[Niteshade]

The premise behind this "FYI" notice is an easy one: Grounds do not always look like grounds to your audio or communication system.

There is a big difference in what wire or solid metal (even THICK solid metal) looks like to DC and AC. Noise for the most part is AC or pulsed DC (square waves). The horrid truth is that a solid earth ground does not exist in real time to AC or square wave based signals like it does to DC. All grounds have an impedance since they are made out of metal. The name impedance means that something impedes the flow of electricity at a specific frequency. A stretch of wire that appears as 4 ohms on an ohm meter can look like millions of ohms at high frequencies. The reverse is true: If a stretch of wire is resonant at a certain frequencies, it will act like a noise magnet! In a nutshell, a ground wire or system is an inductor (or resonator/antenna) and can possibly work against you.

Another fact: All step up and step down transformers inside your electronics appliances can be thought of as isolation transformers. The only thing connecting your gear to the outside world is the ground wire. There is a considerable amount of electronic gear made without an external ground system (two prong plug instead of three). 

The silly thing about isolation transformers is that they have ground wires. Well- that bridges both sides of the so-called isolation transformer and it's now useless. 

Important: If one device in your system is 100% isolated, make sure everything that is connected to it is 100% isolated form the mains as well. If not, it could be dangerous and/or you will be defeating the purpose of total isolation.

Whatever you do, you do at your own risk. I am just relaying some facts and information and not providing hook up data.

This whole notice can be summarized: Ground systems are not always noise sinks. In fact, they can be resonant at certain frequencies and pick up noise.

A good read: http://www.industrialcontroldesignline.com/howto/212501871

[gerald porzio]

http://www.audioholics.com/education/cables/debunking-the-myth-of-speaker-cable-resonance

A small dose of measurement trumps myth in my book.

[ctviggen]

You have to be very careful when discussing "ground".  For instance, the neutral wire is connected to earth ground at the breaker box (as is the so-called "ground" wire).  Therefore, even gear with two prong plugs is grounded to earth ground.  This means that the neutral prong connects your gear to the "outside world".

[Niteshade]

It does depend on how the internal connections are made. Some plugs are non-polarized, although that is not as common as it was during the 80's.

This power supply has no relationship to the mains as the step-down transformer is acting as a isolation transformer: http://www.elecfree.com/electronic/wp-content/uploads/2007/09/lm317-linear-power-supply-regulator-15v3v45v5v6v9v_15a.jpg

You have to be very careful when discussing "ground".  For instance, the neutral wire is connected to earth ground at the breaker box (as is the so-called "ground" wire).  Therefore, even gear with two prong plugs is grounded to earth ground.  This means that the neutral prong connects your gear to the "outside world".

[HAL]

Looks like an interesting book. 

[poseidonsvoice]

http://www.audioholics.com/education/cables/debunking-the-myth-of-speaker-cable-resonance

A small dose of measurement trumps myth in my book.

Blair,

Thanks for well thought advice.

Gerald,

Excellent link.

Anand.

[Niteshade]

I forgot to mention something to those who are not as well versed in electronics:

A.C. is otherwise known as Alternating Current. AC, unlike DC can be broadcast without the use of wires. RF (Radio Frequencies) are also AC.  I wanted to mention this since some people might think that AC only refers to what is in your home's mains.  AC refers to any current that switches between positive and negative, in relation to neutral over a period of time.

Paulsed DC can either ride above or below neutral, bot not both. Pulsed DC is often referred to as a square wave. You computer operates on pulsed DC. AKA: A 3ghz CPU operates on a 3GHZ square wave from its reference clock.  A DC square wave should not be confused with an AC square wave- but they can both cause havoc.

[sts9fan]

I don't understand what you are saying if one is isolated they all should be.  If you have one unit that has signal gnd connected to earth say a pre. Won't this connect the whole chain to earth?  Maybe I am missing the point.

[Niteshade]

The idea is do disassociate everything form the mains. If one item is not isolated, even if something else is, the isolated item is no longer isolated since it will reach earth ground through an appliance it is connected to. I.E.: It would make no sense to isolate an amp if the preamp is earth grounded.
 

