Another electrical question

Atmasphere · Jun 10, 2015

Speedskater said:
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

I'm very familiar with the pin 1 problem as we made the world's first balanced line preamps offered to audiophiles.

Occam said:
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

In a nutshell, this is an easy problem to sort out. First: the chassis should be tied to the ground pin of the AC cord no if ands or buts.

Second: the circuit ground is not the chassis. A connection is made between the two with an impedance high enough to render ground loops impossible. Rectifiers are handy to cause fuses to blow if there is a serious problem.

Generally speaking in audio circuits if the chassis is used as a ground return it will be noisier (and higher distortion) due to internal ground loops so there is good reason to separate chassis and circuit grounds.

Third: Balanced and single ended systems are inherently incompatible. Balanced systems may have pin 1 tied to chassis, as no ground currents will be present. However! if you wish to use the two together (single-ended and balanced) that's when you get into transformers and the like. We solve the problem by employing the same practice for grounding as for single-ended outlined above; at any time the chassis can be connected to pin one should compliance with AES48 be required.

If your equipment employs these or similar grounding techniques it will be immune to ground loops and fancy grounding systems will yield no further improvement. It really is that simple.

CGabriel · Jun 10, 2015

Atmasphere said:
In a nutshell, this is an easy problem to sort out. First: the chassis should be tied to the ground pin of the AC cord no if ands or buts.

Second: the circuit ground is not the chassis. A connection is made between the two with an impedance high enough to render ground loops impossible. Rectifiers are handy to cause fuses to blow if there is a serious problem.

Generally speaking in audio circuits if the chassis is used as a ground return it will be noisier (and higher distortion) due to internal ground loops so there is good reason to separate chassis and circuit grounds.

Third: Balanced and single ended systems are inherently incompatible. Balanced systems may have pin 1 tied to chassis, as no ground currents will be present. However! if you wish to use the two together (single-ended and balanced) that's when you get into transformers and the like. We solve the problem by employing the same practice for grounding as for single-ended outlined above; at any time the chassis can be connected to pin one should compliance with AES48 be required.

If your equipment employs these or similar grounding techniques it will be immune to ground loops and fancy grounding systems will yield no further improvement. It really is that simple.

Good Post Ralph. The XLR balanced pin-1 problem is interesting in that there is no real standard practice that is universally followed by various manufacturers. This is largely because many of the consumer products evolved from the standard use of the RCA interface. Then, various manufacturers have different implementations to maintain compatibility with both RCA and XLR interfaces.

Ralph what's you opinion on the following: If a preamp has a grounded chassis to AC safety ground and the signal ground has a specific higher impedance, as you described - then what happens when a CDP is connected that is configured in a similar manner but the chosen impedance between the internal chassis ground and signal ground is different than the preamp? Couldn't this also cause a problem when using RCA connections since the relative signal grounds are at different levels?

Atmasphere · Jun 10, 2015

^^ No- it should be fine. All we are interested in here is that the impedance in question be high enough to prevent significant ground currents that result in buzz. Beyond that the actual value used is not critical at all.

That is the beauty of doing this the right way- when you are done there is good plug and play and nothing is critical.

Occam · Jun 10, 2015

Atmasphere said:
....
In a nutshell, this is an easy problem to sort out. First: the chassis should be tied to the ground pin of the AC cord no if ands or buts.

A given.

Second: the circuit ground is not the chassis. A connection is made between the two with an impedance high enough to render ground loops impossible. Rectifiers are handy to cause fuses to blow if there is a serious problem.

I'd not realized folks were using diodes in their standoffs 60 years ago. Neat.
Is that similar to the ground loop breaker I referenced previously?
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

EDIT - here is an article by David Davenport covering grounding issues that specifically talks about the above SLBs (safety loop breakers) as well as other avenues also discussed in the Muncey, Ott, Whitlock, Brown & AES articles
http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html

ddk · Jun 10, 2015

garylkoh said:
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?

