AC Filtering, Grounding Boxes, Linear PSU and Balanced Power.

[Speedskater]

If you are going to make several filters, the best place for a filter is at the component's chassis. With the filter touching the chassis if possible.

 

Dual receptacle's can be split in to two circuits.

 

Lay-out everything in a way to reduce the length of the Safety Ground/Protective Earth wires from component to component to a reasonable minimum.

 

The real experts on this topic are:

Keith Armstrong

Ralph Morrison

Henry W. Ott

But none are easy reading, nor convenient.

 

More accessible are papers by (but they still require some studying) :

Jim Brown

Bill Whitlock

Middle Atlantic

[Speedskater]

Many segments of the 850 page Henry W. Ott book "Electromagnetic Compatibility Engineering" are viewable online. If you just skip the math formulas it's vary readable.

EMC Books

 

As for the old Ralph Morrison books, I purchased some of the used, online for $10 to $15 each.

But Mr. Morrison writes in field theory rather than circuit theory. It's hard to transfer field theory to real life.

[Speedskater]

Here is on almost readable Keith Armstrong article. The interesting part is well down the page.

 

"Fundamentals of EMC Design: Our Products Are Trying To Help Us"

 

Author : Keith Armstrong, Cherry Clough Consultants

04/03/2012

 

Fundamentals of EMC Design: Our Products Are Trying To Help Us | Interference Technology

 

****************************************************

This is a Keith Armstrong youtube. But I don't remember watching all of it.

 

[h=1]Understanding EMC Basics Part 3:

Grounding, Immunity, Overviews of Emissions and Immunity,[/h]

 

Fundamentals of EMC Design: Our Products Are Trying To Help Us - See more at: Fundamentals of EMC Design: Our Products Are Trying To Help Us | Interference Technology

Fundamentals of EMC Design: Our Products Are Trying To Help Us - See more at: Fundamentals of EMC Design: Our Products Are Trying To Help Us | Interference Technology

[Speedskater]

'YashN' you do not want an inductor nor a switch in the Safety Ground/Protective Earth conductor. Some experts write that capacitors from the Hot & Neutral to the SG/PE are not the best of ideas, as the caps just dump noise on to the SG/PE.

 

To get real information on power line filters, you might look to the Henry W. Ott 850 page book "Electromagnetic Compatibility Engineering".

EMC Books

 

An on-line search just might come up with a lot of Chapter 13.

 

13. Conducted Emissions

 

13.1 Power Line Impedance

13.1.1 Line Impedance Stabilization Network

13.2 Switched-Mode Power Supplies

13.2.1 Common-Mode Emissions

13.2.2 Differential-Mode Emissions

13.2.3 DC-To-DC Converters

13.2.4 Rectifier Diode Noise

13.3 Power-Line Filters

13.3.1 Common-Mode Filtering

13.3.2 Differential-Mode Filtering

13.3.3 Leakage Inductance

13.3.4 Filter Mounting

13.3.5 Power Supplies With Integral Power-Line Filters

13.3.6 High-Frequency Noise

13.4 Primary-to-Secondary Common-Mode Coupling

13.5 Frequency Dithering

13.6 Power Supply Instability

13.7 Magnetic Field Emissions

13.8 Variable Speed Motor Drives

13.9 Harmonic Suppression

13.9.1 Inductive Input Filters

13.9.2 Active Power Factor Correction

13.9.3 AC Line Reactors

[Speedskater]

.....................................

So I believe the diversion to ground is deliberate, but that's also why I was asking earlier about how to properly implement the inter-component contamination isolation as currently, there doesn't seem to be anything to prevent the noise along the GND line from one component from going to the next one.

 

How would you do it?

I would try to reduce the resistance/impedance from one chassis to the next. Because the higher this impedance is, the more the noise currents will try to use your interconnects as a path back to their voltage sources. Bill Whitlock gets into this problem in some of his papers.

So from component to component, heavy short SG/PE conductors are best.

[Speedskater]

'YashN' what I was attempting to describe is a small effort to what may be called.

