Grounding problem with a dedicated line?

Really, there's not much to check or measure. We know that the ground loop was formed by 30 feet of ground wire from your dedicated outlet back to your circuit breaker box, through its bus bar, and then back through 30 more feet or so to the other outlet. It is unlikely that re-tightening the wires or even replacing the whole circuit wire would correct this basic problem.

If the outlets are with a few feet of each other in the same wall, one might add an accessory ground wire between the two outlets, to tie their grounds together and shorten the loop (as long as you don't point out what you've done to an electrical inspector). That would require opening up and patching the drywall, and since you've already fixed the problem, is unnecessary.

You could do the same externally, make an "illegal" cord, a single wire with a normal power plug on each end, wired to only the ground pin, and insert the plugs into the power strip on each circuit.

 

I was about to make a helpful comment, but remembered that I swore I was never going to on this thread again. It might be construed as an SQ hazard.

 

What you stated before came to be the case..at least it seems that way. Ralph doesn't seem to think this is the case ( at least if I am reading his posts correctly). The fact that the issue went away when I connected everything to the strip and then powered it from dedicated line would indicate that the ground loop was broken...is that not right??

 

Well that's somewhat true...after all I don't want to add something to the system that results in a loss of SQ but at the same time reduces the slight buzz that was evident. To be clear, I am not saying that what you suggested wouldn't reduce the hum/buzz....but it sure looked like it would interfere with the SQ...and this according to several other members of my a'phile group who have either experienced the addition of the transformer, or who have added additional connections into the line. Nonetheless, i do/did appreciate your suggestion (s).

 

You have eliminated the ground potential differences. It is always recommended to run a hi-fi from one powerpoint using a strip. I wonder how this thread became so long as the answer was given on the first page. All lines will ultimately come to a common earthing point at the consumer unit so there may be in effect a loop.

 

No that is not right. In your case the ground loop circuit, using both the convenience outlet branch circuit and the dedicated branch to feed your audio equipment, was the problem. A difference of potential, voltage exists between the two equipment grounds of the outlets. THAT is what caused the ground loop and hum/buzz.

IF the dedicated branch circuit is installed correctly, using best practices methods for installing an audio branch circuit, the 10-2 with ground NM sheathed cable, (Romex is a manufacturer's Trade Name), the dedicated branch circuit is not the problem, imo. The problem is using the 15 amp, #14awg wire convenience outlet branch circuit in the mix.
Possible reasons? There are many.

Back to your question:

How can there be a ground loop circuit when only one equipment ground is being used? In your case the ground loop is caused when using both branch circuit equipment grounds.


How about an update on the electrician's visit? Did he check out the dedicated branch circuit and make sure it was installed and wired per the NEC bare minimum electrical safety requirements/standards?

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For what it's worth I feed my 2 channel audio system from two dedicated branch circuits that are 75ft each in length. I followed best practices for the type of wiring used and for the installation of audio branch circuits. And yes the wiring method meets the NEC as well as my local AHJ.

Wire? 10-2 with ground NM sheathed cable. Both circuits are fed from the same Line, Leg, in the electrical panel. In fact the branch circuit breakers are directly across from on another.

My system is dead quiet.

 

I was questioning about the ground loop going away once all on the dedicated line, as Ralph seemed to believe that this wasn’t the problem..unless I’m understanding his points incorrectly.

Last night we didn’t have time to check the panel, but my friend is coming by again today to do exactly this. I will be referring him to this thread to make sure he checks the right things...although he is a licensed electrician, so I probably don’t really need to do that...but it can’t hurt.

 

That might be the case in the UK, but it doesn’t seem to be so recommended here in the US. In fact, running my very powerful ss Rowland amp off the strip along with everything else results in a definite reduction in SQ. See my posts above. Even running the ss amp off the second gang and everything else on the strip utilizing the first gang of the dedicated 20 amp line, results in a loss of SQ. Luckily the Jadis tube amps don’t have that much draw...and so the all on the strip set up works fine.

 

My electrician friend checked out my panel and the connections at the dedicated line.All good, although he did tighten the ground connections at the panel. They weren’t loose, but he felt tighter would be better.

 

Even if the ground wire were 6" long you would still get a ground loop if the equipment is susceptible. The length of the ground connection IOW is irrelevant. The equipment really shouldn't be putting anything signal related into the ground connection.

Did he check from the outlets you were using? Did he check the convenience outlet and line? Did he check the power strip?

 

We checked all outlets and we checked polarity/grounding on the strip...all good.

 

@DaveyF,

But did the electrician measure the voltage between the convenience outlet equipment grounding conductor and the dedicated equipment grounding conductor?

There were/are several problems with trying to use the convenience outlet branch circuit and the dedicated branch circuit to power the SACD player and the 2 mono amps.

Here is an old quote from a White Paper by ExactPower.
(For some reason the Link is no longer any good. The last time I clicked on the Link was in May of 2013)

"Less than 300 microamps of ground loop current can cause hum as it flows in an unbalanced audio interconnect cable. However, harmonics of 60Hz that are generated from lighting dimmers or switch-mode power supplies sound like Buzzz mixed with a bit of Hummm and are more easily coupled by even smaller currents. Harmonics can add together when equipment is powered from different phases, so clearly there is an advantage to specifying same-phase electrical service to power the electronics systems in most cases....