I don't understand what you are saying if one is isolated they all should be.  If you have one unit that has signal gnd connected to earth say a pre. Won't this connect the whole chain to earth?  Maybe I am missing the point.

[gerald porzio]

Altho it's no help w/ ground loops, shielded cables go a long way toward rejecting the dreaded RF/RFI which can be found in the heart of the Amazon rain forest to the corn fields of Iowa & the wheat fields of Kansas, Toto. Altho it goes against the audiophile bible, there are excellent shielded cables.

[Niteshade]

Are you referring to shielded interconnects or shielded speaker cables or both? The RCA's I use are always shielded.

Altho it's no help w/ ground loops, shielded cables go a long way toward rejecting the dreaded RF/RFI which can be found in the heart of the Amazon rain forest to the corn fields of Iowa & the wheat fields of Kansas, Toto. Altho it goes against the audiophile bible, there are excellent shielded cables.

[rollo]

Altho it's no help w/ ground loops, shielded cables go a long way toward rejecting the dreaded RF/RFI which can be found in the heart of the Amazon rain forest to the corn fields of Iowa & the wheat fields of Kansas, Toto. Altho it goes against the audiophile bible, there are excellent shielded cables.

 You are correct about RFI, if we could see it we would see nothing else but a dense haze. We are surrounded. My house has plaster walls over wire lathe. I connected the lathe to ground creating a pseudeo faraday cage.
 

charles

[gerald porzio]

Spkr. cables really don't need shieding as the signal is relatively strong. However, having an overmodulating ham radio operator next door can change all that, but now we're talking real longshots.

[Niteshade]

There was a member on here a while ago who was getting interference through their speaker leads. I think it was a near by radio station. I know that radio stations can be a PITA when they're close. Otherwise, I 100% agree- the speaker leads generally do not invite interference.

[sts9fan]

I disagree that it makes no sense. It is for safety and for keeping away ground loops. This is the lab and we build our own stuff. I think it is a bad suggestion not to have your gear grounded to earth. That's why I have one component earth grounded. I think it is safe and super quiet.

[Niteshade]

Look at this link: http://www.industrialcontroldesignline.com/howto/212501871


Connecting a local ground to a WAN ground can either help or hinder or do nothing to aid in noise reduction as a result of every single path having reactive properties of some sort.

It is debatable whether grounding is always safe. That is a very application specific subject.

For example: My grandfather was a electronics engineer for the Air Force and designed radar systems. While in Florida, the DUT's were struck by lightening frequently. They were grounded!

My grandfather recommend that the earth grounds be removed. The lightening issues became less of an issue.  That is logical: Lightening wants the past of least resistance and a well grounded dish looked pretty yummy!  This flies in the face of common reasoning, yet it worked.

What I did: I grounded my radio room but did not ground my antenna! When a storm was around, the antenna was always unhooked from the radio. It had zero ground reference! I have never been stuck. Areas around (very,very close) to the house were struck over the years, but never my antenna. Oh- In speaking of RF issues, I used what is called a ground tuner. It made my groduning system resonant with the frequency I was transmitting on and bled off access RF to ground. Without it, I may as well never have had a ground going into the room. I did get an RF burn once (I got burned from brushing against a GROUNDED radio chassis while transmitting!). That's why I got the tuner. My SWR's were indeed low: 1:2 to 1, but at 1KW out, even a little loose RF can hurt.

Grounds are not always what we believe they are, as the original post states and the referenced web site/book states.

I 100% agree that in many cases it is unwise not to be grounded. BUT...in other cases you have to use your head and understand what's going on. Isolation can be as important as grounding. Circuit analysis skills are necessary and a working knowledge of reactive components & RF are important too.

Another good link:

http://www.radioworks.com/nbgnd.html

[JoshK]

Do you always build with double insulation standards?  If not, you are inviting yourself to a lawsuit.  Its one thing for a DIYer to risk their own skin and another for a manufacturer to intentionally violate safety standards.

Look up grounding by Dan Banquer.  Kris's suggestions seems to conform with this principle and is in compliance with safety standards.

