why balanced power last before component?

Late news. Is it possible the new grounding product for shunyata may improve the equitech 2q by filtering the ground?  I also just read fascinating information on Nyquist noise and how Einstein once again had involvement. wow

@ptss Einstein theorized that such noise existed but assumed it was not measurable. Johnson showed that it was and Nyquist explained why. So both names are associated with noise from resistors. Do you know which ground connection is being filtered in this case? If we are talking about the 3rd wire of an AC outlet (the ground connection) I find myself skeptical. This is because a properly designed bit of audio gear should put no noise into the safety ground- although that word 'should' is there telling you this does not happen all the time!

Other things unrelated to audio might put noise in that ground. But you might want to keep in mind that putting any kind of impedance in series with the safety ground could lead to Bad Things- like a shock hazard, as the difference in potential between the equipment and the basement floor could be enough to create a shock hazard.

Its on this account that I don't do anything that might mess with the purpose of the safety ground.

I've always been curious about the idea of balanced power. Funny thing is though, the balanced transformer systems I have seen use a center tap which goes to ground.

Its very well known that this will degrade its noise performance. If there is noise common to either side of the AC line it will get though easier if there is a grounded center tap.

This is because no center tap is truly a center tap- they are always off by just a tiny amount. This is why in most balanced systems no center tap is used.

I have read the PDF from the Furman site; it appears that there is likely a better way to do this than use a center tap. It could yield another 20 db lower noise...

Here are the NEC requirements. You're not running balanced power everywhere, just the audio system, right? At any rate you might want to read all the way through:

NEC 647, which defines the requirements for balanced power systems, places some important restrictions on both their installation and use.

1. Conductors must be sized so that the IR drop does not exceed 1% of the line voltage under a load equal to 50% of the branch circuit current rating, and so that the
combined IR drop of the feeders and the branch circuit wiring does not exceed 2%.
2. A dedicated Equipment Ground conductor must be run to all equipment and each receptacle.
3. All receptacles must be protected by a GFCI.
4. The neutral must be bonded per NEC 250, and must also be connected to the grounded conductor of the circuit that feeds the system.
5. Balanced power systems are restricted to industrial and commercial occupancies.
6. All outlets “shall have a unique configuration” and must be identified using specific language called out in NEC 647.7.
7. There must be a receptacle having a grounded circuit conductor (i.e., conventional unbalanced power) within 6 ft of each receptacle for the balanced power system.
8. All lighting fixtures connected to balanced power must be specifically rated for 60/120 VAC balanced power, must “have a disconnecting means that interrupts all
ungrounded conductors,” and must be permanently installed.
9. Isolated ground receptacles are permitted. Balanced power systems are expensive, and their noise reduction capability is limited to about 10 dB. Isolated ground systems are generally a far more effective and less costly solution.

This might be old hat for you, but that final point is where I was going...

No, although more detail would be helpful.

The comments do support my view that individual grounding is cheaper and more effective. It would be nice to see exactly how though, as my opinion is based strictly on the observation I made earlier about center taps and these guidelines don't provide any supporting data.

It is a nice list of customers, but I think there is more to it than that.

I've read stuff off of their website but I see troubling comments. Here is one:

Can the problem of AC noise common in Class-A tube amps be addressed? How about noisy guitar amps?

The answer is of course 'yes' (BTW this is in the article 'lifting the ground', http://www.equitech.com/articles/enigma.html).

Fixing the problems in the quote is easy through proper grounding, and its not rocket science. I have found that a lot depends simply on whether the designer knows what he is doing or not- and has nothing to do with the AC power (and apparently, nothing to do with whether the designer is an engineer for a pro audio company or high end audio). A lot of noisy guitar amps are simply that way because they don't ground the circuit and the chassis properly. Class A amplifiers, FWIW are no more prone to noise problems than any other amplifier as the quote suggests. When I see stuff like this it makes me suspicious.

Indeed, further down we have this comment:

The power resembles a balanced audio circuit or an XLR input from an unbalanced to balanced audio transformer.

This is not true. If you want to do balanced, the thing you **don't** do is use a center tap! The reason is as I mentioned earlier- you reduce the CMRR figure significantly simply due to the fact that the center tap is not in fact at true center.

