Grounding and Noise Floor

Bill Hart · Nov 20, 2012

I started this thread because of a comment of T-Bone's in another thread (don't know if you hyphenate, but anybody that has the same name as the legendary guitarist is OK in my book, hell, even if it's a reference to steak, not music, I'm still good with it).
Here's one question, to get the ball rolling:
I use high efficiency speakers over which you can hear all sorts of nasties that might get lost in the murk on a less efficient speaker system. I went through the tortures of the damned to get my AC sorted without using line conditioning- basically just a subpanel and dedicated lines, additional ground, and checking polarity, lower noise leg of 240 v line, etc. System is very quiet but there are still grounding differences between the different dedicated lines and different components, depending on how they are grounded internally, can create issues- usually manifest by a very low level hum. I eventually get that sorted too, or find something that is causing it elsewhere in the house (or in one recent instance, work on a transformer one down from ours on the pole).
Anyway, that's the precis. First question:
how can those external star grounding things, like the Granite Audio thing and the much more expensive one, the name of which escapes me, really do much? I get the idea of star grounding stuff, but you still have the 3rd pin on the AC power cord plugged into the receptacle; it's not like you are really lifting ground on the AC and replacing it with the external star grounding scheme.
I get how the Brits advocated going into one receptacle to reduce grounding differences and then using a distribution block (that itself may be star grounded). Maybe my system would play off one 20 amp outlet, i never tried it.
And, relatedly, daisy chaining grounds among dedicated lines?
(Don't worry, I'm not about to start fooling around with the stuff in the wall. But, these questions have been at the back of my mind for a while, and since T-Bone volunteered that he knew a bit about this area, I figured I'd have a go at it).
TIA.
Bill Hart

mep · Nov 20, 2012

I once knew a guy name Ribeye that played a mean hambone. One thing that I have done is buy a chunk of copper bus bar, drill and tap holes in it for screws, and run ground wires from all components to the copper block with one wire from the copper block going to the wallplate screw that my preamp is plugged into. I got this idea from Ampex Roger and I have been happy with the results.

Bill Hart · Nov 20, 2012

Mep, i may be wrong, but I think what you described is essentially external star grounding of the various components. The issue gets complicated because of the grounding schemes within each component, which are in turn connected to each other through the various signal cables. Then, add to that, the 'ground' pin on the power cord connecting to the receptacle. It is these layers that I'm trying to parse through. I do have the Granite Audio device that I bought years ago, and it helped, to a degree, with certain set-ups I had. But, as I indicated in my question, I'm not sure how that can work effectively if you are not cheating the ground at the wall, which is considered risky. (FWIW, you can ground the Granite Audio device itself to the wall but that still doesn't answer the question).
And as a postscript, I used to really liked aged Porterhouse a la Peter Luger, but have become a bone-in aged rib-eye kinda guy. More flavor, a little less dense texture. I can't eat that stuff like I used to, though.
Thanks for weighing in (no pun intended).

TBone · Nov 21, 2012

I generally don't like to discuss these type of modifications with fellow audiophiles because it really could result in damage, and not just the equipment. Hell, I've made some doozy mistakes in the past modding certain electrical components, so I'm much too aware of the potential dangers. One must also be aware that these mods may void warranties and could be law / insurance dependent. It's also very much a system dependent activity, in which one particular system or an individual component may require a completely different setup. Dirty mains is also location dependent. The bottom line, what worked within my particular system is unique to my system.

I'll provide an example:

Certain equipment, such as those that use pulse based power supplies (ex: Linn*) can pollute a system internally. Hence, within my system, each component is not only separated from the mains, but more importantly, from each other using dedicated power line conditioning. But that's easier said than done, power line conditioning requirements are often system/component dependent, unfortunately not a one size fits all fix.

Add to the fact that, in my area, grounds can introduce lots of noise to a system, so I have a "floated" requirement that others may not require. However, I soon realized that not everything in my system could be floated without causing "loops", hence a "star" grounding scheme was introduced for certain components that required ground. This was - very much - a trail & error affair, one that was totally dependent on my system. For that reason, although I consider "floating" one of the most critical requirements when trying to attain superior noise floor characteristics, it's difficult to communicate my setup potential effectiveness for another system half a world away.