[Mike B.]

This is a very important topic but probably better left to EE types. I have followed the Blowtorch Preamp thread at DIYAudio. John Curl is a master of low noise circuits for audio applications. The lengths necessary to keep RF out of the enclosure are monumental by themselves. Then you deal with the stray electrical contamination  inside. The simple tweak of choosing the lowest chassis voltage measurement by switching AC polarity should give an idea of this type of pollution. Having 15-40 volts of AC riding on the chassis can't be good.

[Niteshade]

Here is a good thread by Dan Banquer:

http://www.diyaudio.com/forums/everything-else/29982-grounding-practices-consumer-audio.html

If there are ground noise issues, isolation transformers do exist so that equipment does not have to be modified. The transformer might be grounded, but it may still help.

A shock can only occur if you are in contact with two different potentials. An isolated system makes it so you cannot be in contact with varying potentials. If an AC main of appliance A were rubbing against the chassis and you touched it (for conversation, it's a metal chassis) and touched appliance B, that was also ungrounded (isolated from the WAN ground), you would not receive a shock. If B were grounded, there would be a bad shock. (It's the birds sitting on high tension wires scenario.) Those are facts.

I wanted to keep this informative and not a "Do this or that" kind of thing. People can process these facts as they like as I stated in the original post. I think it's interesting and can add insight to noise elimination.

Do you always build with double insulation standards?  If not, you are inviting yourself to a lawsuit.  Its one thing for a DIYer to risk their own skin and another for a manufacturer to intentionally violate safety standards.

Look up grounding by Dan Banquer.  Kris's suggestions seems to conform with this principle and is in compliance with safety standards.

[Occam]

......
Another fact: All step up and step down transformers inside your electronics appliances can be thought of as isolation transformers. The only thing connecting your gear to the outside world is the ground wire. There is a considerable amount of electronic gear made without an external ground system (two prong plug instead of three).

And any such component (Class II appliance) should carry an ETL (UL,etc...) designation as such. This means the component has been tested at a government certified, qualified testing lab that both the internal components and construction lower the risks of fire and/or electrocution below a given standard in order for it to be a Class II, 2 prong component. I assume your products have a proper 3 prong plug/inlet, and connect that mains ground to any accessible metallic exterior?

The silly thing about isolation transformers is that they have ground wires. Well- that bridges both sides of the so-called isolation transformer and it's now useless. 

Hardly silly. The connection for the safety ground has 2 purposes on an isolation transformer -
1. To provide a capacitive/electrostatic shunt connection to a shield  interposed between primary and secondary. Otherwise, such a design would forfeit the majority noise reduction.
2. To reestablish the neutral bonding to ground as required by code/safety reasons.

Important: If one device in your system is 100% isolated, make sure everything that is connected to it is 100% isolated form the mains as well. If not, it could be dangerous and/or you will be defeating the purpose of total isolation.

As Dan Banquer has pointed out, there are no standards in non balanced, consumer components as to signal ground/mains safety ground bonding. But there are standards on mains safety and chassis bonding. You really can minimize ground loop noise/hum without endangering life, limb and property.
http://www.audiocircle.com/index.php?topic=19860.msg177365;topicseen#msg177365

Whatever you do, you do at your own risk. I am just relaying some facts and information and not providing hook up data.

Not quite facts, but your interpretation of them.
 

This whole notice can be summarized: Ground systems are not always noise sinks. In fact, they can be resonant at certain frequencies and pick up noise.

A good read: http://www.industrialcontroldesignline.com/howto/212501871

Indeed, a  very good read. Section 8.8.2 which explains a shield's noise reduction purpose in an isolation transformers. The articles are very good, I just find it puzzling how make your conclusions.

PS - I just saw your latest post referencing the same Dan Banquer post on grounding practices. Great reference. If all your components are built to Class II standards, fine, you largely eliminate ground noise problems as you've no mains ground connection. Otherwise, please don't  'float' your safety ground, but actually understand Dan's discourse on signal ground to safety ground bonding. Dan, please jump in here.