 

Ralph Morrison:

STGP :: Signal Transport Ground Plane

ZSRG :: Zero Signal Reference Grid

 

Henry W. Ott:

ZSRP :: Zero Signal Reference Plane

 

Keith Armstrong:

Conductive Structure

[Speedskater]

The Tripoint Troy is a very, very expensive and beautiful box! But I don't know just what it hopes to accomplish. In another forum, there have been long threads about the Tripoint and the somewhat similar Entrec. All I can guess is that they are huge boxes filled with a secret material and connected to audio components in a rather random fashion. It seems that the users think (incorrectly) that bad noise & interference currents go into the box and just disappear. A heavy copper terminal strip or bus bar would do a much better job of connecting the chassis's of all your audio components together.

 

 

In all fields of electricty and electronics there are still some people that believe the Mother Earth acts as a sump or sink for noise & interference currents. This incorrect idea is extended to these boxes with their secret materials.

 

 

While in fact noise and interference currents only interest is to get back to their voltage source. What is their voltage source? Why it's the Neutral of that big power company transformer down the street from your house.

[Speedskater]

Speedskater, the Tripoint Troy is meant for connecting each of your components' chassis to it. The device also connects to mains Earth.

Isn't that similar to what you proposed in Post 37? The only difference I see is that the Tripoint device asks for chassis to its box individually rather than all together.

These should be doing the same thing ideally, no?

If the box has very low resistance from connector to connector, than it could act the same way a heavy copper terminal strip does.

 

The difference is that the Entreq wasn't planned for chassis grounding at all, just signal clean-up. Moreover, the box doesn't connect to mains Earth. In this respect, it's more intriguing than the above.

Any thoughts on what secret method they use for this signal clean-up?

 

Now, these manufacturers are playing catch-up a little seeing the positive reports from users of both camps, including those benefiting from both boxes.

Better, I don't know, but I think that would be a similar thing to what the Tripoint devices do, but again, not the Entreq.

I find it a bit challenging to keep track of just which box and which special cable does what. Not much in the way of spec sheets or instructions for these products.

 

I think it's more correct to say that they will preferentially try to go back there with the lowest impedance route. It is also important to consider energy conservation and energy conversion.

Could you expand on this thought, I'm not sure of where you are going.

 

Thus, would a silver terminal strip and bus bar, with silver ground leads do better than an all-copper solution?

At the low frequencies involved, not enough difference between silver and copper to even think about it.

But silver plating could cut down on corrosion.

[Speedskater]

Here again, what's if it's silver rather than copper?

No need for silver (or silver plating) at these low frequencies.

 

I can only speculate as have no idea, nor have I tried one, but if we're talking of the Entreq, I think it could be inducing losses through energy conversion within the box. Whether this is technically feasible, I don't even know, and I'm not even sure I can experiment with something similar at home. Well, I could always try.

If he puts a resistive load in the box, then more of the noise currents will find other paths, like your interconnect cables. What we want to to is get all of the chassis's to the same reference plane voltage.

 

Not considering impedance is a mistake.

..........................................................

Now, for Entreq, the box specifically is said by the manufacturer to deal with 'stray currents which are low voltage but high-frequencies', not low frequency.

Yes, we have to consider the impedance (not just the resistance) of the conductors in this system.

No matter how big we make round wires, they don't do well with increasing frequency.

What does much better are wide flat straps and wide flat braids.

[Speedskater]

Some of those currents also go back through mother Earth ! Chatswood Telephone Exchange in Sydney is right alongside Chatswood Railway station. Until they improved the Old Exchange earthing, occasional problems happened to trip the large 52V 2,000A Rectifiers. The same happened occasionally when Westfield shopping centre, which is 100s of metres away down the road, started up it's escalators , main lighting etc. just before opening for the day . No, the incoming A.C. voltage didn't drop much when that happened.

Yes current is happy to use Earth as a path back to it's source. Earth has a point to point resistance of nearly zero Ohms even if those points are separated by many miles. The problem is making good connections to Earth, those connections may cost tens of thousands of dollars each. Even in the AM broadcast radio band, much of the signal travels through the Earth. But about the only current that sees Earth as a destination (rather than a path) is lightning.

[Speedskater]

No need for silver (or silver plating) at these low frequencies.

