The DNA of the Atlas Cables Power Management System

Why do we need to consider the use of high-quality power cables?
Traditionally there as always been an assumption that any power cable will be
satisfactory for use with a hi-fi or home theatre system provided that it will handle the current drawn and provided that it is electrically safe. As a result it has been quite common to find that users have spent large sums of money to build up a high performance entertainment system with good quality interconnection cables yet have powered the components through the same cables they would use to power an electric kettle or a lap-top computer. Similarly many systems can be found to be plugged into a low-cost distribution board purchased from the nearest supermarket.
There are two problems with this level of “false economy”. First it is the case that you cannot get out of the loudspeaker cables what you cannot take in through the power supply cables. So if you have losses at the mains supply end you will hear equivalent losses at the loudspeaker end. Although we all accept the improvements that good quality inter-connects and speaker cables can bring to our hi-fi and home cinema systems there is far less acceptance of the potential benefits of the changes that can be made on the mains power side of the equipment. Which is odd because the sounds that come from the loudspeakers are generated by the power from the wall socket modified and controlled by the input signal. And even amongst designers who should know better there has been an assumption that the mains supply is near enough a perfect 50Hz sine-wave or at least good enough to do the job. But in practice that supply suffers from a number of problems including nasty interference and radio-frequency signals; transient spikes; an asymmetrical wave-shape with consequent distortion harmonics; an unwanted dc component and fluctuations in level.
It is worth noting that the generator companies generally do an excellent job in
providing a supply that is reasonably clean and stable in terms of voltage and
frequency. The problems usually starts in the immediate locality of the home and
many of these problems are caused by neighbouring users. The street supply is
shared so any unusual loads in other buildings will affect the quality of the supply.
Unwanted harmonics and interference can be added by old motors (central heating pumps are popular culprits) whilst some appliances draw power in a way that clips the tops off the originally pure sine-wave waveform of the supply.
Probably 99.9% of hi-fi enthusiasts stick with the power cables that came with the equipment and plug the system into the nearest wall socket often via one or two distribution boards purchased at an attractive price from the nearest store. And the system appears to work OK so why make any changes?
Well let’s start with the socket on the wall. It is likely to be fed from a ring-main which is a power cable which starts at the distribution box (fuse-box) and continues from socket to socket in a daisy chain until the cable arrives back at the  box. The primary advantage of the ring main is that no single outlet can load down the supply to the detriment of an outlet in another room; every outlet gives the same output voltage. The disadvantage of the ring main is that if one appliance, like an old sewing machine or a WiFi router, puts interference onto the mains line then it will appear on each and every socket. Not only are there unwanted “interference” signals on the mains supply but there are also many such signals being transmitted through the air so the shielding of the supply conductors is very important. All the power cables of the system generally go to one set of outlets, and they are usually tied together or laid on top of each other. They also tend to physically crossover the AV interconnects and speaker cables so giving the opportunity for mains borne interference to be injected directly into the audio signal with predictable and undesirable results. So the power cables ideally need to be shielded from each other and from the audio/video cables. As we describe later this is usually achieved by having an outer shield of braided copper wire or foil.
The picture above shows the tangle of cables seen behind many hi-fi systems. A few minutes spent routing the interconnect; loudspeaker and power cables into separate neat groups usually gives immediate benefits to the performance.
Finally the power cable must use thick enough conductors to allow adequate power to flow to your equipment and it needs to make a good connection to both the wall outlet and the product through the use of high quality connectors on both ends.
When audio engineers design power supplies they go to great lengths to keep theinternal supply voltages as stable and predictable as possible. In doing so mostengineers assume that the incoming supply (230 volts at 50Hz in Europe) will bestable. So you will see amplifiers with very large toroidal power transformers andoversized reservoir capacitors all of which keep the impedance of the supply (itsresistance to the follow of electricity) at virtually zero. However there is a constantrule in the design of power supplies; you can only get out what you put in. Thisdoesn’t just refer to the power you can draw it also refers to the circuit losses.


In the primary circuit, the incoming mains supply circuit; there are a number oflosses. These include the losses of any cables or wires; the losses through anyconnections; the losses introduced through fuses or contact breakers and the lossesthrough and filters in the power supply lines. Now these losses may seem small butthey do add up and start to have an effect. This can be shown by doing some simplecalculations. Imagine we have a typical domestic supply chain to an amplifiercomprising the power socket on the wall; the power plug (with perhaps an internalfuse); a length of cable into a distribution board; the internal wiring of the distributionboard and its output sockets; the power plug; another length of cable and the IECtype plug and socket. Now for our example imagine that the total end to endimpedance is 2.5 ohms and the current drawn by the amplifier varies between almostzero and 6 amps depending upon the music level.At the peak current level the voltage loss in the primary circuit will be 6 x 2.5 = 15volts so the supply voltage into the amplifier will drop an appreciable 6.5%.This loss will also dissipate some power = 6 x 15 = 90 watts. This power dissipationwill cause a temperature rise which in turn will cause the resistance of all the coppercomponents and wires to rise. Imagine now that the internal temperature of thecopper cables rises from 20 degrees C to 8o degrees. The resistance will increaseto 3.1 ohms; the voltage loss to 18.6 volts and the power loss to 112 watts. As morepower is dissipated so the temperature will rise causing the vicious circle to continue.Now a voltage drop of under 10% may not seem much but with many amplifierdesigns it can cause a very audible compression of the sound so such losses mustbe minimised.

