Sound Application CF-X Power-Line Conditioner

January 2001

by Jeff Fritz

Review Summary


“Noise was reduced to near inaudibility,” while “low-level detail in the upper registers was improved, with the music that was embedded in the noise floor extracted”; “dynamics were not truncated or blunted by a lack of current-carrying ability.”


“Line conditioner/spike protector with 12 highly conductive copper-bronze outlets that are more robust than even hospital-grade outlets and 1/8″-thick, type 101 OFE buss bars that carry the current — 6 kilowatts worth continuously.”


“Manufacturer recommends 200 hours of break-in on a large inductive load such as a vacuum cleaner or table saw. Even with this, the unit is said to improve over two to three years.”


“Costly, but perhaps the ultimate power-line product and protector for expensive or elaborate systems.”

Products that are more expensive than their competitors must have quantifiable characteristics that separate them from the pack. At least this is the case if those products are to be accepted as genuine in the marketplace. The type of product is really irrelevant, owing more to those characteristics that typically cross over to multiple consumer goods. Craftsmanship, performance, finish, research and development, and parts quality all combine to define high-end audio. One could easily say the same characteristics apply to automobiles, furniture, or fine watches. The point is that consumers are willing to pay a premium price if the product can address the above areas in a way that exceeds expectations.

The subject of this review, the Sound Application CF-X, attempts to define itself in a realm where few components of its kind dwell. But does the CF-X’s price reflect levels of performance and craftsmanship that justify its existence? The question is, of course, dependent on many variables, including related system components, power-line quality, and musical preferences. It is not possible for a reviewer to make a blanket judgment for a consumer, especially when those previously mentioned variables are unknown outside of the review system. What a reviewer can tell you, though, is how the component stands up when the microscope is on performance within the context of one system, to one set of ears. From these observations, a perspective buyer can determine if the package warrants over four grand and an audition under familiar circumstances.

Power conditioning has been all the rage for the last few years. A variety of products are available to address the problem of contaminated AC. The way in which theses products operate, however, is quite varied. Power regenerators, filters, conditioners, parallel inductors, cable sleeves, proprietary circuits — you name it; all are available to make better what the power company delivers to your home. With so many choices, it is hardly surprising that the results are all over the proverbial map. These products are not only not created equal, but if used improperly, they can actually degrade performance. The standard rule of thumb is to know what you are buying and what problems the unit purports to solve.

The hardware

The Sound Application CF-X is built to an extremely high standard, although it’s rather unassuming in appearance. The chassis is a black anodized aluminum box with six Hubbell receptacles, offering 12 total outlets located on the top panel for connection to your system’s components. These sockets are special, being constructed of 90% copper-bronze (zinc/tin) alloy. According to the manufacturer, they are more conductive and display superior wear characteristics while not losing their grip pressure over time. By comparison, the standard female wall socket is brass, consisting of 35% copper with most of the rest being low-conductivity zinc.

The 20-amp IEC input receptacle plugs into the wall via a stiff power cord. There are no LEDs, which according to the manufacturer, degrade sound quality. The real story lies inside the unit, where reportedly no expense has been spared to achieve the desired results. Current capability is impressive, 6 kilowatts continuous, owed partly to the 1/8″-thick type 101 OFE  buss bars that carry the current. Parts include 6N copper wire, Carlingswitch magnetic circuit breakers, and custom Caddock Ultra Precision resistors. All connections are 100% point-to-point. The entire device is hand-built over a 12-hour period by Jim Weil, the owner/designer of Sound Application.

Weil, of course, believes his approach to power conditioning is the best. He is openly critical of some of the other popular approaches, such as transformer-based technology. Due to the large amount of current available from your wall, Weil does not advise insertion of a device that would limit the available dynamic power to your components. According to Weil, this only restricts dynamics and shrinks the soundstage. The Sound Application approach is to provide a 23-stage, wide-bandwidth (2.5 gigahertz) EMI/RFI filter, while not restricting current flow. This means you can connect those big, bruiser power amps without worrying about taxing the CF-X, which also protects your gear with an 11-stage spike-and-surge-protection circuit. Before installation, the manufacturer recommends 100 hours of break-in on a large inductive load such as a vacuum cleaner or table saw. Even with this, the unit is said to improve over two to three years.

I installed the Sound Application CF-X in my system, using a two-stage approach. First, the DVD player and preamplifier were connected. I spent approximately two weeks with this configuration. I then added the main power amp, and finally the subwoofer amp. This enabled me to test the claim that the CF-X does not limit current in real-world, high-stress installations. I must say that it was very nice to have one component handle all the power-conditioning chores. The multiple-boxes-daisy-chained approach is not at all an attractive prospect. This multicomponent capability should be considered when doing a price comparison with other units that have less capacity. It may be necessary to purchase numerous lower-capacity units for even a modest system when you condition the power amp’s line as well.

Regarding break-in, I did follow the manufacturer’s recommendation to a degree, running a vacuum on the CF-X for several hours straight while not at home. Although Mr. Weil does recommend longer, it was not feasible for me to complete the specified 200 hours.


