Parallel-type Mains Filters

The best solution for audio

(and more)

Is your audio system really performing at its best ?

Even the best high-end music reproduction system may not be able to express its full potential if it is not placed in the best conditions in every respect.

You have certainly noticed that your system does not always sound the same. Probably in the evening hours the sound is more engaging, more complete, richer. The system has not changed, so the cause of this phenomenon must be sought externally.

And the first determinant is certainly the quality of the power supply, whose job is to provide all the energy the system needs.

Your system needs ENERGY,

unlimited and clean!

The main prerequisite for achieving ideal performance from any audio device is to power it with equally ideal energy. This concept is simple to understand in theory but complex to implement optimally in practice.

The first thing to understand is the indisputable fact that current power grids are unable to guarantee the original perfectly sinusoidal waveform for which they were originally designed. This is due to electrical pollution produced by a multitude of devices that generate interference of all types and frequencies (industrial machinery, photovoltaic systems, household appliances, low-energy light bulbs, etc.).

This interference is fed into the network and propagates both on the power line, consisting of the phase and neutral conductors, and on the ground line. The latter plays an important role because, in addition to ensuring electrical safety, it constitutes the reference potential for the musical signal. It is therefore clear that the pollution propagating on this conductor irreparably compromises the integrity of the signal.

Further disturbances are produced by the components of the audio system themselves, each of which feeds back a series of impulsive and harmonic disturbances onto the line that powers it, in proportion to the amount of current absorbed and the non-linearity of the internal power supplies.

“Electronic power supplies don’t pull current in a linear fashion like a light bulb, fan or simple motor would. The full-wave bridge rectifiers and digital switching supplies in electronics draw hard on the AC line, pulling instantaneous bursts of current off the highest and lowest peaks of the sine-wave. This happens within milliseconds in order to fill power supplies storage capacitors. Both full wave bridge rectifiers and digital switching supplies create a significant amount of noise during this process that extends in frequency to the 50th harmonic of the line frequency. What this means, is that from the perspective of power-supply, AC transmission is a near-field, high-frequency occurrence not a low frequency 50-60Hz event.” (Shunyata Research)

“I don’t hear any noise …”

That is the answer of many, and it is probably the same answer you would give. If so, then some clarification is needed.

If you distinctly hear a noise, such as a hum or hiss, it is likely to be a defect in one of the system components or imperfect wiring, such as a suboptimal “ground” connection. In this case, the cause of the problem must be precisely identified, which is unlikely to be solved by the use of power filters.

… but the noise is always there

Even if you do not hear it directly you still feel the negative effects: Insufficient realism, reduced and unstable three-dimensionality of the image, poor naturalness, listening fatigue. The end result is less emotional involvement than one’s expectations.

Using an apparent oxymoron:

you only hear the noise when you take it off

How to remove it ?

The first action to be taken is the insertion of a filter that succeeds in eliminating disturbances without affecting the delivery of the necessary energy.

What type of filter should be used ?

There are basically 2 macro types of filters used to eliminate power grid noise: series-type filters and parallel-type filters.

Those of the first type are, mistakenly, the most popular. This has contributed to the substantial disappointment underlying users’ skepticism of this type of filter, which, in the face of insufficient noise reduction in the audio band, also offers a loss of dynamics and “verve” that is always perceptible.

The real, and only, solution for reducing network noise is “parallel” type filters. This solution may be instinctively counter-intuitive if by similarity one thinks of air or water filtration.

However, the comparison is deeply flawed: in these cases, the purpose of the filter is to separate very different substances (e.g., for air: impurities, dust, pollen, solid contaminants, solvents), typically by retaining unwanted components within the filter and letting the filtered and cleaned element pass through.

In the case of mains power the situation is completely different, because the “matter” is the same: it is still only electric current. What distinguishes “good” from “bad” energy is only its waveform, or rather its frequency distribution, that is, the set of frequencies that characterize it.

Parallel filters:

maximum effectiveness without leakage

Electrical noise is made of the same form of energy as the musical signal: once the noise present in the audio band has merged with the signal and contaminated it, it has become part of it and it is in fact impossible to separate it again. Electrical noise has become acoustic noise.

It is therefore necessary to operate before this happens.

Only “parallel” type filters are able to effect a drastic reduction in unwanted frequencies without limiting the energy delivery of the fundamental component at 50Hz, the only one our electronics need.

Working in parallel with the network, parallel-type filters become the preferred pathway for noise, which is thus absorbed and eliminated before it can enter the components of our valuable audio system and compromise its reproduction quality.

And what are the benefits ?

The strong reduction of electrical noise is paramount operation to preserve the original dynamics of the musical message, resulting in a more realistic and involving reproduction:

Realism

Is not music a continuous alteration of sounds and silences ?

But if silence is never really such, if “black” is just a dark gray, everything will be perceived as unreal, reconstructed, distorted in its concreteness. And this is what too often discriminates, even to an inattentive listener, reproduced sound from real sound.

Involvement

In the lower part of the dynamic range is where most of the ambient information is located, the information that if reproduced correctly immediately transports us to the center of the original musical event.

If this part of the signal, so important but at the same time so delicate because it is characterized by very low energy levels, is blurred by noise, the musical event distances itself from us, leaving us “on this side.”

Safeguarding this invaluable information is therefore the key step to totally immersing oneself in the pleasure of immersive, realistic and exciting listening.

Why choose Apotema mains filters ?

Proprietary solutions: we use non-standard configurations that are the result of years of laboratory and field testing, which have confirmed their effectiveness in different and diverse contexts, even outside the strictly audio field.

Selected components: we purchase and test hundreds of different components and use only those, very few in fact, that guarantee full achievement of our objectives of quality, reliability, durability and continuity over time

Aluminium shielding body: it would be unfortunate if disturbances could be radiated back into the surrounding environment, partially nullifying the effectiveness of the filter. This is usually the case with filters with plastic housing. All our filters have a housing made entirely of aluminium, which prevents the propagation of EMI/RFI noise.

Mechanical strength: no plastic! The body is made entirely of thick aluminum alloy, which is particularly vibration-free to ensure reliability and durability in all conditions of use.

Italian design: in addition to the indispensable superior technical performance, it is also necessary to enhance the aesthetics of the audio system as a whole, combining harmony and uniqueness with objects that not only fulfil their task but are also pleasing to the eye.

Not just Audio!

The effectiveness of Apotema parallel filters also extends to high-quality Video

The benefits that can be obtained by eliminating electrical noise from the power supply extend far beyond the realm of high-quality music reproduction.

A concrete example in which Apotema power filters have brought real benefits concerns the world of high-resolution video reproduction in home theaters: better reproduction of colors and infinite shades, less background noise, denser blacks, and more engaging and natural images can be achieved by inserting a parallel filter in the audio-video system’s power supply.

And now?

From Theory to Practice

Now it’s finally time to move from theory to practice with hands-on experience.

And there is only one, single way to verify the real effects of a component: insert it into your own system.

So all you have to do is try an Apotema filter in your system !