Pre-warning: this is a rant.

There are all kinds of shields:

Medieval

Viking

Roman

Riot shields

Face shields

etc

But here I'm wanting to talk about cable shields.

Again, the word "shield" might provoke thoughts of armour provided by heavy rubber or plastics, or braids made of non-metallic or metallic materials. But mostly, these are mechanical shields.

I have even read of interconnect cables that use metallic shields which aren't used in any electrical sense - not connected. It must be that those who make them either don't understand interference, or physics, or they perhaps think that interference might add some sound-effect.

Then, there are those who think twisted pairs are effective against interference, and yes, it is true, they are, but only where the send and receive circuits are geared to interference cancellation - e.g. telephone wires - plus narrow band filtering. OK if you want a telephone sound...

But when it comes to connecting single sided inputs and outputs, a proper electrical shield is a must, but a lot of cable makers don't understand why.

This picture shows why at least 100% shielding in required.

The shield or screen (not to be mistaken by this next image)...

...holds the grounds of both send and receive equipment at the same potential. The signal is referenced to ground, and by holding the grounds at the same potential, then one doesn't electrically "wiggle" differently to the other, and the signal sees no change - and no interference.

You see, you're travelling at 67,000 mph and rotating at 1,000 mph at the same time right now, but seeing everything else within the atmosphere of planet earth is doing likewise, we don't notice, and that's how low impedance shields work.

Remove the shield (or screen - means the same thing) and replace it with a wire, as such making it the equivalent of a bell wire pair, and most of the "arrows" (inteference) lands on the signal, and also on the return wire - which was the shield, but isn't anymore - and both ends "wiggle."

But from say a CD player perhaps you don't hear any interference, and that's down to signal to noise ratios. Now phone somebody on a DECT phone and put it right up to the bell wire pair, and you'll understand signal to noise ratios.

I admit you can get some surreal sounds using bell-wire equivalent interconnects between a high level source and amp, but is surreal better or just surreal? Actually, it's just being silly, with added hubris, which causes money to change hands. I have heard the cranky responses, like "you could feel the electrons in the air listening last night". What about the music?!

A phono stage differs greatly from a CD player. A CD player output amplifier produces unity gain or perhaps a little more, but it's source - the DAC chip - is low impedance. A phono stage amplifier produces gain of around 100 with a high impedance input (MM) or gain of around 1000 for moving coil.

Capacitance and mutual inductance couple any interference introduced into the output back to the input, and where negative feedback loops are fast in high quality stages, the interference, which is at radio frequencies, gets an easy ride to the phono stage input. There being no narrow band filtering, so that you get a wide frequency response, then the interference is amplified along with the signal. The next thing you know, there is an email complaining that our phono stage has gone noisy!

Play with fire and you get burned.

But these interconnects are so well publicised. They're in a language allien to engineers, but somehow communicate great things to the average customer. The reason for this is zilch education from the glossy magazines - they, through their ignorance are also taken in. Of course they're ignorant - real measurement went out the window in the 1970's - replaced by wine tasting.

OK, there are magazines that more recently bought and boast about audio analysers, but in my opinion, it's all the gear and no idea! I've heard all the BS from some reviewers claiming how they designed semiconductors for the multi-nationals, so why are they now working for £50 a page?

I recently read about carbon fibre shielding and had to laugh in disgust. How resistive is carbon fibre? It is so resistive that they started making HT leads for petrol engines using it as the HT conductor, to reduce interference with car radios (1970s). They make resistors out of carbon - carbon is resistive - and so much so that it is useless at shielding out interference - you may as well use plastic braid!

Now, shall we go back to school and remember what the science teacher said: "there is no such thing as an insulator - just poor conductors". Then again perhaps the teacher was too interested in politics...

Shiny metals - metals that can be polished - are good conductors and make good shields: copper, steel, aluminium.

Poor conductors are wood, plastics, carbon fibres, cotton, teflon, air and a vacuum (to name a few). They will conduct electricity given sufficient potential. Air does exactly that - ever heard of lightning?

None of the above have any use in shielding.

Some think that laying or knitting a ground conductor next to a signal conductor shields the signal conductor. OK, perhaps in its shadow, but interference is from all angles. It was once explained to me over a beer, that using silver foils with one at right angles to another, afforded sufficient shielding. My expletive filled response almost got me kicked out of the bar! That was 20 years ago - the BS has been around quite some time.

What's more, is the accusation that "other" cable makers are copycats - that they're not innovative. There is a reason for people like me using properly low-impedance shielded coax - if that's what's meant by copycat. It's because it works - has always worked - and will always work.

By the way, we now have to have it made at great expense in 10km (6 mile) minimum orders. If only the BS worked, it would be much more profitable.

A few years ago I developed a hypothesis about the best places to put tubular ferrites on interconnects. These are our Lautus cables.

Around the time of their launch I was approached by a UK distributor of a knitted interconnect for support in a court case brought about by the advertising watchdog - the ASA. I refused because I disagreed with the claims made about it. I refused because the claims made no sense in physics, and I apologetically said so.