The initial test I conducted was to examine the noise floor with all components at idle. Before installation of the CF-X, I noted the noise coming from the speakers with no program material playing. There was a faint hash present that could be detected from 4″ to 6″ from the tweeter. This may not seem like much, and indeed most systems exhibit this much or more noise at idle, but remember that this is present without the preamplifier or amplifier amplifying the signal. It would certainly increase as gain increased, enhancing the chances of audibility from the listening position. With the Sound Application CF-X powering the front-end player and preamplifier, the noise was reduced to near inaudibility. With my ear pressed to within 1″ of the tweeter, I could detect noise ever so slightly. And I mean barely. This is a considerable lowering of the noise floor. As we get closer to the ideal sound, these seemingly minute gains in resolution are important. The proverbial black background becomes a holographic space inhabited only when music is present. This was a great start.

The other observation during this exercise was that the CF-X was completely silent mechanically. There is simply no sound whatsoever emanating from the device itself. My experience with other conditioners/filters suggests that this is significant. Component and system hum can drive me crazy, many times countering the positive effects the unit is having in other parts of the sonic spectrum. This is a good result to say the least.

When examining noise, or the removal of it, I find it helpful to listen to acoustic music. It is somehow easier to subtract the ambient noise embedded in a recording when real sounds are recorded in a natural space. Listening to Rebecca Pidgeon’s Four Marys [Chesky JD 165], I was able to determine how the CF-X was interacting with the system when music was present. One of the first questions I answered was how the unit affected the treble. It would be disappointing if lowering the noise floor were coupled with a loss of high-frequency detail and resolution. I’m happy to report that resolution was slightly increased, while the frequency response was unharmed. Low-level detail in the upper registers was improved, with the music that was embedded in the noise floor extracted. This is not a characteristic that you will notice on all recordings, or for that matter on all systems.

The upper treble must be present to truly reveal just how much the CF-X helps. If you have intentionally rolled off the upper treble with dark-sounding components, speakers, or cables, due to etch and grain, it may be necessary to remove the tone controls and try your system anew with the CF-X installed. It will not correct for frequency-response anomalies, but it may reveal a more delicate treble by removing the noise masking the sound.

As stated earlier, the frequency response of the system was untouched by the CF-X. This aspect of performance therefore did not affect overall soundstaging accuracy. For instance, Diana Krall’s vocals in “Let’s Fall In Love,” from the When I Look Into Your Eyes CD [Impulse! IMPD-304], remained in its proper place, with realistic scale. Width and depth of stage were also untouched, although the air around the performers appeared sonically more realistic. This again had to do with the ability of the CF-X to extract detail from the noise floor of the system. It simply gave me a clearer view into the music without detracting in any way.

Dynamics were not truncated or blunted by a lack of current-carrying ability. As this aspect of the CF-X’s performance was something that the designer pointed to as a strong suit, I gave the unit a workout under the most extreme circumstances imaginable. I connected the main system amplifier and later the subwoofer amp to the CF-X, which even at idle would not be possible with some power conditioners. Then the workout began. The new Gladiator soundtrack [Decca 289 467 094-2] is one of the most remarkably lifelike recordings I’ve heard. Its clean, unfettered dynamic realism exceeds that of some of my other favorite soundtracks by a noticeable margin. The Hans Zimmer production is dramatic! Any type of system compression would rob this music of the life and vitality that I know are present on the disc. The CF-X was capable of supplying the system with enough oomph to do this work full scale. In fact, the sound could become downright scary as the music built to a climax in the “The Battle.” Talk about the edge of your seat!

One area you would expect to suffer if current was a problem would be the bass department. Those who have read my reviews know that I am a bass fanatic. If the system is not full range, it simply doesn’t provide the scale needed to faithfully reproduce some works. With the Aragon Palladium I use to drive my subwoofer connected to the CF-X, I played some of my more current-sapping bass tracks, including “I Love You” from Sarah McLachlan’s Surfacing CD [Arista 07822-18970-2]. This was produced with all the room-pressurizing power imaginable. This track has sustained bass, the kind that can tax a power supply that can’t keep up over the three-minute-plus playing time. The Aragon as fed well by the CF-X showed no apparent limitations.


If your primary goal is the reduction of the noise caused by RFI and EMI, I heartily recommend the Sound Application CF-X for audition. A quick check of your system’s noise floor with and without the unit is easy, and it will give you some idea as to how much your components are being affected by AC grunge. The unit substantially reduced the noise floor of my system, which paid dividends in the areas of high-frequency purity and low-level resolution. If you are worried about any frequency-response anomalies, the CF-X showed none. Best of all, the CF-X did its job without a single problem, either mechanically or sonically. Add to this the ability to power and protect all but the most complex systems from a single unit, including large amplifiers, and you have a one-stop spot for your power-conditioning needs.

Associated Equipment
Loudspeakers: Wilson Audio X-1 Grand SLAMM series III with XS subwoofer.
Amplifiers: Jeff Rowland 8T, with Aragon Palladium for the subwoofer.
Preamplifier: Coda 04r.
Digital: Pioneer DV-606D DVD player.
Interconnects: Harmonic Technology Pro-Silway Mk II, Nirvana S-X Ltd.
Speaker cables: Harmonic Technology Pro-9 Plus.

Reprinted by permission from SoundStage