedicated ground rod, but as soon as tie lines were hooked up there was hum. The sheild of the tie lines bridged the two ground schemes. The rest of the rooms had their ground tied to the building's ground (which was fine) via the AC service ground. Once the tielines were removed there was no hum (until they were used.)

Also, ground rods need to be fairly deep and the soil needs to be damp enough to conduct properly. The service GND is lmost always completyely adequate.

Another common problem in large facilities is multiple GND points due to new AC service being added. Each panel has a GND and anything connecting both GNDs will cause hum.

Also, iso transformers can easily generate a field that will cause hum in guitars and other stuff. I know where a VERY expensive 1:1 AC transformer is in a sub basement of a studio where I disconnected it, but it was WAY too heavy to move. The hum went away! It's field caused more hum than it ever eliminated!

Whether it has been our 80Kw live rig or a studio with a vintage Neve and Pro Tools HD I have never had hum or noise because I have made sure that the AC distro system was designed correctly. Generally if I rip out all of the audio and AC wiring and start fresh there will be no hum.

I have read about "balanced AC" for years, but I have never needed it.
Besides, the power supplies in equipment is not designed to operate on balanced AC.
If your AC is designed and built correctly it isn't neccesary to have a balanced AC system. It is one of those silly theory things that no-one really uses very often. It just isn't neccesary because hum and noise doesn't occur because there is 120V on one line and the other lines go to earth! The fact that a power supply sees a "un-balanced" AC source is of no consequence in 99.9% of noise problems.

Also, without fail... every time I have had a hum issue and since I primarily do live work these days it happens quite often, there is an obvious and easily remedied solution. The challenge is finding the problem in timely manner, but it almost always comes down to a ground issue. It might be a cable with the GND prong removed on a video projector or something in the lighting rig plugged in with the audio, but it's usually simple once you identify the problem. When you are charging many thousands of dollars a day for a production there cannot be hum!

In a studio it is even simpler because you don't have as much to deal with.

I do suggest wiring your equipment where the sheild is only tied at the source (the output of a device and not at the input of any device.) This is easy to do at the connectors feeding the devices. I will add that I DO NOT wire our live audio rigs this way and I just added two 96 point TT patchbays and re-wired my entire home recording rig WITHOUT dropping the imput side of the sheilds and I have no hum at all. Using wooden rack rails isn't neccesary because when the sheild is tied at only the source (output) of a device there is no way for a ground loop to occur... even with metal racks.
The sheild is still able to drain away any AC, RF noise same as if both ends are tied. All devices definitely need their GND prong on the AC plug for this to work!

Here's a tip:
Un-plug everything. Power the console, plug up the power amp and wire up the monitors, plug it in. There should be no hum. Now, add each piece of equipment into the system. When you encounter hum the piece that you last plugged in is probebly causing the problem. Fix it and move on until everything is plugged up and running quietly. This always works.

Also, keep in mind that I build ALL of my electrical from the service entry to the quad boxes that I plug the gear into.

Generally I have found that AC distro is by far the most neglected part of audio.
I know peope who know A LOT about audio practice, but know absolutely nothing about AC. I was also lucky because I spent a few years in concert lighting and film location lighting. I even provided generator power to festivals and concerts. I'm one of those guys that can tune a Hammond B3 with a non crystal controlled gennie (what dumbass ordered that?)

As far as trying to isolate yourself from appliances goes, I have seen people try to keep their audio on one 120V leg and the appliances and other "bad" stuff on the other 120V leg (typical single phase.) This will not work because you have a common nuetral and all "un-used" EMF is sent back to the AC system via it. If a dimmer buzzes (you aren't usig SCRs are you?) it'll send hash down the nuetral which everything is connected to. It is very expensive to completely isolate an audio system because it takes two electrical services tied to two seperate transformers.

Also, power conditioners don't isolate the GND because they wouldn't meet UL specs. They also don't "slow down" the AC.... what-ever that means! The generators powering your local AC grid are MIGHTY powerful! That AC is coming through until a breaker is tripped. You ain't "slowing it down!" You can load down a transformer and get voltage sag, but a studio won't do that. Lights will. Running too long and thin of feeder cable will as well. It's not a studio issue unless you have extremely poor wiring and an HVAC system pulling a lot of amperage. Very rare.

