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How to hook up dedicated power to your listening room.


Tyll Hertsens

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I'm setting up a listening room and need to run a dedicated power line to it. So I'm starting this thread to talk about how to do that.

I assume I have to ohm out the lines going to my breaker box and then figure a way to separate some of the power lines going to that room.

Then I have to install a new breaker for that circuit, and wire the ground differently for that breaker to a ground rod outside hammered into Mother Earth.

Is that right?

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I don't think you want to do a ground rod, but I'll let Kevin or someone with more experience weigh in on that. +1 on running new wiring, and probably plan for 20A circuits.

Getting a low ground impedance is harder than you might think, and depends on the soil resistivity where you are. In good wet ground it can be as low as 500ohm-cm. In sandy or gravelly soil it can be up to 10,000ohm-cm

Assuming the worst cast of 10,000 ohm-cm, and a 1" diamter rod buried 20 feet deep has a ground impedance of 18 ohms. 6" diameter buried 100 feet deep (and try driving that in!) gets down to 3.4 ohms. So it is very difficult to get a low impedance to ground with a single rod.

One way to go for a prectical set up is to use an array of rods. 20 rods half an inch diameter buried by 8 feet and with a rod-rod spacing of 8 feet gives a (theoretical) 4ohms in 10,000 ohm-cm soil. You can buy rods like that easily.

All this stuff is from Grounding and Shielding Techniques in Instrumentation, 3rd Ed, by Ralph Morrison.

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The psaudio powerplant can in some cases cause more trouble than it fixes.

Plus it is limited in power. Would never work on my stack of krell.

I did a one inch diameter solid copper ground rod 12 feet long. Beat it

into the ground with a 10 lb sledge hammer. Took quite a while. Attached

it to a 6 gauge stranded copper wire and ran that into the side of the

house next to the media room. Pounded the rest of it in about 6 inches

under ground to make sure my quality landscapers did not hit the thing

with the lawn mower. Its about one foot from the side of the house.

Its stuff like this that has caused me to bust up my left elbow.

My new very overpowered snowblower has caused me to bust up my right

elbow.

Balanced and highly isolated power is the only way to go. Massive

donuts for the win.

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So, Kevin, do I tap into the mains prior to the breaker? Just guesing here: install new breaker; run cable to room; hok up to wonking great doughnuts; run to dedicated floorboxes in room?

Also, run new ground to room and install ground on tranformer secondary?

Sumpin' like that?

Oh, thenks Craig. I'm somewhat aware of the problems getting a good earth ground, but your comments put a point on it. oil at my house is fairly rich loam and moist. I have a low spot the run along the back of my property and should be fairly moist and soft. I'm wondering a bit abwout how long a run it is to the room; likely in the neighborhood of 100 feet. Fat cable should be fairly low resistance though, I'll have to lok that up. Am I shooting for some nominal acceptable resistance to ground? 10...1...0.1 Ohms?

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Add 220 volt breaker to mains box. 30 amps should do it.

Buy one of the balanced transformers, say 5kw or more.

220 volt primary, 110 volt balanced secondary.

If you were in illinois, you would be required to put

everything into conduit. Which also includes the

donut inside a nema rated box.

Keep the donut as far away from the music room as practical,

the things buzz and have a gigantic magnetic field.

Basements are a great place for these if you have a basement.

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I have read advice suggesting running two lines from the two halves of your balanced power feed (They're not phases. I don't know what they're properly called), then splitting the load between them. One monoblock to one, one to the other, sources to one, whatever. Given that I would have to disassemble half my house to run new lines, I haven't tried it, but it seemed reasonable at the time I read it.

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sho''nuff.

Also, I think it would be interesting for a future article if you kept notes about the process. I always read about reviewer's dedicated power lines, but never about the process or behind the scenes of the installation.

Here is one Dinny: http://www.6moons.com/audioreviews/theroom/1.html

I know groan 6moons, but it is a good read.

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  • 2 weeks later...

Having a good Ground is important, but I'd emphasize that IMO even more important is that all Outlets and or Circuits that the System is plugged into have the Same Ground Potential. My main system uses 2 dedicated 20 amp circuits (1 each for the mono Amps) and 1 dedicated 15 amp circuit for the Front End. Since I live in a 2nd floor loft in a building that I don't own I couldn't mess with the Ground that has been provided to my panel. What I could do was make sure that all of my connected equipment is seeing the same Ground.

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Having a good Ground is important, but I'd emphasize that IMO even more important is that all Outlets and or Circuits that the System is plugged into have the Same Ground Potential. My main system uses 2 dedicated 20 amp circuits (1 each for the mono Amps) and 1 dedicated 15 amp circuit for the Front End. Since I live in a 2nd floor loft in a building that I don't own I couldn't mess with the Ground that has been provided to my panel. What I could do was make sure that all of my connected equipment is seeing the same Ground.

The other good idea is to route all the power cables closely together. That minimises the loop area that could inject airborne RF interference into the ground, or radiate common mode interference that is coming up the power or ground lines.

Might be worth trying an air cored toroid in series with the overall ground. That way you keep the protective ground connection, but now have a high frequency block to stop utility ground shit from getting up the earth. Make a wooden donut maybe 6 inches in diameter, and wind as much heavy gauge green/yellow wire as you can around it. Wire in some very safe manner in series with the overall system ground.

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