Proper Grounding a system

[mmerrill99]

4 slides from Jim Brown (audiosystems) http://www.audiosystemsgroup.com/InfoComm-Grounding2012.pdf 

Quote

Technical Grounding

• The primary purpose of technical grounding is to minimize the flow of power-related noise currents on the shields of signal wiring, while also providing the equipment grounding required for safety
• Technical grounding should also provide a suitable reference for cable and equipment shields at radio frequencies."

 

Quote

 

"Two More Important Definitions: Common Mode and Differential Mode

•  A differential mode voltage is one that exists between the two wires running together in a cable –At any instant, currents in the two wires are equal and opposite
• Differential mode is what we use to carry a signal (or control voltage) on a cable"

 

Quote

Common Mode and Differential Mode 

• A common mode voltage or current is one that exists along a cable (that is, end to end), and there is no voltage difference between conductors
• Virtually all common mode voltages in our systems are some form of noise

                    –Power-related voltages between equipment grounded at different points

                    –Radio signals picked up by our cables acting as receiving antennas

 

Quote

Noise Coupling Mechanisms

• IR drop on shields of unbalanced signal wiring
• Pin 1 problems –Improper shield termination within equipment
• Inadequate low-pass filtering of inputs
• Cable imbalance lets common-mode noise inside

                –Inductive imbalance between shield and signal conductors

               – Shield-current-induced noise (SCIN)

               –Capacitance imbalance of cable • Inadequate shielding of internal wiring

 

[mmerrill99]

If you read Jim Brown's articles & slides, the problem seems to be "Noise between grounds makes leakage current flow on the cable shield "

 

One solution offered is to use beefy copper shield:

Cable Type                                    Shield/100 ft         Noise dB

Generic RG6 Quad Shield             16 ohms               +23.5 dB

Belden 8241F (Copper braid)        2.6 ohms               + 7.5 dB

Belden 8281 (double copper)        1.1 ohms                     0 dB  

[mmerrill99]

The fact of the matter is that a lot of audio systems suffer from"Noise between grounds makes leakage current flow on the cable shield"

 

If you use differential cabling &/or class II throughout your system you will probably not be exposed to this but how many people here have these configurations? 

 

Yes submarines & Aircraft are tightly engineered & medical systems are also tightly controlled as to the amount of allowed leakage current. 

 

The removal of this noise is audibly perceivable as is evidenced by many here.

[mmerrill99]

1 hour ago, marce said:

If you are adding a ground box or similar I would strongly suggest that any difference in sound is due to noise being added, by the addition of an antenna. Of course I would expect a product like this to show some standard EMC noise graphs to show they are actually reducing noise by what must be a significant and measurable amount.

I don't know if or how such grounding boxes work but the reports seem to suggest they do & seem to support the type of audible improvements that reducing such noise usually entails?

Others have achieved the same effects with low impedance grounding wire between chassis which is very much cheaper but aesthetically less pleasing & indeed another approach is to use beefy shielded cables - I'm sure there are other solutions?

 

What is your reasoning for suggesting that the noise reduction is significant?  

[mmerrill99]

8 minutes ago, Speedskater said:

Real reports don't show that at all!  Only casual listening auditions do.

There are no repeatable, reproducible, proctored listening tests.

 

What equipment do you have & can you show me the repeatable, reproducible, proctored listening tests for each of your audio devices, please?

[mmerrill99]

1 hour ago, Speedskater said:

I'm not the one making extraordinary claims.

And if I did some blind tests and found no differences, would you accept the tests as evidence that the grounding boxes don't work?

They are not claims - they are listening impressions

Why not grant others the same lee-way you grant yourself - that is to use & enjoy their audio devices & rport what they hear without being challenged to provide what you yourself haven't provided "repeatable, reproducible, proctored listening tests"?

 

There is another site on which you participate called audio science review where your views are very welcome - do you not find it satisfying enough to post there?