AudioPrism Power Foundation III Power Line Conditioner

by Doug Blackburn

If you’ve read some of my other reviews and articles (and perused SoundStage! Talk Online), you know that I think power-line conditioning is a problematic but necessary part of a good high-end system. The problem is that there is no single product that’s universally "the best." Every system has different needs which are dictated by the components in the system. Every power grid is different. Every home is different. Luckily for us, when a power-conditioning device works well in one location, there are many other places it may also work well. Just don’t let yourself fall into the trap of trying one power conditioner, finding that it makes no difference or that the system sounds worse, then assuming that no power conditioning will benefit your system. Most likely, there is a device out there that will improve the sound of every high-end system.

This brings us to the subject of this review, the AudioPrism Power Foundation III. There are three Power Foundation models, the Power Foundation I, II and III. All share the same eight-outlet configuration and what AudioPrism calls "Quiet-Line" filters to suppress electro-magnetic interference (EMI) and radio-frequency interference (RFI). The difference in the three models is in the number of proprietary ACFX modules included inside. The best description I have of the ACFX module is one from AudioPrism—"a high-speed proprietary damping circuit." The Power Foundation I has no ACFX filter modules and sells for $300. The Power Foundation II has one ACFX module connected to all eight outlets and a price of $450. The Power Foundation III has two ACFX modules, one connected to the six "source" outlets and one connected to the two "amp" outlets, and costs $600. All Power Foundation models include a one-meter detachable power cord that is also sold separately for $75, or $125 for the more popular two-meter length.

For filtering, the Power Foundation III uses multiple Pi filters (parallel capacitors and series inductors) that, according to AudioPrism, can "reduce or eliminate reflected harmonic power distortion from home appliances, computers or stereo equipment back into the power line." This infers that the power conditioner is fully or partially (more likely) correcting the power factor of components plugged into it. Power-factor correction requires a fair amount capacitance in parallel with the primary winding of a transformer (or motor winding). This kind of filtering can be quite effective in many systems. Pi filters are well documented and have been around for at least 40 years, probably longer. However, AudioPrism took the extra steps to perform spectrum analysis on the AC power going into and coming out of typical audio components. They used CAD tools to optimize the tuning of the filter networks to provide the highest degree of attenuation of the noise spectrum that was possible for each of the three Power Foundation models. The filter networks were also designed to minimize any possible interactions between two or more components. Thus, AudioPrism ended up with filtering that is a combination of common mode and differential mode—using a combination of series and parallel elements—built around the Pi-filter model.

For this review, the Power Foundation III was given a thorough wringing out with a variety of digital and analog sources, tube and solid-state preamps and amps, as well as laserdisc players, video monitors and surround decoders. I won’t spend a lot of time describing the sound of the Power Foundation III. "But WHY? Isn’t that what reviews are FOR?" Well, sort of. But keep in mind that there’s no guarantee the Power Foundation III will sound the same in your system as it does in mine. So rather than write three or four paragraphs about the sound quality I experienced, I’ll just say that with all the different hardware configurations I used, the Power Foundation III improved the sound of the system in comparison to the same configuration without a power-conditioning device. This is half the battle—finding a device that improves things. If you really push me up against a wall, I’d say that in my system two VansEvers PLCs (combined price over $1,200) were preferable to the single Power Foundation III. I don’t want to make too big a deal about this, though. It’s a slightly unfair comparison: two units versus one, and double the cost.

What does a good-sounding power-line conditioner do for a system? You get less background noise, but you’d never know you even had the noise until you hear your system without it. Many people think that because they can’t hear some obvious noise in the background, there is none to remove. That’s incorrect, but not obviously so until you hear a good PLC. Here’s an example of what I mean.

I work in one of those office areas that are a sea of open cubicles. One of the things done in these kinds of work environments is piping in noise over speakers—a kind of hiss. This camouflages many background sounds and supposedly keeps phone conversations and other kinds of personal noise from carrying across the entire area. After just minutes of hearing this piped-in noise, you pretty much stop noticing it. But every once in a while the noise will stop for a few minutes at a time (Rebooting the noise computer? Who knows?) and you immediately notice what the noise was doing while it was on. You can hear many sounds you couldn’t hear before. Voices carry a lot farther when the noise is off, and you hear detail that the noise was masking. Something similar happens in your system when you lower the noise floor. The side effects are highs that sound "prettier," details you can hear that you never noticed before, and a harmonic purity that was never there. Most PLCs will make some improvements in bass detail that are easy to notice too. The Power Foundation III was no exception to these general rules.

You may be tempted to put this 6"W x 9.5"L x 2.5"H box on the floor. Don’t or you will suffer the fate of lame sound. Like the VansEvers PLCs, the Power Foundation III responds quite noticeably to placement and tuning. At the very least, place the Power Foundation III on a good shelf or platform. To get even better results, use an isolation base (commercial or DIY) and experiment with different kinds of feet until you get just the sound you like.

The size of the Power Foundation III was manageable, and with eight outlets, it permits connecting the components in a number of differently configured systems, even home-theater systems. The Power Foundation III has two dedicated high-current amplifier outlets, and many amps will sound better when plugged into these. If you do happen to detect a slight loss of dynamics when connecting a high-current amplifier, you can plug the amp into the same wall outlet as the Power Foundation III. You will still receive sonic benefits because some of filtering is in parallel with the AC power.

The AudioPrism Power Foundation III performed well in my system, so I feel comfortable urging you to put this one on your list of PLCs to try. But you have to promise to try a few others before deciding on the one that’s your personal best.

...Doug Blackburn
db@soundstage.com

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