Unfortunately, certain audio goals require per system due-diligence, and the results are not always easily applied to other systems.

tb1

(*) When Linn adopted pulse based power supplies, they acquired a level of transparency beyond prior models. However, I soon realized that unlike prior models, their PB-PS could pollute an entire system from within, often beyond recognition. I understood years ago that Linn must have been aware of this issue, even though few, including the audio press, understood this particular situation. Relatively recently, Linn came out with a "new" PB-PS. It's traditional Linn ... sell, deflect, fix, then supply an "upgrade" path ...

Speedskater · Nov 21, 2012

When things get tough, this is what Audio Precision does:

Robh3606 · Nov 21, 2012

I have used the star ground system in my HT and it works quite well. I also have a dedicated AC line for it and a seperate line for my stereo as well. It can get a bit complicated though depending on the internal grounding of the components. Rane has a really good grounding Technote that helps explain why ground loops can be such an issue in some set-ups.

http://www.rane.com/note110.html

Rob

mep · Nov 21, 2012

whart said:
Mep, i may be wrong, but I think what you described is essentially external star grounding of the various components. The issue gets complicated because of the grounding schemes within each component, which are in turn connected to each other through the various signal cables. Then, add to that, the 'ground' pin on the power cord connecting to the receptacle. It is these layers that I'm trying to parse through. I do have the Granite Audio device that I bought years ago, and it helped, to a degree, with certain set-ups I had. But, as I indicated in my question, I'm not sure how that can work effectively if you are not cheating the ground at the wall, which is considered risky. (FWIW, you can ground the Granite Audio device itself to the wall but that still doesn't answer the question).
And as a postscript, I used to really liked aged Porterhouse a la Peter Luger, but have become a bone-in aged rib-eye kinda guy. More flavor, a little less dense texture. I can't eat that stuff like I used to, though.
Thanks for weighing in (no pun intended).

Bill-One accepted way to ground your system is to lift all grounds execpt the preamp. Each component in the chain is grounded to the next component via the ground connections on the ICs. Running a star ground from all of the components to a chunk of copper ensures they all have the same ground potential. If a component still is causing any hum issues, you may have to take the cheater plug off and try it straight in.

valkyrie · Nov 21, 2012

Couple of basic thoughts - from a guy who has run a lot of Romex in his career.

The "third wire" or the "earth ground" goes back to your breaker panel where it is tied to the common (return) on the AC line (three wires to your house - a common, a +110, and another -110 - the two "hot" lines are simply 180 degrees out of phase with each other - this means that when one signal is at +90 degrees (or at 110 vac) in its sine wave the other hot is at -90 degrees (or at -110vac) thus providing a difference of 220 volts for your dryer, your AC unit and your stove or whatever you have that requires higher voltage).

The "Three prong plug" and supporting wiring system accomplishes two objectives. The larger plug "fork" ensures that the "hot" signal is NOT on the case or outside of the appliance being used (almost all AC appliances will work fine no matter what side of the device is placed at "hot" but if the outside of the device is "hot" and you touch a grounded surface you are now a conductor with no baton). The other thing that is accomplished is that the extra ground wire (the third hole) gives a better grounding system for the entire house. This extra ground wire is NOT AC return (except at the breaker panel) and thus should be isolated from all the noise - hopefully.

If you are having "hum" issues with your stereo gear I would first suggest that you determine if the sound is actually a 60 Hz tone - many test CDs have a 60 Hz tone on them so you can learn the "sound of sixty". If the hum sound is NOT 60 Hz then it is uncorrelated "noise" and probably due to something external to your AC power system. This could be your neighbor running his table saw - or your wife running the hair dryer. Or your infernally noisy computer polluting the AC wiring.

If it is 60 Hz then begin as the others have suggested - start with a minimal system and determine if the hum is still present. If it is then inspect your devices and make sure that all of them have the three wire wall plug. If one does not then reverse the plug orientation as it enters the wall. Does that diminish or remove the hum? If it does then what you have discovered is that one device probably had AC hot on the wrong side of the circuit.

If you go to a minimal state with your system and you still have noise present, and that noise is 60 hz AND all of your components have three wire AC plugs. Then you more than likely have a problem with your amplifier or preamplifier. At this point we have to drag out the o-scope and start probing on the bench.