Also, whenever you deal with issues regarding AC ground remember that ground is only a SAFETY NUETRAL. It is really there to provide an extra nuetral in case the actual nuetral comes un-bonded (comes loose.) This way there isn't 120V (or more) going to a device without anyplace to get to earth other than through YOU! They both tie to the service ground at some point. Using a ground rod defeats this abilty and you could shock your ass! It effects audio noise because it is used as a place to drain away EMF and RF before it gets in the audio sugnal path.

Good luck.

Ask specific questions and I'll try to help you.

Sorry if I confused things with all of this!

Danny Brown
Old 1st October 2005
  #5
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Boy, I have never heard so many incorrect statements and wrong ideas in my life...
I would STRONGLY suggest getting a good electrician and a good tech that truly understands grounding, bonding and ground loops.
I just finished wiring a studio from the ground up and NOT one piece of gear was lifted, used the AC ground rod, by the way is mainly for lightning protection. Lifting the AC ground on gear esp. power amps and consoles is dangerous.....
Balanced transformers cancels out any stray or equipment induced currents.
Never heard of slowing down the AC...
Old 1st October 2005
  #6
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Quote:
Originally Posted by nukmusic
I have always wondered how the Furman units perform. Maybe it's worth the extra cash???


http://www.furmansound.com/products/.../balanced1.php





don´t buy a furman! My Furman broke four times!!! it´s not for studio use. I know more people with this problem!

cheers
cdmast
Old 1st October 2005
  #7
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Along with many other musician types who record in apartments, living rooms, other peoples' houses, rehearsal spaces, clubs, churches, etc., I have no control at all over the wiring in the walls. So, doing it the 'right' way isn't an option. I use an Equitech, which has totally eliminated buzz and hum. Very pleased with it.
Old 2nd October 2005
  #8
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hociman's Avatar
 

Advice

Some of what is here is good, and some is bad. I agree with the evaluations of the postings to date, so I won't comment on those.

One thing I would do is buy an outlet tester. For about $10, you can plug a small device into your outlet and find out if it is wired properly or not. Fixing an incorrect wiring job may not be easy, but at least you will know that such a condition exists.

If you are going to AES, look on the program for a session featuring Bill Jensen of Jensen Transformers. He gives an excellent presentation on grounding, both fact and myth. In his opinion, balanced power is only necessary for video applications. You may find otherwise.

Never lift the electrical ground! tutt
Old 2nd October 2005
  #9
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I have seen balanced power installs that worked very good, I have seen basic isolation transformers work great. Have seen neither one work very well. Lifting the ground is not a solution IMHO, a good install is the result of expert planning and research, not a hit and miss strategy. Sorry if I sound anal.. but this is important, safety is important....
Old 2nd October 2005
  #10
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button's Avatar
 

There are three different issues being mentioned by people here:
1 - AC quality
2 - Tech Earth/Ground quality
3 - Interconnect problems, hums, buzz etc.

1 - It's quite easy to test AC quality where it enters the building, and there are many commercially available solutions to solve inadequate AC supply problems.

2 - I've designed/specified a lot of studios and in some cases, especially "in the countryside", it has been necessary to sink an earth rod. But it's absolutely essential that the entire building uses the same rod.

3 = By far the thorniest problem, and the troubleshooting procedure of plugging one box in at a time etc is quite fruitless. As soon as a bit of new gear or a band and their gear are introduced, the whole procedure is invalid.
Quote:
Originally Posted by dbbubba
I do suggest wiring your equipment where the sheild is only tied at the source (the output of a device and not at the input of any device.) This is easy to do at the connectors feeding the devices.
This is excellent advice, but the following should be added: the studio should be circled by a grounding bar, every ground on every bit of kit is lifted, and EQUAL length earth straps are run to the chassis of every bit of kit. This is where you may have heard of wooden racks. Clearly if equipment is bolted into metal racks, there's a possibility of ground loops. I've seen wooden racks, and I've seen isolation grommets and what have you. Personally I think the best option is to treat the racks as part of the system: make sure the metal rack completely encloses the equipment, and make sure that equipment has some paint scraped off to the rear of the mounting ears so there's a secure connection between equipment and rack. Then the entire metal rack just gets one earth strap.

