advice on dedicated line

Good comments by the others. I agree that two lines should be adequate for your relatively low powered system. I would add that experimentation with what components are plugged into which line could very well be worthwhile. And it is even conceivable that you could find that best results are obtained with the entire system connected to just one of the dedicated lines.

I say that because while on the one hand connecting power amplifiers and digital components to a separate line from the one powering components that generate or process low level analog signals can minimize coupling of electrical noise from the former to the latter, a tradeoff may come into play, depending on various factors such as the internal grounding configuration of the specific components. The tradeoff being the possibility of increased susceptibility to ground loop issues, especially if the connections between components that are on different dedicated lines are single-ended (utilizing RCA connectors) as opposed to balanced (utilizing XLR connectors).

If those interconnections involve analog signals, the symptoms of ground loop issues would be either low frequency hum or high frequency buzz, or both. If those interconnections involve digital signals, the symptoms would be more difficult to predict or identify, but may involve a general reduction in clarity, to an unpredictable degree.

As far as surge suppressors are concerned, for optimal protection you should have one for each dedicated line. Again there is a possible tradeoff, however, as some people find that sonics benefit from having their power amplifier plugged directly into the wall, with no surge protection or power conditioning.

I and a number of other members use this $259 8-outlet BrickWall surge suppressor/line filter with excellent results. Note that it provides some degree of noise filtering between each of its four duplex outlets, as well as between those outlets and the incoming AC.

Best regards,
-- Al

Margot, I believe that as you appear to suspect the statement does seem to imply that if two dedicated lines are being used, the safety ground connections of their respective outlets (the U-shaped openings of the outlets) should be connected together, and in turn wired through a single ground wire back to the circuit breaker panel. However, I feel pretty certain that if that is what the statement intends to indicate, it is wrong.

While I am an electrical engineer and not an electrician, I suspect doing that would be neither code compliant nor proper practice. I suspect that your electrician will tell you that each dedicated line has to have its own safety ground connection running back to the panel together with its AC "hot" and neutral wires. (The "hot" connection, btw, being the smaller of the two vertical slots on the outlet, and the neutral connection being the longer of the two vertical slots, which is T-shaped on a 20 amp outlet).

Hopefully one of our electrician members will comment further.

Best regards,
-- Al

I doubt that there is much likelihood that having a 15 amp breaker instead of a 20 amp breaker would ever make a meaningful difference with respect to protection of the equipment, especially given the protracted breaking times circuit breakers generally have for marginal overloads. The fuses in the components are primarily what protect the components. The breakers are there primarily to protect against overheating of the house wiring, and to protect against the possibilities of electrocution or fire that might otherwise result if an insulation failure in a component were to cause a short between AC and chassis.

Yes, two 20 amp lines, or even one 20 amp line, is certainly overkill with respect to the current requirements of Margot's system, and the majority of other systems. However, the associated heavier gauge wiring, and perhaps also the more substantial outlet and breaker, could conceivably provide a sonic benefit by reducing both AC voltage loss and AC voltage fluctuation that would occur in the wiring as a result of the fluctuating current draw of the system, particularly of the power amplifier.

So while I see the possibility of a benefit from having a 20 amp line rather than a 15 amp line, albeit perhaps a slim one, I see no downside.

Regarding two lines vs. one line, as I indicated above there are tradeoffs involved, which don't have much if any predictability. And experimenting with different configurations of what is plugged in where is arguably the only way to assure optimal results. So if Margot is going to the trouble of having one dedicated line installed, I see no reason for her to not have a second one installed at the same time, thereby providing the flexibility to try different configurations.

Best regards,
-- Al

TLS, thanks for the inputs.

02-08-14: Bifwynne
In your opinion, does the Brickwall surge protector constrict the amp's access to AC wall current to any significant extent, at least to the point where I might be able to detect a change in sonics?

Bruce, I've never performed any carefully controlled experiments to assess that in my system. And in any event I would not want to extrapolate results in my system to other systems, especially those that include Class D amplification (for which AC current draw fluctuates dramatically with the dynamics of the music), such as you have in your subwoofer.

As I'm sure you realize, there are undoubtedly some audiophiles out there who would contend that it degrades the sound big-time, and others who would contend that it is completely transparent. And undoubtedly there are some who would reject it "a priori" because it does not have a detachable power cord that can be upgraded. I chose it after weighing the opinions and experiences of many others, as well as its design characteristics, which to me are suggestive of a "less is more" approach to line filtering, while of course taking its price into account.

