Dominic Marsh concludes his three part series on mains cables. YOU can read Part 1 here and Part 2 here. 

And now for the final part of my musings on upgrade or aftermarket mains power cables.  I am trying very hard to keep it simple for those folks who have no electrical or electronics knowledge, who can hopefully get their head around such complexities without being bamboozled by technicalities.

SAFETY WARNING:  Hifi Pig does not advocate anyone making ANY unauthorized or unsafe changes to their mains supply or equipment in ANY way. Always consult a professional and qualified electrician.  Be safe out there in audiophile-land folks.

Based purely on my experience and observations, aftermarket power cords seem to be least effective with switch mode power supplies and that is because they lack large reservoir and smoothing capacitors and I believe I may know the reason why. With conventional linear power supplies as in transformer, rectifier(s) reservoir and smoothing capacitor(s) circuits, power demand is usually met by the energy stored in the reservoir capacitors provided the demand is of short duration and of low demand current draw.  However, when current demand is high the capacitors are supplying the required energy for short durations, but they are unable to discharge and charge at the same time – they can only perform one function at a time.  The power amplifier section will still draw more power even though the energy is being drained from the reservoir capacitor, but where will the amplifier get it from?  Good question. 

In acute situations, the amplifier will “clip”, that is run out of available power for the amplifier section and that is clearly audible to anyone that’s heard it as it is a rather memorable sound.  High-ish but lesser power demands below that clipping threshold could result in an increase in distortion, but what if the power supply is only slightly lagging behind the power amplifier’s power demands?  I believe that is where bass boom artifacts arise, which then can lead to a “loud” or “shouty” kind of sound, which then leads on to clipping as power availability from the supply diminishes and a poorly rated power cord that cannot keep up with the power supply’s demands either simply exacerbates that.

A switch mode power supply on the other hand regulates voltage by switching on and off rapidly and curtailing the “on” time of the electronic switch when controlling an AC waveform derived from a high frequency oscillation circuit from a frequency generator in the power supply module, usually at a frequency well above human hearing capability.  So, instead of adjusting the power output up and down in a linear fashion from a Direct Current source (hence why it’s called a “linear” power supply) the switch mode power supply effectively chops up an AC waveform into “lumps” of energy which is then smoothed in a capacitor to provide a constant DC current source that the amplifier requires.  The power adjustment comes from varying the amount of time the switch (Usually a transistor and sometimes known as the “chopper” transistor) is allowed to conduct in the ‘on’ position , so the longer it is conducting the more energy is produced and stored in a capacitor and reducing the ‘on’ time of the switch commensurately reduces the energy output.  The major benefit of this design is that it is more efficient, produces less heat from the energy saving and less costly to produce too, even though some switch mode power supply PCB’s are well populated with many discrete components.  Yes there are generally some transformers in their design but they are minute compared to the ones found in linear power supplies.

A good indicator of power supply capabilities can be found in the quoted specifications for an amplifier fed into an 8 Ohm load and a 4 Ohm load.  If the figure given for a 4 Ohm load is double that for an 8 Ohm load, then the power supply has been designed with plenty of reserve power and any figure less than double, should be viewed very cautiously as that power supply isn’t a very capable performer.  So if the specification sheet says “100 watts into 8 Ohms, 200 watts into 4 Ohms”, that is a good indicator, whereas “100 watts into 8 Ohms, 125 watts into 4 Ohms” tells you then that the power supply should be regarded as inadequate.   Even though pre amplifiers, CD players, streamers and DACs etc., all benefit from an upgrade power cord, the effect seems to be less dramatic than with an integrated or power  amplifier.  The one component where it has had no effect at all is turntables.

“What’s that got to do with an aftermarket power cord?” I hear you ask.  On its own very little actually, but in the context of the entire chain between wall power socket and speaker cones it is an essential link component in that total chain and any weakness here will be reflected right through to the speakers.   I explained this in Part One of this blog the reasons why an aftermarket power cord can, in my  opinion, have a profound effect on sound quality and I am trying to mesh that knowledge in with the explanations given in this part.

Over the years I have probably heard all the inane arguments about kettles boiling faster from an aftermarket power cord (Has anyone actually created or carried out such a test? I doubt it), their vacuum cleaner cleans better, blah, blah, blah, but it has been reported many times that televisions will also benefit from an aftermarket power cord upgrade with more vivid colours, better contrast, less on screen noise/speckles and better sound quality too.  I really must get around to trying this one day.

Copper, yes, silver, yes, but what about other metals?  I have experimented with aluminium wire, gold wire, platinum wire, carbon, steel wire and unobtainium wire, which all sounded completely different, but that was used in constructing interconnects and speaker cables, which I may cover if readers wish me to do so.  With regards to mains cables however, I have only heard differences in silver and copper cables, the former significantly reducing hiss, while the latter seemed to ‘slow’ the sound down slightly, which was only noticed during direct comparison between copper and silver cables, the effect was only slight may I add, so those of you with copper cables can still sleep soundly at night and heavy gauges of copper wire should trouble you even less.

So there you have it, my take on the why’s and wherefore’s of aftermarket upgrade mains cables.  You may not agree and that bothers me not one bit if you do, as it’s not meant to be the definitive answer to the age old debate over cables.  It’s the only way I keep myself grounded on why I have spent quite a tidy sum on the cabling in my own system, so if it does likewise for you too then it has been worthwhile.   I fall back on this because I don’t subscribe to the notion that any cable only has the three basic parameters of resistance, inductance and capacitance.  No sir.  To me those measurements are rather primitive and two dimensional at best, plus when there are still debates about which direction electricity flows in and how lightning is created still to this day remains a complete mystery to even the most eminent scientists, then my entirely subjective version still holds true with me.  The objectivists also said that the human ear wasn’t sensitive enough to detect changes in sound levels below 3db, yet a Spanish blind testing panel a few years ago noted that changes down to 0.1db could be heard by the listening panel, so that’s another misconception blown out of the water.

SAFETY WARNING:  Hifi Pig does not advocate anyone making ANY unauthorized or unsafe changes to their mains supply or equipment in ANY way. Always consult a professional and qualified electrician.  Be safe out there in audiophile-land folks.

Dominic Marsh