Those who suggest "every piece of equipment had to have it's own AC cord earth attached (for safety)" have never worked in a very large facility. It's a recipe for loops and buzzes.
Old 2nd October 2005
  #11
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Those who suggest "every piece of equipment had to have it's own AC cord earth attached (for safety)" have never worked in a very large facility. It's a recipe for loops and buzzes.[/QUOTE]
The last studio I wired from the ground up was a real studio: 44 input console, 40+ pieces of outboard gear ect and had no problems. Done correctly and the same scheme thruout maintained a clean quiet system can be obtained. I used metal rack rails too.
I will say that every piece of gear has to be designed and built correctly to have a real quiet room. All it takes is one piece of crap to change things.
Old 2nd October 2005
  #12
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button's Avatar
 

Quote:
Originally Posted by nosebleedaudio
The last studio I wired from the ground up was a real studio: 44 input console, 40+ pieces of outboard gear ect and had no problems.
I'm so glad it worked well for you. But 40 pieces of outboard is just 4 little racks with 10 bits of kit ... it's not what I meant. I meant multi-room facilities with machine rooms etc. I have worked in smaller studios where one careful guy had installed everything and left the AC cord grounds on and everything was fine.

If you re-read my post you will see I'm not recommending NO ground, I'm recommending the SAME LENGTH of ground path for each piece of gear. If you ground each item through the AC cabling, everything will have a different length ground path.

I'm sure we're singing from the same hymn sheet, though ...
Quote:
Originally Posted by nosebleedaudio
I will say that every piece of gear has to be designed and built correctly to have a real quiet room.
Old 2nd October 2005
  #13
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[
I'm sure we're singing from the same hymn sheet, though ...[/QUOTE]
Yes we are, more than one way to wire a studio...
These days large console installs are fewer and fewer..
Old 4th October 2005
  #14
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Bob Ross's Avatar
 

Just an aside regarding balanced power:

Here in the US, according to the National Electrical Code (I think it's NEC Article 647), balanced power is restricted to installations in commercial & industrial applications; it is not approved for residential locations.

Home studio owners, read that again: Not approved for residential locations, according to the National Electrical Code.

Wonder why Furman or EquiTech don't mention that in their ads?
Old 4th October 2005
  #15
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It's not in the equitech ads, but it is on the website:

http://www.equitech.com/support/647.html


I have a question- I have a big resonant 60hz hum coming in off the street. I figured this out by disconnecting EVERYTHING in the building and plugging in a piece of gear and listening.

I also have an equitech but it doesn't stop the hum. I have a separate technical power panel that is grounded to the mains panel which is grounded to a rod in the earth. I could if necessary, ground the technical panel to a separate ground rod. I haven't done that yet though because I'm pretty sure that the AC coming in is what's dirty, and that I don't have a ground problem.


How can I stop the hum?
Old 4th October 2005
  #16
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button's Avatar
 

Quote:
Originally Posted by faeflora
I have a separate technical power panel that is grounded to the mains panel which is grounded to a rod in the earth. How can I stop the hum?
The first step is to check at the point of entry to the building, before any spurs, technical panels or anything. Then check the building wiring, spur by spur. There's a possibility you have more than one earth in your system. Maybe a plumber connected the chassis of an electric heater to a water pipe in the downstairs bathroom. The water pipe goes into the ... earth.

And the "rod in the earth." Is it really in the earth?

You can have the earth quality checked with an earth resistance meter. If there is only one ground conductor, a clamp-on meter is ok. If multiple conductors connect the electrical system to the grounding system, a traditional three-pole ground resistance meter must be used.

