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Have you tried anything you can but your power amp still keeps buzzing?


Weird mechanical noises, vibrations coming out of the case and not from the speakers?


Noises that come and go, in a apparent casual way but sometimes in relation of the time of the day and the day of the week?


Have you tried a conventional mains filter and nothing changed? Maybe could it be a ground loop?


No Way!


These noises have nothing to do with ground loops, network harmonics, spikes or overvoltages: all of those have already been solved by our other BlackNoise filters and accessories, here the reason is different:


it all depends by direct current (DC) over mains network.


Even a very small value of DC it’s enough to saturate the amplifier transformer; it starts to vibrate, but also to supply power with greater effort, lower efficency and, noise aside, to overheat!


The phenomenon regards all kind of transformers, either toroidals or not, but

The Zero is provided with

a 40cm built-in cable

What does it mean “direct current” into mains network??


Electric energy on the mains network presents itself to measurement instruments as a wave made of two symmetric half-waves, one with a max positive peak, the other with a max negative peak.  The crossing point between them occurs right in the middle, in a intermediate and neutral point that has a value exactly of… zero!


If, for any reasons, this point ceases to be zero and takes on any other value (it doesn’t matter if positive or negative) it will no longer be perfectly at the center and the two half-waves will no longer be symmetric, not anymore each exact mirror of the other.


This is the after-effect of the new position of the reference “zero”: in other words now in the mains network there is a certain amount of “direct current” (zero not zero amymore!) added.


The aim of our Zero filter is exactly to bring back to… ZERO the reference point, perfectly restoring the original symmetry of the mains network electric energy.


As a final touch, DC asymmetry brings along a good number of noisy odd harmonics, them too completely wiped out with the insertion of the Zero!

But how is possibile that DC enters the mains network and is superimposed on it??


Did you read the tecnical box on the left?? It does contain all basic informations to understand what is explained here :-)


Truly, DC does not “enter” into the mains network from outside, but rather borns out of the electric network itself, out of the way some electric appliances, both “old style” and of new generation, make peculiar use of the electric energy.


For example, suppose the existance of an electric appliance that would use only positive half-waves. In this case, only the negative ones would remain and the reference “zero” crossing point would assume a more positive value trying to “counterbalance” the asymmetry.


Well, don’t suppose any more! It is exactly what happens, some devices do exactly that! The common household hairdryer it’s a perfect example, used at half-power interposes a diode in the circuit that cuts away half of the incoming wave. The net result is a conspicuous amount of DC that now is superimposed on the network!


Other modern appliances, like HVACs systems (but also washing machines, refrigerators, dishwashers and many others), vary their motor speed using just part of the incoming electrical wave, creating the very same negative effects.

toroidal ones are especially sensitive because they always work very close to their saturation point: even a small amount of DC is enough to make them buzz and overheat. This is so much true regarding high power toroidal transformers, those that almost exclusively are wired into power amplifiers. The Zero cancels out the irritating noises, returns to the amplifier the full  energy delivered by the power supply, lowers the working transformer temperature making it to last longer… at a price lower than the MiniBlack: what can be asked more?


Small and with a short integrated cable, the Zero is of immediate use: it has just to be inserted between the electronic and the mains, the power distributor or the BlackNoise* mains filter to completely kill any DC noise.




*Best resuls are obtained with the Zero located at the output of a BlackNoise filter, while with BlackNoise power distributors you can put it either ways.