Choosing Unbalanced RCA Audio Cables for Home Use: What Really Matters? - Shielding & Directionality Questions

[mansr]

So you form a loop?

Huh? I cracked open the plug housings and removed some moulded plastic. This revealed two insulated conductors crimped to the plug along with a shield connected to the negative side at the "far" end of the cable. There was enough of the shield protruding at the "near" end that a suitably placed crocodile clip could connect it to the negative wire. With this connection made, the measurements become symmetrical, close to the "reverse" image I posted earlier. To be clear, both of those images were obtained with the cable unmolested.

 

[Boromirka]

If you want a good name brand, get some Blue Jeans cable. Good non snake oil cable. Good quality ends. It's maybe more than you need. But the piece of mind is inexpensive.

Even cheaper and still fine get monoprice premium cables. You can order direct or from Amazon.

Bluejeans is kinda expensive because of shipping. As for Monoprice, too stiff from what i read from reviews

 

[mansr]

Bluejeans is kinda expensive because of shipping. As for Monoprice, too stiff from what i read from reviews

Amazon Basics should be fine.

 

[Blumlein 88]

Bluejeans is kinda expensive because of shipping. As for Monoprice, too stiff from what i read from reviews

They are a little stuff and thick, but not as stiff as most AQ.

 

[Sal1950]

Great that i found this thread by accident. Which cable should i use afterall?

If you want a good name brand, get some Blue Jeans cable. Good non snake oil cable. Good quality ends. It's maybe more than you need. But the piece of mind is inexpensive.
Even cheaper and still fine get monoprice premium cables. You can order direct or from Amazon.

Blumlein88 took the words out of my mouth as I was reading thru this thread tonight and are what I use here.
I don't find the Monoprice to be stiff at all compared to any quality cables, the bluejeans coax would be stiffer.
Either of the recommended companys will ship to EU.
A 4" circle in bag, could easily be bend tighter.

 

[rwortman]

It seems obvious but maybe someone should point out that if you are using coaxial cable to make your interconnect and you only connect the shield at one end you won't get any sound. If you are using twisted pair to make an unbalanced interconnect and you only connect the shield at one end, I don't see how that helps. I thought the point of connecting at one end was to avoid ground loops. With unbalanced you connect the grounds together anyway. How would the shield shield better by being connected at one end only?

 

[DonH56]

It seems obvious but maybe someone should point out that if you are using coaxial cable to make your interconnect and you only connect the shield at one end you won't get any sound. If you are using twisted pair to make an unbalanced interconnect and you only connect the shield at one end, I don't see how that helps. I thought the point of connecting at one end was to avoid ground loops. With unbalanced you connect the grounds together anyway. How would the shield shield better by being connected at one end only?

Assuming signal return is provided by the twisted pair, then lifting the shield at one end will not form a ground loop and will not provide a coupling path for EMI/RFI since it does not form a complete loop. That allows the shield to act loosely like a Faraday Cage to "block" external signals (noise) from reaching the actual signal source and return wires. Connected at both ends, you can get current flow (and thus voltage and magnetic fields) in the shield from noise (externally applied or due to any difference in potential between the components at the ends) that could couple to the signal.

Very handwaving (and thus not completely technically accurate) but HTH - Don

 

[Deleted member 2944]

Sounds pretty accurate to me.

 

[invaderzim]

I'm not a huge fan of the Monoprice ones. I got a small cable like shown from them and while it will bend it typically doesn't like to and will try to return to straight

They can be forced into a bend but some other cables are definitely more floppy. I'm not a huge fan of trying to run the Monoprice ones around and through things because they tend to fight it. They will push any really small and light equipment around to where it suits them better.

Is there a bluejean equivalent in the EU that would save on shipping since the person asking is from there?

 

[pierre]

I'm not a huge fan of the Monoprice ones. I got a small cable like shown from them and while it will bend it typically doesn't like to and will try to return to straight

They can be forced into a bend but some other cables are definitely more floppy. I'm not a huge fan of trying to run the Monoprice ones around and through things because they tend to fight it. They will push any really small and light equipment around to where it suits them better.

Is there a bluejean equivalent in the EU that would save on shipping since the person asking is from there?

https://www.thomann.de/intl/audio_c...=true&feature-47038[]=RCA&feature-10698[]=RCA

Not really an equivalent of Blue jean but plenty of options , Amazon basics alse works well in Europe (except for Switzerland)

 

[ripvw]

Just ordered some of this from Blue Jeans Cable:

https://www.bluejeanscable.com/store/audio/LC1-design-notes.htm

1 foot pair for $30 plus shipping

IMO this is on the high side of pricing for non-snake oil cable. I have had great experiences with Blue Jeans Cable products for years so I stuck with them - but I certainly would not spend more than this amount.

 

[rwortman]

Assuming signal return is provided by the twisted pair, then lifting the shield at one end will not form a ground loop and will not provide a coupling path for EMI/RFI since it does not form a complete loop. That allows the shield to act loosely like a Faraday Cage to "block" external signals (noise) from reaching the actual signal source and return wires. Connected at both ends, you can get current flow (and thus voltage and magnetic fields) in the shield from noise (externally applied or due to any difference in potential between the components at the ends) that could couple to the signal.

