Dispelling ground myths

microstrip

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Maybe? I'm keeping an open mind on that. Maybe it's just that RogerD has addressed the low hanging fruit i.e. <500KHz - does this cover the frequencies of leakage currents from SMPSes & LPSes? Maybe this is the main culprit? It seems that with the increase in the use of SMPSes (including computer audio) this has become more of an issue?

Any current digital circuit has pulses with a typical rise time of less than 10ns - the usual rule of thumb immediately tells that the noise bandwidth will be larger than 35 MHz! People should think about it when they claim that their DACs have galvanic isolation. And yes, most of the references in literature think mostly about the 50/60Hz.
 

jkeny

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Any current digital circuit has pulses with a typical rise time of less than 10ns - the usual rule of thumb immediately tells that the noise bandwidth will be larger than 35 MHz! People should think about it when they claim that their DACs have galvanic isolation. And yes, most of the references in literature think mostly about the 50/60Hz.

Yes but again RogerD's success with ground strapping is not 50/60Hz hum - so I'm interested in what frequencies it is addressing - do you believe this is re-routing noise > 500KHz?
 

jkeny

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Roger probably owns a multimeter to check for voltages.

What will this tell us - the difference potential between chassis? Do you really think this is at the root of what Roger is achieving with PEC technique - sure some potential diff is needed for current to flow but is this the most important aspect?

As I said, it would be good to see a measurement of what current frequencies the chassis ground connections are transferring?
Then it would be good to see what is measurable on the analogue out of a DAC & if nothing found admit that the chosen measurements are not revealing what is audible
 
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Speedskater

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You gotta keep up or at least read your own posts :) - from your references - PEC :: Paralleled Earth Conductors (although I think he is using a star ground configuration?)
This is what RogerD is using and what Audio Precision recommend for optimal measurements - so not really that situation specific, don't you think?
Duh! Well I did say they were for reference.
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Paralleled Earth Conductors
That's something Jim Brown has written about, but darn if I can find it.
It's not an AC power concept.
It's about running heavy conductors in parallel with the interconnects from chassis to chassis.
And he is talking about heavy conductors, maybe equal to three 10AWG wires. Although flat braids are better.
Now for a simple system or a long run to the power amps it's fine, but a big system with lots of interconnects it will be a mess.

Better would be a large copper bus bar/terminal strip centrally located, with a heavy conductor to each chassis.
 

jkeny

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Duh! Well I did say they were for reference.
==================
Paralleled Earth Conductors
That's something Jim Brown has written about, but darn if I can find it.
It's not an AC power concept.
It's about running heavy conductors in parallel with the interconnects from chassis to chassis.
And he is talking about heavy conductors, maybe equal to three 10AWG wires. Although flat braids are better.
Now for a simple system or a long run to the power amps it's fine, but a big system with lots of interconnects it will be a mess.

Better would be a large copper bus bar/terminal strip centrally located, with a heavy conductor to each chassis.
References are for eh.... reference :)

OK, that's what you mean by situation specific - it won't look good on some systems, not that it won't work on some systems?
 

Speedskater

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What will this tell us - the difference potential between chassis? Do you really think this is at the root of what Roger is achieving with PEC technique - sure some potential diff is needed for current to flow but is this the most important aspect? .............
Yep it is. Common Impedance Coupling noise is when two chassis are at different leakage current potentials and use the interconnect shields to equalize. So short Safety Ground wires or chassis-to-chassis PEC wires wire reduce the leakage potentials.

More likely measurements will reveal problems the are not easily audible.
 

Speedskater

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References are for eh.... reference :)
OK, that's what you mean by situation specific - it won't look good on some systems, not that it won't work on some systems?
It will work, but it will be hard to implement.
============
Either way it wont look good.
Slide121.jpg
 

RogerD

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Duh! Well I did say they were for reference.
==================
Paralleled Earth Conductors
That's something Jim Brown has written about, but darn if I can find it.
It's not an AC power concept.
It's about running heavy conductors in parallel with the interconnects from chassis to chassis.
And he is talking about heavy conductors, maybe equal to three 10AWG wires. Although flat braids are better.
Now for a simple system or a long run to the power amps it's fine, but a big system with lots of interconnects it will be a mess.