You need to find someone local to you who knows their sh1t and check it out. The power company are very helpful in some countries, in other places their definition of a ground seems to be a small nail covered with soil.

I see you are in the US ... this link has some fairly solid stuff (I have no connection to the author):
http://www.mikeholt.com/news/archive...Resistance.htm
Old 4th October 2005
  #17
11413
Guest
Quote:
Originally Posted by cdmast
don´t buy a furman! My Furman broke four times!!! it´s not for studio use. I know more people with this problem!
mine has worked fine since 98... no, wait.. one of the LEDs on the meter died.

it's just a transformer, what can break?

Last edited by 11413; 4th October 2005 at 06:49 PM.. Reason: typo
Old 5th October 2005
  #18
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7rojo7's Avatar
 

I have an 8kvA UPS followed by an 8kvA isolation transformer. These are in shielded, ventilated, silenced flight cases, as are my noisy Computer, FibreChannel and PCI expansion devices. I get 115v across each leg to ground plus the ground. The power supplies in my gear don't notice the difference, not even the racklights, or gtr and bass amps. I have different lines out of the iso tx for the computers, the gear racks with IEC strips, studio outlets with french plugs that prohibit a phase inverted attachment (common occurence here in europe), the amplifiers and cue systems and an aux circuit. I do the branch distribution with PowerCon connectors which are very helpful in maintaining phase coherence within the system. PowerCon in and out on my rackmounted 10 socket IEC strips lets me daisychain and the sexed plugs and sockets assures that no mistakes can happen and they're very sturdy, compact and they lock in place.
this system stays in the studio or goes out on location and protects me from anomalies of all sorts, except those that occur from within the system. It's extremely important that everything you use is connected to an isolated system and that there are no direct connections from outside the system, any signal that's attached to another system should have an isolation tx.
I have my shields (audio) lifted at the inputs of all my pre's and other gear and amplifiers, this is fairly standard and you won't bring in any noise thats on the sheild into the input, CMR does alot more than the shield, my patch bay is completely wired all points attached for flexibility and stability.
My AC is wired all points attached everywhere, I drop it with an adaptor if I must.
Don't plug any electric clocks, chargers or motors into the tech system. Flip the phase of all devices that don't have 3 prongs (lots of amps) to see if it makes a difference in the noise factor, mark the plug with nail polish defining the hot side and mark the hot side of your adapters.
Old 6th October 2005
  #19
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Jay Kahrs's Avatar
Quote:
Originally Posted by faeflora
I also have an equitech but it doesn't stop the hum. I have a separate technical power panel that is grounded to the mains panel which is grounded to a rod in the earth. I could if necessary, ground the technical panel to a separate ground rod. I haven't done that yet though because I'm pretty sure that the AC coming in is what's dirty, and that I don't have a ground problem.
Was your balanced power transformer installed by an electrician who knows what they're doing? Generally, unless they're installed right then there isn't much of a benefit to having one...and they're only going to fix certain types of problems anyway and won’t do anything for the common problems that crop up inside a control room. A lot of electricians aren't sensitive to the needs of A/V systems so if you need to call one it's worth asking if they know about that stuff so they don't create problems.

Dirty ground can leak onto the hot of the AC if it's bad enough. Tying the tech panel to it's own ground (seperate from the rest of the building) is worth a shot and probably should've been done in the first place. Remember, ground is referenced to 60Hz...120Hz is AC...only an octave up!

Generally, if it's a one-room bedroom studio you can usually get away with putting all the gear on one circuit so there's a common ground. If you need to lift ground from a piece of gear you should lift the audio ground, not the power ground! I've been in a couple places with wooden rack rails and stuff like that, but that's more of a band aid. If there's noise coming from the rack it's usually because one piece of equipment isn't happy sitting next to some other piece. In that case the only solution is to phyiscally move the gear to a different spot in the rack.

Eddie Calletti had a great article on power problems in either the current or last issue of EM that's highly worth a read. He's got all kinds of cool tricks in there like the old standby of using an AC radio to locate hum!
Old 6th October 2005
  #20
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I'll try running a separate ground for the studio, but I'm very skeptical.

