Power, what's needed?

I ended yesterday's post asking the question "is filtering enough?" And that question references something basic about the power coming out of our wall–power that isn't perfect. We take for granted the quality of our home's power, just like we take for granted the purity of water coming from our taps. Most electric providers in North America, Europe and parts of Asia deliver excellent, reliable power–at least when it comes to keeping the lights on–not necessarily high quality when high end audio and video are concerned. And that's the part most of us either ignore or aren't aware of. In order to answer yesterday's question we have to first have a little learnin' about the problems we face as designers. The three main issues with AC power quality are: noise, shape, and level. Let's start with noise, it's the most prevalent, the easiest to fix, and the least important when it comes to how our audio equipment sounds. Your home and the power lines that feed it act as one big antenna. Connecting your home to the power lines takes hundreds of feet of exposed, unshielded wire. That wire runs through walls, goes underground, flies above your house to utility poles, heads over to your neighbors, and their neighbors, is spliced, diced, and exposed to every form of radiation our technological civilization has to offer. And don't for a moment think the amount of radiation penetrating your skull at this very moment is low or inconsequential. Unless you live deep in the desert without computers, cell phones, cable or access to radio stations, you are bombarded with a lot of electromagnetic radiation on a constant basis. Hundreds of AM, FM and television broadcasts invade us every second of the day, and that's just the tip of the iceberg: police and fire, cell phones, high voltage power lines, ham radio, air traffic control, radar, intersection traffic sensors, satellite beams, our stereo systems, microwave ovens, AC motors, CB radio, even the damn sun bombards us with electromagnetic radiation. And, at the heart of all this electrical noise, our homes sit out in the open with bare copper wire antenna sucking it all up, injecting it into our sound systems. All this crazy energy can reasonably and easily be reduced by the use of a power filter; more commonly called a power conditioner. But none offer a free lunch. If you'll recall yesterday's discussion about filtering, we remember that too much of it restricts flow. Think of water again. If you want to clean dirt from water, you force that water through a filter. The more aggressive the filter, the more restricted the flow. Cleaner, but pinched off. And the same thing happens with power. There are two types of power filters: series, the most effective (and most intrusive), and parallel, the least effective (and least intrusive). A series power conditioner simply means a filter element (typically a coil of wire and a capacitor) is placed in line - breaking apart the wire so power is forced through the device, like a link in a chain. A parallel filter (usually the same coil and capacitor) is attached in addition to the power wires–not breaking the flow–but redirecting the noise from one wire to the other as opposed to converting noise to heat (as a series conditioner does). Think of a duplex plug–the kind you likely have, with two AC receptacles fed from one wire. When one wire feeds two plugs, that is a parallel connection. An example of a series power conditioner would be our own Dectet, while examples of parallel conditioners would be Shunyata or the PS Audio Noise Harvester. Series power conditioners have to be carefully designed. Too aggressive and they bleach the sound. Parallel power conditioners are the least intrusive sonically, but tough to design and be effective–and they are never as effective as a series filter. Tomorrow we'll look at AC power problems that play a more significant role in audio quality.