Not long after that an anonymous university lecturer put in a complaint to the AES about my explanation of my hypothesis. I had no choice but to remove it.

I had claimed that the USB version had a ferrite placed at the anti-node of a frequency considered to be a cause of interference.

This was related to the velocity factor - which exists - but was rubbished, and so any explanation as to where the anti-nodes occur, was discounted as fantasy. At the time I had Cherry Clough assisting me with EMC (I was paying for their services), but even explaining to the ASA that I was using their own consultant used in their court case, it made no difference to the ASA. Talk about hypocrisy!

Cables have a science all of their own, but it's real science, and not the BS many are taken in by.

As such, I have decided to give away the hypothesis surrounding the Lautus USB cable for anybody to criticise. It might take me some time to gather the proof of the physics involved, but in doing so I wish to demonstrate the difference between BS cable claims and real physics.

Before closing this post, I will show you a quote from an aviation cable manufacturer, which completely rubbishes the ASA accusations:

"The delay from one end of a cable to the other is inversely proportional to the VOP: the lower the VOP %, the longer the delay.

This can be important in relative signal timing for navigation systems, for example. Delay is independent of frequency. In effect, it is the defining factor of the electrical length of a wire or cable."

The salient point being "Delay is independent of frequency".

My next question, I have seen people talk about PC-OCC and PC-CCC copper cables. Do they make a difference compared to some good quality OFC, or is the construction of the cable more beneficial than the material it has been made from?

Electrically, they probably measure the same, but can they be audibly different?

It was 1978 by the time I got around to studying digital logic, thanks to the Elektor Digibook (South Yorkshire lads weren't supposed to be educated). One thing I recall above all the truth tables and logic functions, was a thing called propagation. Even though logic chips were becoming faster (and smaller - Moore's law), if one leg of a control input had more stages than another, the result would sometimes not be as predicted. A "glitch" would occur, because one trigger would reach a gate before the other. Therefore, each leg must consist of the same number of processes, and that could take some ingenuity to comply with.

This wasn't much different to wave propagation speed which was part of my RSGB VHF licence exam cramming, which I was also trying to fit in. In the event, I didn't take the exam. You see, I was also holding down a full time job in AV.

Much later, in fact only 19 years ago, working on Nottingham University's newly acquired Boots building - installing the stage PA system in its lecture theatre, I found myself having to help the visual side of the install.

There was a 60 metre RGB cable going from a podium to a roof mounted projector, and the picture was ghosted badly. The semi-pro DVD player, even though supposed to be able to drive the cable, wasn't doing well. In my toolbox I had some clip-on ferrites, and thought it would be worth a try placing them on the cable - the ends of the cable I could reach. It didn't work, and I was about to give up, when I wondered if moving them a little way along the cable would make any difference. After a lot of mucking about, the picture sharpened and the ghosting had gone.

I'm usually told I'm wrong, so I don't like commenting on conductance issues like this. But silver is a far superior conductor than copper, and I at least, can tell the difference blindfold when a copper interconnect is replaced by a silver one. Therefore perhaps the people are right?

I don't care what purity, quality, coating or alloy they use. If it isn't shielded sufficiently and uses a "slow" dielectric, then how the hell can they tell?   

I believe so. You can always check for the correct wording  https://en.wikipedia.org/wiki/Velocity_factor - https://en.wikipedia.org/wiki/Velocity_factor

Not too shabby if I am not mistaken. It also has aluminium foil and copper braid shields.

The conductors are made of UP-OCC copper in a twisted pair, which I have soldered to some silver plated Neutrik XLRs. I make them up myself mainly due to being a cheapskate, and because I can make the exact lengths I need to avoid having excess cabling behind my rack. 

I was tempted to try a more exotic connector than the Neutrik XX series plugs until I saw the prices.

n=v/c (speed of light in the medium / speed of light in a vacuum)

I doubt this is a coincidence.

Also:

c= 1/sqrt[(epsilon)0·(mu)0]

Ferrites add inductance to wires, making them higher impedance on reaching, and exceeding their frequency range. Tiny ferrite beads would be threaded onto transistor base leads to get rid of radio breakthrough. I'd learned this as part of my RSGB exam course (the exam I didn't take). But I thought every electronics guy would know that, so perhaps the "university lecturer" didn't do the radio ham stuff?

(I could not afford to fight the UK government - its advertising standards department. Not that the government itself is squeaky-clean - party's etc. They were effectively denying the workings of physics.)

By clipping the RS Components ferrites onto the DVD cable (Nottingham University job, 2003), and adjusting their position to a point where the ghosting stopped - so we all got paid - I'd obviously discovered something and that something remained at the back of my mind until after the development of the Bitzie DAC, some 10 years later.

I was sure the Bitzie DAC could do better sound quality than I was getting and started to investigate boutique USB "audio" cables. Even with OFC copper and gold plated terminals, I couldn't detect any difference compared with a stock short USB printer cable.

At that time, we were also looking into placing ferrites on an audio coaxial cable (which became the Lautus). Simply placing a ferrite tube anywhere on the cable gave no audible result, until I started to increment its position inch by inch. It seemed that at one position the bass improved. I wanted to know how.

