The Aneto DC Blockers

The Aneto DC blocker is a component designed to tackle the problem of DC offset. It contains a standard DC blocking circuit which can help reduce the distortions in component power supplies that can be created by mains DC offset.

Aneto DC BlockerHiRez Aneto

But naturally, when we designed the Aneto, there seemed no point in not including those other major aspects of our technology, so the Aneto also contains a Jaya shunt RFI filter, an acoustic absorption labyrinth and in the HiRez Aneto, passive EMI absorption too.

What is mains DC offset?

Our mains is generated in huge power stations by rotating generators that produce a sine wave of alternating current, at high voltage (up to 400kV). This power is then carried around to our cities and towns by large pylons, where it then gets reduced down in local transformer stations to the voltages we receive into our homes. The sine waves that these final transformers put out are symmetrical around zero volts. That is, they go ‘plus’ and ‘minus’ by the same amount. Our mains nominally quoted as 230V RMS in the UK and 110V RMS in the US for example, and that equates to peaks of +/-340 in the UK and +/- 170 in the US. At any time of the day though, you might expect that peak value to vary as the times of high demand load up the system, but also the positive and negative values to be ‘equal and opposite’.

But that is not always how it is. Sometimes other equipment being used in the hose or in the local vicinity, may draw more power from either the positive half of the wave, or the negative half. With this uneven load, and the resistance of the cabling back to your local transformer, now means that the sine wave is not equal around zero. Indeed, the supplier may ramp up the supply to maintain their contractual obligations, so the half of the wave that is high, may actually be pushed even higher! If you rectify a sine wave that is correctly referenced around zero, has the same plus and minus value, you will get a net zero DC voltage. However, if you rectify a sine wave that has different positive and negative values, that isn’t equal around zero, you will get a resultant net DC voltage, and the system now has, in addition to the AC current, a standing DC current flowing.

DC offset graphgraph showing two power signals, one with severe DC offset


So there’s the basic theory. The result of all that is that your power supply sees a standing DC current in addition to the intended power wave. This doesn’t always cause a problem, bout it can upset linear power supplies, causing the mains transformer to saturate on one of the half cycles of the wave (the higher peak). this can cause the transformer to buzz audibly, creating more vibration in the system, and also produce clipping pulses which create electrical noise.

Configuration and Options

As you can see from the picture, the Aneto is built in the same general format as a Jaya shunt filter. Housed in our normal 220mm aluminium extrusion with a captive lead at one end. The main difference though is that the lead has an IEC plug on the end, and the other endplate has an IEC socket. So, of course you use the Aneto in-line. Internally, the DC blocking circuit is inline, but as usual, the Jaya filter is in shunt configuration so not adding further impedance to the current path.

The Aneto comes in three performance options, Standard, Silver and HiRez. Like all the other Vertex products these options bring a range of technology and performance. The Standard Aneto uses our silver-plated copper conductors, a standard Jaya filter and a standard acoustic labyrinth. The Silver Aneto uses solid-silver conductors, a silver plus Jaya circuit and enhanced acoustic labyrinth. The HiRez Aneto adds the superior HD MS Rhodium plugs and sockets and all the EMI and RFI reduction/absorption technology.

Use and Performance

The Aneto is really a bit more of a specialised item, compared with most of the main Vertex mains components. You may or may not suffer from DC offset in your home, and the performance of your hi-fi components may, or may not, be affected by DC offset. Telltale signs are buzzing or vibration coming from the chassis of a component, a noticeable drop in performance when particular pieces of household equipment go on or off (particularly with pumps, fans or refrigerator units) or a marked change in performance at peak power demand times.

The thing to do is speak with your Vertex dealer, and try an Aneto on a home demo. There really is no other way. One Aneto should ideally be used in line with each single component. The DC blocking circuit tends to work best when only supplying one power supply (the maths is complex!). But you can use one to supply your whole system (up to 13A).

Experiment and listen to the results. In initial listening tests at dealers some found a good general improvement using one Aneto to feed all the front end components. Others found it was more equipment specific, with results on some components, particularly high-end DACs to be excellent.

And do your experimenting within the systematic approach thinking. Consider overall what might be the best Vertex cost/performance balance for your system. With our mains products, try the mains leads and distribution blocks as well. And see if an Aneto adds value to the solution.

By the way, feedback from those people who have had good results is that there is more clarity solidity and stability to the sound. Timbre is more natural and vibrant and imaging is more precise. In complex pieces the strands of the music remain more easily followed and the emotional intent of the composition is much more engaging.


OLYMPUS DIGITAL CAMERA Standard Aneto