Any leakage currents on the safety ground wires of split single phase load circuits fed by different phase legs will add together due to the 240V potential difference....

Power conditioners do not solve any of these common problems: Cross phase coupling (doubles hums & buzzes) .... What actually does solve them: Same phase power.

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Split Single Phase electrical service is most commonly found in residences and smaller commercial buildings, and is commonly used to feed AV equipment. One key advantage that single phase has over three phase is that while harmonic currents are still present, it is not possible for the “triplen” components to add in the neutral. In addition, use of split single phase can result in at least a 6dB reduction in noise floor as compared to three phase if the capacitances of the connected equipment are relatively well balanced. However, any leakage currents on the safety ground wires of split single phase load circuits fed by different phase legs will add together due to the 240V potential difference."
http://www.exactpower.com/elite/assets/pdfs/theTRUTH.pdf

In one of my posts to this thread I asked you to check the breaker circuit numbers on the electrical panel breaker's front cover. From the circuit numbers I can tell if the two circuits are on the same Line, Leg, or fed from both. If you had a multimenter you could also find out by checking for voltage from one receptacle Hot contact of the convenience duplex outlet to one of the duplex receptacles Hot contact of the dedicated circuit. If both circuits are fed from the same Line, Leg, the meter will measure zero Vac nominal. If fed from both Line 1 and Line 2 The meter will measure 240Vac, nominal.


Another problem you have with the convenience outlet branch circuit is the non audio loads that are connected to the circuit.
Type of lights? CFL, LED? Dimmer/s? Electronic ballast florescent lighting? Any induction motor loads? We already know there are higher than 60Hz frequencies harmonics on the circuit. We know that because of the buzzing sound you were hearing through your speakers.

How many wiring connection joints/splices are there in the run from the electrical panel to the wall outlet used to feed the SACD player? What type of wire connectors are used? Are any of the connections not mechanically solid/tight and or corroded?


Could you have ended up having/hearing a ground loop hum after feeding your 2 channel system from the single dedicated branch circuit? Yes, imo, if the SACD player or either or both of the two mono amps had an AC leakage, ever so small, from the hot AC line to the chassis, current would flow on the equipment ground back to the AC source. A closed ground loop circuit.
The electrical service, AC power system, in your home is a Grounded AC Power System.

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Jim, since I have effectively removed the problem by having all of my gear on the dedicated line, I didn’t ask my electrician friend to dig too deeply into the issue with the convenience line. The cable for the dedicated line has no breaks between the receptacle and the breaker. My friend made sure that the connection coming to the breaker was tight and that the ground wire...and only the ground wire, from the dedicated line connected tightly to the ground bar in the panel. That bar is connected to a cable that attaches to a copper rod (actually two about six feet apart) that are imbedded several feet into the ground. About a year ago, I replaced the cable from the transformer in my street( upgraded it to a 500 amp capacity cable in a conduit) and we dug up my driveway to bring this new cable to the transformer ( don’t ask the hassle, never mind the cost of doing this!). At the same time, we added a brand new 200 amp panel and had the power company replace the connections at the transformer...with upgraded brass. The whole job was done with permits and was fully inspected. The dedicated line was installed with no breaks and according to my electrician friend, was done to code and professionally. My friend is pretty convinced that there was a ground loop occurring due to an off set in the dedicated line and the convenience line...which apparently is pretty common. Now that I am only using the dedicated line, all is fine...in fact so much so that my electrician friend, who had never heard a high end system before, commented that he was totally blown away and couldn’t believe what he was hearing! I am more than pleased at this point...the mix of CAT, Jadis and Esoteric is exceptionally musical.

 

If it works don't fix it? Actually a pretty good approach IME... But it would have been nice to sort out what was actually going on. Some other time, right? Enjoy!

This is what I meant by 'something else' going on. Not so much as a ground loop as just additional noise in the ground itself. And is a common problem on opposite phases.

 

Ralph, I wasn’t paying my friend to do this job, so I didn’t want to impose on him anymore than necessary. Since the system issue was fixed, I figured what he did was pretty good...and I think it certainly gave me the peace of mind that I was hoping for.

 

So, 8 pages on this thread, and the takeaway is: put all your gear on the same side of the line. If two sides of the line are serving your audio room, it should be no surprise that you might be fighting noise, quite independently of a ground loop.

 

Ralph, I don't know about others on this thread, but I appreciate all of the information and thoughts that several members, including you, posted. I want to thank all of those folks who chimed in here, as personally I learned quite a bit over the last eight pages and thought the responses were very helpful. The situation for me is now no longer an issue, plus I have also decided to look into a power conditioner for my system...which at one time I wouldn't have considered. Along with possibly a better power strip.

 

Personally I don't like power strips- it works better IME if you are able to plug directly into the wall. I had an extra outlet installed on this account.

