The inside of the chassis is shown below. There are two toroidal transformers, so that UltraPure Symmetrical and Symmetrical circuits are isolated from one another. The various coils are inductors that serve as low-pass filters (the transformers also act as low-pass filters).
Below is shown a graph of the AC output from the hot leg vs. ground. The unit was plugged into an inexpensive surge protector that was plugged into a 120 volt Variac (a variable transformer that can be used to keep the AC line voltage at 120 volts).
The red line is taken directly from a socket on the surge protector. The blue line is from one of the Symmetrical filtration sockets on the UltraPure, and the green line is from one of the UltraPure Symmetrical Filtration sockets.
You can see that both types of filtration reduce noise in the < 60 Hz region and > 20 kHz region, all the way up to 90 kHz. This upper frequency area is where RF noise resides, and RF, although inaudible itself, can interact with frequencies in the audible band, producing distortion. Therefore, it is a very good idea to reduce it (RF) if you can, and the UltraPure does it when using the UltraPure Symmetrical Filtration circuit.
Noise in the audible regions are overall, not reduced, when you take into account the fact that it goes down on either side of the 60 Hz fundamental, but up in the 3 kHz - 6 kHz region. The Symmetrical filtration circuit has an increased amount of noise in the 30 kHz - 40 kHz region. Of course, one must take into account that both symmetrical filtration circuits are also balanced, and this means a better ground connection, especially if the Star Grounding System is used in your components.
I have used a number of line conditioners over the years, and what I have found is that they have the most effect with mass market equipment. The reason for this is that mass market products tend to have the weakest power supplies, and it is a component's power supply that is responsible for delivering clean DC to its parts.
The UltraPure seems to do a good job of removing noise above 20 kHz, so I would expect it to be a valuable item in the typical consumer's home theater which uses mostly mass market components. Although the more expensive combination of the EP15A and SP15A would likely do even better at removing noise from the AC power, the fact that they cost more than some entire home theater systems makes them not practical for that kind of use. The UltraPure does fit the bill however, at $1,995, giving you both filtration and balanced power.
ExactPower is a notable company in the area of AC line conditioners. Their newest product, the UltraPure, appears to perform as advertised. It gives you low-pass filtration and balanced power, at an affordable price.
- John E. Johnson, Jr. -