Since 1995 it has been incumbent on audio equipment manufacturers to comply with EMC regulations, which is easier to understand if you'd done such as the RSGB exam (which I didn't sit). And because EMC testing using trial and error costs the earth, it is better to understand what's involved. When you do, then you can self-certify and avoid costly EMC certification - but you have to be able to provide convincing evidence should you be hauled in front of a committee. I trust the reader will understand the responsibilities we take and put it in perspective with the BS they seem often conned with.

So, back to the studies. I mentioned earlier about signal propagation. Go over to https://en.wikipedia.org/wiki/Signal_propagation_delay - https://en.wikipedia.org/wiki/Signal_propagation_delay

and have a read, as it will save me having to explain it here.

Note this quote from the text: "Wires have an approximate propagation delay of 1 ns for every 6 inches (15 cm) of length"

You might think that we're talking about ultra high frequencies and skin effect etc, but note the salient point from my earlier post: "Delay is independent of frequency". That comes from the aviation industry - not Hi-Fi.

I am sure computer network geeks will also know about this, especially those dealing at an infrastructure level, such as Ethernet over 500 metres of cable?

It suggests that a wavelength has a length in a cable. It must have, and in radio ham'ing, antenna cable lengths are tuned using a VSWR meter. That's something I remembered from my RSGB studies.

In other words, a number of cycles of a frequency fit into a length of cable a number of times. There are actually calculators online which will tell you the length per frequency. This is not the fairy tale stuff of pretend interconnects, it is real science - the sort the world depends on.

Therefore, as the signal "travels" along the cable, it starts at zero - which is a node, and either goes negative or positive, depending on phase, and reaches its first quadrant - which is an antinode, and then its next quadrant which is zero - and a node again, before reaching it's third quadrant - which is its second antinode, and then completes its first cycle at the fourth quadrant - which is again a node.

For a particular frequency there is a particular length: "Wires have an approximate propagation delay of 1 ns for every 6 inches (15 cm) of length"

I'll let you digest this before embarking on the next stage.

It is a shame that you don't have a lab where you could irradiate a length of cable with high intensity radio waves in the MHz range you wish to attenuate and have a machine that precisely moves a ferrite ring through the cable sheath then measures the dip in response at and around the chosen frequency (corresponding cable position).

Based on the notion that "Wires have an approximate propagation delay of 1 ns for every 6 inches (15 cm) of length", at a frequency of 100MHz the first antinode should appear at 15 inches.

Ash wrote: VOP % = Velocity of Propagation, given as a percentage of the speed of light?

From what we know, insulation conducts badly (that's what all secondary school science teachers teach at some point in the syllabus). The wires are insulated and so the insulation must have a braking effect on the signal. Cable manufacturers quote the VOP percentage (OK, they don't quote it on mains flex, but you can work it out). By quoting it, it must exist?

(the ASA "snitch" was in denial about this and the ASA chose to believe the "snitch")

I wanted to know where, in a particular cable, the first antinode of a particular interfering signal occurred.

A property of a ferrite tube is that it can work as a transformer, and that property is used in power line filters to reduce interference. By transforming two wires against each other there becomes an effective short circuit at a particular frequency.

In the current probe I've been working on - and with, it can have a single turn and still produce the required current measurement. It is better from a resolution standpoint to have more turns, so the current probe has ten turns to return a volt per amp reading. I include this to aid the reader's imagination in understanding the following.

The smallest number of turns you can have is a half turn. This is where a wire passes through the permeability of a ferrite.

The ferrite increases the impedance of the wire passing through it for frequencies in which the ferrite is designed to attenuate. By mutual inductance, two wires passing through it loose energy to each other as in a shorting transformer, or differential choke used in a power line filter.

Therefore this must have an attenuating effect on signals "passing through" a cable, but all so often has no effect.

However, placing the ferrite in a determined place along the cable had the effect of clearing the ghosting image on the DVD cable.

What must the coincidence mean. What way can we work out where to put the ferrite?

First we need to know the interference frequency. Is that anybody's guess or can we find a spectrum of interference frequencies that include some common ones that apply to most if not all locations?

In my essential EMC compliance work, I have to know these things, and I have books written on the subject by Keith Armstrong, who is an authority on EMC. Otherwise he's known as Cherry Clough Consultants. Therefore the ASA used Keith Armstrong's evidence in their court case against a knitted cable distributor, but would not accept evidence from their own expert in my defence.

Nevertheless, I am still able to sell the results of my work, as long as I don't tell you how it works, because there is no evidence that it does. And as such, here I am giving you the hypothesis, because hypothesis is a word that passes the legal hurdle.

The hypothetical interference frequencies are 100MHz and 200MHz which are the centre frequencies of the bands used for transmission of analogue and digital radio broadcasts, which feature highly on the EMC spectrum. There are other interference frequencies - that is obvious - but these two are intentional and available 24/7 from a transmitter near you, and so are quite powerful peppering frequencies close to the fundamental band's central allotted frequencies.

