The Bottom Line on

Line Conditioners
What do those fancy line conditioners do that a $10 power strip doesn't?

More-and less-than you might think.

by Brent Butterworth

 

 

 

 

 

 

 

 

 

 

 

 

 

Home Theater March 1999




There's so many things to be concerned about when you're putting together a home theater that you have to ignore something. AM/FM tuners, for example-who really cares how good the tuner is inside their receiver? Or videotape-when's the last time you actually sought out a certain brand?
Then there's the things you maybe can ignore. Do you really care how your speaker cable affects your sound? Maybe. Do you care how good or bad your VHS VCR is? Maybe.
For most of us, the AC coming out of the wall falls into that "maybe" category. Most people know that electrical spikes and surges can damage your audio/video gear. But beyond that, is wall AC OK? Or does it need further refine ment if the components it powers are expected to reach peak performance?
A few weeks ago, we didn't know. Since then, we ve spent a lot of time Irving out line condi tioners of every price, size, and configuration. We've plugged them into our systems, tried all of their features, and compared them in a blind test to see what effect they have on the picture and sound of a typical home theater system. And we've come to some conclusions that, frankly, surprised us.

What's Wrong With Wall AC?
 AC is one of those things we never think about-even most electronics textbooks con sider it to be a simple, 60-Hertz, 120-volt RMS
sine wave, and mention any impurities only in passing. But it's not that simple. Hook up an oscilloscope to a wall outlet, magnify the image enough, and you'll see little ripples riding along on the big 120-volt wave. Those little ripples are the result of radio-frequency and electromag netic interference, from sources like radio, fluo rescent lights, motors, and high-frequency switching in appliances. The switching power supplies used in most computers are a notori ous source of such interterenc~they switch power from the AC line on and off at very high frequencies, thus causing small fluctuations in the voltage all of your other appliances receive.
RFI and EMI don't harm your audio/video gear, but they can affect its performance. Everyone's heard the results in extreme cases of interference-the buzz from an electric razor coming through your stereo system, for exam ple. Many audio and video enthusiasts consider RFI and EMI to be harmful in more subtle ways, though, degrading the sound and pic ture in ways that aren't obvious to the casual observer, but clearly audible and visible in high-end home theater systems.
All power supplies, though, filter out almost all EMI and RFI. Most audio/video components include fairly large filter capacitors in their power supplies. These capacitors are designed to filter out the 120-Hz hum coming off the power supply's rectifier: they also filter out any frequency above that. If these caps can filter out high-amplitude 120-Hz ripple to the point of inaudibility, they'll certainly do something to
filter out, say, 90-megahertz RF interference with a strength of a few microvolts. Many high- end audio manufacturers also add small "bypass" capacitors across the big power- supply caps: these can, in some cases, do a better job of filtering out high~frequency interfer ence than the big caps can. Some manufacturers who go to great lengths in designing their pow er~supplies actually recommend that you use no line conditioning at all: they feel that many line conditioners limit current to a point that outweighs the benefits of the additional RFI and EM filtering.
If you're watching the oscilloscope at just the right time, you might notice a spike-a very short pulse of high-voltage electricity. Most people think spikes come from lightning, and, of course, they do. But they can also come from your appliances. Usually, spikes are the res~lt of a phenomenon called "inductive kick." This occurs when the electricity feeding into an inductor (for example, the armature winding in a motor, or the primary winding of a transformer) shuts off. The inductor discharges, throwing voltage back the way it came, into the AC line. If there's a switch between the transformer/motor and the AC line, the voltage coming back from the inductor can build up to such high levels that it can even arc across the switch contacts and find its way back into the AC line.
Spikes can permanently damage your home theater system. A lightning spike can burn out critical components on a circuit board in a frac tion of a second. Milder spikes, like those from appliances like refrigerators and air condition ers, can sometimes do immediate damage, but often do their damage over time. (I learned this when I worked as a copy editor at Spin maga zine, which was headquartered in a beat-up old New York City office building. Thanks to the spikes thrown off by the building's ancient elevators, I spent a lot of time replacing power supplies in the editorial department's computers.)
Spike protection, even in inexpensive devices, is generally considered to be very effec tive nowadays-that's why you see so many power strips that offer a warranty that replaces any gear connected to the power strip that's damaged by spikes. Some of these warranties cover up to $50,000 worth of gear.
Protection from RFI and EMI, though, isn't guaranteed, and effects on audio and video per formance can be tough to prove. Thus, we decided to line up a random selection of line conditioners priced from a couple hundred bucks to a couple thousand bucks, plug 'em into our system, and find out if we could hear or see a difference.

