Electronics > Beginners
Cable shielding audiophool or facts?
janoc:
--- Quote from: helius on November 15, 2018, 06:59:27 pm ---To be precise, the return path is through a lossy, low-quality distributed capacitor.
--- End quote ---
Nope. At audio frequencies the impedance of such capacitor would be such that it wouldn't have any chances of meaningfully working. The setup would only work if both devices are powered from mains and then the circuit closes through the mains - with all of the wonderful consequences of that, such as hum, noise, distortion, etc.
If even one side of the setup would be a battery powered device (let's say a phone having the cable stuck in its phono jack), you would hear zilch.
FriedMule:
I have talked to the audio-addicted and tried to understand what he is talking about.
I am not sure about that but I have made a crude drawing.
xavier60:
Ground loops are not a problem if resulting voltage drops do not become an input noise signal.
vk6zgo:
--- Quote from: Richard Crowley on November 16, 2018, 02:51:28 am ---
--- Quote from: vk6zgo on November 16, 2018, 01:09:00 am ---Not necessarily, I have seen plenty of unbalanced circuits which use a pair of conductors & a screen.
But, of course, this doesn't make your comment invalid.
--- End quote ---
True enough. But that is NOT the scheme presented by the OP. Else we wouldn't be still discussing this.
--- Quote ---Interestingly, in my experience, it [telescoping shield] is fairly unusual in Broadcast work,
--- End quote ---
It is rather a common technique.
Refer to the "Bible" of the audio interconnection world, Rane Note 101 "Sound System Interconnection"
https://www.rane.com/note110.html
In Figure 4. Interconnect chart for locating correct cable assemblies...
Note in particular connection diagrams# 1, 2, 5, 6, 7, 8, 11, 12, 13, 14, 17, 18, 23, and 24
More than half of the diagrams show telescoping shield schemes where the shield is connected on one end only.
As you observed, ALL of them feature a second inside wire which provides the return path for the audio circuit.
And the examples here show both balanced AND unbalanced interconnections.
In ALL cases where a single-conductor shielded cable is used, the shield is connected on BOTH ends.
Note in particular, scheme # 20 which is RCA to RCA.
--- End quote ---
At least in Oz, Broadcasting organisations are obviously apostate and don't read your "Bible". ;D
Numbers 21 & 22 are the default, with the others used in special circumstances as per my previous post.
Richard Crowley:
That drawing shows an explicit send and return loop/circuit for the audio (red & blue wires).
That is very different than what the OP originally showed us. That is why I kept insisting on a diagram.
That is essentially circuit #6, 12, 17, 18 etc.
But with an extra telescoping shield from the other end.
--- Quote ---Would that have any effect on EMI or RF?
--- End quote ---
Very doubtful. And certainly not worth the expense/effort .
Just another exhibit in the museum of audiophool hyperbole.
Take some conventional engineering practice and extend it well into absurdity.
And then, of course, you can charge ridiculous prices to convince people it is some new magical scheme.
Audiophoolery is a cross between cognitive bias and medicine-show snake-oil quackery.
Audiophools have NEVER been able to demonstrate objective evidence of any of their claims.
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