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The Downside to Dedicated Lines vs. the Benefits

From an AC power grunge perspective, my main system currently seems very quiet. That is, I don’t have any ground hum issues, and I have to raise the gain fairly high and then get my ear quite close to one of the speakers before I can detect any hiss or other noise. It is truly the quietest system I’ve ever had experience with. Never the less, I do know that paying attention to AC power issues can reap other benefits, including an improved soundstage, imaging, better dynamics, etc.

I built this system from the ground up about a year ago and am now at the phase where I’m beginning to work on optimizing it. Back when I started planning it out, there was no question that I would be putting in a couple of dedicated lines. However, now that I’m at the point where I’m about to begin the project, and after a ton of reading and research, I’ve begun to have some serious reservations.

My concerns are mainly over the potential for introducing (or increasing) ground or ground-loop noise and/or hum. From what I can gather, powering interconnected components (especially non-balanced, or single ended, components) from multiple circuits, whether dedicated or not, raises the risk of this occurring.

I also understand the type of components as well as the system’s overall configuration plays a part as well. If I could summarize the details of my system and get some opinions about whether I run the risk of messing with an already good thing, I’d be very grateful.

The majority of my gear sits in a metal rack (Middle Atlantic) in an enclosure located directly behind the front wall of my listening room. XLR cables feed through the wall to a couple of mono amps that sit in the listening room near the speakers. The system currently doubles as a HT and 2ch rig and, as with most folks here, will no-doubt evolve and experience its share of equipment changes. As such, there’s a good chance I may not have a fully balanced system at any given point in time.

Right now, all of the audio gear, a cable box, an active sub, and a 60” plasma TV run off of one 20 amp circuit. There are various other wall-wart devices using the circuit as well (computer switch, rack fan, the receiver for my RF remote control, etc.) There might be a couple of incandescent lights that run on it too, but no other devices or equipment.

Everything currently runs through a couple of top-of-the line Belkin ‘Pure Power’ UPS/Surge Suppress/Conditioning units. Plans always were to repurpose these units after the dedicated lines were installed. However, considering the virtual lack of AC grunge despite all that’s plugged into them, I’m amazed at what these units are capable of.

If I do go ahead with installing the dedicated lines, I would put in a 100 amp sub-panel in the room that houses the rack. I’d need to pull about 80 feet of wire back to the main panel. (BTW, I don’t know much about the electrical trade, so if someone could offer guidance on what type of cable and gauge I should run, I’d appreciate it.) I’d then run 10/2 cryo’d romex (just because) out to three or four audiophile grade duplex outlets. Unfortunately, with where I’d be putting the sub panel, an isolation transformer wouldn’t be practical.

I would like to keep the existing branch circuit in place, and plug all the non-audio gear into it via the existing Belkin units (wall warts, cable box, TV, etc.) The front end equipment, sources, sub, and amps would go on the dedicated lines… directly at first…but eventually I’m sure I’ll end up trying one or two of the better power conditioners that are often sold here on Audiogon.

Now…from all that I’ve read, it appears that the above configuration could be prone to ground noise/hum issues. If I’ve correctly understood a publication that Middle Atlantic has out, a large part this potential comes from the fact that the metal rack serves to interconnect all the components stored in it.

What I’m concerned about is this. Since these interconnected components will be plugged into different circuits…i.e., a branch circuit that terminates at a panel 80 feet away, while the rest will use dedicated circuits that terminate a few feet away at the sub panel….will I end up with ground loop noise issues? As I said, the system is already very quiet and I would hate to lose more than I would gain.

Is there any wiring strategy that might help avoid it? I’m not sure I exactly understand the concept, but if I told my electrician to ‘star ground’ the dedicated lines, would that be enough? Should I instead think about putting the subpanel closer to the main panel? On the other hand, would it be better to not risk it and instead invest in one of the uber-top of the line power conditioners, or perhaps a power regenerator?

