Electronics > Beginners
Cable shielding audiophool or facts?
Richard Crowley:
--- 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.
FriedMule:
What if you made a outer shield (anode) with no connection at all and a inner shield (cathode) only connected to one unit.
In that way, would the outer shield be charged by the RF and EMF from the air and the inner shield would act as the cathode, sinse the charged anode can't discharge
it would get saturated and block for every additional "charge" from the outside?
Richard Crowley:
A cable is not a capacitor (except accidentally).
A cable is supposed to CONDUCT a signal from one end to the other.
In order to have a CIRCUIT, there must be a complete path from the source all the way to the destination.
BOTH the inner ("signal") conductor AND the outer ("shield/screen/ground/return") conductor must go all the way through.
Again, I urge you to draw out your proposed scheme and show us the signal path including the return.
Until you do this, you can throw together any number of fantastic words but they mean nothing.
Show us the circuit. Else this conversation has gone on far longer than it deserved.
RandallMcRee:
I think you all are going off on wild-goose chases. You are just speculating about that cable. The OP has not even given us a schematic. This is the beginner's section. The OP (no offense) seems not to have investigated the actual cable in any detail. We should not be disparaging something without evidence and throwing around wild accusations.
That is why my original responses are so brief.
Whenever I have investigated these audiophool cables I have usually found solid engineering mixed with exotic materials: the engineering makes it work and the gold/silver/palladium sells it. But now I am speculating!.
ebastler:
--- Quote from: FriedMule on November 13, 2018, 04:49:45 am ---Sorry for my bad wording, what I mend was: "I think that audiocable goes to ground via the outside shield that also are used as the negative wire and often connected to the case?"
--- End quote ---
I think it's clear by now, but just to state it explicitly:
The shielding approach which you proposed in your initial post does not provide a gound connection via the outside shield(s). Because each of the shields is connected on one end only, they obviously do not provide a continuous ground connection between the two devices. Hence, this does not work unless there is another, proper ground connection inside the cable.
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