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.
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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.
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@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.
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@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.
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@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.
Big Volta’s “V” is for DC Volts.
little Volta’s “v” is for AC volts.
Back to the OP’s question…
When a 2 wire and shield cable is used with an RCA it can have the second wire soldered on the “negative”, the positive, or left completely off.
(On an XLR we would solder it to the -180 side.)
It is kind of like 1/2 a transformer, if we look at it like a twisted pair, so I would suggest that one attaches it somewhere. I use the negative side, but the center pin seems like a valid choice.
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@jumia
Simple answer to your question is it depends.
There are two standards for RCA. Single ended RCA which uses one wire for signal (the inside pin) and usually is shielded (the outside ring) but the shield is not required for functionality.
The second standard is Differential input RCA which is balanced like XLR and uses two wires to send signal on wire one and inverted signal on wire two. No shield is used.
Both cables will work on any equipment but generally, you will get better results using the correct cable with each standard.
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The second standard is Differential input RCA which is balanced like XLR and uses two wires to send signal on wire one and inverted signal on wire two. No shield is used.
There is no standard for balanced differential amplification using an RCA connection. If such a thing is used expect a bit of the Wild West.
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Recent answers Have been amazing.
The RCA connector - isn't it designed to accommodate one conductor and then gripping the shield where it is soldered at the base of the connector. So how does the RCA connector accommodate 2 connectors(positive and negative) and a ground wire.
I really like atmaspere’s answer including discussion about the shield carrying the signal. It made a lot of sense to my simple mind.
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https://www.youtube.com/watch?v=QOagVDZLQnA |
@jumia At one RCA connector shield and negative/return wire are both soldered at the base of the connector while signal/positive wire is soldered to center pin. On the other side only two wires are soldered while shield is left unconnected/floating.
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Since you are only concerned with single ended RCA interconnects with coaxial cables, I will share my experience with you.
For many years I used a fine 75-ohm Belden #9259 oxygen free single center conductor coaxial cable with a bare copper braided shield over a polyethylene foam dielectric. This was my principal preamplifier output to my mono block power amps input for many years. I really had no complaints. Due to a change in my room arrangement, I was forced to construct new & longer interconnects. I was unable to acquire an adequate amount of the Belden #9259 cable without purchasing an entire roll.
I did however receive a timely tip from a respected analog guru. He recommended Mogami W2549 coaxial cable which has 2 OF center conductors + bare copper braid. You can experiment with it in 2 methods: 1) solder 1 center conductor to the RCA + cup, the other center conductor to ground & the bare copper braid as the shield or 2) solder both center conductors to the RCA + cup & the bare copper braid as ground. Interestingly, the company that I purchased the cable from (Redco) actually terminates them per method 1 (above). However, I chose the second method.
I made my main pre to power amp interconnects 25' long. 2 more pair 1 meter long and a 4th pair 2 meters. After about 300-400 hours of "run-in" I was more than pleased. Doing this project requires some good tools, materials and diligence or alternatively, pay someone or business to do it. If you are a DIY person, you may wish to select an RCA connector with a crimp connector option for the braid so that you only have to solder the center conductor(s). I found that soldering the braid to the ground of the RCA connector to be the most difficult part of the process, mostly because the RCA's that I chose didn't leave me much real estate to work in.
I was not able to compare these particular Belden vs Mogami coaxial cables in my system fairly, but I am very pleased and settled with this decision & execution. The Mogami cable is exceptional in every aspect with vivid detail and dynamics.
I hope this has provided some limited comparative insight.
Best luck
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I like Mogami too. I have their 3173 Cable as a interconnect between amplifier and preamp. This is a little thicker than the 2549 and also has a drain wire Plus 2 conductors. In this situation the drain wire is connected to both sides.
Still breaking in and thus far it’s a wonderful cable and very inexpensive.
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I've heard inexpensive star quad from Straightwire that Excell.
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So how does the RCA connector accommodate 2 connectors(positive and negative) and a ground wire.
@jumia Simply by careful soldering.
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So how does the RCA connector accommodate 2 connectors(positive and negative) and a ground wire.
^Twist them together.^
I put together some XLR to RCA yesterday.
On the Neutrik XLR:
- The two clear wires twisted together to pin 2.
- The two blue wires twisted together to pin 3.
- The shield all twisted up and soldered to pin 1.
On the RCA:
- Clear wire pair twisted (XLR pin 2) to RCA center
- Blue wire pair twisted (XLR pin 3) to RCA shell.
- shield trimmed back, and not touching the shell at the RCA.
On the DAC I split the power and shoved a ferrite core on, with the +V in the one direction and the -V wound the other way.
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Finally I appreciate the help. OK so you combine the two connectors before attaching to the RCA. Makes sense and I guess you have to mix them together.
At least the two conductors had a peaceful journey from the preamp and then all hell broke loose when they reach the RCA connector.
Blue , I believe is the ground connected to the Shell on both sides of Cable as mine have been done and recommended this way.
And the shield is out of the picture by stripping it back
Not sure why the hell every comment above made this issue so damn complicated
Great job holmz
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I dunno @jumia - I needed an XLR to RCA and was not about to pay money and time awaiting a cable.
And it even sounds OK.
The soldering looks a bit rough, but once the end is screwed on, you cannot see it.
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@jumia Specifically I was using Mogami Neglex 2534… 2x blue, and 2x clear, and the shield.
https://mogamicable.com/category/bulk/microphone/quad/
The Mogami is in a brown jacket, so that the WAF abides it laying on a brown wood floor.
I usually order from Markertech and use the Nuetrik ProFi (RCA) or their XLR ends.
But any supplier carries the stuff.
And Canare and others have the same sort of stuff.
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