Hi Gary,

Audiophilia Nervosa wasn't directed at you, it was in regard to the cable thing that some audiophiles have. Its like a life lock, you can't touch it, you can't move it and god forbid to swap it out with longer lengths of wire so you wouldn't to move 200 lbs amps every time you move the speakers a foot over. I was just having a vision of such audiophile physically not being able to give such a box a try without first laying out another giant sum of money on additional interconnects, cooking them and then letting it fester in place for 6 months before listening. I realize that because of so many different backgrounds on international forums such as this often our cultural and written communication styles our intent can become misconstrued by someone of a different nature and decorum. I sincerely apologize if my post was unclear in that sense. Audiophilia Nervosa was never directed towards you but at some of the clients that I'm sure you've also come across.

Getting back to the thread, as far as not trying it out, yes, I haven't tried Steve's box but I've tried enough of them, including custom ones and a couple even wound with silver wires. I don't need another box to know what a transformer will do in line with the signal; nor do you! I'm not even arguing that they can get rid of all the hum and like you I've also used them at shows too, but they're never transparent. They change the quality of the sound, and often, away from show conditions, they all degrade sound quality in a high quality setup. There was also the context of ground loops, you're not addressing the source of the problem just putting a bandaid at the end of chain and a very expensive one in the case of the Audiophila Nervosa, that's my objection to it. In a domestic environment even with less money one can try fix the problem at the source. That's the approach I'd take with a high end system, but just for testing and shutting up a buzzing active sub, yeah I throw a couple in, but not at $2k a piece.

ack · Jun 10, 2015

Atmasphere said:
Second: the circuit ground is not the chassis. A connection is made between the two with an impedance high enough to render ground loops impossible. Rectifiers are handy to cause fuses to blow if there is a serious problem.

I believe the following is an example of this from the Berkeley Alpha Reference:

microstrip · Jun 10, 2015

ddk said:
Great or not is a matter of opinion (...), 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. (...)

david

David,

In high-end audio one man meat is another one poison. I will give you an example - a good friend of mine loves his Mcintosh C2200 tubed preamplifier but could not live with the heat of their tubed amplifiers, and found that the cj premier 350 solid state amplifier sounded very good in his system using the Wilson Audio watt/puppy7. However when we tried using Steve transformer this system experienced a large improvement in sound quality, sounding much better than any much more expensive equipment he had in his system. This could show him how good can sound a good system playing music in his room. He did not like the idea of spending usd 2000 in such box, but after listening to it and trying many alternatives, even much more expensive ones, he had to buy it. He (and others) really enjoy his system in such configuration.

If equipment that according to your words is "fundamentally wrong" can sound better IMHO and preference when aided by "band-aid" than some "fundamentally right" one, I do not hesitate on which I choose.

I own Atmasphere equipment manufactured by Ralph that does not need any transformers between the preamplifier and the power amplifiers and I would never use it in such situation. However I also appreciate some other equipment that can benefit from such high quality transformers.

BTW, we tried several alternative transformers, even some expensive Lundhal ones. In our systems the Flex-Connect surpassed them. Others could find differently.

ddk · Jun 10, 2015

Micro,

Context is everything! These boxes, whoever makes them, builds them primarily as noise filters. Its just a transformer that you stick before the input of an amplifier to take care of ground hum/buzz/noise, whatever, caused by other components, cables, electrical wiring etc., nothing more! Its an Additional box with a transformer, wires, switches and connectors plus you have to add extra wirings and connectors, all of which WILL degrade a Clean signal. I have no argument if you prefer the sound of your system with inline noise filters but that doesn't change the fact that you haven't dealt with source/sources of the problem, that's why I call it a band-aid.

I only suggested Ralph to supply his clients with these boxes as a joke when he said these transformers sound great and can improve sound quality, and he's an OTL guy. Ground loops are a pain, sometimes easy to deal with and other times they can turn out to be very mysterious and very intrusive. A lot of these situations are outside the control of even the best manufacturers, count yourself lucky if you haven't had to deal with it. Enjoy!

david

Atmasphere · Jun 11, 2015

^^ David, I think if you look back at your post #23 I think you will see that you got me confused with microstrip.

ddk · Jun 11, 2015

Atmasphere said:
^^ David, I think if you look back at your post #23 I think you will see that you got me confused with microstrip.

Oops, you're right. Sorry about that Ralph. I must have seen your name in the email update and his post when I clicked on the link.

david

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Atmasphere

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Occam

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ddk

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ack

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microstrip

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