Very handwaving (and thus not completely technically accurate) but HTH - Don

You are correct about the shielding but the grounds on the two devices are still connected by the minus side of the twisted pair in an unbalanced connection. The ground loop possibility is still there. Maybe it shields a little better? I have seen some purchased RCA's with twisted pair cable and in at least one case the manufacturer (monster cable if I recall) connected the shield as return and left one of the wires in the pair unconnected. Not sure WTH that was about. I have always used good quality coax to make interconnects. Twisted pair seems a misapplication to me. I did try a twisted pair with one side connected shield one time when I did have a ground loop hum problem and it did nothing to help it.

 

[restorer-john]

That allows the shield to act loosely like a Faraday Cage to "block" external signals (noise) from reaching the actual signal source and return wires.

A heap of cassette decks used this method- twin shielded internal cabling with the shield only connected at one end. Many of Akai's 80s decks had that arrangement with jumper cables going everywhere past VFDs, transformers and motors.

PS I always wanted a big Faraday cage to sit in with my tinfoil hat on.

 

[DonH56]

You are correct about the shielding but the grounds on the two devices are still connected by the minus side of the twisted pair in an unbalanced connection. The ground loop possibility is still there. Maybe it shields a little better? I have seen some purchased RCA's with twisted pair cable and in at least one case the manufacturer (monster cable if I recall) connected the shield as return and left one of the wires in the pair unconnected. Not sure WTH that was about. I have always used good quality coax to make interconnects. Twisted pair seems a misapplication to me. I did try a twisted pair with one side connected shield one time when I did have a ground loop hum problem and it did nothing to help it.

Signal grounds can be isolated from safety grounds. For a single-ended connection it depends upon how the driver and receiver are designed; you can isolate the ground of a single-ended signal from earth (safety) ground and break a ground loop. I have done it, many have, and a number of consumer components do it. My old ARC preamp did it, my new Rythmik sub does it, for example. Not being an audio tech for years I couldn't say what they are all doing now. It is usually done with a low-value resistor that makes the signal ground path a lower-impedance to the signal path than the safety ground and thus "breaks" the loop.

The purpose of a twisted pair is to minimize coupling from common-mode noise and, in some cases, provide a more predictable controlled impedance. It is often used in a differential design that offers the ability to break a ground loop but those are separate things.

 

[DonH56]

A heap of cassette decks used this method- twin shielded internal cabling with the shield only connected at one end. Many of Akai's 80s decks had that arrangement with jumper cables going everywhere past VFDs, transformers and motors.

PS I always wanted a big Faraday cage to sit in with my tinfoil hat on.

Yup.

The tinfoil hat's a nice idea but it would flatten the hair in your avatar... That is you, right?

 

[Sal1950]

Just ordered some of this from Blue Jeans Cable:

https://www.bluejeanscable.com/store/audio/LC1-design-notes.htm

1 foot pair for $30 plus shipping

IMO this is on the high side of pricing for non-snake oil cable. I have had great experiences with Blue Jeans Cable products for years so I stuck with them - but I certainly would not spend more than this amount.

Well IMHO the point is you will never have to spend more for cable. Their measurements show them to be at the top of the pile of anything ever required for the home user interconnect. you can sleep good at night knowing your fully covered.

 

[HammerSandwich]

PS I always wanted a big Faraday cage to sit in with my tinfoil hat on.

Just remember to ground that hat! Everybody forgets that step.

 

[rwortman]

Signal grounds can be isolated from safety grounds. For a single-ended connection it depends upon how the driver and receiver are designed; you can isolate the ground of a single-ended signal from earth (safety) ground and break a ground loop. I have done it, many have, and a number of consumer components do it. My old ARC preamp did it, my new Rythmik sub does it, for example. Not being an audio tech for years I couldn't say what they are all doing now. It is usually done with a low-value resistor that makes the signal ground path a lower-impedance to the signal path than the safety ground and thus "breaks" the loop.

The purpose of a twisted pair is to minimize coupling from common-mode noise and, in some cases, provide a more predictable controlled impedance. It is often used in a differential design that offers the ability to break a ground loop but those are separate things.

I understand the use of balanced cabling. I was questioning the efficacy of using twisted pair with a half connected shield for an unbalanced RCA cable. It does depend on how the equipment is designed whether you will get ground loop problems from your RCA connections. All I am questioning is whether, if you have RCA cabling ground loop problems, if connecting the signal grounds with a shield or one half of a twisted pair is going to make any difference. I don't think it will.

 

[Sal1950]

I understand the use of balanced cabling. I was questioning the efficacy of using twisted pair with a half connected shield for an unbalanced RCA cable. It does depend on how the equipment is designed whether you will get ground loop problems from your RCA connections. All I am questioning is whether, if you have RCA cabling ground loop problems, if connecting the signal grounds with a shield or one half of a twisted pair is going to make any difference. I don't think it will.

I agree, the problem probably lies in a voltage differential on the AC lines.

 

[DonH56]

I understand the use of balanced cabling. I was questioning the efficacy of using twisted pair with a half connected shield for an unbalanced RCA cable. It does depend on how the equipment is designed whether you will get ground loop problems from your RCA connections. All I am questioning is whether, if you have RCA cabling ground loop problems, if connecting the signal grounds with a shield or one half of a twisted pair is going to make any difference. I don't think it will.

If the signal ground is shorted to the safety ground then no it won't.