audiolab DC BLOCK – Direct Current Blocker User Manual

DC BLOCK Direct Current Blocker

Above: Audiolab ‘DC BLOCK’ all-in-one DC blocker and mains ﬁlter in silver ﬁnish

A dual-action device ensures power does not corruptaudio labs new DC BLOCK removes RFI/EMI whilst banishing ‘DC on the mains’ to deliver pure, rebalanced power to audio and AV system components

Famed for its ampliﬁers and digital source components spanning four decades, Audiolab is now releasing its ﬁrst product designed to improve the quality of AC electricity we feed our audio and AV systems – the dual-action DC BLOCK.Mains electricity has a fundamental inﬂuence on the audio signal as it passes through a system, from source to amp to speakers. The mains supply in a typical dwelling is subject to interference induced by a range of issues, causing the AC waveform to distort before it reaches each component. This creates noise in the audio signal, which degrades sound quality – a situation that continues to worsen as the electrical devices we use in our homes proliferate.One common issue is ‘DC on the mains’ – a problem well known to aﬀect the performance of audio equipment, especially ampliﬁers. In theory, the mains electricity we obtain from the sockets in our homes should be pure AC, with a perfectly symmetrical sine wave alternating between positive and negative phases. However, the presence of ‘asymmetrical loads’ – myriad household devices that usethe AC energy available in the mains cycle unevenly, from dimmer switches to kitchen appliances to computer power supplies – causes the waveform to become oﬀset, resulting in the presence of DC voltage on the AC supply.

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 transformer of the kind often found in ampliﬁers to become saturated, which adversely aﬀects sonic performance and may cause audible mechanical vibration.

By blocking, or cancelling, DC voltage found within the AC mains supply, the Audiolab DC Block corrects the DC oﬀset and rebalances the mains sine wave (see illustration above). But tackling ‘DC on the mains’ is not the only beneﬁt delivered by this dual-action device – it also contains a high-performance audio class ﬁltering circuit that removes RFI/EMI contaminants from the mains supply. This is eﬀective in reducing both diﬀerential-mode noise (exacerbated by cheap switch-mode power supplies used by many home appliances) and common-mode noise (aggravated by airborne interference from phones, Wi-Fi networks and Bluetooth).This combination of technologies ensures that the DC BLOCK does more than solve the problem of transformer saturation caused by DC on the mains; it also helps to unlock the sonic potential of any audio component to which it is connected. The noise ﬂoor drops and the sound gains greater focus, with reduced grain, improved clarity, better-deﬁned bass and ‘airier’ treble. Above: Audiolab DC BLOCK, all-in-one DC blocker and mains ﬁlter in black ﬁnish

Using the DC BLOCK is simple – plug its output into the IEC power socket of an audio/AV component, then connect its input to amains socket (both cables are provided). The device is designedfor use with a single audio or AV system component – Audiolab recommends that if one DC BLOCK is purchased, it should be used with the integrated amp or power amp component within the user’s system to obtain the greatest beneﬁt from the DC-blocking technology. If desired, further units may be purchased to use with other electronics in the system – preamps, source components and so on. With each additional DC Block, further incremental improvements in overall system performance can be expected.Above: Audiolab DC BLOCK, all-in-one

audiolab DC Block speciﬁcations