Basic electrical questions.

Jea48

Nope. I was talking strickly in regards to the lessend effect of spurious noise equating to the distances of the dedicated line runs. Period.

I’m only a former ELECTRONICS tech, and commercial/industrial electrician, not an engineer or electronic designer, so I speak from my own experience.

My reference to phones for example regarded their charging devices impact on the household’s electrical system, not their common use… as I thought we were speaking of how dedicated lines are more the benefit than common circuits. Albeit, dedicated lines are not the end all be all, which I also pointed to quite early on and prior to many of these following posts. Further, more rechargeable devices can and do add derogatory artifacts into the power delivery.

Even UPCs for personal confusers, if not full wave AC power supplies will additionally infuse DC into the homes power supply. Those $100 Radio Shak ‘crash preventers’ do more harm than good.

Whatever the theory and or reasoning supporting such annoyances, the practical approach to remedy them has always been my tact, for in the end a solution is both what is sought and appreciated. Were I to ever tell some customer that they had a difference of potential across the differing grounds to their varying services, and the resolution for it, I’d be wasting both my time and theirs. Consequently I tend to strive for a more simplified approach when I attempt to convey some aspect which provides benefit. Truth be told here too… in some cases I don’t know the why of it, merely the how and what... for in my former vocation only results were more normally sought.

…and isn’t simple, always best?

My techy side does indeed appreciate many of these insights however, so please don’t take any offense as I underline my sense of things here, as well as others have also fortified in other words that which I promoted at the onset.

Thanks all, for the various links given here as well.

Zargon -- I did not perceive any contradictions along the lines you describe when I read Hansen's article.

First, although this is not inconsistent with anything you said in your last post, let me say that I don't think his paper addresses at all the question of multiple dedicated lines feeding the different components of an audio system. He addresses having a single dedicated line to the audio system (as he describes for his own system), and additional dedicated lines for other things in the house, such as large appliances and other noise-makers.

Concerning the inconsistencies you perceive in his paper, I think he is simply saying that the amount of noise coupled over to the audio system from non-audio devices would be SIGNIFICANTLY, though obviously not totally, reduced by having those devices and the audio system on separate dedicated lines.

See the reference I made in my previous post to page 4 of Whitlock's paper, for some indications of the inductive impedance of typical heavy gauge power wiring -- it is substantial at frequencies that a lot of noise can be expected to be at, which I think supports my use of the word "significantly" above.

Then there is the separate question of having multiple dedicated lines for the various audio components themselves. Posts by me and several others above have cited considerations which argue both for and against doing that, but your setup seems to have realized the best of all worlds. Way to go!

-- Al

Jea48,
I have read Hansen's article, and he does a good job of explaining the sources of disturbances on a household AC line. One has to appreciate well designed audio equipment that operates successfully in such a harsh environment. I do have some issues with his statements on Filters and Fixes (Part 2, pg. 7).

A dedicated line from your service panel to your audio equipment (I call it "star sourcing," similar to star grounding) can do wonders to keep noise and harmonic currents out of your audio equipment. With a dedicated supply, your amplification need only endure the noise from its system mates, rather than the hash from the washer, garage door opener, and furnace.

He recognizes the benefit of multiple dedicated lines with star grounding to reduce ground loops. And he recognizes that multiple dedicated lines by themselves do not prevent noise from one line getting on another. But then he contradicts himself by asserting that dedicated lines to a garage door opener and furnace will not pass their hash over to the dedicated audio line. As long as they are all connected in parallel on a common phase at the service panel, they will all share the same voltage disturbances. You can't have it both ways. I do agree that the length of the connection can attenuate conducted EMI and to that extent some of the crosstalk is reduced, but for short runs it would be minor.

This is why I advocate an iso on the audio subpannel and either a second iso on noisy lines or some conditioning at the componant. In my case the subpanel is adjacent to the audio room and less than 50 ft. from the service panel.

PS, thanks again for your excellent counsel when I designed and implemented this a couple of years ago.

Almarg,
The question of whether to tie the ground to common at the subpanel is an interesting one. I chose to do that and not let the audio system float. There are codes which apply to this question and I will let Jea48 address them if he so chooses.

