External Power Conditioning Is Unnecessary

A recent well-written article in this magazine's Expert Viewpoint section promotes the need for power conditioning in home theater systems, as elsewhere. Why the need? To meet user expectations, to provide the best sound and video quality while protecting the equipment from power anomalies that can damage or even destroy electronic equipment, and to improve the bottom line of the seller.

Sounds great and seems reasonable, but how much does external power conditioning really help electronic components and systems, and ought we be selling them? Audio and video components' internal power supplies take the 117 Volt Alternating Current (AC) power from the wall outlet and rectify AC to various Direct Current (DC) voltages needed for each component's internal circuits.

Since it's the DC flow that operates the audio, video and control circuits of the component, for good operation of these circuits it is essential that the DC is filtered and regulated to provide the needed clean and stable DC. You can be sure that manufacturers of quality audio and video components incorporate suitable circuits in their products' power supplies to filter and regulate the DC sufficiently to provide correct and stable voltages; otherwise the component won't work well. And component manufacturers are not ignorant of the fact that available AC power in most places is imperfect and/or contaminated to some degree. Besides, if you were a component manufacturer would you produce and guarantee a product whose performance depends on an external power conditioner, whose inclusion in the system is optional – that is, it might be included in some systems but not in others?

Since the real circuit action takes place after the rectification to DC and not before, of what practical use is "conditioning" the AC power before rectification? Just because AC power conditioning is harmless doesn't make it useful. Electrical spike protection needs a simple filter, not some mysterious kluge, promoted with pseudo scientific words and costing big bucks. Even if the AC power source fluctuates, causing the rectified DC power to fluctuate as well, the regulation circuits of the power supply inside the audio and video components will stabilize the variations sufficiently to enable the component's internal circuits to work properly. If not, the component's internal power supply isn't doing its job and that component ought not to be used.

Depending on external AC power conditioning is like depending on the kindness of strangers – not good enough for prime time. AC spikes generated by lightning and such, as well as contamination of the power line by switched-mode power supplies in micro-processors operating on the same power line as the component in question are also filtered out in individual components' power supplies. If they're not, the component's internal power supply isn't doing its job. Some components do a better job of this than others, of course. Cheap components do it poorly and in those cases, an external power conditioner might help. But instead of buying a cheap component and a power conditioning device to protect it, why not buy a good components that does its own power conditioning?

In components having good internal power supplies, contamination of the AC power line does not affect their performance in the slightest, despite what proponents of power conditioners say. If power conditioners worked as advertised and improved the performance of systems, a demonstrable difference could be detected. So where are the double-blind tests showing improvements? If I was a manufacturer of such products, and if the products actually worked that is, I would devise a portable demo kit that a rep could carry around to show people how great the thing works. How come that in all the years that power conditioners have been touted no one has ever come to see me bearing such a kit? How come I've never seen a convincing demo at a trade show? The next time you hear a really fine sound system in someone's home, chances are that no external power conditioning is in place.

If power conditioning is necessary for fine system performance, how come systems without power conditioning can sound so terrific? Same goes when you see a really beautiful picture on a video display. It's because quality components don't need external power conditioning. During 50 years of designing, installing and servicing audio and video systems in many places, I came across system problems caused by AC power line fluctuations or spikes only three times. In all three cases individual components had poor power supplies and we did not know it. Whether external power conditioners might have prevented these failures is hard to say.

In the first case, a power amplifier, having a switching power supply to reduce its weight, failed in a Caribbean Island hotel installation where large AC power fluctuations are common. It was replaced with a unit that has an ordinary power supply and has worked well since. In the second case, a Plasma Video Display failed following a power surge. Since the Display was damaged beyond economical repair it was replaced with a newer model having a better power supply, instead of the same model plus a power conditioner. The replacement unit hasn't failed in years and probably many power surges since. In the third, more recent case, a hard drive video recorder in our security system failed during a thunder storm. The recorder manufacturer's rep replaced the unit and advised investing in a power conditioner, which we did reluctantly.

Two months later the replacement unit failed following another thunder storm. The power conditioner didn't help, evidently. Before replacing the recorder again I looked inside at the power supply and sure enough, it was fried and flimsy. Experience indicates that a flimsy power supply inside an audio or video component might or might not be protected by the use of an external power conditioner. While an audio or video component with a robust power supply inside does not need external power conditioning, except in unusual circumstances, such as in places having excessive power line fluctuations or unusually large spikes.

Improving the bottom line of the seller is definitely an incentive to selling power conditioners to wealthy clients eager and able to have the best. And it's not hard to sell such products. But if the product's benefits are not firmly established selling it cannot serve the long-term interest of the client. So finding other means to improve the seller's bottom line ought to be preferred. Marketing to consumer fears of system failure and to their desire for performance improvement drives sales of power conditioners and other harmless, swell looking devices whose touted benefits are hard to prove. And there is strong demand for such products, particularly among the wealthy. A thriving snake oil industry has grown in our field to meet this demand. Fancy loudspeaker cables are one of its products. Power conditioning devices are another.

Participating in any aspect of marketing, sales, design and installation of products having questionable benefits must necessarily bring with it negative results in the long run. In the home theater field, where increased demand has brought in new practitioners, already there is a palpable distrust among clients because some of them sense they're being sold products they really don't need. They sense this from the contractors who know full well, and unconsciously reveal to them, that some of the stuff they're selling is snake oil.

The same suspicion is evident in clients' behavior in the home theater showroom. The same suspicion can be seen in internet communications. Our industry is ripe with snake oil and over-due for a cleanup. Since nothing remains hidden for long, eventually we're bound to suffer the consequences of bad business practices we take part in.

When there was a strong demand for Discotheques in the '70's, some club owners used to cut corners to make quicker profits. It seemed to me at the time that they were getting away with it. Where are these clubs today? If we want to stay in business for the long run, we need to make sure the products we endorse, sell and install benefit the client in the long run. With this in mind we ought to be selling only those products whose benefits we understand and can demonstrate. Power conditioners are not one of them.


Alex Rosner is the president of Rosner Custom Sound, Inc, in Long Island City, NY. As a graduate electrical engineer working in the aerospace industry, he turned his audio hobby into a part time business in 1959, founding his present company in 1967. He used to do equipment reviews for the now defunct AUDIO Magazine and has written articles for various trade publications.

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