In radio ham'ing, the RSGB teaches that the communications bands have priority over all other equipment. That if communications interfere with domestic equipment, it is the domestic equipment's fault! As licencing authority the RSGB is government linked (more on that later). The radio ham has to be capable of fixing the interference "caused" by the domestic equipment not being up to scratch. Now, that ought to cover interconnects I should think, especially those designed without due care and attention, that are interference "magnets".

So, back to the hypothetical interference at 100MHz and 200MHz. The first quadrant - the antinode - is the moment of maximum energy (assuming current is in phase), and if that can be "transformed" into the return wire - like a power line filter choke - then as it is a short circuit, the interference signal cannot propagate any further.

However, a half turn transformer is not that effective, but perhaps we can expect some attenuation. And that is precisely why the ferrite is placed at a particular distance from the start of the cable.

To calculate the position of the first antinode you need its quarter wavelength in the medium. Here again, there are online calculators often written by hams, for specific cable constructions, and often the formula is given alongside.

There is no VOP% shown for the PVC covering of the average USB printer cable, but there are other sources of values for dielectric constants, from which the VOP% can be calculated.

On the Lautus USB, I decided that the effects of the 100MHz placement could be a case of the cure being worse than the cause - it could compromise the rise and fall times of the digital signal (0's and 1's), so the 200MHz was used alone.

The higher interference-frequency ferrite position is nearer the cable start than the lower frequency would be, due to wavelengths getting shorter the higher in frequency you go.

From that, you should be asking where the signal actually starts. And that is within the source equipment. If it is from the Bitzie using the analogue Lautus cable, the signal source starts at the output transformer which is adjacent the end of the phono plug pin when plugged in.

As for the Lautus USB connected to a desktop, that's a matter of knowing where the source is on the mother board, and you'll need the closest socket.

I believe from memory I set the distance at 8 inches, and so a couple of inches either way might not make much difference, as it is still within the first quadrant.

Hopefully the description above is in easy to follow basic physics and I haven't complicated it with advanced maths. My opinion is if you are able to follow such a description and it makes sense to you, then stuff you simply cannot understand might not pass the smell test.

The ASA was adamant that if I did not remove the description that they would take legal proceedings. When I asked them about all the fake stuff online, they said I had a right to complain in the same manner, but being a company I would not have any anonymity. I then asked if I could submit a complaint as a member of the public, but they said, as they already knew me, it would still be a company complaint. In the case of a company complaint, the company has to provide full evidence, whereas the "snitch" didn't have to...

I had a friend who was adamant that cables made no difference. I changed my speaker cables to some that were known to be a bit “harsh” and he was amazed at the difference they made.

He used to buy the cheapest interconnects from Amazon etc. but after borrowing a set of cables I had made, he upgraded his cables as he preferred the difference.

A video cable may be different, depending on the length etc.

The difference is not huge between silver and copper, according to my ears. I made myself a UP-OCC silver cable with pure silver connectors. That sits between my phono stage and pre amp. It is very short, as silver is very expensive. Compared to a UP-OCC copper cable with pure copper plugs, it is not massively different. I still use the copper, as I have it. Some people I know have tried silver, but prefer the sound that copper gives. Silver is a better conductor, science has proven that.

Some people even prefer brass connectors as it gives instruments a more lifelike sound. At the end of the day, it is your system, and your ears that you need to make happy. 

One forum I use regularly has people using PC-Triple C copper from Japan. Apparently it is very good, and they are buying these interconnects and then soldering on new plugs. I refuse to go there, as there cannot be a big difference between PC-CCC and PC-OCC to warrant the cost in my view.

You need to know where to draw the line.

More free electrons means higher electrical conductivity, not higher signal fidelity. The resistivity of both is in the same order of magnitude and really quite close so...

1/2 way down page is a chart

Sorry in advance if this is a stupid question.

Good question, so we know which bit we are talking about. In my post I am talking about the conductors in the cable, particularly the core that runs down the middle.

If we were trying to connect equipment with the most conductive material, we would be looking at superconductors. No, not silver; silver is not actually a superconductor. A true superconductor has a resistivity much closer to zero Ohms and requires very low temperatures close to absolute zero (zero Kelvin) and, it seems, very high pressure, to allow free electron trajectory to be as direct as possible within an ultra-pure perfectly organized lattice structure.

I remember reading about why gold is used above silver on RCA plugs, it reminded me about what my gran use to say when cleaning her silver, She hated it.

Out of the coinage metals group (the term used in inorganic chemistry when I was at school) silver conducts the best, then copper, and gold the least (I looked it up in my old chemistry book).

As for gold plated connectors, 9ct is what's used on PCB edge connectors because it's hard (it contains some copper), and I know that because I used to plate PCB edge connectors using potassium cyanide gold solution from Lea Ronal chemicals in Buxton (they shut when everything went to China).

The 24ct used on hi-fi jewellery is soft and wears down in no time at all.

Gold is used because it doesn't corrode.

I was reading about a guy called Mad Mike in the states, who built a rocket to take him high enough to prove that the earth has no curvature so must be flat. Hopefully, as he spiralled out of control he caught a glimpse of the earth's curvature before he died.

