The Quest for Clean Power
How it works - The Power Line Conditioner

A quality power line conditioner will do more than just protect your expensive gear, it will make a difference in performance you can really hear and see.

The AC line conditioner is more than just a power protection device.

This article takes a look at the various aspects of line conditioning - from noise filtering to AC  power regeneration. 

Surge suppression is also another important feature normally associated with power line conditioning systems - however, this is being dealt with in substantial detail in two separate articles under this same section.

A Historical Note:

We thought prior to going into the operational details, it would be interesting to include a short historical brief on the issues that led to development of the power protection industry for home entertainment system.

Up to a few years ago, power conditioners and line protection gear were mainly used by the industry, research, and in laboratories.

It was only after the advent of the home PC that power conditioning and power protection in the home became much of a 'discussed' issue.

In fact, one may argue that it was the proliferation of the personal computer in the home that first raised the awareness of the homeowner to the benefits of power line conditioning.

It was also at this time that we saw the development of an entire industry dedicated to producing power line conditioners and power protection equipment.

Following the increase in popularity of inexpensive surge suppressors for home computers - later followed by the development of reasonably priced un-interruptible power supplies (UPS) - the growing power conditioning industry began to design and manufacture AC power conditioners and protection gear specifically targeting the home entertainment industry.

The Power Line Conditioner - A three-in-one device!

Today's state-of-the-art AC power conditioning gear would normally take a three-in-one approach to help both - protect your sensitive equipment, and similarly important, improve the overall performance of your home theater system.

The basic functionality includes:

• Protection of equipment from voltage surges on both the AC supply and any other connections such as phone line, coax TV inputs, and even LAN connections.

  In this manner, anything that interconnects with your equipment would have to go first through the surge protection circuitry within the line conditioner.

• Removal of  noise from the AC line.

• Correction of voltage fluctuations and waveform distortions.

While power surges on interconnecting cables and power supply feeds are a major cause for system failures, noise, voltage variations, and waveform distortions, are the main culprits for a degradation in the overall system performance.

Removal of Noise from AC Power Lines

For audio-and-videophiles alike,  the next most important reason other than system protection for investing in a power line conditioner, is the elimination of noise from the AC line.

Noise is created by a variety of everyday applications, including radio and television stations, mobile phones, motors, etc. The reduction or elimination  of noise will have a beneficial effect on AV system's performance.

Passive Type Filters: In its most basic form, noise reduction in a power line conditioner is achieved through the use of passive type filtering. The typical filter arrangement consists of a coil of wire (known as an inductor) in line with the input and a capacitor across the line.

The impedance of the inductor increases with frequency, while that of the capacitor decreases as the frequency components of the noise signal increases.

This basic arrangement allows the higher frequency noise components to be shunted off through the capacitor to ground. 

The cheapest form of power line conditioning gear uses this type of passive noise filtering approach. Unfortunately, these basic passive noise-filtering techniques have a rather limited noise reduction effect.

Isolation Transformer:  A second approach to noise reduction  is the use of an isolation balanced transformer. This method of noise reduction is generally accepted as superior to the inductor-capacitor filter arrangement mentioned earlier on. 

Advantages include better noise reduction, and the creation of a balanced AC power feed. A balanced AC feed is considered far better for audio and video gear.  Its disadvantage is a higher cost, limited power delivery due to the damping effect of the transformer, and increased size, weight and mechanical noise. 

While these basic filtering techniques are capable of eliminating the very high frequency component of noise on the line,  yet they have  a major limitation.

They simply cannot address the real and significant problem associated with noise in the audio spectrum, nor can they regulate the AC voltage, or restore the symmetry of the AC waveform.

These are the real culprits to an overall degradation in AV system performance.

Use of AC Regenerators: Correcting voltage fluctuations, waveform distortions, and noise in the audio spectrum

A power line conditioner using a handful of passive components alone such as inductors, capacitors, and transformers can only eliminate the higher order frequency components from the power line. 

In reality, the main culprits to poor audio and video performance in the home theater are not the higher frequency harmonics but rather the lower frequency harmonics in the audio spectrum. These lower order harmonics are generated by a variety of  radiated noise sources, or as a result of clipping or uneven loads on the AC line, both in the home as well as within the surrounding neighborhood.

If what you are after is to regulate the AC voltage, correct the waveform symmetry, and possibly eliminate even the lower order harmonic noise, then your only way forward is a power line conditioner with AC regeneration. 

Click on image to enlarge Monster MP AVS2000

One such typical unit making use of AC regeneration is the Monster Cable MP AVS2000 Home Theatre Automatic Voltage Stabilizer - an excellent heavy-duty unit designed with the home theater in mind.

It is designed to stabilize the power line fluctuations in order to deliver a constant supply voltage to your home theater gear.

AC regeneration is a more recent development and represents the state of the art in power line conditioning. 

Basically, AC voltage from the wall socket is fed into the AC regenerator, which has an electronic equivalent of a power generator inside.  Using the power from the wall, the generator creates completely new AC voltage that is virtually noise free. 

For the more technically minded, the whole setup normally takes a two stage approach or double-conversion process where the AC is first converted to DC, conditioned and then converted back to pure AC sine wave power. In this manner, it is possible to guarantee a pre-determined AC waveform and output voltage irrespective of the AC input.

The electronics used in the DC to AC inverter are very similar in design to those employed in computer grade uninterruptible power supplies UPS), where the DC in this case is being feed from a lead-acid battery.

The advantages of AC regeneration coupled with a suitably rated surge suppressor and adequately designed line filtering, include:

• The complete elimination of any noise on the line,

• Complete voltage regulation,

• Balanced power which is more suitable for AV equipment,

• Elimination of any distortion components (harmonics), and

• Full system protection. 

However, there is a price to pay for all this. Power line conditioners using AC regenerators bring about added heat, increased size, and a substantial higher cost. Expect to pay anything between USD1500 to USD2000 and over for a typical AC power regenerator. In comparison, a power-line conditioner with surge protection and basic noise reduction, would cost no more than hundred dollars.

Power line protection strips, surge suppressors,  UPS, and home theater line conditioning equipment at affordable prices.

We have put together a vast selection of power protection gear from major suppliers at our online Home Theater Store.

Products range from small inexpensive power protection strips, reasonably priced UPS, and complete home theater power centers for improved system performance.

The links below will take you straight to the respective product pages:

• Electronics: Power-Line Protection

• Electronics:  Uninterruptible Power Supplies

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Last updated on  21st February 2005

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