What's better, one conductor or two conductors for an RCA interconnect?

@jumia

A shielded RCA cable (not coax) is 2 conductors, one for ground, and one for signal, plus a 3rd "conductor" which is the shield. The shield will extend the full length of the cable, but only connect on one end. The shield is effectively a Faraday cage preventing RF energy from getting into cables inside of it. Yes, the shield is potentially an antenna. However, if it is connected on only one end, any RF energy should be shunted harmlessly to ground.

If you connect the shield on both ends, and the RF energy generates a large current in the shield, then it could induce a difference in ground voltage which will (or could) show up in the signal on a single ended system. That would also require the stars to align such you had a huge amount of RF and that your audio system converts the RF into something audible. More likely is an electrostatic conduction path which the shield will provide some protection for, or not and/or a magnetic path for which it may provide protection or not. There is more complexity than this and it would take far too much space to put here so I found you a good link. (and RF is obviously both electric and magnetic field).

Most fields have a lot of lore, pass down through the ages, repeated, reinforced, and wrong. Just look at this hobby! Electrical Engineering is no different (and nor is physics). What works in one situation may not work in another, hence rules of thumb often cause bruised thumbs.

This particular link takes a very hard line on cable shielding (not system level noise). From a practical stand point as an end user, you cannot ignore system level noise in order to perfect shielding, but your takeaway should be that unless everything is designed properly (his examples of mil-spec and FAA), then there is no 1 correct way for every instance, only a correct way for your particular instance. I know most of this paper will likely be over your head, but I think perusing it will give you a feel for what the issues:

https://www.emcstandards.co.uk/cable-shield-grounded-at-one-end-only

Let us change the problem to a phono cartridge and a pre-amp. By your understanding, even if one side of the phono amp input is grounded, the system is "differential", and hence will receive the full benefits of twisted pair wiring. That is wrong. I noted that @atmasphere who supported you above uses a true differential input on the phono inputs to his preamplifier (for improved noise rejection).

@deludedaudiophile  To be clear no direct line can be drawn between single-ended and balanced lines as they are mutually incompatible. A phono cartridge in most tonearms is a balanced source, but usually its operated single-ended, leaving you with that weird ground wire that has to be hooked up to avoid buzz. When you run it balanced the ground wire is gone, instead there is the shield of the tonearm cable with a twisted pair inside, much like the tonearm tube itself.

FWIW dept.: the use of capitals is to honor the people that did the early research; Hertz, Ohm, Volt, etc. are all names of people but 'kilo' and 'mega' are not- they are multipliers. So you see kOhms, kHz, kV or mV (milliVolts). Anything else is either ignorance or being sloppy, and yes, I've been there.

So I’ve inquired about one conductor versus 2 conductor as part of an RCA interconnect. There has been a substantial response from very very smart people.

Unfortunately, somehow the brilliance is having trouble leading to a point where someone can understand what is being said. brilliant people herein don’t really do a very good job explaining things Beyond extremely technical jargon.

This thread of information is a testament to how challenging it is for brilliant minds to communicate in a manner that can be understood by us average mortals. Truth be told this discourages people and is an unattractive aspect of this hobby of sorts.

Do these really brilliant people know that most people reading the comments have no idea what they’re talking about. It’s really really hard to understand.

I have always considered True genius to be the ability to explain a very complicated situation to the masses. Otherwise what’s the point.

@atmasphere AFAIK we should write symbols of units named after person with capital unit letter V, kV, A, kA, kHz, kW etc. but spelled out units with lowercase : volts, amperes, ohms, watts.  Multiplier doesn't change that, so it will be kilovolts, kiloohms, kilowatts, kilohertz.  The only exception is when unit contains two words like degree Celsius.   

 

@kijanki I try to always use caps in the spelling too.

@jumia Look at it this way. If the signal is passing through the shield as it does when only the shield and center connection is present, then the construction of the shield and any noise to which its subjected to will affect the sound, some of it possibly in the form of added intermodulation distortion as the noise is impinged on the signal.

When the shield is separate from the signal this won't happen so it sounds better.

The actual technical description is more complex as you know; this is the Cliffnotes version.