Electronics > Beginners
Cable shielding audiophool or facts?
Richard Crowley:
You are all ignoring the elephant in the room.
The show-stopping problem with this goofy scheme is that THERE IS NOT RETURN PATH FOR THE AUDIO CIRCUIT. In an unbalanced circuit, the shield/screen IS the return path for the circuit. If there is no connection between the source shield/screen/return and the destination shield/screen/return, then THERE IS NO CIRCUIT HERE.
Telescoping shield is a long-established way of breaking a ground-loop problem between pieces of professional audio gear. But IT ONLY WORKS WITH BALANCED CIRCUITS. Because the balanced pair inside the shield is the COMPLETE CIRCUIT which is INDEPENDENT from the shield/screen.
This audiophool scheme takes a perfectly legitimate technique (telescoping shield) and extends it to the absurd point of completely disconnecting the return path by having two disconnected overlapping shields which serves exactly NO useful purpose.
helius:
To be precise, the return path is through a lossy, low-quality distributed capacitor.
Richard Crowley:
--- 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 ---
Right. Which "serves exactly NO useful purpose" at audio frequencies.
CatalinaWOW:
If reported correctly there is no return path through the cable. In my mind the jury is out on that. Who knows what the cable actually has in it.
The reality is that this will function in a great many systems, since they have a grounded chassis and will get a return through the earth ground. Makes a joke of the shielding, but what did you expect?
vk6zgo:
--- Quote from: Richard Crowley on November 15, 2018, 06:30:45 pm ---You are all ignoring the elephant in the room.
The show-stopping problem with this goofy scheme is that THERE IS NOT RETURN PATH FOR THE AUDIO CIRCUIT. In an unbalanced circuit, the shield/screen IS the return path for the circuit.
--- End quote ---
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.
--- Quote ---If there is no connection between the source shield/screen/return and the destination shield/screen/return, then THERE IS NO CIRCUIT HERE.
Telescoping shield is a long-established way of breaking a ground-loop problem between pieces of professional audio gear.
--- End quote ---
Interestingly, in my experience, it is fairly unusual in Broadcast work, except for low level circuitry like microphones & pickup cartridges for vinyl record replay equipment.
At the higher levels & better S/N ratios of audio reticulated around Studios, it is not necessary.
--- Quote ---
But IT ONLY WORKS WITH BALANCED CIRCUITS. Because the balanced pair inside the shield is the COMPLETE CIRCUIT which is INDEPENDENT from the shield/screen.
This audiophool scheme takes a perfectly legitimate technique (telescoping shield) and extends it to the absurd point of completely disconnecting the return path by having two disconnected overlapping shields which serves exactly NO useful purpose.
--- End quote ---
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