Whatever opinions or advice I can get from the Audiogon community would be appreciated.
shutterman
dlcockrum's avatar
dlcockrum
2,105 posts
 
Two factors to consider:

1) Done properly, it is good to run analog and digital components on different lines on the same phase of the fuse box.

2) How much current does your amp(s) draw? If it is a high power model, it will benefit from having its own 20 amp line.

If you want to isolate your analog equipment from the digital (without a power conditioner) and your amp really needs its own dedicated 20 amp line, then you will need 3 lines!

I have not used the Belkin units but I strongly suspect that you will find after installing dedicated lines that your system will sound best without them (it probably will sound better without them now).

If surges are your concern, then use the blue whole house unit that has been recommended numerous times on Audio Asylum.

If you must use a power conditioner (don't just assume that you do), you are right to only consider the SOTA: Synergistic Research Powercell 10SE, Audience aR6-T, etc. You would want to run all of your components through these for maximum benefit (only need one "strong" 20 amp line).

Running two lines is indeed not significantly more expensive that running one as others have said. If it works out the your system works better through a single line, you really haven't lost much money.

The trick to eliminate ground loops is to run all of the lines powering your equipment to the same phase (leg) of ground in your fuse box. It is also a good idea to isolate all of the "noisy" lines on the other phase from your equipment. Your electrician should understand this readily.

Minimizing ground leakage as perfectly described by Inline phil is also a worthwhile exercise.
bigamp
216 posts
 
Interesting post, and timely. I am involved in a very similar scenario at the moment. There seem to be two conflicting lines of thought here. The first says put everything on one circuit. The second says separate out digital and analog. And what if you have two channel system combined with an HT system? This seems to compound the issue -- do you put your receiver, cable box, and DVD player on the "digital" circuit or does this taint your hi-end CD player's circuit? Seems like there should be a universally-accepted answer on this issue.
stanwal's avatar
stanwal
3,147 posts
 
LOL, Bigamp. Quick, name ONE universally accepted answer in audio. I have two dedicated 20 amp lines and usually try to separate the analog and digital. Despite having 2 BPT power strips I usually have too many of one to segregate them. Perhaps there is a valid theoretical answer, perhaps not; but the best application will very with your system, try it as many ways as you can and see what works the best for you.
shutterman OP
7 posts
 
"The trick to eliminate ground loops is to run all of the lines powering your equipment to the same phase (leg) of ground in your fuse box. It is also a good idea to isolate all of the "noisy" lines on the other phase from your equipment. Your electrician should understand this readily."

Understood. However, in the configuration I've detailed above...wouldn't the fact that I'd have interconnected equipment (via the metal equipment rack) on a mixture of a branch circuit plus dedicated curcuits still not cause an issue?

The existing branch circuit (which will continue to feed the cable box installed in the rack, the plasma TV in the other room, the wall wart devices, etc.) is terminated and grounded at the main panel 80 feet away. The dedicated lines would terminate, and I assume be grounded at, a subpanel less than 10 feet away.

I understand that the subpanel itself is then grounded back to the main panel, but wouldn't I still essentially end up with interconnected components (via the rack) sharing two different circuits...circuits that are initally gounded at two different places? If so, wouldn't this establish a large ground loop?

As far using the same phase or leg is concerned...as long as I tie the sub panel to the same leg that the branch cucuit is on, will everything in the sub panel then be on the same leg? Or should I alternately space the wiring(i.e., skip a breaker row) within the sub panel?
jea48
2,944 posts
 
The existing branch circuit (which will continue to feed the cable box installed in the rack, the plasma TV in the other room, the wall wart devices, etc.) is terminated and grounded at the main panel 80 feet away. The dedicated lines would terminate, and I assume be grounded at, a subpanel less than 10 feet away.
09-17-09: Shutterman
If you are going to install a sub panel, feed all audio equipment that will be inter connected by ics from the sub panel only. Any thing fed from the 80 ft branch circuit and connected by ics to equipment fed from the sub panel will surely cause ground loop hum, jmo.....
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