The Face Off
 To test the line conditioners, I enlisted assistant editor Joe Hageman and contributing editor Steve Gutten berg as panelists, in addition to myself. For them, the test was blind: They had no idea which line conditioner was plugged in at
any one time. I performed all the switching. We used a relatively high-end system, including Aerial Acoustics 7B, CC-3, and SR-3 speakers, a Sherbourn 5/1500 amp, an Acurus ACT3 pream p/p rocessor; a Sony DVP-53000 DVD player, and a Zenith lnteq 36-inch TV. I plugged all of the components into each line conditioner in turn, and plugged each line conditioner into one of the 20-amp circuits (with medical-grade outlets) in our New York listening room. At the beginning of each test run, and then once again halfway through, we plugged all the gear straight into the wall to remind us how the system performed with no line conditioner in place. To make the test more difficult, I plugged a computer with a switching power supply into the same AC circuit. Even without that, though, this
should've been a tough test-it took place in a New York City skyscraper with elevators, huge heating/air conditioning systems, and thousands of computers running all at once.
Our test included products in a wide range of prices, from ILab's $199 Auto Strip Model 8 to Cinepro's $1,800 Power- PRO 20. We received more products for this test than we could evaluate in a single article, including lower-end products from Audio Power Industries and Panamax, an affordable, rack-mount strip from Leviton, and a new line conditioner from Monster Cable: we'll get a review of these in as soon as we can.
Before we go further, understand that your results may vary, especially if you have a "problem" component in your system that's extremely susceptible to interference, or that has poor grounding. All of the components we employed in this test have been working well, and we haven't experienced any obvious interfer ence or grounding problems in our New York listening room.

B. The Ultra 115 sports nine outlets, but for $1,500 we'd like to see more.
Audio Power Industries
 Audiophiles can be insanely faddish, moving from one "miracle" product to the next in search of perfection. It's even hap pened with line conditioners, but there's one name that continues as a fixture in audiophiles' sound systems no matter what the current fad might be: Audio Power Industries. This company's Power Wedge line conditioners win raves from audiophiles year in and year out.
The $1,499 Power Wedge Ultra 115 is the company's top-of-the-line product. It offers nine outlets, of which there are three types. One supplies up to 300 watts: it's intended for use with your TV. Four outlets supply power (up to 15 amps) for ampli fiers. The remaining four outlets supply up to 120 watts each: they're for use with source devices and preamp/processors, and they're isolated so that electrical anomalies thrown off by one component can't enter the other components through their power lines. This isn't a lot of outlets for $1,500, obviously, and we could use more isolated outlets. Also, the Ultra 115 offers no current-sensing or remote- switching capability.
The Ultra 115 contains a center-tapped input transformer, which converts the AC power from unbalanced to balanced. Let's explore that a little further. The AC from your wall has three conductors, one "hot," one neutral," and one "ground." The hot and neutral carry the actual AC power: the ground is intended as a common reference for all your electrical appliances, although ft's simply connected to the neutral line back at your home's breaker box. Thus, the voltage potential of the ground is essen tially the same as that of the neutral line. In a balanced AC system, though, the ground is at a potential between that of the hot and neutral lines-at the top of the AC sine wave, the hot is at +60 volts, the neutral is at -60 volts, and the ground is at 0 volts. Line conditioners typically shunt noise and spikes to ground, but remember, the ground's connected to neutral further up the line. Thus, it's theoretically more effec tive to have a completely separate ground, combined with balanced AC lines.
The Ultra 115 has a switch for each of the 120- and 300-watt outlets, which lets you select between floating (disconnected) ground, unbalanced AC, and balanced AC, we used the balanced setting for our testing. Joe and I both felt that the Power Wedge Ultra 115 let our system achieve the best performance we heard in the Face Off. (Joe ranked it number one: I tied it with the Cinepro PowerPRO 20.) Joe felt that it brought out the subtlety of Foley effects in soundtracks. I thought the soundstage on music cuts deepened, and percussion sounded more detailed. To me, the improvement we got from the Ultra 115 sounded to me like what you'd get by switching to a slightly better digital-to- analog converter. On the Desperado DVD, the dialogue actually sounded spittier and harsher, but I suspect that's because the Ultra 115 helped the system reveal the flaws in the recording. Steve, however, ranked the Ultra 115 only fourth out of six line conditioners: he felt it cleaned up the midrange but thinned out the bass.
The improvements we heard with the Ultra 115 were certainly subtle for $1,500, but in a high-end system, this device makes sense.