Then again, some people don't want to be helped, or if they do, they take a little and then deny you did anything for them.

As I rounded the steep uphill bend between drift covered dry stone walls, just before the crest I stood on the brakes and sledged to a standstill. The object was difficult to make out in the blizzard. It turned out to be a BMW sports tourer right across the single track road. I pulled on my big jacket and braved the driving snow. Wiped the snow from the drivers side window and saw the bewildered face. It took a while for him to come round and become communicative. I explained that I'd have to tow him over so I and the farm tractor could get through. Once straightened I was able to take the steep grassy verge that was somewhere under the white stuff and get past. I then told him I was going to hook up the tow rope and get him the 100 yards to the ploughed highway. Incredibly he refused, saying he wanted to try to get out all by himself. I said "good luck", got in the Defender and drove the remaining ten miles home. This memory has remained fresh in my mind ever since.

The insights you provide are interesting. However, this is a cable thread, and they have a history of always finishing badly on hifi forums.

I was hoping we could clear up a few myths about different material types, and the influence they have on the sound.

Should we just replicate studio cabling if we want to replicate the recorded music at home, as the sound engineer heard it?

Graham "Out of the coinage metals group (the term used in inorganic chemistry when I was at school) silver conducts the best, then copper, and gold the least (I looked it up in my old chemistry book).

As for gold plated connectors, 9ct is what's used on PCB edge connectors because it's hard (it contains some copper), and I know that because I used to plate PCB edge connectors using potassium cyanide gold solution from Lea Ronal chemicals in Buxton (they shut when everything went to China).

The 24ct used on hi-fi jewellery is soft and wears down in no time at all.

Gold is used because it doesn't corrode."

 A stranded center conductor will reduce high frequency skin effect and make the cable more flexible.

HF skin effect is only worrisome in very long cables... >50 meters.

A solid center conductor will be great for home audio.

 The insulation material used is more important in all audio systems.

There are no statements made by me here that can be construed as being my opinion.

 Yet there will be some that don't believe there can be any common knowledge learned in years' past that can be true today.

 And others that still believe that all audio travels in magical ways through wires and circuits.

 To them the earth is still flat...

            I hope they find the edge and fall off!

People sometimes like cold meals at zoos in Thailand leaving curious strong gorillas puzzled.

Years ago I tried to explain Gold doesn't oxidise at normal temperature and pressures, it is organic residues from handling that create the problems. Anyway back to topic...

Pseudo-balanced cables anyone?

Surely Pseudo-Balanced cables are sometimes a necessity, even if not ideal?

As discussed, the dielectric is important. 

There is a small difference between the conductivity of copper and silver (about 5% based on the IACS measurements), but surely we need to look at the system in it’s entirety? 

If you have gold plated brass plugs, then there is no need to go to the expense of silver cables. Surely the quality of cable required is relative to the “weakest link” in the system? PCBs are mostly copper tracks, with gold plating for the solder pads. Why do we then add in brass connectors? I am not saying it is wrong, but if we want to hear the recording as it was done originally, then adding additional losses (even though they would be very small) will take us away from the recording? In reality it probably makes very little difference, but a pure copper connector would seem to make more sense, except for the issues with oxidation (so regular maintenance would be required).

Then there is the question about the crystal structure/boundaries in the copper itself. Obviously the manufacturers of this OCC copper will tell you that it is required, as electrons flow better footprint audio. But is this marketing science, or real science? Are these small differences measurable? I have some OCC balanced cables that I have compared with Mogami W2549 microphone cable, and the OCC cables sounds better, with a more open sound stage. Is this down to the copper alone, or will the Teflon dielectric help?

Or does it perform the same, and I am just kidding myself I can hear a difference?

In my experience, one of the most important things in an interconnect is the joint between cable and plug, and this is where the quality of workmanship of people like John C come into play. He has probably soldered up more cables than I have hot dinners. You can have the best cable and plugs known to man, but if the joint is not done well, they will not perform to their best.

I apologise upfront if these are stupid questions, but this is the type of information we are subjected to in this hobby. If these are just myths, then it would be good to clear up what really matters.

I am blissfully ignorant with my DIY cables, as I measure them using my ears, and if I am honest, did not really notice a difference with my silver cable. I only use it as it was expensive to make, and I have it.

I fitted a CuSat between my phono stage and pre amp. Result? Yes it is. Sounds great.

I have not compared it to my DIY cable. Just plugged it in, and put some vinyl on. The only complaint. It is far too long, but then it is the loan scheme cable, so it has to suit all systems for length.

I think if I was to do one of the “blind tests” that forums speak about, I would be hard pushed to tell the difference between this and my much more expensive silver cable. More investigation is required, but I may be able to answer a few of my own questions within the next few days.

I appreciate that Graham offers well made, properly shielded cables. Here in the U.S. there are a few manufacturers that offer all kinds of un-shielded, twisted wire type cables. A few of them are closely affiliated with some large national dealers and they push the stuff hard. I've been told through reliable sources that profit margins on some of these cables are very high, so dealers have an incentive to push them whether they think they are any good or not.