There is a very simple test that can be made to check some of the losses of theprimary circuit. Play music at a fairly loud level for an hour or two and then switch thepower off and touch accessible items in the primary chain such as the mains powerplugs. If they are warm to the touch then you have significant losses because whereyou have losses you will have power dissipated and when power is dissipated thetemperature will rise. So if the power plug is hot to the touch you will reveal veryserious loss problems which need to be addressed.Mains Power ConnectorsMost people pay little attention to the mains power connections for after all a plug is aplug is a plug. However even though they all meet the electrical safety standardsthey do vary considerably in the quality of the metal conductors used; the design andeffectiveness of the clamping of the wires to the conducting pins and in the designand effectiveness of the mating between the pins and the contacts inside thematching socket. Many low cost UK style power plugs and sockets (13A fused style)have a contact area totalling less than 0.5 cm² yet these will be found in manydesigns of distribution boards which handle high levels of current. It should also beremembered that the supply voltage may pass through a fuse link built into the powerplug so this component should also be of the highest quality and designed to ensurea clean low-loss connection within the plug. The Atlas fuse link has fine silver platedend-caps in place of the usual low-cost; low-performance tin-plated components andwhen used in Atlas plug-tops it ensures a very good connection.


The UK 13 Amp 230 volt power plug and the IEC power plug are typical of the Atlasrange and feature copper bronze pins which are highly polished then plated with 1.25microns of pure Rhodium; a micro finish which ensures an excellent connection andhence better overall performance. The care in design extends to the substantialbodies which are precision moulded in heavy duty Polycarbonate.

What factors does Atlas consider in its cable design?

In designing power cables Atlas always consider five key things. These are; thequality of the conductors; the quality of the insulation; the effectiveness of theshielding; the quality of the connectors or plugs and finally the durability and safety ofthe finished product.For the EOS power cables Atlas uses Oxygen Free Copper (OFC) conductors whichhave a high purity and therefore do not degrade with time. The insulation material is“Teflon” a form of PTFE which not only provides excellent insulation way beyond therequired standard but also shows virtually no degradation over tens of years use.Atlas uses the best connectors currently available as can be seen in the picturesabove. Power Plugs are available for the IEC connector; the Schuko style 220v plug;the Nema 110v plug; and the UK style 13A 230v plug with a silver fuse link.The function & design of cable shielding and screeningThe home of today is flooded by electromagnetic waves; radio frequencies ofnumerous kinds from short transients created by machinery and burst transmitterssuch as is used for radar and Police transmissions to the Wi-Fi and Bluetoothwireless system used throughout most homes. Although we cannot hear thisinterference directly it does have effects that can severely degrade the quality of theaudio signal we are listening to. Many of the circuit components used at audiofrequencies do behave as resistors, capacitors and inductors. But at higher RFfrequencies the so-called “parasitic” properties of many components come todominate and some capacitors turn into inductors; some inductors turn out to behaveas capacitors and so on. Furthermore such RF frequencies and fast interferencespikes can be transmitted across circuit board without any need for direct wires sothey are very difficult to control. If such interference enters, say, an amplifier it canget into the sensitive stages through an input; a feedback connection or a powersupply line and be able to overload the input transistor stage and cause it to “latch”for a time. During that time and any additional time it takes for the amplifier torecover it will not be operating correctly and the sound quality will be severelydegraded although not in a way that is easy to describe. Indeed in even worse casesthe interference signals can cause the amplifier to oscillate with the risk of damageand a long-term loss of performance. And this can often be happening without thelistener becoming aware of a specific problem.RF and interference signals can be reduced by adding screening or shielding thecomplete cable. A cable shield may be composed of braided strands of a metal suchas copper or a non-braided spiral winding of copper tape, or a layer of conductingpolymer; a metal foil which is bonded to a plastic film. This is the type of shieldingused for Atlas EOS power cables and the shield acts as a Faraday cage so that anyelectrical signals on the outside of the cage will not be present on the inside of thecage. The shield works by shunting electromagnetic energy (the RF or interference signal) to the ground. To do this effectively a shield needs to cover the conductorscompletely, so that RF energy cannot readily pass through any holes in the shield; itmust have good conductivity so that energy can be easily conducted to the ground;and naturally there must be a good connection to the ground at the end of the cable.