Cinepro
 Cinepro's best known for insanely high powered amplifiers, but the company also offers a selection of line conditioners, the most expensive of which is the $1,799. PowerPRO 20. Like the API Power Wedge Ultra 115, the PowerPRO 20 offers balanced AC power, although doesn't offer the options of floating ground or unbalanced power, as the Power Wedge does. It has front outlets: on the rear, there are four isolated outlets for digital gear, and eight more outlets intended for analog gear. That's a lot of outlets, although we'd like to see more isolated outlets. As with the Power Wedge Ultra 115, there's no provision for remotely switching the outlets on or off.
I thought the PowerPRO 20 sounded about as good as the Power Wedge Ultra 115:1 was surprised at how kick-ass and dynamic the system sounded when we plugged everything in to this conditioner. The soundstage got bigger, and the sound became more detailed and delicate. The only difference I heard between the API product and this one is that the PowerPro seemed to yield a more deliberate and cleaner, but less airy, sound~I felt it was really a chocolate- versus-vanilla thing, rather than a clear case of one being better than the other.
Steve and Joe, however, weren't as impressed by the PowerPRO's perfor mance and ranked it fifth out of six. They both felt that it improved the sonic detail and seemed to do a great job of eliminat ing background noise. But Joe felt that the sound seemed brighter in a way he didn't like. I have to wonder, though, if Joe was really hearing more of the actual quality of the recording that was masked by the lesser line conditioners.
Even if Joe and Steve don't agree with me, I think Cinepro's got a nice product here. At $1,800, it's $300 more than the API Power Wedge Ultra 115, which offers five fewer outlets, but similar (maybe even slightly better) performance.

Current Design
 When they started designing the PC-B Plus line conditioner, Current Design sought out the advice of several custom installers, who suggested lots of extra features most people wouldn't think of including. Thus, the $895
PC-B Plus comes fully loaded. It's also designed for outstanding performanc~ there's no need for separate digital outlets or separate high-current outlets, because all the AC traces on the circuit boards are extra-beefy half inch on both sides of the board) to handle high current, and all of the outlets are isolated from each other, with individual filtration for every outlet, to pre vent electrical anomalies thrown off by one component from sneaking into other com ponents through the AC line. You can pretty much plug in anything to any outlet.
The PC-B Plus's back panel has eight outlets. All are spaced to accommodate wall warts (the little AC adapters that come with so many products these days), and the top ones are turned upside down for the same reason. One of these outlets is unswitched (for your VCR or anything else that needs constant power), and another includes current-sensing, so that when you turn on whatever's plugged in to this outlet, the whole system fires up. (You can also flip a DIP switch so you can just use this as an unswitched outlet.) Each of the six remaining outlets can be configured as switched or unswitched. The outlets fire up and shut down one after the other, and you can adjust the delay between the out lets, so there's little chance of pops caused by turning on your source devices when the power amp's on.
There are also three pairs of F-connectors for antenna/cable/satellite input and output; these provide spike protection on all your RF lines. (One is completely isolated from the chassis, which might help you eliminate a ground-loop problem if it exists.) There are 12-volt inputs and out- puts, so you can fire up the PC-B Plus from a pre/pro, a projecfor, or any other device that puts out a 12-volt trigger, and you can also use the PC-B Plus to activate any device with a 12-volt trigger input, like a motorized screen or a lighting controller. There's a phone line input/output pair, too, for spike protection on the phone line for your Divx player, WebTV box, or satellite receiver. This pair actually uses RJ-45 lacks with protection for two lines, so if you use RJ-45-to-RJ-1 1 adapters, you can protect two phone lines.
The front panel offers adjustment trim mers for the current sensing (so it'll work even with a component that draws very little current) and turn-onnurn-off delay. There's also a master on/off switch, an incoming AC voltage meter, and an XLR socket that accommodates an optional Littelite, the same kind of equipment light used on mixing boards.
The PC-B Plus seems to perform well- Steve picked it as his second favorite, saying that the sound opened up, the instruments in the music tracks sounded cleaner, and the Foley effects on DVDs sounded clearer. I felt exactly the same way, placing the PC-B Plus in the same tier as the API Power Wedge Ultra 115 and the Cinepro PowerPRO 20. I thought every thing sounded cleaner than with the line conditioners in the second tier, and I thought the background noise was remarkably low. Joe, however, was com pletely at odds with Steve and me, saying the PC-B Plus made the system sound hashy and bright.
At $895, this product is not inexpensive, but it really seems to have some high-horsepower line-conditioning cir cuitry inside, and it's got a great feature package to boot.


A. With its $199 price tag ( not to mention glowing reviews from two editors ) the AutoStrip Model 8
was dubbed the bargain of the face-off.