In your opinion, how much risk is there that an AC power surge will and could take out my amp. I live in the Philly area and am tied into a large urban utility grid. And yes, we are affected by occasional power outages, especially weather related (e.g., most recently resulting from the snow and ice storms affecting the NE).

Your guess is as good as mine. I suppose a good answer would be that the risk is minimal but not negligible.

On balance, do you think the risk of unprotected AC access outweighs the benefits of direct AC access, sans artifacts?

Personally I would not want to have any expensive audio equipment unprotected, but obviously that's a personal decision that each audiophile has to make for him or her self.

Best,
-- Al

Its been mentioned many times to have the digital components on their own dedicated line.... Why is it recommended not to share the same AC line as analogue components?

The most significant generators of electrical noise in most systems are components containing substantial amounts of digital circuitry, and power amplifiers. Some of that noise will be fed back into the power cord of the component which generates it, from where it will to some degree propagate through the power wiring to analog components, with unpredictable but potentially perceptible adverse sonic effects.

Everything else being equal, the longer the wiring path is between the power cords of noise generating components and components that may be susceptible to that noise, the more that noise will be attenuated. The most significant reason for that perhaps being the inductance of the wiring. The inductance of wiring is proportional to length. A given amount of inductance presents an impedance which is proportional to frequency. Electrical noise generated by digital circuitry tends to be at very high frequencies, and therefore can be significantly attenuated by the inductance of a substantial length of wire.

Secondly, is a surge protector using isolated receptacles an alternative?

It's certainly an alternative to consider and/or try, and in fact that's what I do with my CDP, which is the one digital component in my system. How that approach would compare with having a digital component on a separate dedicated line can't be predicted with any certainty, as it would depend on many unpredictable and unknown variables, including the technical characteristics of the noise generated by the particular digital component, how the particular analog components would react to that noise, the characteristics of the filtering that is provided between receptacles, and the susceptibility of the particular components to ground loop issues if they were to be put on separate dedicated lines.

Best regards,
-- Al

Jim, thanks for chiming in. Margot, Jim (Jea48) is the foremost expert on electrician-type matters on these forums.

To answer some of your recent questions:

Would it be workable for me to get 6 outlets instead if 4 in case I ever wanted to plug in a small fm receiver to listen to the news? Or is that pushing my luck?

That may be within reason, but as Lowrider indicated it would probably be simpler and better to expand the number of outlets with a power strip. The one he referenced includes a surge suppression function, as does the more expensive BrickWall device I suggested earlier. If you wanted to further expand the number of outlets provided by a surge suppressor/power strip, you could plug into one of its outlets a simple but well made power strip having no surge suppression or line filtering. I need a lot of outlets for my system, more than the 8 that are provided on the BrickWall, and I use this Hammond power strip for exactly that purpose, plugging it into one of the outlets on my BrickWall. For good measure, I connect relatively non-critical components (e.g., FM tuner, cassette deck) to the power strip, and more critical ones directly into the BrickWall, although I'm not sure that has much if any significance.

The one thing I would not do is to have two power strips that both provide surge suppression and/or line filtering in series with each other. Don't ask me why; just instinct :-)

I am assuming that if I just have one 20 amp line the points Elizabeth initially raised (circuits on same leg, nothing adding to more than 120) are not things I need to worry about.

Correct.

I'm gathering from Al's post above that should I get around to upgrading power cords, longer is better? Is this also true of interconnects?

Generally speaking the standard power cord length of 6 feet or thereabouts is considered to be optimal. In the two-line situation, the benefit I referred to of higher inductance between the power inputs of noise-generating and noise-susceptible components results almost entirely from the length of the house wiring, from the outlet of one dedicated line back to the circuit breaker panel, and from there to the outlet of the other dedicated line. The inductance of the power cords is relatively insignificant.

In the one-line situation, it's possible that having a longer cord on some of the components might be beneficial in some cases, but other effects such as voltage loss might outweigh that.

Interconnects (and speaker cables) are a completely different story. The shorter those cables are the better, if the goal is accurate signal transmission. The one situation in which a longer interconnect cable might be beneficial is if you were trying to compensate for some coloration in the system, such as an overemphasized treble. But a better way of fixing that kind of problem would be to determine and address its root cause.

