Grounding Rods - urban myth or practical solution?

I wouldn't say sound "quality" is at risk but noise floor could be. Having a solid ground is important but more important is all the gear having an equal path or potintial to what ever ground you have. A good PC power supply will provide good clean low voltage feeds to all the parts inside the computer no matter what happens at the AC input. But it will also send all it's garbage back down the ground. The power supplies in all your will do this and that's normal. If your house ground is good that should be enough. If it's not then the first step would be to improve the ground for the entire house first. If you still get ground loops or more noise then you would expect then you may want to think about a seperate ground for your studio.

In one of the apartments I lived in before I got my house there was only one outlet in the room that had a good ground. So I had to run all my gear off that outlet and run a wire from all the racks to that ground to stop the ground loops. You can get a tester at Radio Shack or a home center to test the outlets and that will at least let you know if things are wired correctly.

If you had all analog gear like in the old days a ground might help the sound "quality" of things like amps but today with swtiching reguatled power supplies in PCs it's not a quality thing it more just a noise floor thing.

Thanks as usual yep and ohhey.

Ya know - at this juncture, I'm not even sure if the gremlins I've been chasing are real gremlins. By all outward appearances, I don't have a problem - at least not according to the test data and the various other band-aids I've tried. Yet, in the back of my mind I can't shake the feeling that I do have a problem that might be ground or AC related.

In terms of driving stakes into the ground behind my house like some sort of vampire hunter, I might pursue thatl, but not now. The ground is freaking frozen and covered with 6 inches of snow at the moment. Better to wait until spring I guess. I'm still waiting for some sort of recommended game plan from the electrician. He was going to confer with some colleagues before rendering a formal opinion on this matter. But his gut reaction this morning was to drive a ground rod and separate the studio circuit from the rest of the house. We'll see. I wish there was some way of testing this theory before committing sledge hammer to copper rod.

For the record, it's not the stake in the ground that's expensive, it's tying all of your outlets to it (and even that's not TOO bad, by electrical standards).

If you're going to go to the trouble, you may as well have them run new circuits from the service panel while they're at it. Gives you room to grow, and fresh AC to go with your new ground wire.

Cheers.

Having a separate grounding rod has been the subject of debate for decades. Every audio consultant I've ever known has always insisted on one, as well as an isolated ground, and a "star-grounding sytem" and several other schemes. All of these ideas have some merit and MAY help, but the only real way to avoid problems is to do everyhting by the book. Make sure all electrical devices have an earth ground, hopefully at the same point, used only balanced audio lines, isolate the shield at the output of of all audio cables, use only quality braided shielded cable, and DON'T use cheap surge suppressors. You're 99% assurred of having a hum-free system this way. We have had good results with SurgeX power conditioners, and the upscale Furman Voltage regulators are worthwhile if you have a local fluctuation problem, but most of the cheap "conditioners" are just outlets in a box with a cheap "spike" trap that can introduce issues.
Oh, and if you're going to pound the stake into the ground, attach the connector first! I installed a ground rodyears ago thru a concrete slab (hammerdrills are amazing!) and didn't realize that the sledeghammer would deform the end of the rod to point that I had to hacksaw off about 4" to get the connector on. I had a bad day....

Important detail...

Story from some magazine I read a long time ago:

This studio had an annoying intermitent noise problem. The engineers who worked there had tried all the traditional solutions, like making sure the ground wire was properly attached to the chassis of each piece of gear, star grounding scheme, etc. They would implement some new scheme and think that they were getting somewhere, the noise would be gone for a few days, then mysteriously reappear when the technicians had not changed anything.

Finally in utter frustration they called in an eletrician to see if he could find the source of their problem. He came with his son who he was training to be an electrician. So he checked all the wiring and the panel and the outlets and declared that he could find nothing obviously wrong. He went outside and checked the grounding rod which was sunk into the earth outside the back of the building and it seemed intact. He went back in and started checking everything again, assuming that he had missed something. The boy got bored and wandered outside. While he was gone the noise suddenly stopped. Everyone got real excited because they figured the electrician had found the problem. Unfortunately he had done nothing. He was getting ready to leave when the noise reappeared. He went back to work looking for the source of the problem. After another couple of hours the boy got bored again and excused himself to go outside. Once again the noise stopped. Now the electrician was totally confused. He could find not reason for the noise to have stopped. He asked everyone to tell him what they had been doing when the noise stopped. They each told him in turn and there was no obvious connection.