Shadorne and Jea48 -- I went through the Bill Whitlock paper and presentation you linked to -- really super!!! He's absolutely right when he says these issues are not adequately addressed (or addressed at all) in EE curricula, and even EE's often don't know the difference between a ground loop and a fruit loop. :)

Shadorne -- thanks very much for the compliments. As someone with a digital design background, and who builds his own pc's, I agree 1000% that pc's are particularly proficient noise generators, due primarily to the fast edge speeds (rise and fall times) that are present on the innumerable digital signals running around in them, as well as to the large currents that can be change value very quickly as a result of fluctuating demands on the cpu and other devices.

Whitlock very persuasively supports what you said about high impedance shields, in single-ended interconnects, saying that they are typically one of the most major contributors to noise problems. He makes the point that ground offsets and resulting noise are inevitable (although they can be minimized), but it is the resistance of the shields of single-ended interconnects where that noise typically gets introduced into the signal path to the greatest extent. Therefore single-ended interconnects should be as short as possible, and selected for the lowest possible shield resistance.

Blindjim -- Re signal attenuation per unit length of cables, you are probably thinking of video or rf transmission lines, where both the cable impedance and the signal frequencies are well defined and controlled. I don't think that the attenuation is determinable in a meaningful way for noise components that are present at many unknown frequencies and are being conducted through power wiring that has poorly defined and controlled high frequency characteristics. But see page 4 of the reference below (one of those that Shadorne and Jea48 provided) for some rough indications of the impedance of typical power wiring.

For those who don't have time to go through the 140 pages or so of these two references, I'd suggest at least looking at the following pages of this link:

http://www.jensen-transformers.com/an/generic%20seminar.pdf

Page 12: "how the noise gets in"

P. 14: "solutions"

P. 20: "choosing cables"

P. 21: "a checklist" -- especially good!

P. 27: "always ground shield at driver (at least)"

P. 28: "unbalanced to balanced interfaces" (if applicable)

P. 40: "Many of the benefits often ascribed to power treatment schemes are simply due to plugging all system equipment into the same power strip or dedicated branch circuit. For obvious reasons, this is always a good idea"

P. 40: "surge suppressor cautions" (they can do much more harm than good if used improperly)

Thanks again,
-- Al

Maybe you are not familiar with Charles Hansen

Or maybe I am. I have read the work of, met in person, and/or had close working relationships with many brilliant people . . . most of whom I disagree with on one thing or another . . . in spite of the fact that I hold them and their work in high regard. This is why the concept of peer review is a cornerstone of so many disciplines, and the proper citation of multiple sources is a requirement for any scholarly paper.

Again, I encourage those interested in these subjects to get their information from multiple sources, and give at least a quick glance to bibliographies and sources.

That's exactly how I work it:
Sep/exclusive circuit for Amp and Sub. 20amp, PS Audio Soloist outlet.
And since I am not wealthy enough to rewire the entire house with yet more new circuits, the rest of plugged into a good power conditioner off an existing house circuit. The digital stuff IS plugged thru an Iso transformer which provides additional benefits.
If I were starting from a Clean Sheet of Paper, I'd have hi power and low power dedicated lines and a whole house arrestor installed. I think a major limit yet unaddressed here is that, for example, I have only a 100amp service to my house. The TRUE addict would have double panels, maybe a 200amp total service with one panel dedicated to the HT/Sound system.

One point of interest here is what was said about the actual length of the ckts themselves. I read somewhere there is a formula for figuring out the db per feet in loss. I don’t recall it now, but I know it happens. This effect occurs using dedicated lines as an added benefit, though it’s seldom if ever expressed as such.
12-11-08: Blindjim

I have read that also.... I looked last night and could not find the article. I know it is out there.
>>

In regards to ground loop hum.....
.

Al,

You are correct about ground loops - usually ground and neutral are connected at the electrical panel. If you have different equipment plugged in to different locations and then chained together for audio purposes there is indeed a greater risk of a ground loop. Provided house wiring is correct then the major culprits are high impedance shields on interconnects, imbalanced RCA consumer gear and power supply leakage from components.

The digital issue is I believe related to the use of switched mode power supplies - which is common these days as they are cheap. These can create noise on AC power which can affect some equipment with less than perfectly designed power supplies. I have not seen any proof of this but my experience suggests that PC's are particularly nasty/noisy - they also vary in demand as a function of processor requirements - simply look at a Playstation - how hot it runs and the tiny size for all the current it takes....