I am not sure here if Tripoint deals only with low frequencies or if it also deals with higher ones - cannot recall seeing a reference in a post somewhere about the type of frequency.

In this case high frequencies would be about 100MHz. Some FM transmitters have parts of their circuits silver plated.

But in this case we are dealing with low frequency noise & interference currents. Almost all of which are well under 100kHz.

 

I can only speculate as have no idea, nor have I tried one, but if we're talking of the Entreq, I think it could be inducing losses through energy conversion within the box. Whether this is technically feasible,

That's supposing the use of a resistor, but what if it's something else?

If the box converts it to heat, then in effect that's a resistor. But maybe the box converts it mechanical motion, or maybe?

[Speedskater]

The return current takes the lowest impedance path. At low frequencies (good old 60/50Hz) the dominating factor is usually the DC resistance of metals, so silver would be better than copper, IF you had the cross sectional area of both metals. But making the copper wire a little thicker does the same thing for a much lower cost.

As the frequency increases the inductance of the path starts becoming more important than the DC resistance, this transition happens at fairly low frequencies, it starts at about 1KHz and by 15KHz inductance is significantly more important than DC resistance. From 15KHz up to several MHz the cross section of the metal and dielectric are important in the inductance. Getting above that skin effect comes into play and the geometry of the outer surface and dielectric become of prime importance.

So things like buss bars and thick wires may be important for noise issues with low frequency components, they are not that important for higher frequency components.

John S.

Some nits to pick:

 

The return current takes the lowest impedance path.

The return takes all available paths! In inverse proportion to their impedance. And therein lays the ground-loop problem.

So let's make it:

Most of the return current takes the lowest impedance path.

 

so silver would be better than copper

But it would be a poor engineering decision to do so.

 

the geometry of the outer surface and dielectric become of prime importance.

Yes, flat, wide, thin copper strips (or maybe braid) are good choices.

 

So things like buss bars and thick wires may be important for noise issues with low frequency components, they are not that important for higher frequency components.

True about the thick wires, but bus bars are an ideal choice at higher frequencies.

 

Note that Buss is a fuse company.

[Speedskater]

Poor engineering? Why?

Why:

a] High cost

b] Lack of availability.

c] No significant engineering gains.

Just use a one size larger copper item.

[Speedskater]

Are these the ones involved in the chassis?

 

In audio systems, the noise, leakage & interference currents that we are most concerned with are all power line related. The are generated by power supplies or small circuits that we can think of as power supplies.

 

Almost anything that you buy today and plug into an AC outlet has some sort of power supply (including CFL & LED lights). Any of these power supplies can generate noise. But most of these noise currents are under 100kHz. The noise voltages over 100kHz can be filtered with small capacitors.

[Speedskater]

Having spent decades working in industrial ®&D engineering departments, I can safely say that 'cost' is first and 'availability' is high on the engineering criteria list. The new product engineering review meeting would not go well if solid silver components were involved.

While silver plating does fill some special situation needs, switch contacts are the only place for solid silver that I can think of.

[Speedskater]

This is business, but not pure engineering...

Cost/accounting being a factor is what made the ground plane and other good things disappear.

Now I strongly disagree with that idea.

Cost is one of the most important factors in good engineering!

[Speedskater]

Ralph Morrison writes that in some cases, it's better to use galvanized steel rather that copper for ground planes, STGP's or ZSRG's.

 

Why?

a] Lower cost.

b] Easily available.

c] It's robust.

d] Easy to work with and easy to make good joints.

[Speedskater]

..............

makes me ask the question:

are there any disadvantages that arise if we start using very large copper items?

We can think of most items involved as two dimensional, the third dimension is mostly for mechanical considerations. Things like handling, joining and screw threading.

 

Ralph Morrison writes about entire computer room floors. But at that large size, it's almost always a grid or mesh. Then he writes about how to make a multi-floor grid.

 

But the disadvantages are:

a] cost

b] size & weight

c] diminishing returns

[Speedskater]

Not for pure engineering. Let's keep cost out of the equation for now, thanks.

Sorry but in the real world good engineering is all about cost!

