Fine Tunes #23

Reader Bill Huey reminded me recently that I'd promised to cover pre-War buildings that have hot and neutral electrical service but no ground. Why the rush? Bill was about to move into just such a dwelling. (Hey, never mind the furnace and the roof—what about my stereo?!)

One thing you have to understand: If you don't have ground, ya gotta get it! There's just no fast'n'easy way around it. And, once again: If you don't know what you're doing, call an electrician. Deep-fried audiophiles cannot subscribe to Stereophile. (No, that's not the only reason I love you.)

Trying out the effects of properly grounding your system can be "Fine Tunes" cheap, but installing a proper ground can run you a few hundred well-spent bucks. Here's the poop on bringing Mother Earth into your listening room.

A very inexpensive way to establish a ground is to do as we do in our 100-year-old loft building: Find a cold-water pipe, clean it up at a convenient point, and fasten a tight-fitting coupler around it. You'll find commercial products for this application that have a big nut on top for establishing a good connection with the ground wire. It has to be a cold-water pipe—hot water passes through a water heater and so loses its ground.

If you set up this type of connection, don't forget the Pernicious Galvanic Effect: the tendency of dissimilar metals to react chemically with each other and thus cause noise or a voltage drop. If you're using an old iron pipe, pick up an iron coupler. The same applies for copper—use a copper coupler. If you think a cold-water connection is strictly Mickey Mouse, remember that the Utilities themselves have been using this technique for years.

If you live in a renovated building, check with the Powers That Be. If the water-supply lines have been replaced, it's likely that the cold-water connection from your building to the municipal supply uses a modern plastic coupler. There goes your ground.

Using a water pipe [snicker] makes experimenting with grounding quick and easy: Just strip a couple of inches off the end of a cheap roll of RatShack jacketed copper wire and wind it a few times around a cold-water pipe. Run that to the grounding post on your preamplifier and listen for its effect.

If you use this method, run a length of thick copper wire from the coupler to a point near your receptacles. We routed ours along the back of a closet that opens almost directly on the system. Then we loomed equal lengths of beefy copper wire from the back of each of the eight hospital-grade duplex sockets to the heavy-gauge bus bar snaking back to the coupler. These grounds serve dual-quad 20-amp receptacles for the front-end components, and dual-quad 30-amp sockets on a separate run of BX cable for the amplifiers.

Using equal lengths of conduit to the breaker box eliminates the potential for hum caused by unequal ground currents riding the lines. Kathleen actually pulled the BX cable through the ceiling/roof crawlspace. What a babe—she came out looking like a chimneysweep! (You're right, I have no idea how I got so lucky, and no, I certainly don't deserve it!)

Another trick for "capturing" ground in a pre-War building involves cable TV. By law, cable providers are required to establish ground at the point of entry into the building. That's what causes some integrated audio/video systems to buzz like bees: two separate grounds equals one unhappy audiophile. Never fear, a number of video products are available that isolate the grounds—Mondial's Magic, for instance—and ensure peace in the household. Your local Sing The Body Electric professional might be able to tap into the cable's ground for your system's use.

Perhaps a better, if more expensive, method for establishing ground for your system (not your abode) is to use an electrician and have him or her install a composite grounding rod directly into terra firma. Run a ground wire from that ground rod to your listening room. The rods aren't pure copper, by the way—a common misconception. A copper spike would interact with the soil and form an oxide coating that would actually insulate the rod from earth. Exactly what you don't want.

However you find it, ground should be established directly within isolated duplex receptacles with a screw-down connection on the socket itself. Isolation is important; cheap sockets can derive their grounds through the attaching screws of the metal box within the wall. Theoretically, a ground wire will be attached to that box, but sometimes, in slap'n'dash construction, it's not. Still, you might get ground with a box like that from the metal conduit carrying the wires through the wall back to the breaker box. An uninsulated socket used for your new ground would probably develop a bad case of hum because of the difference in potentials between the lines—just what you want to avoid.

A related tidbit: Most people don't realize that a ground line is simply a redundant neutral/return circuit. In fact, in the average breaker box in the average home, neutral and ground are probably clamped beneath the same ground bar. They should be at the same potential, but they usually aren't, for a host of reasons previously covered in "Fine Tunes."

So you might think your building is without ground—your sockets may be only two-bladed—but it may, in fact, have a ground through the BX conduit or a ground line attached on the receptacle box. You never know what you'll find, especially in pre-War buildings—another good reason to consult a professional and insulate your receptacle. (Ahem.) Reader Huey did it:

"Thanks, J-10. I'm finally getting a dedicated line with isolated ground for my new listening room."