As for RF/EMI - never been a problem for me - so I'd agree with Eldartford that this is a much rarer problem.

Here is a useful resource. Enjoy! BTW - it is great to see some well thought out posts on these subjects - I read your thoughtful posts with interest.

In my own system, I have installed an isolation transformer feeding the subpanel, with separate dedicated lines to each component. To address the issue above, I have put a second isolation transformer on the CD dedicated line to keep its digital hash from contaminating the other components.

This has proved very effective for me, as there is now no difference in the background noise level between the CD player while off, and the CD player playing while muted. If you are contemplating multiple dedicated lines off a single subpanel, I suggest you consider this approach.
12-10-08: Zargon

Zargon,
I was burning the midnight oil last night when I responded to your post. I forgot to address your comments in regards to the use of good isolation transformers.

The application of iso xfmrs as you have is a great way to go. Especially using iso xfmrs on your digital equipment.

Cellphones and cordless phones emit far higher frequencies than the frequency components of the digital hash, other component-induced noise, and power line noise that we have been speaking of. I believe cellphones operate in the range of 800 to 1900 MHz or so, while cordless phones are around 2400 MHz. Audio equipment seems unlikely to have any detectable sensitivity to frequencies above perhaps a few ten's of MHz, and perhaps much less than that.

Also, as you appear to realize, these kinds of issues are likely to be dependent on location, house wiring, system components, system interconnections and setup, and listener.

Regards,
-- Al

Sorry to rain on the parade, but I have been unable to find any evidence of RFI interference with my audio system. I do live in a rural area where the RF energy is probably lower than in cities. However, I have tried activating cordless phones and cell phones within inches of the equipment, with no effect.

Has anyone else done this experiment?

Just to follow up… as I said above and as another has said here… dedicated ckts merely limit the immediate impact of untowards interference from other household appliances, various lighting t-formers, cell phone chargers, etc. They don’t ultimately prevent this interaction… it is more a subdued, or less impactful contact.

BTW… cheater plugs work on thihngs other than audio and video gear, ie., dishwasher,., fridge, phone, faxz, etc. that’s where I put mine… not on my audio gear… and only if those items were also possessing non conductive surfaces.

Dedicated lines and or cheater plugs will not prevent nor eliminate ground loops. To eliminate the ground loop issue find the cause. Generally it comes from your telephone, cable, or satellite equipment… or some other porrly isolated or grounded item. A simple inductor can dispel this issue and why so many simply use transformers of one sort or another.

A minor difference of potential at one ground point, if several or more than one is used, can also cause such an event.

One point of interest here is what was said about the actual length of the ckts themselves. I read somewhere there is a formula for figuring out the db per feet in loss. I don’t recall it now, but I know it happens. This effect occurs using dedicated lines as an added benefit, though it’s seldom if ever expressed as such.

Another item is the cost to benefit ratio… or in other words “overkill”.

Unless we’re talking new construction implementing numerous single serve power lines just isn’t financially feasible for the majority of folks. A few sources, a preamp, mono blocks, and say a sub or two means 8 separate lines…. Which are all tied together at the breaker box anyways, seems of and by itself as overkill to me.

Rather the digital issues should be addressed, if any, at the device… or by a wholly separate and individual power supply and line (s).

As dedicated power lines aren’t prevention measures, and only limit initial impact of other on site problems, look to power conditioning, power isolation, and other grounding measures to further aid the supplied items… and there are still some precautions to be taken doing those tasks… and or find and eliminate, exchange, or replace the culprit causing them.

From an electical engineering perspective, separate dedicated circuits all connected to the same subpanel would all be in parallel with each other. This means that any spurious artifacts from a component fed back into its dedicated circuit would be superimposed on all other dedicated circuits. Other components power supplies would have to deal with these artifacts, e.g., filter them out. In this regard, this approach is not any better than a single dedicated circuit.

I would think that the inductance of the one or two hundred feet of round-trip wiring that is involved is likely to be significant at noise frequencies.

