There are three types of hifi tweakery that should make no difference and yet have impressed me most: digital data transport, equipment support and mains power changes.
I’ve described changes to the former in other posts and will write about my feelings on the technical reasons why it matters in a later post.
Quickly I’ll also note that I’ve found equipment supports to matter in a subtle way, and have used SAP Relaxa magnetically levitating platforms to good effect in the past; but can’t any more as they are too wide for my AV cabinet. I can clearly understand how vibration might affect a turntable, and for similar reasons also change the sound of a CD player, but electronics?
I saw a YouTube video of an engineer that worked for a major capacitor manufacturer holding up a capacitor wired in such a way that it acted like a small, tinny speaker. As it charged and discharged in time to the music, it vibrated and made sound; by inference, the reverse influx of vibration into the capacitor created electrical charge as well, and they had found that a vibration-damped and clamped capacitor sounded better.
This I can understand!
Now we come to mains power. How is it that such a significant difference can be made when swapping out a mains cable, or fitting an earth spike, or some kind of filter from Isotek or Shunyata or whoever? Surely 240V and 50Hz travelling down miles and miles of cable into the home isn’t going to care about the last m of cable?
But it does.
I have some hypotheses. Bear with me, because I am not a scientific genius and have probably based those hypotheses on some dodgy assumptions.
To my mind, the cables (and some conditioners) make a difference through these parameters:
1. Cable thickness
2. Cable material (Copper, Silver, silver plated copper)
3. The quality of that material (OFC, OCC, 6N and so on)
4. The dielectrics (rubber, plastic, Teflon, air, silk, cotton – although the latter 3 may not be legal for mains)
5. Shielding
6. Geometry (Litz, solid core, stranded, multi-stranded, circle/oval/rectangle cross section, and some combination of all of these)
7. Plugs, plug materials and tightness of contact
8. Cable length
9. Grounding
In theory, for any mains cable having broadly similar values for resistivity and voltage drop, capacitance and inductance, a 240V 50Hz sine(ish) wave will make its way into your equipment pretty much the same regardless of all of the parameters above, and make no difference to the sound.
But it does!
Here comes the hypotheses. Let’s agree that electricity represents a flow of electric charge. Whilst electromotive force travels as near to the speed of light as makes no difference, charge itself travels relatively slowly. The example is a hosepipe that you plug in to a tap some distance away. When you turn the tap on, it takes a short while for water to make its’ way down the pipe and into the eye you had put at the end of the pipe to see where the water was.
Now imagine the hosepipe is already full of water and has a nozzle at the end with a trigger grip – you squeeze it to release water, release it to cut the flow. Because the water pressure is constant all the way along the hose, as soon as you pull the trigger the water is released, but it was water already at the end of the pipe and not water just starting its journey from the tap.
Wire is usually made of metal, which has a very large number of free electrons that like to move around. Apply a voltage and they all start moving the same direction, because electrons at one end of the wire are pushing the ones next to them (like charges repel) which push the ones next to them and so on and so forth. If there is no circuit, they can’t move anywhere and no amount of voltage, within reason, will force electrons to flow.
Stuff that isn’t metal, such as glass or water or a plastic comb, doesn’t have lots of free electrons and it usually takes physical force to brush a few off – like, say, rubbing a nylon jumper or combing your hair. Electrons are broken off and kind of stick around, pushing against each other to distribute themselves as far apart as possible. This is static electricity.
So, charge is now flowing down a wire into your equipment; at least, that’s how it works for Direct Current, which is what happens inside your equipment itself, even if the power cables are carrying Alternating current with packets of charge moving one way and then the other about fifty times a second. Charge moves through your equipment into capacitors, through resistors, around transformers and into transistors, MOSFETs and valves as required, switching back into alternating current of course as soon as the charge leaves the power supply section and starts to carry signal.
What happens inside your equipment is the conversion from mains power AC into lower powered DC, and this usually requires some kind of rectification network. Which means – charge flows forwards into a capacitor, and stops there. On the backwards cycle of the AC, diodes prevent the charge from flowing back down the wire; perhaps a small amount of charge gets pulled down the neutral leg from your equipment. All those free electrons being sucked out of the mains and into a capacitor bank to be used. If they weren’t being replenished from somewhere, eventually you would run out of free electrons. Where do they come from?
Well, from within the lattice of the metal itself, of course, and that from metal further down, and past the consumer unit, and to the transformer locally serving your housing area. Since it is replaced by charge physically flowing from the other end of the cable eventually, you never run out of charge, and the speed of flow of charge is still fairly fast. But, of course, there are peaks in the sine wave, and troughs too, when a bunch of charge is maximally forced into your equipment and held there to be used.
How quickly this charge both flows in and is replenished determines how effectively you get power. It’s the amount of charge – the physical quantity of electrons – that Is driven forwards and into the capacitor with a big push from the wall as the voltage rises on the AC waveform, reaches its peak and maximally transmits charge, and then slowly fades. If the cable is thick, there are more free electrons because there is more metal, and the impedance drops and more charge can flow more quickly.
This seems to me to be a valid reason why a thick power cord lends weight, body and dimension to my system, particularly the power amp, which needs a lot of free electrons available to drive speaker cones – even horns with massive magnets. Even the best power supply can benefit from having its reserves more immediately replenished. Cable material and its quantity matter here as well – silver is more conductive than copper because it carries more free electrons by weight. So there is more free-flowing charge which is replenished more quickly down the wire.
Next, there is the physical action of the electron flow down the power cord on the dielectric, which by design does not conduct and therefore behaves like the comb, balloon or glass rod. There is a quirk of nature called “skin effect” which means an AC waveform tends to push charge towards the outside edges of a conductor as oscillations and voltages increase. This is a known phenomenon, which carries the additional effect of making the charge flowing down the wire travel alongside the dielectric - rubbing against it, in fact. So a static field is created on the insulating dielectric, and interference is the result. Maybe silk and cotton work better than rubber, taking more or less effort to release their charge and therefore adding to or subtracting from the mains waveform in an even-order way, rather than un-harmonically and odd-order? This doesn’t strike me as impossible, and correlates with what I’m hearing with the PHY.
… and then you get the dreaded RFI and the influence of other magnetic and electric fields as you run cables across each other and into the back of your equipment. My house is awash with radiation from the microwave, WiFi, Bluetooth, DECT phones, other equipment, and then of course from mobile phone base stations and television and radio transmissions.
A well-designed power cable may filter out RFI and the effects of static and mechanical/electric/magnetic interaction, leading to an uplift in audio quality. Combining that with a thick cable of the right material and geometry should provide the most free electrons with the fastest flow of charge into your equipment. Ensuring all the contacts are clean and tight stops the fight of electrons rushing forwards from vibrating physically and losing energy which could otherwise fuel your equipment.
All of these things make a difference, and it is all despite the power to your wall socket coming through miles of low-quality, thinner cable; because the hifi’s power supplies are connected to that last few feet of cable, it really isn’t at the end of the supply, but in the middle.
With my system, I’m liking both the harmonic and natural sound from the cotton/silk wrapped PHY and the depth and weight of the homebrew 6mm2 copper, but can’t get the latter without losing the former. On balance, I can’t do that and homebrew would go back – unless I could find another thick cable with the right dielectric (Teflon?) and at the right price. It isn’t rocket science, despite the hype surrounding some very thick cables, so I’m sure it must be possible…..
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