Audio Power Industries Power Wedge Ultra 116 power conditioner

Considering that not that long ago there wasn't even a product category for balanced AC line conditioners, we seem to now enjoy a plethora of the critters. Cinepro offers the PowerPRO 20 (reviewed in Stereophile, November 1998, Vol.21 No.11). And Equi=Tech, which caters more toward the pro end of the field, offers one that I have yet to hear. Now Audio Power Industries weighs in with their own approach to the genre.

Why balance AC? The AC grid was developed to safely deliver power over great distances, but it developed at a time when the principal uses for electricity were lighting houses and powering trolley cars. The system that evolved uses a three-wire distribution system: a ground; a neutral, tied to ground; and a "hot" 120V wire. This sort of system is "unbalanced," and can pick up noise along the way since neutral is never precisely at true ground potential. And then, modern appliances such as computers and digital electronics actually dump RFI back into the lines, greatly exacerbating the background noise level.

Balanced AC ain't perzacktly new—I am told golf courses have used a version of it since the mid-'40s. But as the electrical environment has gotten more and more saturated with line-borne noise and RFI, an increasing number of equipment manufacturers have looked for ways to isolate audio gear from the power grid. Some have resorted to battery power, but balanced AC rejects common-mode noise—noise that is picked up equally on both legs of a balanced system—without requiring that the components themselves be redesigned. No wonder it's catching on.

Evil communications corrupt good manners
The Power Wedge Ultra 116 is part of a new family of API products that ranges from the minimalist (2 sources, 2 amps) PWU 112 at $749 to the PWU 116 itself. Unlike API's older Power Wedge models, the new Power Wedge Ultras have nondescript façades. More than anything else, they look like amplifiers—they're housed in sturdy metal cases with nothing fancy showing on the outside other than the Audio Power Industries logo.

Inside, it's a different story. API's Les Edelberg credits Muse's Kevin Halverson with most of the innovative features in the new Power Wedge Ultras. Unlike the PowerPRO or the Equi=Tech, which use a single, large "balanced" transformer common to the entire audio system, the Power Wedge Ultras use individually balanced transformers for each outlet. Why does this offer an advantage? Let's say your entire system is tied into one large transformer. According to API, if any of the components has appreciable leakage back into the powerline, then all of the components connected to the transformer can be affected. Common-mode rejection for the entire system will be greatly compromised.

Each isolated outlet uses a high-quality transformer, which offers substantial improvement over the split trannies shared by the duplex outlets of the original Power Wedges. The new units offer less leakage and heftier outputs than the older API gear.

The Power Wedge Ultra 116 has a bank of four amplifier outlets, one 150W outlet, and five 120W outlets. The 150W and 120W outlets each have three switched configurations: floating, balanced, or neutral.

In most cases, balanced mode (±60V, center grounded) will work best, but not always. Some components are designed to "anticipate" neutral ground reference. This doesn't mean that there's no ground, merely that there's no ground reference in the AC itself. When ground is "floated," the impedance of the equipment attached determines the neutral/ground reference. In this setting, the output is still balanced. The "neutral" or normal setting (120V over 0V, the typical domestic AC setting) is not balanced, as it references ground to neutral, but the component still benefits from the power conditioner. When all else fails, this choice might well squelch ground noise.

This switchable option allows for the widest range of flexibility in eliminating powerline-induced noises. And it's easy to use—no more searching for your cheater plugs five minutes before your audiopals come over. (That's when my system always develops hum.)

Transformers are, by their very natures, superb LF filters, so Halverson and Edelberg took special pains with the HF filtration on the PWUs. Each source outlet has its own fully shielded filter module operating across the line in parallel, and the same is true for the nonisolated amplifier outlet bank. As a result, unlike most powerline filters, the Power Wedge Ultras don't dump the filtered garbage back into the green safety wire, where it can recirculate into other connected components.

