Another electrical question

[Atmasphere]

As SS said above, if you're going to run multiple lines it would be best to run one larger capacity line to a subpanel or breaker box that is located as close to your system as possible. This will minimize potential differences in your grounds. I think if you measure how much power your system actually uses you'll find multiple lines was overkill and unnecessary.

As long as the outlets are wired properly this should make no difference at all.

If you are experiencing ground loops and the outlets are indeed correctly wired, your equipment has a grounding design flaw that should be corrected.

I find it odd that some manufacturers understood how to do grounding in audio equipment as long as 50 years ago, and today is still not that hard to find new equipment that is clearly improperly designed. Such is high end though...

 

[microstrip]

The cheapest solution - where sonic penalty is immaterial is the Rane Balance Buddy. That's something currently am using in my measurement systems to isolate the computer. I've also tried the Jensen, and other transformers and they are not transparent.

Steve's Flex Connect, on the other hand, IS transparent. On some systems, the impedance matching even makes the system sound better.

Gary,
I can confirm it - a great sounding device. Also operates miracles when you connect a tube preamplifier to a high gain solid state power amplifier or balanced sources to unbalanced inputs.

 

[ddk]

Gary,
I can confirm it - a great sounding device. Also operates miracles when you connect a tube preamplifier to a high gain solid state power amplifier or balanced sources to unbalanced inputs.

Great or not is a matter of opinion Micro (Ralph), the catch is "sounding"! Transparent is when you don't notice that something is there. The cheaper units do the same gain and SE to Balanced tricks, nothing new or special here. I don't know the actual price but I think I saw it quoted at $2k somewhere here, are you seriously recommending $4k plus all the additional wires for a couple of little transformers on the input of their amps with a straight face? Tell me if its more than band-aid for when things are fundamentally wrong and I might give some credence to it. (And if its that great sounding why don't you recommend it outright to all your customers to use in between your components?)

Please ignore the orange writing, it was addressed to the wrong person!

david

 

[DaveC]

As long as the outlets are wired properly this should make no difference at all.

Absolutely not true. The subpanel will tie the grounds together closer to the components reducing the impedance between the component's grounds, which will reduce noise induced due to ground potential differences.

IF good electrical practices were prevalent both in component design and electrical service to audio systems we wouldn't need band-aids like $2k isolation boxes and $$$$ aftermarket grounding systems.

 

[Speedskater]

Absolutely not true. The subpanel will tie the grounds together closer to the components reducing the impedance between the component's grounds, which will reduce noise induced due to ground potential differences.
IF good electrical practices were prevalent both in component design and electrical service to audio systems we wouldn't need band-aids like $2k isolation boxes and $$$$ aftermarket grounding systems.

How very, very true.
Whether the differences are audible will be situation specific. But 'good engineering practice' is always 'good engineering practice'.

 

[ddk]

Absolutely not true. The subpanel will tie the grounds together closer to the components reducing the impedance between the component's grounds, which will reduce noise induced due to ground potential differences.

IF good electrical practices were prevalent both in component design and electrical service to audio systems we wouldn't need band-aids like $2k isolation boxes and $$$$ aftermarket grounding systems.

+1

 

[Atmasphere]

Absolutely not true. The subpanel will tie the grounds together closer to the components reducing the impedance between the component's grounds, which will reduce noise induced due to ground potential differences.

IF good electrical practices were prevalent both in component design and electrical service to audio systems we wouldn't need band-aids like $2k isolation boxes and $$$$ aftermarket grounding systems.

I agree 100% to the latter statement! However regarding the former, I have found that if the component design is correct, it will be pretty well immune to the ground connection and no ground loops will ever arise. This is entirely because there will simply be no ground currents in the ground connections, so no ground loop.

 

[DaveC]

I agree 100% to the latter statement! However regarding the former, I have found that if the component design is correct, it will be pretty well immune to the ground connection and no ground loops will ever arise. This is entirely because there will simply be no ground currents in the ground connections, so no ground loop.

AFAIK, there are no standards recognized for "correct" design wrt ground isolation in components so it is a good idea to minimize impedance between grounds, both by using cables with low resistance ground connections and by optimizing AC service. Further, whatever ground isolation techniques you think are correct may not be entirely effective anyway. If you're going to install dedicated electric service for your audio system you may as well do it the best way possible. Adding a breaker box isn't too difficult or expensive and could make a noticeable difference, especially if the main panel is very far away.

 

[Speedskater]

As for standards, Neil Muncy (RIP) wrote this paper in 1995:

"Noise Susceptibility in Analog and Digital Signal Processing Systems"
NElL A. MUNCY, AES Member

(you will have to do a web search, because it has no permanent URL )

It became known as the 'pin 1 problem'.