Star grounding and all of the other techniques mentioned do not have much of a chance of making anything better in regards 60 Hz hum - remember that in a modern home with three wire plugs and wall receptacles that you have a very robust grounding system ASSUMING that every device powered up has the proper three wire AC wiring going to a three-wire wall plug.

If you add even ONE device (component) that does not meet the qualifications of the preceding paragraph - then you have a problem waiting to happen. If you do have a component that has a two wire plug - regardless of who made it or how high it "pedigree" is - then you should convert that device to standard AC conventions as soon as possible. Actually this is quite easy.

best of luck

DonH50 · Nov 21, 2012

People think of electrical current flow like water that pours from a hose into the ground and disappears. It's really a loop, with ground being the return path. You do not want the return path to differ from the signal (delivery) path or things get out of synch. As Mark notes, ensuring every signal line has a matching ground is one way to help. Normally signal ground flows through the shield of your interconnect, but that shield is often coupled (directly, through a small R, or capacitively) to the chassis or earth (outlet) ground. An extra ground connection creates another, potentially harmful, loop. The idea behind star grounding is that every component has just one path to the common ground point, it is the same path as the signal return current path, and that one ground point then provides the final earth ground.

Note the ground wire in your outlet is considered a safety ground and should not normally carry any current anyway.

Edit: I was writing while valkyrie was posting, he was faster.

Our posts are in agreement.

microstrip · Nov 21, 2012

Just to remember that in Europe (230V 50Hz) the neutral is not tied to the ground in your panel. It is grounded only at the local power station. If you touch the neutral wire with the ground wire you will probably trip down your differential protection breaker. Also in many countries the three prone Shuko plugs are not polarized - they can be inserted in the reverse position, exchanging neutral and phase.

Also remember that star grounding is just the start. Some equipment has badly designed signal grounding that mixes with power ground lines and diagnosis of an hum problem can be a nightmare, even for experienced people.

The reference book on this subject had a new edition recently:
http://www.amazon.com/Grounding-Shielding-Circuits-Interference-Techniques/dp/0470097728/ref=dp_ob_title_bk/178-8031296-2270069#reader_0470097728
Perhaps I should replace my old first edition!

Bill Hart · Nov 21, 2012

mep said:
Bill-One accepted way to ground your system is to lift all grounds execpt the preamp. Each component in the chain is grounded to the next component via the ground connections on the ICs. Running a star ground from all of the components to a chunk of copper ensures they all have the same ground potential. If a component still is causing any hum issues, you may have to take the cheater plug off and try it straight in.

Yep, I'm all quiet these days, and use cheaters to help identify where i have an issue, just saying, it's bedeviling sometimes. And do you think that running with grounds (except, say for preamp) lifted is safe and relying only on the ICs?
And my question to Tbone also included whether you could rely solely on the external star ground system (which itself gets grounded to the wall through a dummy AC plug) and lift the AC power grounds to the components?

mep · Nov 21, 2012

I think you are still grounded safely if you run a ground wire from each component to a copper bus bar and the bus bar is grounded.

Bill Hart · Nov 21, 2012

Robh3606 said:
I have used the star ground system in my HT and it works quite well. I also have a dedicated AC line for it and a seperate line for my stereo as well. It can get a bit complicated though depending on the internal grounding of the components. Rane has a really good grounding Technote that helps explain why ground loops can be such an issue in some set-ups.

http://www.rane.com/note110.html

Rob

Yep, I've read that more than once in the past, i probably have it bookmarked.

I'm not raising this b/c I currently (no pun) have a problem but it's always an issue with this horn system it seems. And it tied to the whole noise floor discussion in that other thread. Which led me to bring up some of those questions, like can external star grounding be a substitute for the 3d pin on the AC cord. I need to read the rest of the posts here carefully....

Bill Hart · Nov 21, 2012

mep said:
I think you are still grounded safely if you run a ground wire from each component to a copper bus bar and the bus bar is grounded.

That was the question, and bingo, answer. You get a steak of your choosing.

