Test of cable shielding, does it matter

[ShiZo]

After seeing this video I made sure every cable I bought for my system was shielded. I have a ton of wallwarts and different types of cables ontop of each other.

Is that proper form? Does it make a difference to use shielded cables?

 

[Lambda]

Does it make a difference to use shielded cables

No.
Long answer, your equipment should be shielded. but if its not... unlikely but maybe in some special cases.
This is snake oil.

There is no reason for the cables to be garden hoses size and or expensive
Propper Lapp cable with shielding is maybe 15$ +2*20$ for audiofool Rhodium platted beryllium copper connectors.

so maybe 60$ to have a nice looking cable but dont expect to hear a difference

 

[Bob-23]

Does it make a difference to use shielded cables?

If you have long interconnectors (say, longer than 6 or 7m) between source (dac) and amp, the quality of the shielding comes into play - not well shielded cable may pick up noise which then gets amplified. So, the cable before the amp is critical.

Edit: Well shielded cable doesn't have to be expensive. Buy it per meter/inch - so that you can see how dense the braid around the inner cables is. (If you've got a soldering iron.)

 

[dougi]

Certainly for low level signals, like turntable to phono pre they can make a difference. Below is a noise floor comparison of two cables into a Project DS2 phono stage in mm mode, measured on it's output. Even changing power supplies made small differences. The kimber is an unshielded, tri-twist type of cable. Project is shielded with connection at amp end only.

 

[Gregss]

Certainly for low level signals, like turntable to phono pre they can make a difference. Below is a noise floor comparison of two cables into a Project DS2 phono stage in mm mode, measured on it's output. Even changing power supplies made small differences. The kimber is an unshielded, tri-twist type of cable. Project is shielded with connection at amp end only.

View attachment 113613View attachment 113614

Hello,

Shielding of low level signal cables makes some sense, the lower the signal level (phono signals) the more sense it makes. However shielding the last four feet of power cables is pretty much nuts. What about the other 99.999% of the power cables in the wall and back to the electric company?

Regards,
Greg

 

[dougi]

Hello,

Shielding of low level signal cables makes some sense, the lower the signal level (phono signals) the more sense it makes. However shielding the last four feet of power cables is pretty much nuts. What about the other 99.999% of the power cables in the wall and back to the electric company?

Regards,
Greg

Agreed. Shield the ones you need to. Note in my phono example I still couldn't hear any difference. I used the Kimber pbj for years becaue of the low capacitance for mm carts. I now use rg6 based video cables. Shielded and low C.

 

[solderdude]

Shielded mains cables (the wires themselves) are cheap and can lower radiated emission.
They are specifically handy when one has to drive speed controlled heavy duty motors with servo control wires running alongside those power cables.
The trick is to ground them properly for HF. This is not the same as safety ground which serves a totally different purpose.
Proper HF screening is basically creating an extended Faraday cage between 2 connected devices.
When one device is properly EMC screened (audio equipment can be but isn't any more the moment you connect a cable) what a proper screen will do is basically elongate the cabinet's enclosure right up to and around the transducer. The latter can be a pickup or something that is driven.

The moment you let wires 'stick out' the device can pick up RF again. The longer the wire that sticks out is the lower the frequency it can pick up can be. (This should be interesting for those using screened speaker cable as speaker enclosures are rarely all metal. The wiring inside the speakers isn't screened and pick up RF.

Anyway... back to mains cables. Suppose one has a screened mains cable that is connected to safety ground with a short wire inside the amp.
That short piece of wire (several cm) is an inductor (high resistance) for frequencies used n cell phones etc. It works like a good connection for audible frequencies and well above that.
So the screen is basically an extension of the metal amp enclosure. It also works well as safety ground. The latter is the purpose of the green/yellow cable and why that is (should be) connected to the enclosure.

As the video showed the detector cannot detect the mains (audible range + several harmonics) on the cable any more. Regardless if current flows or not. So yes it does screen (reduce dramatically) LF fields but does a poorer job for very HF signals.

Suppose we have a nice rack and someone decided to use poorly screened interlinks for instance and to make it neat ties all these wires in one nice bundle then the screened mains cables might actually help lower induced hum in the audio cables.

Keeping mains and audio cables separated at least a few cm and only cross them at 90 degree angle will help reduce coupling effectively. There is no need for screening mains cables.

Having one screened cable (for the power amp for instance) running along side generic mains cables in the same bundle is pointless.

Also such a screened cable, unless it has filters inside, wont do anything against RF emission and immunity being lower for the connection itself (it helps a bit directly around the cable for lower frequencies) The moment you plug such a cable in a wall socket and the wires from the wall socket onward are NOT screened all the way further that means the cables are leaving the 'elongated enclosure' and will emit and receive RF as normal.
Also the safety ground wires will. The safety ground wires in the wall are high impedance for RF and low for mains frequencies.
That's exactly what we need for safety ground and that's what the wall sockets provide.
Safety ground NOT RF ground.

 

[pedrob]

Hello,

Shielding of low level signal cables makes some sense, the lower the signal level (phono signals) the more sense it makes. However shielding the last four feet of power cables is pretty much nuts. What about the other 99.999% of the power cables in the wall and back to the electric company?

Regards,
Greg

It's not just phono signals that are susceptible. CD players, Blu Ray players, amplifiers etc are impacted.

Shielding power cables in your room makes a lot of sense as you want to keep the area around your equipment as clean as possible. Unfortunately at best it is only likely to reduce atmospheric contamination by a certain amount, so if you are really serious you would shield all cables; both power and interconnects, even if the are shielded as the shield is often the return signal. As solderdude alluded, unused ports act like antennas with a direct path to circuit boards, so it's a good idea to fit dummy shielding plugs to address that issue. Going further, most equipment creates its own problems and internal power supplies should be shielded as much as possible.