B. There's 10 outlets in all, with 8 switched ones onthe back, and two more on top ( one unswitched and
the other a current sensing outlet).

ILab America
 Everyone's seen a power strip before- there's one under almost every desk in America. ILab's $199 Auto Strip Model 8 is sort of like the most deluxe power strip you've ever seen. It has a total of 10 outlets. Eight are switched; four of these are spaced from the others so you can easily insert a wall wart.
There are two more outlets on top. One is unswitched, for powering a VCR or any other device that needs power 24-7. The other is a current-sensing outlet-when you switch on the component plugged into this outlet, all of the switched outlets will turn on. A small knob on the side lets you adjust the current sensing.
The Auto Strip Model 8 also has an IEC type socket and a detachable power cord, plus minijacks for 12-volt trigger input and output. Thus, you can power up the AutoStrip by sending it 12 volts DC (as put out by some pre/pros and most projectors), and it can also send out a 12-volt trigger to acti vate motorized screens, lighting controllers, etc. Also, the AutoStrip has two mounting holes that make it easy to secure to the side of a wooden cabinet. This is a pretty amaz ing number of features for a $199 product. Although the AutoStrip has fairly basic surge/spike suppression and simple line- filtering circuitry, Steve actually felt it made the system sound better than with any other line conditioner. "It sounds the most different," he said. "The image is substantially bigger, there's more detail, and the sound is clearer overall. The bass sounds more like real bass." (Steve had the sweet spot throughout this test, too, and as a hardcore audiophile, he's usually a pickier listener than Joe and I.) Joe liked the AutoStrip, too, raving about the sonic detail and saying it made the system sound almost as good as it did with the API Power Wedge Ultra 155 and the XS Technologies Strata 1000. I, however, felt the system sounded the same with the AutoStrip as it did with straight wall AC.
With so many useful features, rave reviews from two editors, and a very reasonable price, this little device has to rank as the bargain of this Face Off. It's not available at retail, but you can order it through an 800 number or through the company's Website.


Panamax
Think of Panamax's MAX 2000 as the Apple Macintosh of line conditioners. Most line conditioners are analogous to the early PCs-they're unsophisticated and give you very few opbons. But like the first Macintosh, the MAX 2000 gives you a level of control you never dreamed possible.

The $829 MAX 2000 has an LCD screen on the front that lets you select and adjust its many, many features. You can use this screen and a couple of buttons on the front panel to configure the 10 outlets on the back in a wide variety of ways. Two of the outlets feature current sensing; two are independent, and the other six are grouped in banks of two each. Any of the independent outlets or banks can be set to turn on when you turn on a device plugged in to either of the current-sensing outlets. (You can set up bank 1 to fire up when current-sensing outlet A is active, bank 2 to fire up when current-sensing outlet B is active, and so on.) Each inde pendent outlet or bank can also be set to turn on when the MAX 2000 receives a 5- to 30-volt DC signal from a device like a pre/pro or projector. Each independent outlet or bank can be set up for unswitched operation, so it's always on. And you can set up each independent outlet or bank with whatever turn-on and turn-off delay you choose.
As with all of the other line conditioners reviewed here, all of the outlets are pro tected aoainst spikes and surges. Three RF input/output pairs protect your gear from spikes on your antenna, cable, or satellite line. A phone line input/output pair protects against spikes on the phone line attached to your satellite receiver or Divx player. Two contact clo sures let the MAX 2000 activate relays:
there's an unswitched 12-volt output you can route through these relays to operate a projection screen, lighting controllers, etc.
The display gives you a readout of incoming voltage, and also lets you pro gram in the maximum and minimum incoming voltage levels the MAX 2000 will tolerate before shutting your system down. It also tells you if you've got a grounding or polarity problem.
The last, and perhaps most surprising, feature of the MAX 2000 is that it has a output lack on the back that connects to an infrared emitter. You can teach the MAX 2000 the power-on and power-off commands from your remotes, so that it automatically powers up your gear when the system comes on. It learns upto 16 commands. This feature is really handy for gear that doesn't turn on automati cally when it gets AC-it can save you a few button punches every time you turn on your system.
There's no doubt that this product is the leader in its field when it comes to fea tures, but its performance as a line condi tioner didn't impress the panelists. Steve and I both felt the system sounded no better with the MAX 2000 than it did plugged straight into the wall; Steve actu ally thought it might have sounded a little worse than the straight wall-AC in spots. We both felt the sound was harsher and less detailed than it was with our favorite line conditioners. Joe felt a little more posi tive about it: he ranked it fourth out of six in the Face Off.
What's amazing, though, is that of all the products in this Face Off, this is the one Joe and I are fighting over. In our testing system, at least, the sonic differences
between these line conditioners are so subtle that we're more interested in the MAX 2000's incredible convenience fea tures than we are in the top-notch perfor mance of the API Power Wedge Ultra 115.