In my own system, I have installed an isolation transformer feeding the subpanel, with separate dedicated lines to each component. To address the issue above, I have put a second isolation transformer on the CD dedicated line to keep its digital hash from contaminating the other components.

Interesting approach! The combination of isolation and bandwidth limiting that the transformers provide would overcome the concerns I expressed about ground loop noise, while still achieving the decoupling benefits of multiple dedicated lines. Excellent! Do you tie the system to a (single) earth ground at some point, though, to keep it from floating relative to earth?

Regards,
-- Al

12-10-08: Kirkus
I'm mostly with Al on this one. The paper that Jea48 refers to is interesting and has some valid information, but there are also some typos and mistakes . . . and I think that some of his conclusions are a little questionable.

Kirkus,
Maybe you are not familiar with Charles Hansen

Charles Hansen - Manufacturer, Ayre Acoustics, Inc.
============================

12-10-08: Zargon
From an electical engineering perspective, separate dedicated circuits all connected to the same subpanel would all be in parallel with each other. This means that any spurious artifacts from a component fed back into its dedicated circuit would be superimposed on all other dedicated circuits. Other components power supplies would have to deal with these artifacts, e.g., filter them out. In this regard, this approach is not any better than a single dedicated circuit.

Many would disagree with you.

In the instance of a sub panel where the sub panel might be installed in a close proximity of the audio equipment where the length of the dedicated branch circuits were very short, then I would agree with you.

Quote from Shunyata Research:

There is up to a hundred feet of wire in the walls, so the last 6 feet of power cord can’t possibly make any difference.

Answer: The PC is NOT the last 6 feet as stated in #1 and the local current and EM effects directly affect the sonic performance of the component. The power cord is not the last 6 feet, it is the first 6 feet from the perspective of the component. The further a noise source is from a component, the less of an impact it will have on the components power supply. The high-frequency noise sources that have the greatest impact on audio and video performance are the system components themselves -- which are usually all in close proximity of one another and all emit radiated fields of high-frequency noise. A well designed power cord can act as a noise-isolated extension of the primary winding of a component’s power supply and will help isolate the power supply from the fields of radiated RF and EM noise energy that is ever present in all electronics systems.

The further a noise source is from a component, the less of an impact it will have on the components power supply.

If you reread Hansen's article you will find he is basically saying the same thing
.

I have read on many occasions various AGON members stating that in effect "separate dedicated circuits alone help decouple components from one another".

From an electical engineering perspective, separate dedicated circuits all connected to the same subpanel would all be in parallel with each other. This means that any spurious artifacts from a component fed back into its dedicated circuit would be superimposed on all other dedicated circuits. Other components power supplies would have to deal with these artifacts, e.g., filter them out. In this regard, this approach is not any better than a single dedicated circuit.

In my own system, I have installed an isolation transformer feeding the subpanel, with separate dedicated lines to each component. To address the issue above, I have put a second isolation transformer on the CD dedicated line to keep its digital hash from contaminating the other components.

This has proved very effective for me, as there is now no difference in the background noise level between the CD player while off, and the CD player playing while muted. If you are contemplating multiple dedicated lines off a single subpanel, I suggest you consider this approach.

I'm mostly with Al on this one. The paper that Jea48 refers to is interesting and has some valid information, but there are also some typos and mistakes . . . and I think that some of his conclusions are a little questionable. With ANY of the Audio Express, Audio Amateur, Glass Audio, etc. articles, I HIGHLY recommend also reading follow-ups in the "letters" section of the following issue(s), as there is frequently a bit of ongoing dialogue. I definately would NOT just take them as gospel, simply because they're published in an audio magazine.

But there are cases, esp. with multiple high-powered amplifiers, that I can see some benefit to having multiple circuits run. But if all of the issues that Al mentions aren't taken into account when the circuits are wired, then it will likely make things worse.

In professional sound, lighting, and video, multiple circuits and distros are usually required simply to provide anywhere near enough current . . . not to mention a combination of house and generator power. This is also usually the main portal a grizzly parallel dimension of horrific shocks, sparks, and humm that knows no ends . . . so for a domestic system of modest power requirements, a single dedicated circuit avoids a LOT of pitfalls.

Jea48 -- That was an excellent paper; thanks!