I've also seen all kinds of weird gimmicks like mysterious black boxes attached to cables, (usually containing some type of circuit!), battery powered cables that light up, etc. Often the specifications on these cables are hidden from the buyer.

Some of these may be harmless enough in certain usage situations but with turntables, it is a well established fact that they can cause problems.

Awhile back someone was asking for advice on their system and mentioned they had one of these "mystery spec" high end cables attached to their turntable. They were using a high output MM cartridge and wanted to know why things sounded off. I told them to ask the cable manufacturer what the capacitance of the cabling was. The response was that it was "proprietary". You can probably imagine that the capacitance was very, very high and likely unsuitable for their cartridge.

lfc jon wrote: We have these box's here, the ones you pug onto the cable  (I'm assuming these are box's your on about) There is a debate on which end you put them on or if they work or not.

The ones I'm talking about are called "networks" by cable manufacturers. They are in the middle of the cables usually and permanently attached. Thick black boxes you'd have to saw open because they are sealed with glue or something.

Next up is my “copper fashion” cable with an OCC twisted pair - polyethylene insulation, a Mylar foil screen and an ofc copper braid. The “copper fashion” cable also uses gold plated copper plugs, but not the plastic “fashion” ones. These are proper “locking” RCA plugs, but they do have a reduced surface area of contact as there is some plastic to ensure the plug locks on securely.

I also have a “copper fashion 2”, again an OCC twisted pair but this time Teflon insulated, spaced out with cotton, wrapped in paper. This has an aluminium foil screen and a copper braid.

Also entering the fray is a “silver fashion” cable. This is two single crystal UP-OCC silver conductors. These conductors are maintained at equidistance thanks to the use of PE tubes and insulated with PE jackets. A triple shielding drastically limits the impact of interference, with a PTFE layer, an Al-Mylar foil and a silver-plated copper braid. These use pure silver Aeco branded “fashion connectors”.

Based on the “specifications” alone, it has some stiff competition. But do these marketing orientated specs make any difference? I hope not, then I can stop wasting money on cables, and get some proper CuSat cables made to suit my system.

Well done good Sir.

Pity they stopped making the original CT100. 

Out of interest (I am trying to learn), what benefit does a coax have over a twisted pair, when the "cold" is used for the system ground, and the braid is connected at the source end?

Going back to this original post, where does a shielded, twisted pair fit in to the scheme of things?

If I were to connect the shield at source end to the outer of the RCA connector, along with the -ve/return conductor, and use +ve for the signal alone.

From what I understand, it will have a higher capacitance than a coaxial cable, but what are the other drawbacks?

I agree that an unshielded twisted pair is not a good idea, but it seems to me that some people like a bit of distortion in their music.

It would seem to suggest that shielded twisted pairs work well in audio.

Anyway, CageySat is still in the system, I may swap it out in a bit with a shielded twisted pair and see if I notice a difference in sound. Electrically speaking, the cable should be close enough that there should be no perceivable difference.

Another myth that I don’t understand/believe is cable burn in, but that is another contentious topic. I don’t understand how the audio signal is able to alter the molecular structure of a metal.

I think you've misunderstood what I was saying.

Correct me if I'm wrong, but my understanding is that for a traditional RCA "interconnect" cable like we use at home, ideally we want the shielding (braid + foil) connected at both ends where the connectors are.

Some cables are "directional" (e.g. sometimes arrows marked on them) where one end of the shield is left "floating" or disconnected at one end. Ideally we don't want that. A poorly made cable might be made from a length of shielded wire (e.g. coax type), but neither of the shields are connected to the male RCA connectors on either end of the finished cable.

Amplifier stability would be down to the design of the amplifier itself.

Poorly shielded cabling, poorly made cabling, unsheilded cabling, etc. can make an amplifier with poor stability perform even worse.

Quite possibly. 

£6,000 and/or 6 months in prison plus criminal record.

Enforcer: Local Authority Trading Standards network

"huh, what's that for?"

Breaking EMC legislation - it's breaking the law - it's a criminal offence!

"So, who has to comply?"

The easier answer is who don't have to comply - interconnect producers and turntable producers.

(because there are no EMC standards for interconnects or turntables - yet)

So, I must know how to comply, and comply, or I will be treated as a criminal under UK and EU law.

Not that this is news to me. My first encounter was as a freelance being appointed as EMC rep for a Yorkshire amp mfr. in 1997. Having to attend EMC seminars where the first thing you're told is that non-compliance is a criminal offence.

Now, do you all get that?

Then I will try and explain again.

There are two ways to demonstrate compliance.

1. By having your products tested by a certified EMC lab.

2. By self declaring your products meet the relevant standard(s), in which you have to weigh up your own abilities in being able to, with evidence, convince a court that you are in compliance.

EMC testing is extremely expensive because it uses up test lab time, which isn't cheap, so as a small producer I assessed my own abilities and decided on 2.

However, I felt I needed some support so paid a smaller amount (still four figures) to Cherry Clough Consultants for "EMC probing". This gives a good indication whether your products have a chance if taken by Trading Standards to a certified EMC lab.