So when I see stuff like this I begin to wonder- does this guy know what he's talking about? Apparently he knows power but not balanced line operation...

What I am seeing here seems to boil down to this: If the equipment has design bugs in its grounding scheme, the balanced power will help. If the equipment has no grounding bugs, there will be no improvement.

This has everything to do with the fact that if the audio equipment is grounded correctly, there will be no current in the ground connection. IOW if there is current in the ground connection, you have a problem!

FWIW I have followed some threads on some of the grounding products like the Entreq Tellus. I did a survey of owners, who I asked to do some measurements for me. What I found was that in 100% of the cases where the owner reported an improvement through the grounding system, the audio equipment associated had a grounding problem somewhere in the system. I may be jumping to conclusions here but I am thinking the same thing is going on with balanced power. Its there to fix bugs in the grounding design of the associated audio gear.

IMO if there are such bugs in the audio gear, it should be fixed (whether the designer knows how to do that is another matter altogether). This will solve more than just AC power issues- it will also solve ground loop issues.

I have found that designers in this industry often do not like being told that they have introduced a bug in their product.

The way you ground audio equipment BTW is simple: the circuit ground in the gear is kept isolated and insulated from the chassis. This includes the input and output connections. The chassis is directly grounded to ground through the AC cord. The audio ground is then referenced to the chassis through a resistance, one that is large enough to prevent any significant ground currents. In this way the equipment will not put any current though the ground and will be immune to ground loops.

Its simple- not rocket science, but you would be amazed at how many designers have not sorted this out. As a result there is a lot of snake oil out there dealing with the aftermath of poor grounding, and its not limited to high end audio.

^^ thanks for that, I did not find that in my search. Someone asked about balanced power on the OTL Asylum over on audioasylum.com, to which I responded:

One thing about balanced power- equipment is not designed for it. Here is an example:

If you are to meet UL or EU directives (CE mark), the fuse has to be able to blow to protect the user. The tricky area is what if the power switch, which is mounted to the chassis, gets shorted to the chassis and allows it to become 'hot'? The fuse will blow, because it is in series with the chassis. Now the same thing is true of balanced power.

But what if something happens such that the other side of the line shorts to the chassis? What then? There is no fuse for that. As best I can make out, in this situation there will be 60VRMS on the chassis- IOW it will be 'live', as in a balanced situation there is no 'hot' and 'cold'; both side are 'hot'.

As long as everything is working, balanced power offers lower noise if you have bugs in your equipment's grounding scheme. This is because if there is a grounding bug, there will be current in the ground connection. This can cause ground loops and in a really bad situation even damage something. Balanced power offers a solution for this. But ideally, there will be no appreciable current in the ground, because in a properly grounded audio system, the circuit ground floats at chassis potential, but they are not the same circuit- IOW its bad design practice to use the chassis for a ground!

A lot of audio manufacturers have not sorted this out, and it does not matter what field (pro audio, broadcast, high end audio) they are operating in. For this reason you will see some pretty respected names extolling the virtues of balanced power.

The part about there not being a second fuse is pretty important. In nearly all equipment made, there is an assumption that the 'neutral' side of the line as at ground. So if it is shorted to the chassis not much can happen- thus no fuse for that side of the line.

Balanced or more correctly, symmetrical power, is not anticipated by any equipment manufacturer or designer I know of. What this means is that if the chassis is shorted to the other side of the line from the fuse, 60 volts RMS (84 volts peak) will be exposed to the operator. If this occurs in the wrong environment and conditions, it could mean instant death.

Now you could have a fuse in the power circuit and that would be a good idea because if it is not there, the transformer supplying the balanced power will be damaged if there is such a short. But you would want to have separate fused outlets for each unit in use so that anything running on the balanced power would have protection for the user.

I've looked at several balanced power products and not been able to see any such fuses (which would have to be selected by the user) which suggests to me that they could be dangerous to use.

Actually, if a GFCI is installed, it does not need the ground circuit to operate correctly. So what is needed is exactly as the NEC requires: each outlet must be of the GFCI type.

If the installation does not have GFCI outlets for every component used, then there is a danger. But otherwise its OK as far as the user is concerned.

If there is a short in the equipment as I had proposed in my prior post, the GFCI outlet will still trip. So my safety concerns were the result of over-thinking this...