[Speedskater]

I think we got the Tripoint devices function covered and understood, but the Entreq is still slightly mysterious. They purportedly use a mineral + silver mixture internally.

If any of these boxes don't contain a block of copper or aluminum or steel or similar, then the only thing that the box is doing is draining your money. And all the connection points/terminals need to have a near zero Ohm resistance from one to another.

 

The story I see behind these boxes is that bad electricity flows into the box and just disappears!

Nothing like that happens in the real world whether it's to a box or to Earth.

 

********************

Back to an earlier question:

A silver item will function exactly the same as a one size larger copper item. Where one size larger is about 107% larger.

[Speedskater]

Here's another thought:

..........................................................

Now, if indeed we can chassis ground and clean up the signal thanks to our ground lead across all the components, what is the addition of an Entreq box with leads connecting to a free RCA shield actually doing?

Because different manufactures connect RCA jacks to the chassis in many different ways, we can't be sure just what is happening!

(an RCA jack is a chassis connector)

Some 20 years ago, Neil Muncy wrote a paper on the correct way to install any and all chassis connectors. That paper is referred to as the "Pin 1 Problem" paper. But in hi-fi equipment it common to see incorrect RCA jack connections (even see some incorrect XLR jack connections). So we would have to examine on a case-to-case basis to see what they did.

 

How does it manage to further clean up the signal? And if it really does that, what is it removing?

I'm not at all sure that it cleans up the signal. Because in some incorrectly wired RCA jacks, this Entreq lead can act as a great interference antenna. So with this small amount of added background noise the audiophile will hear a real difference. This small background noise is sometimes perceived as added definition or sparkle. And because he just added something, it will be deemed good.

 

Notice that no one would ever put a battery powered O-scope or meter on the speaker terminals and examine the changes.

[Speedskater]

The existence of plates of some sort in both is already established.

Has the connector to connector resistance ever been measured?

 

Not mine, I haven't bought any of those.

Good, let it be someone else's money.

 

Could impedance matching be the important thing happening here?

Your AC power line's source impedance is just a fraction of an Ohm, so the closer to zero Ohms this entire grounding system is, the better.

[Speedskater]

Here are several pages of photos on how one Ham radio operator did his station.

 

W8JI Contest Station

 

***********************************

Note the two 200 foot antenna towers at his place. So lightning was a major concern. Also static buildup before the storm. At the broadcast transmitter, we would see huge arcs across the tower insulators hours before the storm.

[Speedskater]

Wait a minute, the "Ground Zero" has an engineering explanation for what it does? He will never be able to sell that to audiophiles! He needs to add some big scientific words or suggest some secret ideas.

 

Three small points:

 

a]and have different distances to travel back to earth ground

It's not to Earth Ground it's to the power company Neutral at the main breaker box.

 

b] I have no idea what the 3 position switches are all about. Why would you add resistance?

 

c] Having a test measurement protocol is good, but an SPL meter is the wrong choice. It lacks resolution and can't discriminate between room noise and audio system noise.

[Speedskater]

The Core Audio Technology papers and videos are rather good, but he needs a good technical editor person to come in and clean-up many points.

 

Much of his material comes from the mostly Power Point, 215 page paper:

 

An Overview of Audio System Grounding and Interfacing

by Bill Whitlock, President

Jensen Transformers, Inc.

Life Fellow, Audio Engineering Society

Life Senior Member, Institute of Electrical & Electronic Engineers

 

An audio system is rarely a plug-and-play affair. Noises often plague the

system even if everything is done according to conventional wisdom. Did the

electrician screw up? Is the AC power dirty? Is the equipment to blame? Are

the cables poorly shielded? This presentation will discuss the "secret" forces

that drive ground loops, how they contaminate our signals, and new tools to

make troubleshooting faster and easier. Among the topics will be equipment

design errors that can make life miserable for installers and users, how

manufacturers manipulate "specs" to deceive, how new test standards and

instruments can make manufacturers honest, why expensive cables probably

won't help, and things your electrician can do to reduce or eliminate problems.

 

***********************************************************

His web-page has links to this and several other good papers.

But it would be best to read the above Bill Whitlock paper before getting into the Core info.