XS Technologies
 Computer guys have much different needs than we home theater freaks do. They don't really care that much about how clean their AC is-after all, a little RFI isn't going to change an ASCII character or screw up a calculation, and you certainly wouldn't hear a subtle improvement in WAV fiIe playback with those cheap plastic junk speakers most computer geeks use.
All the computer guys care about is that there are no spikes to destroy their power supplies (or worse, their motherboards), and that the AC doesn't stop coming. If the AC to the computer cuts off, you lose unsaved data on any file you might be working on, and if the hard drive's spin ning when the AC dies, you could lose large chunks of data on the hard drive. That's why so many hardcore computer geeks use an uninterruptible power supply, or UPS. A UPS contains a backup battery that keeps the computer running so that you can save your files and shut the computer down in an orderly fashion if the AC cuts out.
XS Technologies is now offering a UPS designed for home theater: it's rated to provide five minutes of full-power opera tion if the AC dies. The $599 Strata 800 has six AC outlets, the first four of which are switched and backed up by the UPS, the fifth of which is switchable but not UPS supported (for high-current devices like amps), and the sixth of which is unswitched and UPS protected (this is the one to use for your VCR). All of the outlets are protected against spikes and surges. It also has phone-line jacks and two RF input/output pairs, all with spike protec tion. That's a decent feature package, but most home theater systems will require more outlets, and it'd be nice to see remote power-up/power-down capability via current sensing or a 12-volt trigger. The coolest thing about the Strata 800 is the removable front panel, which can serve as a wired remote control; you can hide the Strata 800 behind your rack and keep the remote out front. This remote lets you switch five of the outlets off or on individually, and turn all of the outlets on and off. The Strata also offers power sequencing, which helps eliminate the popping sounds you sometimes get when your amp's turned on and you switch on a source device. Outlets 1, 2, and 3 come on first; there's a one-second delay between each outlet's power. Outlets 4 and 5 come on 10 seconds later. Turn the system off, and it shuts down in reverse order.
Do you need a UPS for home theater? Probably not. Sure, it's a bad thing to turn off DVD players and VCRs when they're operating, but in my experience, they'll survive lust fine unless you make this an everyday practice. The only home theater component I feel benefits from UPS pro tection is a laserdisc player: pulling the power from an LD player when it's running can make it freeze up.
The advantage of UPS for home theater is that since you're charging a battery constantly, and drawing power from that battery, you can get an almost perfectly clean, 120-volt sine wave that's free of noise and unaffected by drops or spikes in AC-line voltage. This capability helped the Strata 800 to a healthy placing in our listening/ viewing tests-Joe ranked it second, while Steve and I ranked it in the middle of the pack. Joe felt the system sounded almost as good with the Strata 800 as it did with the $1,495 API Power Wedge Ultra 115, citing excellent sonic detail and a quiet background. Steve felt it gave the sound an airier, sweeter quality. Although I felt it did a lot to clean up the Foley effects in Desperado, I felt that on music, it made the system sound just slightly better than when it was fed with unconditioned AC.
The Strata 800 gives good perfor mance, and its power sequencing, phone- line and RF filtering, and cool detachable remote make for a decent feature package. We'd like to see more outlets, though, and some sort of remote on/off triggering.

The Bottom Line
 Certainly, the differences in audio perfor mance we found with these line conditioners were subtle - less apparent, even, than the differences we've often heard when changing speaker cables. And we noticed no differences at all in video performance. (That's not to say line conditioners can't affect video performance in certain cases- technical editor Mike Wood has found that using a line conditioner greatly improves the performance of the Deuce scan converter.)
Based on what we saw and heard, we think it's time for a paradigm shift in this product category. With high-end audio systems, certainly, performance is what matters-there's little need for fancy
remote switching or current sensing, and a product like the API Power Wedge Ultra 115 or the Cinepro PowerPRO 20 works per fectly in such a setting. But in a home theater system, which is typically far more complex and difficult to operate than an audio-only system, we feel the convenience you can get with a fully featured product like the Panamax MAX 2000 outweighs perfor mance differences you might get with a real, heavy-duty line conditioner. Of course, it'd be great if someone combined outstanding line conditioning with a full set of features for home theater; the only product we've tried so far that really meets that description is the Current Design PC-B Plus.