If you're thinking that the PWUs seem to take as much care to isolate components from one another as from the AC line itself, you're right. Les Edelberg says, "I believe the components are frequently the biggest culprits in creating this noise in the first place."

That do corrupt my air—I banish you.
Does all of this translate into better sound? That depends on your system, of course. Every audio system is a chain, and we all know the saying about the weakest link. Don't look for the Power Wedge Ultra—or any other line filter, for that matter—to compensate for a component that's dragging your whole system down. It can't do that.

What it can do is allow your components to do their jobs without having to strain against a compromised power system. This it certainly does, and does well. I used the PWU in a variety of systems, and it worked in all of them. Now I don't mean that, all of a sudden, all the noise I'm normally plagued with went away. In fact, I'm not normally aware of any noise. But music sounded more emphatic—the contrasts between loud and soft seemed greater, and textures were more limpid, less grainy.

Does that constitute a huge difference? Not day-and-night, no. But when you construct a system with a certain level of resolution, eliminating anything that stands between you and the music becomes meaningful. And the better the system, the harder—and more expensive—it is to squeeze out further improvements.

In that context, the Power Wedge Ultras certainly performed. When your system includes superb monitors—the B&W Nautilus 801s, for instance—any change in resolution becomes audible. I consistently preferred the sound of the upstream components with the API PWU 116 installed. Plain Chant Parisien (CD, Harmonia Mundi Suite HMT 7901480), by Ensemble Organum under Marcel Pérès, offers phenomenal resolution—the massed voices ring clearly against the acoustic of a large reverberant hall, suspended by enormous masses of air. But with the PWU 116, the voices seemed to float aloft longer. The gradual decay of the acoustic lasted, or at least seemed to last, longer, and the contrast between the voices and the vast hall seemed greater.

There's a lovely Sanctus that pairs André Campra's chant with Marcel Pérès' organ. The interplay between voice and room, organ and room, and voice against organ seems simple, but actually presenting all of these elements in the proper proportion poses a complex challenge to any system. This, I presume, is where lowering the noise floor pays dividends. Using the PWU 116, I could hear much farther into the acoustic—and in a recording such as this one, where the acoustic is one of the featured players, that offered tremendous musical advantages.

I wish I could tell you that I compared the sound of my system with the API Power Wedge Ultra 116 and the Cinepro PowerPRO 20 and heard vast differences, but I didn't. If there were differences in the sound of my system using one or the other, they were so slight that the time involved in unplugging everything from one AC filter and plugging it into the other obscured them. And, I have to say, whether or not there will be differences between the two might very well be extremely system-dependent. Using the systems I tried, in the electrical environment I tried them in, I wouldn't choose one over the other on sonic (you should pardon the expression) grounds. But that doesn't mean I don't have a preference.

Over the years, as an audiophile, as a hi-fi salesman, and as a reviewer, I must have connected a few thousand different system combinations. That's the fun part—mostly. Given the corresponding wide range of electrical systems I was connecting all those components to—not to mention the variations in the construction of the gear I was connecting—I must have spent hundreds of hours tracing hums and other annoying, electrically induced noises. That's the part I hate, and API's clever three-way grounding system offers a convenient and clever alternative to connecting, reconnecting, and generally futzing with every link in the chain. I like that. I want it. And if I were shopping for a powerline conditioner, I'd pick the one that had it. In fact, I am and I will—this is one review component that's not returning to the manufacturer.

For this corruptible must put on incorruption—I Corinthians 15:53
Audio Power Industries' Power Wedge Ultra 116 is a well-built, intelligently thought-out solution to the problems of powerline-borne noise and the vagaries of ground-loop hum. It is not a Band-Aid for systems that have not solved problems in the audio realm, but no AC conditioner is. If your system is sonically refined enough, the PWU 116 can take it to an even greater level of resolution—and who wouldn't want that? I recommend the Power Wedge Ultra emphatically.

Audio Power Industries
2624 South Rousselle Street
Santa Ana, CA 92707-3729
(714) 545-9495