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Interconnect BS vs Science

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2022 at 11:23pm
Only £57.75...

Great for electronic design engineers - after reading it you will know how to spot dodgy cables.

An EMC book

Here's a randomly selected page showing some of the types of interference.

An EMC randomly selected book page

Unfortunately, record players / turntables will never comply and that's why there are no enforceable standards for them. But there are enforceable standards for the electronics which I have to follow. It is however very difficult to comply fully because the downright silly way turntables have not progressed toward any EMC, and so it is a case of trying to marry up electro-magnetic incompatibility with the electro-magnetic compatibility I must follow.

Now, I do that and at the same time try and increase the musical performance, and that also depends on correct shielding, which the above book clearly explains. Unfortunately, single sided signals of the type used in playing records do not lend themselves to the EMC techniques required by law, but other than those unsurmountable difficulties our products meet with EMC regulations (most having been tested by an accredited EMC test lab, paid for by a distributor, and hence owned by them).

The customer is kept in the dark over such things by the wine tasting press, because, I guess, it would not be good for advertising business.

I will add, that these things would have been of interest to hi-fi enthusiasts years ago, before the BS settled in.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2022 at 6:28am
Now, the chap in the picture on the book cover was used by the ASA as an independent expert in a case against a cable manufacturer's UK distributor.

But when it was my turn to be attacked by the ASA, I started quoting chapter and verse from that independent witnesses book, and verbally accused the ASA of hypocrisy. The explanation for the Lautus USB cable is in that book, but I was expected to produce measurements taken by myself rather than state the theory that the scientific world states is proof.

You can't argue with a reprobate mind.

At the same time, large corporations that have the legal muscle, ARE getting away with FAKE descriptions which state their cables are shielded - that they contain a shield - but hide the fact that it isn't properly connected electrically.

Some of the wriggle-out words used are laughable from the engineer's perspective, but look plausible to the non-technical consumer. It helps if the cable manufacturer has a large following, even if that manufacturer got its position by cheating.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CageyH Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2022 at 8:33am
Originally posted by Graham Slee Graham Slee wrote:

I must have published this drawing in another topic, but here it is now in its rightful place.

correct shielding

The first of the four illustrations show the correct way of interconnecting single sided signals between equipment, using a fully shielded coaxial cable with its shield connected both ends.

The shield carries the shield of both devices, joining them together as one whole Faraday shield.

CD made it possible for the other illustrations to exist. Before CD everything used transducers with the tiniest output - tape heads and phono cartridges. Such wiring would be considered lunacy in those days.

The latter three illustrations depict several "boutique" interconnects - even "value for money" types from famous manufacturers (sorry, but I'm under obligation to tell the truth - but I will not name names).

A shield not connected at all (as I've seen in manufacturers descriptions) is just mechanical reinforcement. It is wide-open to all frequencies of interference.

A shield connected one end only is a copy of the cheat used in balanced connections, usually on stage, and possibly illegal in that application these days. But that was for balanced connections. When used for single sided signals (RCA phono plugs, DIN etc) it is sometimes thought of "pseudo balanced". There is nothing balanced about it!

The shield connected one end only can be seen as an enlarging shield which gets larger in diameter the further away from the connection it gets.

The open end diameter is the same as the length of the interconnect. Now, find a wavelength to frequency converter online and put in that length and then divide that frequency by four because RFI works well with quarter wave antennas.

Now, get to know the radio spectrum. Don't expect to hear music or voice, although you might, but it will generally be noise of all kinds.

DECT phones, wi-fi, even radiation from mains cabling from powerline ethernet adapters. Where is it going to go first? It is going into the output of the high gain device - the phono preamp or tape head amp.

Coupled by unavoidable capacitance, it negotiates to the input and gets amplified, so do not be surprised if your new super wideband fast slewing phono stage gives you your own back!

And as for the last of the four illustrations, this has no shield at all.

If a manufacturer states 100% (or completely or fully) electrically shielded, then that must comply with the sales of goods act, and a manufacturer must know that. If it states any other then it isn't properly shielded and know that in any other explanation of a shield means subterfuge is taking place!


As part of my upgrades on my SL1200 (The last One I hope), I have made a phono cable based on image 1. The cartridge tags will be wired directly to the RCA sockets I will be fitting, and the phono cable will connect between the TT and phono amp.

I am currently using the cable between my phono stage and pre-amp, and to be honest it sounded a bit flat at first. A day later it sounds better.

What has changed, the cable or my brain? 
How can a small signal change the way a cable affects the sound?
Is there a scientific argument that backs up cable burn in?
Kevin
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2022 at 10:15am
All I know is the dielectric will have been subjected to dielectric strength testing using a 3kV "flash" test. Then re-reeled onto drums containing a particular length.

You make a cable and it is then first used, and if left in position passing nothing, which is in reality, noise (if the equipment is left on), and then a day later it sounds different.

So, what is the scientific difference? As I've mentioned before, the "flash" test is getting a bit closer to HVDC than signal, and grid engineers know of a thing called space charge.

It is known to cause acceptable damage to the dielectric, but if a HVDC cable burns out, it is known it is at the point of that acceptable damage.

HVDC cables are hefty, but CT100 coax is tiny by comparison. Could it be "harmed" in a similar way? The "flash" testing is required by law.

Now, as I don't want to be ridiculed for making suff up, so I need to refer you to this page:


And then you can understand clearing voltages in a dielectric, which is a posh name for insulation in proximity with conductors.

As for the noise signal being sufficient to be able to clear the fault, I have no evidence one way or another, but if it did, I'm sure it would take a heck of a long time than the very short time required by a self healing capacitor?

After all, a cable is a capacitor, isn't it?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2022 at 10:47am
Originally posted by CageyH CageyH wrote:

What has changed, the cable or my brain? 


You were given a brain at birth that is equipped to understand great things using powers of observation. That's where the physics we know so far came from - observation - using the senses connected to the human brain. Everything mankind knows in fact. Such that it can design a radio telescope and iron out every fault and launch it from a rocket to its position one million miles away, to a particular position in space, that is known by observation spanning many years, to be the Goldilocks spot.

What's more, it works!!!

So, observe things and test all things, and chuck out anything proven to be marketing BS.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote CageyH Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2022 at 11:24am
My point is that the brain is able to adjust.
A good example of this is when you change your prescription for glasses. It may seem strange at first, but after a few hours/days/weeks, you get used to it.

Is it the same with a cable?
Kevin
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 05 Apr 2022 at 11:30am
Obviously.

However, by selecting reference points where mood doesn't come into it, we can then hear a difference if there is any. A bit like calibrating test gear.

But each to his (hers/its) own. And in your area of work it is tuned to whatever you do. And my line of work it is tuned to what I do. I don't know why anybody could deny that, unless they don't work or don't think?
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