To clarify what I said before, I disconnected EVERYTHING from the mains and technical panel. I forgot to mention that I also lifted ground (AC not Audio) on my test piece of gear but STILL got hum!

That's why I guessed that I had dirty AC from the street.

Any other ideas, based on that info?

Thnkx.
Old 6th October 2005
  #21
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Jay Kahrs's Avatar
Quote:
Originally Posted by faeflora
I'll try running a separate ground for the studio, but I'm very skeptical.

To clarify what I said before, I disconnected EVERYTHING from the mains and technical panel. I forgot to mention that I also lifted ground (AC not Audio) on my test piece of gear but STILL got hum!

That's why I guessed that I had dirty AC from the street.

Any other ideas, based on that info?

Thnkx.
Ehhh...anybody in the building running a massive motor? Maybe a central AC, walk-in freezer, elevator or something equally dumb and evil for audio? Button has the right idea...it's entirely possible that there's something like a water heater or AC tied to something it shouldn't be tied to and you probably need to get a an electrician who knows about A/V stuff to hunt it down and kill it.

What's the piece of gear you used to test? Did you try different pieces? What if you reconnect the audio ground but lifted the AC ground?

You'd be amazed at what even a minor ground problem can create. A few years ago I started working at a really nice new club as the house engineer. It was all new construction with no expenses spared on the audio side of it because they're doing nationals. There's a seperate 300 amp service & transformer just for audio which is feeding a Meyer rig and whatever. Anyway, we had the nastiest ground buzz for the first six months or so and we couldn't get rid of it. It wasn't enough to be a problem during a show, but when the room was empty and the rig was idling it would drive us up a wall. We tried mucking with the light rig, swapping consoles around, power amps, got a transformer iso'd splitter snake etc.

We eventually found the problem, a shared ground between the phases...and since we had the lights & bar on one phase, the kitchen on another and the audio on the 3rd...well...there 'ya go! You'd think a massive transformer would eliminate stuff like that but it didn't!
Old 7th October 2005
  #22
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Quote:
Originally Posted by Jay Kahrs
Tying the tech panel to it's own ground (seperate from the rest of the building) is worth a shot and probably should've been done in the first place.
Be careful what you say here. A truly separate ground (leading to a separate ground rod in the dirt outside) is both illegal and dangerous, and is counterproductive since the grounds will be at different potentials, which is one of the things you're trying to avoid. According to the code, all grounds and neutrals must ultimately be tied to a common reference point.

If you are talking about pulling separate grounds to the main panel or the common ground rod, that's both legal and a good idea.
Old 7th October 2005
  #23
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Diablo's Avatar
 

Here's what I do to eliminate AC noise:

Use HumFree's on all rack gear. Trust me they work. http://www.americanmusical.com/item--i-DAN-HUMFREE.html

Use a single outlet to drive all your studio gear. Make sure that nothing else is on when you are using your gear. I run my home studio from my laundry room outlets. They are on a 15 amp circuit, which is plenty of power for all of my gear.

I used just a cheap AC noise reduction power strip until I got this: http://www.musiciansfriend.com/srs7/...base_id/112773

Turn off all gear that's not actually being used at the time.

Remove all fluorescent lights from the house or apt.

Remove all dimmer switches from the house or apt.

Voila! No noise.
Old 7th October 2005
  #24
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nosebleedaudio's Avatar
 

Quote:
Originally Posted by faeflora
I'll try running a separate ground for the studio, but I'm very skeptical.

To clarify what I said before, I disconnected EVERYTHING from the mains and technical panel. I forgot to mention that I also lifted ground (AC not Audio) on my test piece of gear but STILL got hum!

That's why I guessed that I had dirty AC from the street.

Any other ideas, based on that info?

Thnkx.
Are you the only one in the building. Have you made sure that the plugs are actually grounded? I have seen in older buildings or houses that were wired with non grounded outlets that someone simply replaced them with a grounded plug that is not connected to anything.
Are you on the same power transformer with other people? If so you may not be able to do anything to eliminate trash on the line.
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