Why all the power cables should be upgraded

So far we have explained that a high-performance power cable should allow theelectrical current to be delivered to the equipment; be it an amplifier or a DVD player;with the minimum of electrical losses and with the minimum pickup of any unwantedsignals which could distort or colour the sound. Yet sometimes users, for perfectlyunderstandable reasons, may chose to change just some of the cables in a systemand then find that the improvements are not as clear as were expected. But RF andinterference signals will always find their way into an electronic system if they aregiven an entry point and once inside they can pass freely from unit to unit becausethere is nothing to impede their progress. The only way to avoid the audibledegradation they bring is to deny them an entry into the system and that meansshielding every single power cable.

Power Distribution for your Hi-Fi system

In an ideal world the best way to connect a hi-fi system to the electrical power supplywould be to provide an output socket on the wall for each individual piece ofequipment; each socket being directly wired into the ring main supply or wired on adirect spur to the consumer distribution unit where the mains power enters the home.However with many systems needing, say 8 to 12 outlets, this is too big a step formost people and can often require expensive re-wiring of the home. So in practicemost people use distribution boards and because such products all look much thesame most people finish up using relatively inexpensive boards bought at the localsupermarket.But the use of such boards can degrade the performance of a good hi-fi system andwill certainly undo all the benefits of using good quality power cables. By contrast awell designed distribution board, such as those made by Atlas Cables, will use highquality output sockets which ensure a low-loss connection with the matching powerplugs. The Atlas boards also use high purity conductors such as OFC covered byhighly stable insulators such as PTFE. They also include a means of suppressinghigh voltage spikes or surges which can easily damage very expensive equipment.This is best done using super-fast acting MOVs (Metal Oxide Varistors) which act asa virtual short circuit when the mains voltage reaches a particular level; typically 260volts. Atlas Distribution Boards fulfil both these requirements but they offer somethingmore and that is Star wiring.The picture below shows the wiring of a typical distribution board and all the outputsockets are wired in a “daisy chain”; that is each wire goes from one socket to thenext and so on.


This means that the current being drawn by every unit in the system passes downthe same conductors so there will be a small but definite effect upon, say, a CDplayer when an adjacent amplifier starts drawing large currents. Furthermore noiseon the supply can move easily from unit to unit.By contrast the star-wiring arrangement used by Atlas Cables and shown belowconnects every unit back to a “star-node” where the supply cable enters thedistribution board. The benefits of this arrangement can be measured and, moreimportantly, heard.


Another thing to remember with distribution boards is never use a board which has aneon indicator. The light you see is caused by the breakdown of the neon gas; abreakdown which creates a mass of high-frequency energy which will find its way intoyour audio circuits.Although the extensive shielding and good grounding performance of Atlas Eospower cables does avoid RF and other interference signals getting into the supply itcannot remove any such signals which are already mixed into the mains supply. Forthis reason the Atlas 4-way Power Block is also offered with a built-in low-loss RFfilter of very advanced design which has been designed to filter out the interferenceand RF whilst adding minimal increase in the impedance to the supply lines.

Protection from High Voltage Spikes on the Mains Supply

Voltage spikes on the mains supply are commonly caused by users who switch highelectrical loads such as those drawn by machinery, lift motors, welders, fluorescentlights, fridges, and so on. When the mains power-supply voltage nears the peak of itssine wave the actual peak instantaneous voltage is 325V. Now if a piece ofequipment is then switched on or off there will be a brief inductive spike of severalhundred volts on top of that sine-wave crest so the peak voltage might be 650 voltsor so. The spike might not last for long but even when of short duration it could do alot of damage to a high performance hi-fi system. Such a voltage spike would beenough to degrade the performance of many transistors and although they wouldcontinue to work they would never again work to their original specification. Even worse nearby lightning strikes can create spikes of several thousands of volts peak amplitude.

Our solution is to incorporate a device which will limit or clip the incoming voltage to asafe maximum. Such devices are called Voltage Suppressors or Varistors and theyare wired between the Live and Neutral lines. Whilst the voltage across them remainsbelow a defined figure they have no impact upon the operation of the system butwhen that defined voltage is exceeded they break down, to dissipate the unwantedenergy. If the over-voltage is high it will usually destroy the device, so Varistors cansometimes be a one-shot insurance policy although most of the time they simply“clip” the voltage to remove any voltage spikes on the power lines.

In Summary

In many ways it is fair to say that much of the investment in a high quality hi-fi systemis potentially wasted if attention is not paid to the quality of the mains supply it ispowered from. The supply must be clean and free from any noise; interference andradio signals all of which can degrade the performance of the system and, in theworse cases, cause permanent damage to the system. To get the best results froma hi-fi system the user should follow some simple rules to ensure that the supply feed(the sockets on the wall) will be adequate then it is essential to wire each and everyproduct through a high quality power cable such as the Atlas EOS cable and, wherea means of power distribution is required, only to use a matched and purposedesigned product such as the Atlas Eos Modular Distribution Board.

But remember. Noise; spikes; and RF signals can find dozens of entry points into asystem so care must be taken to correctly cable the system throughout. The use ofan inadequate power cable into one piece of equipment could turn out to be the oneplace where the degrading signals enter the system.