*********************************
About 10 years later the paper was refined into Audio Engineering Society standard AES48.

More on the 'pin 1 problem':

Pin 1 Revisited
http://www.audiosystemsgroup.com/Pin_1_Revisited.pdf

Pin 1 Revisited -- Part 2
http://www.audiosystemsgroup.com/Pin_1_Revisited_Part_2.pdf

About 50 more good Jim Brown papers & Power Points:
http://www.audiosystemsgroup.com/publish.htm

 

[Nyal Mellor]

My system has a dedicated 20 amp line for each monoblock. I also have a dedicated 20 amp line for my rack (sources, preamp).

I tried using single ended (RCA) cables from my preamp to my amp and noticed that I get a loud hum (ground issue) but this seems to be caused from the circuit that feeds the left channel; if I plug the left monoblock into the right amp circuit, there is no hum.

Can anyone explain why I get hum with one outlet/circuit and not the other? I'm wondering if my electrician did something wrong when I had him add the 2 dedicated circuits for my amps.

Thanks in advance.

It is a difference in ground potential that is causing the hum. Classic ground loop.

I'd check the outlets first. Make sure earth connection is good and tight on the outlet. Obviously make sure circuit breakers are off.

Then check panel end. All the breakers for your audio system should be on the same leg. Your home is fed two 120V legs. That means your audio breakers should not be one on top of the other in the panel, as the panel goes leg A, leg B, leg A, leg B, etc. So there should typically be a gap of one breaker between each audio circuit (note that sometimes the top and bottom most breakers do not follow this pattern in some panels).

 

[Occam]

As long as the outlets are wired properly this should make no difference at all.

If you are experiencing ground loops and the outlets are indeed correctly wired, your equipment has a grounding design flaw that should be corrected.

I find it odd that some manufacturers understood how to do grounding in audio equipment as long as 50 years ago, and today is still not that hard to find new equipment that is clearly improperly designed. Such is high end though...

Ralph,

I've no doubt that a system comprised exclusively of your components would be ground loop/noise free, even with single ended connections. But you don't make digital components, and many less discerning folks might find such an approach limiting....

As DaveC and Speedskater said, there are no AES standards for single ended connections, and given that, trying to resolve responsibility between vendors is a finger pointing pissing contest.

Ideally, minimizing the loop impedance of the safety ground(s) via a single mains circuit, or minimizing that path impedance with a local multi-circuit sub panel works like a charm.

The solution provided by Ayre and Convergent Audio Technology (I use a CAT SL-1) of providing a 3 pin IEC inlet on their non Class II ETL tested components and leaving the ground floating is IMO, at minimum, less than optimal.

Balanced/technical power limits the cancellation of inductive and capacitive coupling to the chassis/safety earth only to the extent of the symmetry of that coupling. IMO, much of the benefit of powering ones whole system via a balanced mains transformer, beyond whatever low pass filtering also provided, is the same minimal loop impedance as a single circuit or sub panel multi-circuit power delivery

It would be nice if manufacturers only connected the signal ground to the safety ground at a single component, typically the preamp, as recommended by the late Dan Banquer. This works quite well, but it requires mucking about with the circuity, if not implemented by the manufacturer.

Single ended inputs could be dealt with via differential circuity, transformers, discrete, or ICs like the THAT 1200, INAxxx or THS fully differential circuits that provide substantial CMRR, even with unbalanced impedances.

And finally, there are ground loop breakers, which placed between a signal ground and the safety ground, can deal with a multitude of sins... Then again, this requires incorporation into the circuity of a component.
http://sound.westhost.com/earthing.htm

Universal harmonization of electrical codes, requiring GFCIs on all mains circuits, allowing the ditching of the problematic safety ground is better left to another discussion.

FWIW,
Paul

 

[ddk]

Ralph,
I've no doubt that a system comprised exclusively of your components would be ground loop/noise free, even with single ended connections.
FWIW,
Paul

I'm curious Paul what makes you so sure about this? Ground loop is just that, most audio equipment are susceptible and some more than others because of their design. Preamps & amps need a source too, nothing works in a vacuum.

david

 

[Speedskater]

.........................................
As DaveC and Speedskater said, there are no AES standards for single ended connections, and given that, trying to resolve responsibility between vendors is a finger pointing pissing contest.
.........................................
FWIW,
Paul

While none of the schematics in AES48 "the pin 1 problem" show singled ended circuits, the earlier AES paper does include discussion and schematics:

2.1 Definition of Pin 1
The term pin 1 will appear repeatedly throughout this
paper. Pin 1 is defined as the terminal or terminals of
any equipment input/output (I/O) connector to which a
cable shield or shields are connected when a mating
cable connector is inserted, regardless of use or connector
type..............for RCA connectors, pin 1 refers to the shell;

2.5 Unbalanced Circuits
A circuit is said to be unbalanced if the impedance
from each side of the circuit pair to ground and all other
conductors is unequal. A condition of dynamic unbal-
ance also exists in otherwise balanced circuits if the
signal levels on each of the conductors are unequal.