However, it does not really address my question, which as you appear to realize was about having MULTIPLE dedicated lines powering different parts of the same audio system. The author describes his own setup, which has a single dedicated line running to a receptacle into which he plugs a diy power strip + switch. He does provide some good information as to connection order, such as connecting the power amp to the end of the strip closest to the incoming ac.

I understand your point about decoupling the power supplies of each component from the supplies of the other components, particularly to isolate digital components from analog components. But I'm uncertain how to reconcile that with the concerns I expressed, about ground loops and the possibility of having ac ground points that are offset from each other at least at high frequencies.

When I get a chance I'll try to take a look at the AA archives you mentioned.

Thanks again,
-- Al

12-09-08: Almarg
Can someone offer either a technical explanation, or at least some persuasive anecdotal evidence, to explain the claim that running multiple dedicated lines to the different components of a single system is beneficial.

Almarg,
Check out page 4. The Ac Power Line and Audio Equipment. Part 2

Digital equipment is the worst. Separate dedicated lines helps decouple the power supplies of audio equipment from one another.

If you search the archives over on AA you will find EEs that discuss the technical benefits of separate dedicated circuits for analog and digital equipment.
.

Thanks for your response. I have lots of info to share with my sparky!

RE Another breaker box?

No. Well, not necessarily. Depends on the breakers actual physical nlayout. are there any blank (unused) spaces? If so your job will be much easier. Also the actual width of standard breakers (if used) allows for some hidden growth by using half sized breakers. Though physiccally half the size they'll carry the same current load and work as effectively.

Standard size is about 1/2 inch across. There are half size breakers called waffer breakers. By removing the standard sized one and inserting two half size ones, you'll gain one additional circuit. Remove two std, and gain two ckts using four waffers.

The main consideration here is this... the current load of the breaker box. Usually there are blanks (unused) spaces in any new installation put there for growth such as this desire. Adding a couple 20a breakers there in std size might be OK. provided there are blanks preexisting. otherwise the choice is this... a sub panel as was said, or the use of waffers.

I can't actually for true tell you that adding a couple half size breakers to gain two added ckts is safe, or right for your situation. I'd need to be there for that... so call one of your electrican friends to come over and have a look first.

I've done it myself in other homes though without issue... BUT TO BE SAFE AND SURE... SEEK OUT A QUALIFIED LOCAL SPARKY TO TAKE A LOOK SEE FIRST.

Where the waffers, if used, are placed (which phase) is a little important too. I had mine put on the lighting phase, instead of on the side supplying all the appliances. As well and if possible placing the new ckts closest to the incoming feed to the panel (top or bottom, depending on the panel) will help too. marginally in some cases, more so in others. Depends on the adjacent ckts.

usually, 'Sparkies' will say it doesn't matter, by and large.

Were I to add a sub panel I would also add an isolation transformer supplying that newest panel too. There are transformers which will also condition better the power incoming and passing thru it as well as isolation from the rest of the household effects.

Lastly, when ya add these new receptacles - ckts, think about adding four outlets to each vs. two, on one or both of the new lines. One never knows what one might need later.

Call an electrician first, in any event.... even if you wind up doing the work yourself.

Can someone offer either a technical explanation, or at least some persuasive anecdotal evidence, to explain the claim that running multiple dedicated lines to the different components of a single system is beneficial. As I indicated in my earlier post:

"I'm uncertain about the concept of having multiple dedicated lines for different parts of the system. I would be concerned that voltage offsets could be introduced between the grounds of the different components, which could lead to ground loop noise. Same goes for having parts of the system on a surge suppressor, and other parts of the system on a different suppressor or no suppressor -- the result would be some degree of isolation between the ac grounds of the different components in the system, at least at high frequencies, due to inductive filtering in the suppressors, and inductance in the house wiring, which might cause ground loop issues."

Regards,
-- Al

3 prong 15 amp outlets are under a buck a piece - 20 amp outlets are about $5 each.
You will need a sub panel to run your dedicated lines.
While you're at it: You may also want to run another dedicated line to run your TV/AV/HT system in another room.
If you're using monoblock amps - 3 dedicated lines would work best - 1 for each amp & 1 for a power conditioner.
All the best

My house has the old two prong outlets, so i'll have to change those out.I know i could use a cheater plug, but i'd rather put in new outlets. I checked the breaker panel and there aren't any extra breakers,so that does that mean i need a new breaker panel in order to install new lines?

