Silentpower from iFi


iFi’s latest ‘audio enhancers’ deal specifically with mains-related noise. The SilentPower range consists of four products at launch: the DC Blocker, the GND Defender and a pair of IEC power cables called Nova and SupaNova. The DC Blocker and GND Defender are designed to tackle different problems that can result in an audible hum. They connect to the power inlet at the rear of any audio component, with the user’s power cable attaching at the other end. They can be used individually or together, depending on the issue(s) the user is attempting to solve. 

The DC Blocker is a neat, effective solution to ‘DC on the mains’ – a problem well known to affect the performance of audio equipment and a significant cause of irritating transformer hum. In theory, the electricity we draw from the sockets in our homes should be pure AC, with a perfectly symmetrical sine wave alternating between positive and negative phases. However, this AC voltage is affected by small amounts of DC voltage, present in the mains supply for reasons that are many and varied – this can cause the AC waveform to become asymmetrical, an effect known as ‘DC offset’. 

The AC transformers commonly used in home audio equipment cannot tolerate the presence of significant levels of DC voltage without being compromised. Less than 500mV of DC – typical in an average household electricity supply – can be sufficient to cause toroidal transformers of the kind often found in amplifiers to become saturated, which adversely affects sonic performance and may also cause an audible mechanical hum. The DC Blocker is capable of cancelling more than 1000mV of DC voltage, thereby correcting the DC offset and rebalancing the AC sinewave. It does this ‘intelligently’, adjusting its performance according to the level of DC detected. This solves the problem of transformer hum caused by DC on mains and helps to optimise the sonic performance of any audio component to which a DC Blocker is connected. 

If you can hear a hum or buzz through your speakers, it is likely that you have a ground loop problem. This occurs when two or more audio components in a system are connected to a common ground (or earth) point via different paths – for example, if two different wall sockets on the same circuit are used to power different components in a single audio/AV system in which the components are connected via electrical (as opposed to optical) signal cables. If a problematic ground loop exists, the GND Defender resolves the issue by disconnecting the loop running through the connected component. By using one or several GND Defenders in a hi-fi system, the user can ensure that all components are connected to a common ground via a single path, eradicating the resulting hum through the speakers. Both the DC Blocker and GND Defender are constructed so that they do not compromise the RFI/EMI shielding or filtering that may be offered by the connected power cable or filtering device further upstream. Their casing has a high dielectric rating and they surpass the highest safety standards. And, with a voltage rating of 90V to 240V, they can be used all over the world. 

The Nova is iFi’s first specialised power cable with a construction that belies its price point, delivering “a serious upgrade over standard mains leads that imbues sound with greater clarity, space and definition”. The Nova has five heavy-gauge, continuous-cast OFHC copper conductors. Two pairs of live and neutral conductors are arranged either side of the grounding (or earth) conductor, which is positioned at the centre of the cable. This geometrically balanced configuration causes the magnetic fields generated by the live and neutral conductors to cancel each other out perfectly, ensuring the grounding conductor is unaffected by residual magnetism and unwanted induced voltage – iFi calls this design Ground Zero. 

A pair of polymer matrix tubes filled with air are arranged either side of the earth conductor, keeping the two pairs of live and neutral conductors apart whilst improving the cable’s overall dielectric performance. Each individual live and neutral conductor sports multiple layers of insulation and shielding. First, a dielectric made from a polymer matrix is extruded over the OFHC copper conductor. Surrounding this is an oxygen-free copper shield. And covering the shield is a further layer of polymer insulation. These individually shielded conductors, plus the air-dielectric tubes, are twisted in a circular helix around the central, untwisted grounding conductor, itself wrapped in polymer insulation – this twisted arrangement further aids RFI/EMI rejection. The cable is completed with a tough yet flexible polymer outer sheath and iFi’s connectors, with oxygen-free copper conducting pins coated in tarnish-resistant 24ct gold. The SupaNova active power cable takes the Nova and adds a cylindrical housing part way down its length. This cylinder contains Active Noise Cancellation II which uses “inverse noise current to cancel out the noise in the mains signal. The way this works is comparable to the technology in noise-cancelling headphones.”

iFi’s SilentPower range begins launching this month. The DC Blocker (£129) and GND Defender (£99) are available now, while the UK-plug versions of the Nova (£169, 1.8m) and SupaNova (£349, 1.8m cable) arrive in July. 


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