Unbalanced circuit connections between devices in a
typical audio installation are usually made with shielded
single-conductor cable. In this circuit configuration the
cable shield is required to serve as one member of the
circuit pair. By making the shield one member of the
circuit pair, the second function of cable shielding [see
Section 2.3.5, function 2] cannot be realized, and com-
men impedance coupling of EMI is invited.

 

[Occam]

I'm curious Paul what makes you so sure about this? Ground loop is just that, most audio equipment are susceptible and some more than others because of their design. Preamps & amps need a source too, nothing works in a vacuum.

david

Hi David,

I'd a number of reasons...
1. I was being polite, and the comment had no bearing on the 'meat' of my post. Nor did Ralph state anything that I thought theoretically impossible. His hubris might well be justified.
2. While I have read Ott, the possibility of my implementing a component with net zero, capacitive and inductive coupling to a metallic chassis is nil, [or I could rely on the inverse square law and make a really teensy circuit board in the center of a really big chassis] Ralph's circuitry, AFIK, is balanced, differential and symmetrical which might be able to pull it off. That, AFIK, is the only way one could make a component with "simply be no ground currents in the ground connections", leastwise in the mains safety ground.

You're right, nothing operates in a vacuum, save for vacuum tubes and radiometers/solar sails. I do believe Atmasphere makes a phono stage, and if its inputs are floating balanced, with that same fearful symmetry in the circuity, one might pull it off. Then again, who would use single ended ICs in an all Atmasphere system?

FWIW,
Paul

PS - I forgot another method of ameliorating potential ground loop issues, a saturating ground inductor. An inductor with high inductance as low current levels, but when subject to a fault, saturates and has low resistance allowing the breaker to trip, per EN 138100; EN 60938-1

 

[Occam]

While none of the schematics in AES48 "the pin 1 problem" show singled ended circuits, the earlier AES paper does include discussion and schematics:
...

Speedskater,

Thanks for the excerpt. If its not too much trouble, you might provide a link, or at least the name of the paper, so I, and others could read it.

TIA,
Paul

 

[Speedskater]

Paul,
See my post #29.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
But a much better deal is this AES Journal reprint:

SHIELDS AND GROUNDS: SAFETY, POWER MAINS, STUDIO, CABLE AND EQUIPMENT, (special excerpt)
The June 1995 issue of the Journal was a definitive and comprehensive collection of information on this important topic. The seven papers by Neil Muncy and other experts in the field have been reprinted into a convenient guide for designers and practitioners.

This is about 85 pages with 7 great papers. And it's only $15 including shipping.

http://www.aes.org/publications/specialpubs/journal_issues.cfm

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
One of the papers is the John Windt "Hummer Tester" which is not available anywhere. Jensen Transformer/Bill Whitlock only has a summary.
Some of the components with hum problems will fail the "Hummer Tester"

 

[ddk]

Hi David,

I'd a number of reasons...
1. I was being polite, and the comment had no bearing on the 'meat' of my post. Nor did Ralph state anything that I thought theoretically impossible. His hubris might well be justified.
2. While I have read Ott, the possibility of my implementing a component with net zero, capacitive and inductive coupling to a metallic chassis is nil, [or I could rely on the inverse square law and make a really teensy circuit board in the center of a really big chassis] Ralph's circuitry, AFIK, is balanced, differential and symmetrical which might be able to pull it off. That, AFIK, is the only way one could make a component with "simply be no ground currents in the ground connections", leastwise in the mains safety ground.

You're right, nothing operates in a vacuum, save for vacuum tubes and radiometers/solar sails. I do believe Atmasphere makes a phono stage, and if its inputs are floating balanced, with that same fearful symmetry in the circuity, one might pull it off. Then again, who would use single ended ICs in an all Atmasphere system?