All the products "probed" passed the Cherry Clough Consultants testing, and I was encouraged to "save my pennies" and spend them on a week the other end of the UK with an EMC lab and all my products. On matters of my health (and the "pennies") I am unable to, and so I still operate on self declaration (as do most of the World's hi-fi equipment manufacturers).

However, South Korea adopted the same standards, but does not allow self-certification, and so our distributor paid for EMC lab testing. All the products passed. Unfortunately, the tests aren't transferrable, but it might help as part of the evidence needed in a court of law.

So when a customer takes me to task that my products cause interference when he uses interconnects with no shielding, the harder he comes down on me, I will come down even harder on him. I politely ask if he will try using "proper" interconnects to assess if there is possibly a fault with our product, and in which case we will take that product back for testing and repair it. But when that customer refuses and constantly blames our products and not the RF entering via his "boutique" cables, then you see the impasse.

EMC is electromagnetic compatibility. It looks at the immunity of the product when subjected to interference, and the interference emissions that the product might cause.

It now includes ESD compliance. ESD meaning electro-static discharge (direct or indirect).

On interference immunity a product is expected to perform to its specification under normal conditions of use.

The use with un-shielded interconnects is abnormal use.

A shield connected at one end only will become ineffective above a particular frequency.

It doesn't matter to that frequency and those above it, which end the shield is attached. If any of those frequencies are present, they will "land" on the wires within the shield.

For the sake of example I said 750kHz, and that only needs to be 1/4 wavelength, so anything above that is getting closer to a full wavelength and exhibiting more power.

Most power amplifiers capable of high quality audio continue to provide gain up to the low MHz, because they have to roll-off without instability, which means at a rate of 20dB/decade. To ensure there is unity (or below) gain at 750kHz, an amplifier with 26dB gain could only have a half power bandwidth to 37.5kHz - flat to less than 20kHz. That would be a poor amp.

Therefore, an interconnect that allows the example of 750kHz or anything in that region is unsuitable for use in high quality audio - no matter which way round it's used.

Feel free to use whatever interconnect BS you want - they're not covered by any EMC standard. But by saying it sounds better is to lead others "up the garden path".

Thanks for the reply. It is detailed and clear.

If I tell anybody that I prefer the sound of a shielded twisted pair, it is only relevant to my ears, in my system. I have limited the influence of RF where I can, as we have no DECT phones. My network is mainly hardwired, but we do have WiFi in a part of the house. There are also no TV/radio transmitters near by. TV reception has to be done by satellite, as we are in a bit of a dip, and cannot get good reception with an aerial.

I understand technically that a coax is better, but that will largely depend on the quality of the coax in question. My cable I have made the CageySat cables from is not a particularly special cable. It was lying around in my garage. The shielded twisted pair cables are more “fashion cables” and they have high purity copper and silver.

If I was to take a shielded, twisted pair cable, and connect the shield and return together, this would be EMC compliant, but I would increase the capacitance of the cable. I know one manufacturer used to make a cable from RG316(?) with the screens disconnected at both ends, as they were used as a Faraday cage. Another manufacturer used to make a single ended interconnect using a shielded twisted pair, where the two cores were used as a feed, and the return was only the screen. It seems you can do 

As you say, there are no regulations concerning interconnects. Marketing science sells cables, and keeps the Cable companies in business.

Something I always wanted to do was to record a track using a specific cable, a coax for example, and then record the same track with a shielded twisted pair cable cable, and do a comparison to see if there were measurable differences. I am not sure if this could be done by reversing the phase, hence why I have not done this, but if all cables sound the same, then there should be no differences.

The other thing that may make a difference is that my amplifier is connected to my pre-amplifier by a balanced connection. My single ended cables only connect my DIY phono stage to me pre-amplifier. This is a hybrid design so uses valves, which means I am probably unlikely to hear any “noise” injected by the cable as the valve noise probably swamps it.

So in short, my findings are probably worthless to anybody else on this forum, but me. 

I would hate to think how much a CuSat would cost if it followed the usual route to market.

You are being told that it's a Faraday cage?

What part of "enclosed" do they not understand?

Now, are you ready to learn yet?

Yes, I know, we live in such an opinionated world that it's now fair game to criticise physics. The physical laws of the universe don't apply here, and all that baloney.

It seems to have passed everybody by why I mentioned that although the earth travels at 67,000 mph and rotates near 1,000 mph, we all appear to be perfectly still.

A faraday cage is an enclosure. It encloses everything inside it so that electrical fields outside it don't penetrate it. Within the faraday cage all is still.

Open the faraday cage and it isn't a faraday cage. There are two openings in the "faraday cage" cable at either end. The cores are not inside a faraday cage.

Now, you wanted to know about coax? Connect two faraday cages by coax, and the shield makes the two faraday cages the same faraday cage.

Got it?

That was my argument with the manufacturer. If it is open, it is not a cage, but he would not have any of it.

The amount of shielding depends on how much noise/interference can be tolerated by the circuit before it becomes objectionable - before it causes the circuit performance to diverge from what is expected.

If you have an input of -50dB with a S/N of 60dB, the equivalent input noise is -110dB.

