Fine Tunes #10 Page 2
So, what to do? The first, easiest, and best way to avoid ground loops and improve the sound of your system in one fell swoop is to run all your components on the same AC line. A single-supply outlet box with a single low-impedance (you hope) ground connection to the breaker box solves many ills. If the preamp, for example, is getting its ground from one outlet while the amplifier is referencing ground at another—one that may be closer to or farther away from the breaker box—the two grounds are unlikely to be at the same potential. Hum a few bars, baby. All wire has electrical resistance, and all currents passing through that resistance manifest a drop in voltage. Depending on where the voltage drop occurs, you'll be faced with more or less hum. Multiply that effect across whatever number of components you have on separate outlets. You'll most likely wind up with different ground potentials at different outlets, the fracas finally converging at your breaker box. And the longer the individual runs of the common resource—the ground—the worse the potential problem becomes. Bottom line, you want everything in the system to be as close in ground potential as possible.
There are many high-quality audiophile outlet extenders on the market. But since "Fine Tunes" concerns itself with low- or zero-cost improvements, I'm here to tell you that RadioShack's power strips are not terrible. So without any sort of major capital investment, it's easy to try the single-line scheme and see what it does for you.
It's going to take me a few columns to fully describe the best ways to ground your system, but for now, I suggest the following. As above, try to run all or most of the system on one good outlet. If you don't have a dedicated 20 or 30 amp line (watch those building codes), run your amplifier from another AC socket, but make sure both sockets are on the same phase of positive as described in the March "Fine Tunes." And don't pollute your audio power line with anything like halogen lamps on dimmers—they're the worst when it comes to injecting radio-frequency hash into your system.
Another tip about power extenders: Connect components starting with the largest power draw, and work back to the lowest power consumer. Keeping high-level audio-signal carriers (amps, CD players) together and doing the same with low-level components (preamp, phono) can be helpful. We'll consider electrical isolation of components in a subsequent "Fine Tunes," but here's another tip worth repeating: Pull the interconnects from your digital front-end when enjoying analog, and vice versa.
I believe we can now say that you have a basic grounding in this vexing subject. badaBOOM! (It's been a while . . . )
To minimize differences in ground potential, the individual components in a system should be plugged into the AC power source in parallel (top). Indiscriminately daisychaining power strips (middle) can introduce noise into low-level circuitry via the ground connection. Alternatively, connect high-current components closest to the wall outlet and sensitive equipment furthest away (bottom). (Diagrams after the Nagra PL-P handbook.)