FWIW,
Paul

PS - I forgot another method of ameliorating potential ground loop issues, a saturating ground inductor. An inductor with high inductance as low current levels, but when subject to a fault, saturates and has low resistance allowing the breaker to trip, per EN 138100; EN 60938-1

Hi Paul,

Ground quality seems to have a significant impact on sound. I played around with different ground conductors coming into the panel and the sound changed significantly with each type/size of conductor. Then the equipment themselves, some sound better with ground and some ground lifted, within the same system, and there's no rhyme or reason for it because in the next installation I might have to ground lift all components. Reason I'm telling you this is that your theory of "simply be no ground currents in the ground connections" might not sound right in the end. Regarding OP, ground loops seem to come in all varieties, some are easy deal with like his, others can drive you mad and none of the expert advice will have any effect. Including ground lifting all components and plugging them into one clean outlet.

david

 

[Occam]

Hey Dave,

Excellent post! I've also found that the ground conductors characteristics, as well as its geometrical relationship to line and neutral conductors have a substantial impact on both subjective and objective measures. Increased leakage to mains safety ground, Y capacitance, seems to correlate quite strongly to (beyond ground loop issues) to subjective height perception, with the right source materials. In my system, my CAT-SL1 preamp subjectively sounds far better with no ground wire in the power cord. As the CAT's mains safety earth is not connected internally, I'd posit that hf differential and common mode noise capacitively coupled to mains safety ground is wending its way into other components that are actually grounded via the mains. I don't use 'Y' in my power conditioner filters.

I'm quite lucky in that my main breaker box is less than 6' from the outlets in my listening room on the floor above.

I misspoke a bit, when I quoted Atmasphere's

simply be no ground currents in the ground connections

, in that all things being equal I would prefer any leakage from all components to be at a 0 potential, but all things never are equal, I'd actually prefer the leakage potentials of interconnected components to be at the same potential and phase, which is a more general case of you don't get current flow.
But I hardly think Ralph is designing to a leakage potential of other the 0, and I still think the only way to get that would be with a balanced, bridged, symmetrical topology. Besides, Ralph's '60 years ago' jibes quite well with the initial patents of the Circlotron.



Regards,
Paul

PS - You've really interesting systems. It would be a treat to hear them.
Paul

 

[garylkoh]

Hi Paul,

Ground quality seems to have a significant impact on sound. I played around with different ground conductors coming into the panel and the sound changed significantly with each type/size of conductor. Then the equipment themselves, some sound better with ground and some ground lifted, within the same system, and there's no rhyme or reason for it because in the next installation I might have to ground lift all components. Reason I'm telling you this is that your theory of "simply be no ground currents in the ground connections" might not sound right in the end. Regarding OP, ground loops seem to come in all varieties, some are easy deal with like his, others can drive you mad and none of the expert advice will have any effect. Including ground lifting all components and plugging them into one clean outlet.

david

David,

You say that different types of ground conductors coming into your panel makes a significant change in the sound, and yet you believe that something that you have not tried to be Audiophilia Nervosa?

This is a band-aid and it can't be transparent by definition. Its a transformer filtering the SIGNAL and messing with the ground connection, that's all. Does it do anything else? It doesn't fix the source of the problem, wether its mains or poor component design. Then you need two boxes and double runs of expensive interconnects $$$$$$ for the Audiophilia Nervosa. Jensen is one the best TRANSFORMER manufacturers in the industry, they're just not into the boutique pricing.

david

 

[Speedskater]

........................
Excellent post! I've also found that the ground conductors characteristics, as well as its geometrical relationship to line and neutral conductors have a substantial impact on both subjective and objective measures.

Bill Whitlock has a paper on power cable geometry:

"Ground Loops: The Rest of the Story"
Bill Whitlock, AES Fellow and Jamie Fox, P.E.
This paper was presented at the AES 129th Convention, 4-7 November 2010, San Francisco, CA, USA

ABSTRACT
The mechanisms that enable so-called ground loops to cause well-known hum, buzz, and other audio system
noise problems are well known. But what causes power-line related currents to flow in signal cables in the first
place? This paper explains how magnetic induction in ordinary premises AC wiring creates the small voltage
differences normally found among system ground connections, even if “isolated” or “technical” grounding is
used. The theoretical basis is explored, experimental data shown, and an actual case history related. Little
has been written about this “elephant in the room” topic in engineering literature and apparently none in the
context of audio or video systems. It is shown that simply twisting L-N pairs in the premises wiring can
profoundly reduce system noise problems.

http://xa.yimg.com/kq/groups/20963848/268252969/name/Whitlock-Fox+-+Ground+Loops+.pdf

Increased leakage to mains safety ground, Y capacitance, seems to correlate quite strongly to (beyond ground loop issues) to subjective height perception, with the right source materials.
Regards,
Paul

Bill Whitlock often writes about Y capacitor and MOV leakage problems.