So I Kracked open some KNu Krystal RCA Kable

[Megalomaniac]

you are wrong and have been misinformed, sorry.

The RCA connector has two parts, the center pin (signal) and the outer shell/body (ground). The outer shell/body is connected to either chassis ground, signal ground or both. Some units isolate signal and chassis ground with resistors or a transformer (that is why you can get different meter readings with amplifiers) to lower noise, but it is still a ground. And for a shield, any shield no matter how constructed, it needs to be tied to ground somewhere to dissipate the EMI (Electro-Magnetc Interference) currents that have been induced on the shield BEFORE they are coupled to the signal carring conductors

[Tirefryr]

Originally Posted by Megalomaniac

you are wrong and have been misinformed, sorry.

The RCA connector has two parts, the center pin (signal) and the outer shell/body (ground). The outer shell/body is connected to either chassis ground, signal ground or both. Some units isolate signal and chassis ground with resistors or a transformer (that is why you can get different meter readings with amplifiers) to lower noise, but it is still a ground. And for a shield, any shield no matter how constructed, it needs to be tied to ground somewhere to dissipate the EMI (Electro-Magnetc Interference) currents that have been induced on the shield BEFORE they are coupled to the signal carring conductors

That would explain why I do not get a reading, but if that is the case, aren't you inducing noise when using a grounded shield? They go through the trouble to isolate the signal ground from the chassis, so why re-introduce one?

I don't know much about electronics, so help me out here. I know when I built motor control panels and Cell phone buildings, there were certain shielded cables that did not get grounded on either end for fear of inducing noise back through the shield. I do know you have to isolate AC from DC and high from low voltage.

[Megalomaniac]

Originally Posted by Tirefryr

That would explain why I do not get a reading, but if that is the case, aren't you inducing noise when using a grounded shield? They go through the trouble to isolate the signal ground from the chassis, so why re-introduce one?

I don't know much about electronics, so help me out here. I know when I built motor control panels and Cell phone buildings, there were certain shielded cables that did not get grounded on either end for fear of inducing noise back through the shield. I do know you have to isolate AC from DC and high from low voltage.

This helps my case further actually. Remember in the picture I showed that the Knu rca shield is not grounded(meaning the shield is not connected to that neg on connector). Well If Knu made an external ground where a wire runs out of the cable and you have to screw it to a piece of metal, then more noise can be induced, but by just using the ground on connector your risk factor is far less.

Why do you think that the Pioneer 880 was having grounding issues people saw, the resistors inside that was trying to keep noise down and isolated burnt out(btw that only happens if someone plugs their rca's in hot ) and to "fix" it all they did was Reground that outer ring of the rca connector.


oh about that cellphone building thing: this might help explain why grounded shields are bad at times:
Cable shielding and groundloops

or cable shield connections there are four options, with advantages and disadvantages:

1. Shield grounded at both ends: Good r.f. shielding but susceptible to ground loop currents that can be VERY large - up to at least 100 A in bad cases.

2. Shield grounded at both end, with large-area parallel bonding wire: Good at r.f. and now the ground current flows mainly through the bonding wire, but the intense magnetic field that may result is not good news. The bonding wire size needs to be, for example, 10 mm^2.

3. Shield grounded at one end only: No ground current but not good at radio frequencies for which the cable is more than 1/8 wavelength long. R.F. interference may actually be worse than for an unshielded cable.

4. Shield grounded at the sending end and grounded through a capacitor (may be two in parallel, for effectiveness from about 100 kHz up to 1 GHz and beyond) at the receiving end: Good at r.f. if the capacitor type and positioning are correctly-designed, and no low-frequency ground current. One capacitor needs to be of the type with an integral spark- gap so that it is not damaged by transient high-voltage spikes that may be induced on to the shield.

[Tirefryr]

Great read!! Thanks.

Another question. . I worked on one of the Pioneers with that RCA issue. I simply ran a wire from the chassis (HU) to the outer RCA shield and the noise was gone. Now that solely defeated their isolation, yet it cured the problem, so why would they even bother with the isolation in the first place? Would it be specific to the design of the HU itself, or just something manufactures do?

[Megalomaniac]

eh the manufactures do their best to keep things(problems) isolated if anything where to happen.

[916SkyGTO]

Wow. I was planning to get that 4 channel rca too. I'm looking for a 4 channel rca that isnt too pricey. Im planning to get the monster cable 4 channel and its around $20 off ebay. Is there any other better deals, anyone can recommend? .

[Neutered Sputniks]

Correct me if I'm wrong...but if the HU and amplifier have different ground levels applied to their RCA jacks, couldn't that cause a current flow if the shielding were connected to the plugs? Now you have current flow through the shield, and that would almost definitely cause an inducted signal to be pushed through to the center conductor (ground loop). Maybe leaving the shield separate from the RCA plugs eliminates that possibility given the extreme number of manufacturers out there?

If all HUs and amplifiers had their RCA jack shields grounded directly to the auto frame, I could see that the shielding being attached to the plugs would make perfect sense. But, given that such is often not the case, wouldn't it be safer to not attach the shielding?

[Megalomaniac]

to avoid the loops ground the shield only one 1 side....the source side.


sure no shielding could work, but they have 4 different kinds of shields on them now that arent grounded so it will be worse for that cable to not be grounded than if it were, it would act as an antenna. only thing helping rejecting all that noise right now is be twisted.