Dedicated lines are a good thing... but not the best solutions of and by themselves.

Dedicated lines merely limit added issues from the rest of the household. remember, ultimately, the neutrals and grounds are tied together. Even still, dedicated is good.

I have 4 dedicated 20A ckts, but use mainly 3 of them. I put better outlets on those 3 too. Nothing fancy, just hospital grade.

Power conditioning, passive or active works. Current and bandwidth limitations are noteable items to look for when selecting the type you desire.

I use passsive filtering/conditioning on all my main rig devices. preamp, power amps, sources, etc. Albeit, different filters for sources than for power trains.

Many do plug amps right into the dedicated wall sockets. Better? Try that first and see how you like it... then add a conditioner of sorts. Then you will actually know what's best for you and your gear.

Lots of ways to go here. Many roads lead to Albuquerque... or is it Rome.

I just had a new audio room wired and brought in two 20 amp dedicated lines to PS Audio Power Port receptacles for amplifiers and two 15 amp dedicated lines with hubbell receptacles for other electronics. It may be a little overkill but I only wanted to do it once.

Well... these responses give me something to think about. I will check ou that Almarg suggested.BTW DrummermItchell- I would assume by your moniker that you play drums. I have been playing off and on (mostly off) for the past 40 years.I should say i make noise rather than play drums.

It definately makes sense to have dedicated Lines,
no extra hitchhikers on your audio lines.I wouldn't want noisy dimmer switches,fridge,micro, ect.messing with audio power.I have subpanel(dedicated 4-15a breakers.4 double receptacles and 2X240v for my Torus PIUs.I did like the
dedicated 15a or 20a(great)BUT I discovered also that amps
like more amperage ,when it comes to music peaks.If I'm correct,Torus PIUs can give up to 100a or 400a(short term)
in reserve power.When I installed a 20a Torus,everything came out with authority,more bottom, ect.I do at times upgrade the odd piece,but the Torus are keepers.they are pricey,but musically,I cant put a price on the satisfaction.
There are alot of conditioners out that can only give what the wall can give(non limiting current,as far as the wall) and some that ruin the music side ,for me that's fine,but I want more,so do my amps.The Torus gives me lots of extra POWER in reserve.
WHAT AN ADDICTIVE HOBBY,BUT SHE"S SATISFYING

You will find a good part of the following thread to be relevant to your questions:

http://forum.audiogon.com/cgi-bin/fr.pl?ymisc&1228674146

As you will read there, recent (but not some older) 20 amp receptacles have a T-shaped slot for the neutral prong, which allows them to accept both 15 amp and 20 amp plugs.

I agree with LK that I would not feel comfortable plugging directly into the wall. I would want the protection of a surge suppressor, that is dedicated to the audio system.

I'm uncertain about the concept of having multiple dedicated lines for different parts of the system. I would be concerned that voltage offsets could be introduced between the grounds of the different components, which could lead to ground loop noise. Same goes for having parts of the system on a surge suppressor, and other parts of the system on a different suppressor or no suppressor -- the result would be some degree of isolation between the ac grounds of the different components in the system, at least at high frequencies, due to inductive filtering in the suppressors, and inductance in the house wiring, which might cause ground loop issues.

The need for a line conditioner (as opposed to a simple surge suppressor) will, as LK indicated, depend on the quality of your ac supply, and also on the designs of the power supplies in your particular components. There might be less need for one if you have a dedicated line, as you stated (depending on whether the significant noise sources are elsewhere in your house, or if the noise is present on the wires that come into your house). Other people's experiences can initially point you in what are hopefully promising directions, but a conclusive determination can only result from trial and error, imho.

Regards,
-- Al

optimum setup is one dedicated line for digital or turntable and one for the amp, rest of gear etc. 20 amp lines are best. use of a power/ line conditioner depends on the quality of your juice but generally will help if you get the right one. surge protection is usually built into many line conditioners but it's good to have a surge protector installed on your fuse-breaker box in case of lightning although nothing protects from a direct hit. plugging amps into the wall is a subject of debate over what sounds best but I like the peace of mind not plugging direct into the wall.