Bill Hart · Nov 21, 2012

microstrip said:
Just to remember that in Europe (230V 50Hz) the neutral is not tied to the ground in your panel. It is grounded only at the local power station. If you touch the neutral wire with the ground wire you will probably trip down your differential protection breaker. Also in many countries the three prone Shuko plugs are not polarized - they can be inserted in the reverse position, exchanging neutral and phase.

Also remember that star grounding is just the start. Some equipment has badly designed signal grounding that mixes with power ground lines and diagnosis of an hum problem can be a nightmare, even for experienced people.

The reference book on this subject had a new edition recently:
http://www.amazon.com/Grounding-Shielding-Circuits-Interference-Techniques/dp/0470097728/ref=dp_ob_title_bk/178-8031296-2270069#reader_0470097728
Perhaps I should replace my old first edition!

I doubt the movie adaptation of that is coming out soon....
But you are right Micro, the way various components are grounded can be problematic. Take my Lamm ML2. For example.
Ever use it?

Bill Hart · Nov 21, 2012

Speedskater said:
When things get tough, this is what Audio Precision does:

View attachment 6745

Skater what does that represent? It's not really separate ground lines to a common point.

Speedskater · Nov 21, 2012

The above Ralph Morrison book, makes the Henry W. Ott book look like light reading.

http://www.hottconsultants.com/book.html

mep · Nov 21, 2012

whart said:
That was the question, and bingo, answer. You get a steak of your choosing.

NY Strip, 1 1/2" thick cooked medium rare and I'm a happy camper.

Bill Hart · Nov 21, 2012

valkyrie said:
Couple of basic thoughts - from a guy who has run a lot of Romex in his career.

The "third wire" or the "earth ground" goes back to your breaker panel where it is tied to the common (return) on the AC line (three wires to your house - a common, a +110, and another -110 - the two "hot" lines are simply 180 degrees out of phase with each other - this means that when one signal is at +90 degrees (or at 110 vac) in its sine wave the other hot is at -90 degrees (or at -110vac) thus providing a difference of 220 volts for your dryer, your AC unit and your stove or whatever you have that requires higher voltage).

The "Three prong plug" and supporting wiring system accomplishes two objectives. The larger plug "fork" ensures that the "hot" signal is NOT on the case or outside of the appliance being used (almost all AC appliances will work fine no matter what side of the device is placed at "hot" but if the outside of the device is "hot" and you touch a grounded surface you are now a conductor with no baton). The other thing that is accomplished is that the extra ground wire (the third hole) gives a better grounding system for the entire house. This extra ground wire is NOT AC return (except at the breaker panel) and thus should be isolated from all the noise - hopefully.

If you are having "hum" issues with your stereo gear I would first suggest that you determine if the sound is actually a 60 Hz tone - many test CDs have a 60 Hz tone on them so you can learn the "sound of sixty". If the hum sound is NOT 60 Hz then it is uncorrelated "noise" and probably due to something external to your AC power system. This could be your neighbor running his table saw - or your wife running the hair dryer. Or your infernally noisy computer polluting the AC wiring.

If it is 60 Hz then begin as the others have suggested - start with a minimal system and determine if the hum is still present. If it is then inspect your devices and make sure that all of them have the three wire wall plug. If one does not then reverse the plug orientation as it enters the wall. Does that diminish or remove the hum? If it does then what you have discovered is that one device probably had AC hot on the wrong side of the circuit.

If you go to a minimal state with your system and you still have noise present, and that noise is 60 hz AND all of your components have three wire AC plugs. Then you more than likely have a problem with your amplifier or preamplifier. At this point we have to drag out the o-scope and start probing on the bench.

Star grounding and all of the other techniques mentioned do not have much of a chance of making anything better in regards 60 Hz hum - remember that in a modern home with three wire plugs and wall receptacles that you have a very robust grounding system ASSUMING that every device powered up has the proper three wire AC wiring going to a three-wire wall plug.

If you add even ONE device (component) that does not meet the qualifications of the preceding paragraph - then you have a problem waiting to happen. If you do have a component that has a two wire plug - regardless of who made it or how high it "pedigree" is - then you should convert that device to standard AC conventions as soon as possible. Actually this is quite easy.

best of luck

Val, let me digest your post before I respond. Thank you for weighing in.