Is it enough to tell the electrician I want 10 gauge wire? Or do I need to supply him or her with it? If so, where would I get #10-2 NMB? (I assume this is what I want.)

The electrician will supply it.

If I had a turntable that would most likely go on the dedicated line with the amplifier, unless the amplifier was Class D? In that case, the CDp, DAC, and Class D amp would be on one line, and the turntable would be on the other?

The turntable should generally (and perhaps always) be on the same line as the component it is connected to. If I recall correctly you have a Creek 50A integrated amplifier, I presume with its optional built-in phono stage. If so, the turntable and the 50A should most likely be on the same line, with the digital components probably being best located on the other line (subject to experimentation).

I'm pretty certain, btw, that the power amplifier section of the 50A is Class AB, for which fluctuations in AC current draw as a function of the dynamics of the music are mid-way between Class D (very high fluctuation) and Class A (very little fluctuation). See this Wikipedia writeup to get a general idea of what these class designations refer to.

In summary, as you've no doubt gathered by now the life of a dedicated audiophile is not a simple one :-)

Best regards,
-- Al

Minorl, thanks for your comments, most of which I agree with. However, I would respectfully disagree with the following, especially in a situation such as Margot's where the power consumption of the system is not particularly high:

I don't buy the argument that everything must be connected to the same tap on the service panel connection. That is really not true and it is really a violation of code.

Regarding the sonic issues that are involved, see my post here, and the links provided therein (the main one being the ExactPower link, which Jim had called to our attention earlier in that thread). (Ignore the first paragraph of my post, which is on a different subject).

Regarding code compliance, Jim can speak to that more knowledgeably than I can, but it seems to me that the only way a system having typically modest power requirements such as this one could cause non-compliant allocation of loading between the two phases would be if the existing installation were already marginally non-compliant, and the electrician then chose the wrong phase (i.e., the one that is more heavily loaded) for the dedicated lines.

The bottom line: I agree with Elizabeth's initial statement regarding this issue.

Best regards,
-- Al

Great reference, Jim (Jea48), as I'd expect from Mr. Whitlock. And all of the sections you referenced make perfect sense to me. Thanks!

Amazing that it took until the last few years for an explanation and measured verification to finally be presented for "what drives 99% of all ground loops."

I note that rate of change of current is indicated on page 31 as being a significant variable, which reinforces the significance of what I said earlier about not extrapolating results obtained with one amplifier class (i.e. A or AB or D) to other classes.

With respect to the comparison chart on page 35, I wonder what the results would be for the situation that probably exists in many older homes where the metal conduit IS the safety ground connection, for example where older two-prong outlets have been replaced over the years with three-prong outlets, or where a three to two prong adapter is being used, with its ground connected to the cover plate screw. I would guess the results of his test in those situations would be fairly good. I assume, though, that modern code doesn't permit installation of conduit containing only two conductors. Am I correct about that?

I note that the BrickWall I had suggested to Margot is based on the series mode non-MOV technology that is recommended in the paper. And I seem to recall that there may have been some kind of relation between BrickWall and the SurgeX brand he specifically mentions.

Regarding the EP-2050 Dodgealum suggested, having looked at the datasheet and other info on it provided at their website it certainly seems to be a good product, that would be a worthwhile investment in many cases. But as a whole-house protector and noise reducer it appears that it won't do anything to reduce the effects of noise generated within the system, certainly in an application that utilizes a single dedicated line. Also, I note that it lists at $730, plus the cost of professional installation. Also, I would note that the absence of audible noise does not necessarily signify that noise is not a problem. Digital noise has very substantial frequency content far above the audible frequency range, and that high frequency content can have effects within the audible spectrum when introduced into analog circuitry as a result of intermodulation with signal and other effects.

The bottom line would seem to be that given the success many audiophiles achieve with both multiple dedicated line and single dedicated line approaches, and given the system dependency and technical unpredictability of the tradeoff between the possibilities of ground loop issues and inter-component noise coupling, it seems clear to me that there is no one size fits all answer, and in general there is no approach that can be determined to be optimal apart from experimentally.

Best regards,
-- Al

Jim, thanks for the detailed and nuanced answer. Good stuff!

Best regards,
-- Al