At his point the boy comes back in. The Father asks him what he was doing just now, and he says he was just walking around outside. The electrician goes through everyone's story again and is at his wits end. Finally he turns to he boy and says "Tell me exactly what you were doing outside." The boy looks all sheepish and doesn't want to answer. The Father endures with the questioning until the boy finally admits that he went outside to the back of the building to have a pee. The Father asks him to show him where he was peeing. Sure enough the kid had been peeing on the grounding rod. Every time he did the grounding rod made a good connection to ground, but as it dried out the ground was lost. As the studio owners thought about it they came to realize that the the noise went away whenever it was raining out.

So there you go, you have to piss on it if you want it to work.

R

I've learned a lot from these messages and links. Thanks!

krizrox,
I'm a little late to this thread, but there are a couple of possibilities I might add. My background includes amateur radio where grounds are also important. Some operators have put water plus copper sulfate crystals around the ground rod; I don't know what this does to foliage or groundwater but it increases ground conductivity; in very dry areas grounds can be a problem because the dry ground is not conductive enough.

In an office where I work we had voltage surge problems because the 3 phases were not properly connected or balanced. Also , in my little studio I have found that SCR type light dimmers are a source of noise

Jeff

PC's are by far the worst offenders for creating grounding noise, simply due to the switched-mode power supply and the method employed to decouple noise from the mains.

Unlike a PC power supply, an isolating linear power supply uses a transformer to convert down mains voltage. The AC output of the transformer is then diode-rectified to pump charge at relatively low DC level into a reservoir capacitor, which in-turn feeds a DC regulator serving to control system rail voltage for voltage-sensitive devices. However, in the process of rectifying the AC voltage from the transformer, rectifier diodes conduct (to pump charge into the reservoir capacitor) and then switch off on the inverse AC cycle. It's this process that creates burst noise on the connecting wires which can escape back through the transformer and appear on the mains wires. Depending upon the mains filter employed (if any) then this can manifest on ground wires as-well, though the use of a transformer between the rectifiers and the mains circuit acts like a large choke.

However, for efficiency and size reduction the switched-mode PC power supply does not first transform down the supply voltage by large transformer before the regulator. What actually happens is that the mains voltage itself is directly rectified and this leads to more aggressive burst noise created by rectifying diodes pump-charging a high-voltage reservoir capacitor. Now as no transformer exists to provide a degree of high-frequency isolation with the mains input, large toroidal chokes and high-voltage capacitors attempt to decouple the noise feeding back onto the supply lines (you can often see these peering through the fan grille - where the mains connector terminates to the board).

In addition to burst noise is the added noise from the switching action of the regulator, occurring at much higher frequency than mains but often within the high-audio band. Rectifier burst noise is likely to give you 100/120Hz noise, whereas regulator-generated noise will generally be in the form of a whistle or hiss.

Sadly, PC power supplies often employ a couple of high-voltage capacitors series-connected across the two AC power lines, with the junction between the two being connected to chassis/earth. This increases the propensity for electrical noise to appear on all grounds coupled to the PC, such as screened cables running out to your audio amp, pre-amp, etc. These capacitors are usually added to meet HF emissions regulations but are often the primary cause for conducted noise in ground circuits.

A separate large bifilar-wound choke on the power lines to the PSU can often help to increase noise impedance to the supply wires and make the earthing circuit more effective by comparison, in addition to localising the noise loop. It's no mean feat resolving noise issues and this is only one measure that can work in some cases. In an ideal world optical or signal transformer isolation can work wonders, but with transormer isolation you're colouring an otherwise flatter signal and is therefore impractical. Active balanced coupling can also work well and preserve flatness, but is often impractical for the usual home studio.

Oh well... just imparting a brief technical insight as I used to develop audio test gear for Phillips PRCS in a production environment, where line noise was forever the issue.


Brendan.

If I was bothered enough to go outside and start sledgehammering a rod into the ground, I'd first go get an isolation transformer and use the output side for my studio. It's a lot like a balanced direct box for your studio's AC power, complete with a ground lift. So, rather than tring to find a better ground from the power company, you can use off-the-shelf technology and create your own. What you get in return is total control over the source and nature of that ground, and you are assured that it is completely clean. Not only that, but the hot side is completely clean, too. Way cleaner than almost any other solution, in fact.

For an example of what I'm talking about, you can look here.

ORIGINAL: losguy

If I was bothered enough to go outside and start sledgehammering a rod into the ground, I'd first go get an isolation transformer and use the output side for my studio. It's a lot like a balanced direct box for your studio's AC power, complete with a ground lift. So, rather than tring to find a better ground from the power company, you can use off-the-shelf technology and create your own. What you get in return is total control over the source and nature of that ground, and you are assured that it is completely clean. Not only that, but the hot side is completely clean, too. Way cleaner than almost any other solution, in fact.