Better would be a large copper bus bar/terminal strip centrally located, with a heavy conductor to each chassis.
Kevin here is Brown's article...

http://audiosystemsgroup.com/GroundingAndAudio.pdf
 

jkeny

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Yep it is. Common Impedance Coupling noise is when two chassis are at different leakage current potentials and use the interconnect shields to equalize. So short Safety Ground wires or chassis-to-chassis PEC wires wire reduce the leakage potentials.
Yes & I was interested in what is the frequency spectrum of the current flowing in the PEC - it would give us a clue to it's origin.

More likely measurements will reveal problems the are not easily audible.
RogerD's PECs are audible, I believe. So if measurements suggest that they SHOULD be below audibility then we either need to review audibility thresholds or we need to find measurements which correlate with this audibility, no?

What about the issue of doing measurements without this PEC bonding between interconnected devices being measured & the measuring device itself? Any thoughts on this?
 
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Speedskater

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..................
RogerD's PECs are audible, I believe. So if measurements suggest that they SHOULD be below audibility then we either need to review audibility thresholds or we need to find measurements which correlate with this audibility.
But no measurements have be done.
The first step in this type of measurement is the listening test.

The 'audibility thresholds' are well established.
The 'measurements which correlate with this audibility' have been around for a long time.
 

jkeny

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But no measurements have be done.
Let me put it another way then. If this statement is made purporting to measure noise differences introduced by a device into a configuration of interconnected devices : "validation here is pretty easy since we are talking about noise and noise can be measured with ease"

Do you think this statement has any validity when the measurement configuration makes no attempt at reducing common mode noise in the manner recommended by:
Keith Armstrong
Jim Brown
Ralph Morrison
Neil Muncy (RIP)
Bill Whitlock

And even Audio Precision?
 
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Folsom

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What will this tell us - the difference potential between chassis? Do you really think this is at the root of what Roger is achieving with PEC technique - sure some potential diff is needed for current to flow but is this the most important aspect?

As I said, it would be good to see a measurement of what current frequencies the chassis ground connections are transferring?
Then it would be good to see what is measurable on the analogue out of a DAC & if nothing found admit that the chosen measurements are not revealing what is audible

You can see voltages across ground, to see if there is more or less between things with and without the huge wire.
 

jkeny

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You can see voltages across ground, to see if there is more or less between things with and without the huge wire.

Are we talking about DC or AC voltage & what level? Do you think a multimeter will be able to measure this?
 

Folsom

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Are we talking about DC or AC voltage & what level? Do you think a multimeter will be able to measure this?

I would try both. I don't know what you'll find, that's kind of the point :p Probe around some see if you find anything.

Obviously it won't do much good if the meter can't go below 1v. You need mv. I've certainly got different measurements while making changes that would be somewhat similar. They don't tell you much about F~, obviously.
 

jkeny

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I would try both. I don't know what you'll find, that's kind of the point :p Probe around some see if you find anything.

Obviously it won't do much good if the meter can't go below 1v. You need mv. I've certainly got different measurements while making changes that would be somewhat similar. They don't tell you much about F~, obviously.
They also will likely tell you nothing about AC voltage as multimeters are very limited in the frequency range for which they can give an accurate ac measurement
 
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DaveC

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Are you saying there is more to be done than reduce impedance between component's grounds to lower noise? :)
 

jkeny

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Are you saying there is more to be done than reduce impedance between component's grounds to lower noise? :)

Sure there is.

But understanding what is actually going on in using this PEC techniques is also a good starting point - what is the characteristic of the noise being reduced - is it static noise at a particular frequency or is it fluctuating - where does it originate from & how is it causing audible differences of the sort RogerD & others have reported (the didn't just report perceived noise was reduced). What level is this noise? How does it show on DAC analogue outs before/after PEC bonding?

You see there are a lot of unanswered questions even with this simple PEC technique
 

DaveC

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Sure there is.

But understanding what is actually going on in using this PEC techniques is also a good starting point - what is the characteristic of the noise being reduced - is it static noise at a particular frequency or is it fluctuating - where does it originate from & how is it causing audible differences of the sort RogerD & others have reported (the didn't just report perceived noise was reduced). What level is this noise? How does it show on DAC analogue outs before/after PEC bonding?

You see there are a lot of unanswered questions even with this simple PEC technique

I'd expect broadband AC noise from 60 Hz on up. Possible sources are induced ground loops, leakage currents, local emf...

It seems obvious that certain substances can actually serve as a "sink" for noise. Silicon carbide, quartz, tourmaline and carbon, probably many more. Hearing what a Furutech GTX receptacle sounds like in regular vs NCF versions is astounding...
 

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