Bill Hart · Nov 21, 2012

valkyrie said:
Couple of basic thoughts - from a guy who has run a lot of Romex in his career.

The "third wire" or the "earth ground" goes back to your breaker panel where it is tied to the common (return) on the AC line (three wires to your house - a common, a +110, and another -110 - the two "hot" lines are simply 180 degrees out of phase with each other - this means that when one signal is at +90 degrees (or at 110 vac) in its sine wave the other hot is at -90 degrees (or at -110vac) thus providing a difference of 220 volts for your dryer, your AC unit and your stove or whatever you have that requires higher voltage).

The "Three prong plug" and supporting wiring system accomplishes two objectives. The larger plug "fork" ensures that the "hot" signal is NOT on the case or outside of the appliance being used (almost all AC appliances will work fine no matter what side of the device is placed at "hot" but if the outside of the device is "hot" and you touch a grounded surface you are now a conductor with no baton). The other thing that is accomplished is that the extra ground wire (the third hole) gives a better grounding system for the entire house. This extra ground wire is NOT AC return (except at the breaker panel) and thus should be isolated from all the noise - hopefully.

If you are having "hum" issues with your stereo gear I would first suggest that you determine if the sound is actually a 60 Hz tone - many test CDs have a 60 Hz tone on them so you can learn the "sound of sixty". If the hum sound is NOT 60 Hz then it is uncorrelated "noise" and probably due to something external to your AC power system. This could be your neighbor running his table saw - or your wife running the hair dryer. Or your infernally noisy computer polluting the AC wiring.

If it is 60 Hz then begin as the others have suggested - start with a minimal system and determine if the hum is still present. If it is then inspect your devices and make sure that all of them have the three wire wall plug. If one does not then reverse the plug orientation as it enters the wall. Does that diminish or remove the hum? If it does then what you have discovered is that one device probably had AC hot on the wrong side of the circuit.

If you go to a minimal state with your system and you still have noise present, and that noise is 60 hz AND all of your components have three wire AC plugs. Then you more than likely have a problem with your amplifier or preamplifier. At this point we have to drag out the o-scope and start probing on the bench.

Star grounding and all of the other techniques mentioned do not have much of a chance of making anything better in regards 60 Hz hum - remember that in a modern home with three wire plugs and wall receptacles that you have a very robust grounding system ASSUMING that every device powered up has the proper three wire AC wiring going to a three-wire wall plug.

If you add even ONE device (component) that does not meet the qualifications of the preceding paragraph - then you have a problem waiting to happen. If you do have a component that has a two wire plug - regardless of who made it or how high it "pedigree" is - then you should convert that device to standard AC conventions as soon as possible. Actually this is quite easy.

best of luck

All digested, at least as much as one of those snakes that swallows things whole and you see the big lump in the middle.
I think what I'm hearing when i have issues (right now the system is quiet) is a combination of things: sometimes, grounding issues because of particular components (I think the Lamm ML2 is always an issue, i don't know why, but i believe most folks that own this amp use cheaters or lift the ground wire internally); noise pollution from other stuff in the house- there are a couple known culprits, including a convection oven in the kitchen, some low voltage lighting in the kitchen, and a humdifier in one bedroom that, whenever it is plugged in, causes a hum in the system. Easy solution to that, don't use the oven, turn off the particular set of lights in the kitchen and unplug the humidifier.
I think the subpanel and wiring was all done properly, I had some good advice along the way to guide my electrician (who unfortunately died but not from something electrical). At this point, I'm not going to re-do the AC for the listening room, b/c we are planning on moving, and I bought the big E=Q wall cabinet as a step forward for the next room. Your comment about star grounding not reducing 60 hz hum is interesting to me. Maybe, when the Granite Audio device did do something effective is was not 60 hz hum. I thought after this many years, I'd recognize what that is, but it sometimes, when the noise is manifest, it is just a low hum, sometimes, its sounds more like a higher frequency ssssttzz, but it is noise, nonetheless. Like I said, right now all quiet on the western front, but every time i introduce a new component, it seems like something comes up and I have to sort it out. And, it isn't just the evident hum or sizzle, what's the grunge that's still there, mucking up the background? This way lies madness, I know, but I want to get this thing to sing as best it can and when I know there is noise of any sort, it makes me crazy.

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