I also noticed that solderdude questioned the benefit of shielding speaker cables when the cables in speaker enclosures aren't. An interesting issue for consideration. So should the cables and crossovers be shielded?

Atmospheric contamination is real and should be taken seriously, not dismissed as snake oil.

 

[tuga]

It's not just phono signals that are susceptible. CD players, Blu Ray players, amplifiers etc are impacted.

Shielding power cables in your room makes a lot of sense as you want to keep the area around your equipment as clean as possible. Unfortunately at best it is only likely to reduce atmospheric contamination by a certain amount, so if you are really serious you would shield all cables; both power and interconnects, even if the are shielded as the shield is often the return signal. As solderdude alluded, unused ports act like antennas with a direct path to circuit boards, so it's a good idea to fit dummy shielding plugs to address that issue. Going further, most equipment creates its own problems and internal power supplies should be shielded as much as possible.

I also noticed that solderdude questioned the benefit of shielding speaker cables when the cables in speaker enclosures aren't. An interesting issue for consideration. So should the cables and crossovers be shielded?

Atmospheric contamination is real and should be taken seriously, not dismissed as snake oil.

Can you provide evidence to your claim?

 

[pedrob]

I've no idea what you mean. I'm not claiming anything.

After all, I'm sure you've heard static noise on AM radio; it's particularly bad around trams due to noisy power supply. Shielding that type of atmospheric contamination might be something worth considering.

Don't take my word for it. Give it a try and you might learn something.

 

[solderdude]

So should the cables and crossovers be shielded?

No, only when one receives radio signals that become audible (through detection or otherwise) via the speaker cables this would make sense, or when the XO/speakers are acting as a receiver. (never encountered this, the impedance and efficiency is too low and voltage levels too high)
I know of no such conditions except with those that live near very powerful transmitters.
In that case shielding mains cables and speaker cables may be one of the very last things to do. Not the first nor a necessary thing.

Shielding from influences in the ether can only be done by a Faraday cage that may have holes sized to the min allowed HF leakage.
This is not feasible in an apartment. 'Electrosmog' is all around us and it's up to the manufacturers job to comply to certain immunity limits.
Limits that can only be reached when devices are connected using proper cables.

When mains and speaker cables would really need this there would only be fully shielded mains connectors, wall wiring would be screened, speakers would have metal grounded enclosures and speaker cable connections would be screened.
They are not, and for good reason... it isn't needed in 99.999% of home audio installations. The remaining 0.001% requires special attention and will require more than screened speaker/mains cables.

 

[egellings]

A shielded cable? What about noise that enters the house wiring that gets safely conducted under a cable's shield into the equipment?

 

[Lambda]

What about noise that enters the house wiring that gets safely conducted under a cable's shield into the equipment

Good point. At this point the salesman wound show you his wide section of mains filter products.

 

[pedrob]

A shielded cable? What about noise that enters the house wiring that gets safely conducted under a cable's shield into the equipment?

True, but hopefully the amount is so low it is virtually insignificant.

I'm sure there are contributors here who would deny the sun is going to rise tomorrow in the morning sky, claiming it won't because it is the earth that is rotating. From a scientific point of view they are absolutely correct but that opinion is rather pedantic and does not consider the view from earth.

For those who accept sensitive medical equipment needs shielding, then I would recommend looking at the shielding inside the LUXMAN D-10X, because the shielding is very well done. It isn't just high end equipment that benefits from reducing internal interference and all manufacturers should isolate power supplies. Reducing DC ripple is helpful, but it is the air borne emissions from the transformers that should be considered. After all, modern equipment has lost the brute force of yesteryear and should now be consider in the same realm as medical equipment.

 

[Lambda]

I would recommend looking at the shielding inside the LUXMAN D-10X, because the shielding is very well done.

LOL! the opposite is true!
This is relay relay bad design from an RF/EMI point of view!

1 everything is big and speed out
2 lots of dual or singel layer PCBs with no ground plane
3 long cables everywhere




if done right it will look something like this

or those who accept sensitive medical equipment needs shielding,

A digital audio source is not a measuring device!
therefore it don’t need to be sensitive.

If your having esoteric ribbon microphones ore phonon cartridges it’s a different story

 

[pedrob]

I'm wondering who decided a measuring device is susceptible to interference and audio equipment is not? Why wouldn't it be? Anyway, it is always better to have an open mind than make unsubstantiated baseless assumptions. Certainly be suspicious, don't believe anyone but be willing to give a try. You just might be surprised.

BTW There's very little difference in the left attachment and I'm seeing lots of long cables, so I don't get the point or criticising one and loving the other. Both probably work equally well.

 

[Lambda]

I'm wondering who decided a measuring device is susceptible to interference and audio equipment is not?

A (medical) measuring device needs to extract analog information form very weak and low impedance impedance signals.
therefore there is a lot of analog gain needed.
Lot of amplification amplifying noise potential noise!
Verry low signals compared to noise give bad SNR.

here's very little difference in the left attachment and I'm seeing lots of long cables

this image is the crapy esoteric device you love.

I don't get the point or criticising one and loving the other. Both probably work equally well.

Although they do completely different things...
No one is made by esoteric marketing people to look fancy to some audio fools.
The other one is made by a team of engineers purely optimized for rational performance with little compromises.

 

[Lambda]

@pedrob BTW. have you ever seen an Audiophile looking power cable on a peace of medical/laboratory gear?

A Rohde and Schwarz spectrum analyzer or scope for >100k€ Comes with a totally regular power cord

Tens of Millions dollars worth of professional reference test gear...
You see shielded power cables?