The output socket is an entrance to the circuit and if an antenna is connected to the output signal conductor, then any radio frequency interference will navigate to all parts of the circuit where the lengths involved allow a quarter wave to exist. This includes capacitive coupling where the capacitance is such that the RF will pass unattenuated.

-110dB is 2.5uV and not far removed from the input sensitivity of a radio receiver tuner.

If the output socket is connected to an interconnect that does not continue the faraday screen of the source to the next stage, then all airborne frequencies will interfere with the wire's electrical field to produce a signal in the wire.

The shorter the wavelength the greater the interference, and radio frequencies are much shorter in wavelength than audio frequencies.

At best, the 110dB gain might pass the frequency back out, but electronic circuitry contains inductances and capacitances that can accidentally "tune" to a frequency and semiconductors (which have a lot in common with the "cat's whisker") given that gain, can detect and amplify any noise contained in the transmission the RF frequency contains.

This may be random noise, or a radio station, or a data transmission of some sort.

For the sake of connecting the two pieces of equipment with coax, enabling the two shielded boxes to become one, this is avoided.

Unfortunately we find ourselves double face palming at the gross ignorance and often arrogance of the type of customer convinced that knitted wire, a non-connected shield, a half connected shield or a non-conductive or resistive shield, is effective shielding. It isn't!

Sheer ignorance and arrogance to boot!

Thank you for arguing on behalf of the truth.

Now, nothing is perfect and there are instances where the faraday shield cannot exist. One example is from a class 2 plastic housed power supply to the equipment it is powering. Why isn't the cable shielded?

Thinking about what we've already discussed, a shield would only be connected at one end, so not very effective against RF.

Therefore, immediately inside the item being powered there must be a relatively isolated area containing an RF choke (10uH in our case) to which the power connection is directly connected as short as possible. The RF choke is assisted by a non-inductive film capacitor to ground, before connection to the bulk capacitor.

I thought I needed to mention this before somebody hopped onto it.

I connected the interconnects between my pre amp and phonostage, and without playing any music I turned the volume up. I started with the shielded twisted pair, and then tried it with the coax.

Unsurprisingly, the coax was noticeably quieter. It had less hum. This was noticeable at levels way beyond my normal listening levels, but it was there, so it must be there at my normal listening levels, adding to the distortion in the signal.

I also am starting to think that any percepted change a cable makes is down to “expectation” bias.

I know I have changed a cable, therefore it sounds better, or worse, as I know what cable I am fitting, and subconsciously, I want it to sound better.

As it was once said by someone in a film “I cannae change the laws of physics, cap’n”.

My basic little test shows me that, as Graham correctly states, a coax cable is better.

If you prefer the sound of a different cable, it does not mean it is better than a coax, it just means you prefer it.

A few years back I used cat 5 network cable as another experiment, parallel wiring the twisted pairs. It probably sounds 'hyper real' to some people but I was unimpressed. Make your own snake oil.

Very True. I am constructing various different combination with different metals and braiding and shielding. Somehow, the same CD will sound different as I expect to. 

Is there any point using high quality OCC copper, and expensive copper plugs, if the solder in the plug is the weakest point?

Then there is the "joint" between plug and socket, a purely mechanical contact relying on a precise mating of the surfaces. The RCA type phono plug and socket is hardly a high tech device, the BNC and even F type connectors would seem better thought out and might offer a better electrical and mechanical solution.

Just a few things to ponder!

Bog standard leaded solder for the coax build.

Thanks Graham. Since you showed the effect I have tried reversing the direction of one phono lead in a pair. Sometimes the change is more pronounced. It is also interesting to use a mixed pair with one side from one cable set and one from another...

Surely science would say it makes no difference.

JDI and let me know 

Audio is an “AC signal”, so how can it make a difference?

I assume that if this was to work, +ve should be connected following the print on the cable, and negative t’other way round?

I don’t own any to change the plugs on, so I am not likely to find out, but a Premium CuSat with better plugs would be good. I know it would cost more, but science would suggest it would be something worth doing, as the conductivity of copper is better than brass? Unless the audio signal only flows in the plating, which is something I cannot see happening.

Initial impressions are a better sound stage. But I need to switch back to be sure.

So if this makes a difference, then a good quality coax cable with an OCC core, OFC shield and copper plugs should give me a small gain?

I hate messing about with cables….

I wish I could measure the signal, and make a comparison to see if there is really a difference, but how do you measure subjective differences in the “3D image” changes?

Nothing to do with purity, plating, solder, alchemy.

 

This is purely subjective, and I have no way of knowing what the plugs on set 1 are made from (as it does not tell me on the website of the shop I bought them from, so I assuming they are brass/phosphor bronze). Set 2 with plugs that Graham would not approve of, just sounds more “open” to my ears, in my system.

But audio memory is not reliable, and I have no fast way to switch quickly between the two.

That is enough fiddling for me. 

Science would seem to suggest that a better conductor would be better for signal transmission, without a loss of some of the signal, which is why I fitted the new plugs. But what do I know about science? I am a mechanical engineer…