The best power conditioners I've seen were made by Elgar (and not for high end audio). Most high end audio conditioners are junk by comparison.

 

Totally disagree. This a mind set from decades ago. The current crop of good conditioners are excellent. Same for power distribution strips.

 

My amps seem to cause most 'high end audio' conditioners to fall right flat on their collective faces, which is why we tell our customers to either get a refurbished Elgar or don't bother- just plug them straight into the wall. The exception are the PS Audio units, but to be successful with them you need one for each channel, which can be rather pricey. The Elgars perform a bit better and are usually available for a lot less (the 28-Amp model, the 3000 series, is often available refurbished for less than the cost of one PS Audio unit). The problem with the Elgars is they have a noisey internal fan that should not be defeated (newer fans might be considerably quieter) so especially with the bigger units it makes more sense to place them near the breaker box and wire them into the electrical system so that they feed the entire audio room. 28 Amps is a lot of current and most audio rooms won't be drawing anything near that. The Elgars products are commercial/industrial and designed as workhorse 24/7 operation. They are not pretty but they are the best out there. Here is an example of a 1000w unit:

Elgar Model 6006B Series 6000B 1000w AC Line Conditioner | eBay

This one likely needs to be refurbished.

IMO/IME its a real shame that hardly anyone in high end audio has stepped up to bat and done what needs to be done with power conditioning as it can make a nice improvement. But if someone were to do these days what Elgar did they would not be cheap either. Elgars employ an enormous isolation transformer that is equipped with a feedback winding. An ultra low distortion oscillator provides a 60Hz sine reference; this is locked to the line frequency and is compared to the output. A power amplifier then sends the resulting feedback signal to the isolation transformer- at the same time bucking the AC voltage. In this way it not only provides a low distortion sine wave at its output, it also regulates line voltage. Pretty slick. No spikes, no line harmonics, just a clean sine wave with low THD.

 

This is interesting and good information. But with all due respect your painting with a very broad brush. I have never heard of amps making a PC fail

Your views are really your opinion as far as the state of the art of these types of products.

I have auditioned and tested dozens of the best on the market, I would be curious which models you have direct experience with and why you consider them junk.

 

I didn't say 'fail' I think I said 'fall right flat on their collective faces' which you might consider a fail but not in the way that stuff is emitting smoke, just fails to be helpful.

I'd be interested in knowing what you think is the best (which can only be one; others are 'better').

Stuff I consider junk: will have no ability to get rid of the 5th harmonic. Stuff that works fine until you run them past 50% of full rated power, where the output waveform becomes distorted. Stuff that is unable to regulate line voltage. Stuff that can't produce a low distortion sine wave output regardless of input. That makes a pretty long list- most high end conditioners in audio today can't do all that. A disturbing number are simply glorified power strips and don't actually do any power conditioning at all. This stuff is all easy to measure.

Why: some of our amps draw a bit of power. All our amps are known through customer comments, reviews and awards as being some of the most transparent made anywhere (Atma-Sphere). Now when we experience an obvious degradation when a given conditioner (for example, Furman) is used with our product and we can measure that degradation as well then I'm simply going to recommend to the customer that he's better off just plugging in directly into the wall. The Elgar has consistently proven to be one of the very few that does not degrade measurable performance and subjective sound experience. Quite often the problem is that the conditioner simply can't handle the current needed to run our stuff. The problem often isn't that they don't have the rating but more to the point that they can't handle a constant heavy current load. We have a lot of power tubes so there is a lot of filament current needed. On top of that, the amps tend to be class A2 with most loads. If the conditioner employs an isolation transformer, if it does not also have a feedback mechanism to kill distortion, it will be in trouble if the power draw exceeds about 50% of the rating. In addition, a simple isolation transformer isn't sufficient to do much at all- it can't filter a 5th harmonic on the line for example.

 

Thanks further detail.

Apologies! Without my readers I read "fail" instead of "fall"...I stand corrected!

So they subjectively degraded the sound, understood. I understand OTL designers in general, and yes, yours are considered some of the best
on the market, if not for the best. But they are not for everyone, and they can be inconvenient. So maybe your case is a special one.

FYI, the manufacturers whose models I have extensive experience with are Shunyata, Audience, Bryston, Synergistic Research, Furutech., PS Audio,
and numerous others. I personally would not consider Furman audiophile grade.

 

Ralph, I certainly did notice that my high powered Rowland amp draws so much current off the wall that when it was sharing the receptacle with the power strip, there was a loss of SQ. The Rowland draws 300 watts at idle, 1200 watts at full operating spec. OTOH, my Jadis amps draw far less and has no issues with coming from the strip ( according to the manual, these draw 125 watts per mono block at operating spec....so far less!)
One of the reasons that i chose my Jadis amps is precisely because they do NOT give off a ton of heat and draw loads of current. Here in S.Calif tube amps with multiple tubes and giving off a ton of heat isn't really that desirable to me...regardless of the SQ.YMMV. There are simply other choices that have great SQ and don't give off a ton of heat due to a forrest of tubes! A space heater is ok in some of the colder climes...