For an example of what I'm talking about, you can look here.

Thanks for the tip - I will look into this.

ORIGINAL: losguy


The other main thing is to keep everything on the secondary side on one ground, separated form the main power completely.

This might be a code violation no? How do you do that exactly and still be "in code"? My understanding is that ground needs to be connected to the mains ground somewhere. You can't have a separate ground running out into the backyard for example. It needs to be tied to the mains ground at some point - or so I thought. My main goal is to prevent death. That would be a show stopper :-)

According to the NEC all grounds shall be connected. One quick description is in some (electrical) services too many ground connections cause "ground loops" and the current running aroung on ground conductors causes voltage rises as it passes through different connectors and the voltage reference levels fluctuate on the ground the DAW equipment or sound reinforcement components uses. The good comments on CPUs with their switching power supplies being their own worst enemy is right on. IMHO and in my working experience in computer room ground problems/resolutions, the type of solution greatly depends on how much money one is willing to spend to eliminate the noise, and even eliminating a lot of the voltage transients that constantly barrage the electronics. Best simple start should always to have a good ground rod system for the home/business, and if multiple ground rods have each connected with a minimun #6 cable in a daisy chain, not looped. If another ground rod is driven say near a studio wall, outside, that must be, per code, connected to the building electrical service ground. It is also dangerous. Whew, a too long email. This is a very important post, and every comment herein has some good comments. Just my 2c.

Joe

Thanks jambrose. Just to be clear, I did not advocate violation of any electric codes whatsoever. In fact, follow them to every dotted "i" and crossed "t", and it will be fine and dandy. But that's apples and oranges to what I was recommending above.

All I recommended was that one plug their Isolation Transformer into their (code-compliant) wall outlet, then plug their entire recording setup into the isolation transformer (nothing more, nothing less). The isolation transformer is UL Listed, and probably approved by lots of Medical Safety Review Boards as well (otherwise hospitals would not use them, or even touch them with a 10-foot pole, or for that matter even a six-foot grounding rod).

Let's not overthink this. One should think of the isolation transformer as a glorified power strip... just one that carries a lot more clout than the $5.99 variety that you get at Lowe's. And about 2000-4000% () more effective than the stupid Monster noise filter that you get at Best Buy for 10X the price.

ORIGINAL: jambrose@cfl.rr.com
Believe it ot not, less than 50 is accepted, less than 25 is typical.

This fact alone is a great argument for using an isolation transformer. The "acceptable" impedance is just enough to keep things safe, but not enough to keep things noise-free. But with an iso, you can create a clean-as-a-whistle, low-impedance ground on the secondary side for your studio equipment with no safety impact, and without having to go to the n-th degree to get the electrical supply ground clean.

ORIGINAL: jambrose@cfl.rr.com
I'm in agreement about the isolation transformers. I used one for every computer room or Telecom POP, to provide the separation of service from other same building elect services, and creating a power distribution network I could document everything from the created dedicated service. The GE super isolation with double farraday shielding between the primary and secondary windings was one of my staples. From 25 to 500kva or better, I always had good fortune with those products. Another was a CPC solid-state tap switcher with again, enhanced shielding between prim/sec coils, and with the advantage of handling brown-outs without switching to UPS power.

Holy cow Joe, why didn't you say so before? You've been holding out on me! And yeah, I've heard about the line-regulating type (the brownout-proof one). Sounds great to me. But I expect they're a bit pricier. Not to metion the 500KVA unit... a studio that needed half a megawatt would be pretty scary!!

As you may know, some most common problems are caused unknowingly by Users themselves (me included!) where they combine multiple component computer network systems, and then plug the multiple components into electrical outlets spanning two electrical distribution panel "streams"; one from an isolated (created specifically to provide the clean power for them) service, and another component into a standard utility outlet (not fed from the created service), inducing/generating electrical noise, hum, and problems. That type of random "plugging in" would connect the two electrical panel "streams" ground...through their equipment via the ethernet or low voltage shielded cabling. Then the erratic problems would start. Some of the nose and hums talked about here may very well be a similar situation, not with computer components (maybe) but audio components,

I think the whole cross-system ground connection thing is what got the safety and code talk started. You basically made the same point I did, that crossing the grounds is a noise issue rather than a safety issue... it defeats the purpose of isolation.