RCA interconnect with shield soldered at one end only

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edwyun

Can a set of interconnect like this be custom made?

To be precise, I'm looking for interconnect with a (+) wire connected to both ends of the interconnect, a (-) ground wire connected to both ends of the interconnect, and a shield that is NOT connected to the (-) ground wire (as some interconnects out there) and where that shield is connected to only one end of the interconnect.  Thanks.

Armaegis

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Re: RCA interconnect with shield soldered at one end only
« Reply #1 on: 9 Feb 2017, 06:55 am »
RCA's only have two connection points. There's nowhere to connect the shield on either end, not unless you decide to add a chassis screw or something.

DaveC113

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Re: RCA interconnect with shield soldered at one end only
« Reply #2 on: 9 Feb 2017, 07:30 am »
Sure, customizing the cables is no problem, I can offer shielded versions of any of my interconnect cables. The cable you describe is the best way to make a shielded single ended (RCA) interconnect cable, the other being a simple coax cable, that type of cable does require the shield to be connected at both ends to function properly. Many cables that are directional have a shield that is connected at one end only. To be clear, the shield is connected to the ground at one end of the cable, which removes it from the signal path and it's really an extension of the chassis. The shield does need to be connected at one end to work properly. XLR cables generally have their shields connected at both ends as ground isn't used as signal path and it improves bonding, or lowers the resistance of ground connection between chassis.

I build shielded regularly for phono use and plan on adding a section to my website in the near future. There's a lot of possible configurations so I'll have to give a quote for each cable but prices are close to the standard ic cable pricing. PM me or email dave@zenwaveaudio.com with the details of your request. Thanks!

DaveC113

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Re: RCA interconnect with shield soldered at one end only
« Reply #3 on: 9 Feb 2017, 07:44 am »
RCA's only have two connection points. There's nowhere to connect the shield on either end, not unless you decide to add a chassis screw or something.

The shield does need to be connected to ground to work properly, there are three ways to design a shielded RCA cable:

1. Coax cable with RCA terminations, shield is ground/- and is connected at both ends. Coax has a single signal/+ conductor at the center of the cable.

2. A cable with both signal/+, ground/-, and shield. The simplest example is a shielded twisted pair, the shield is connected to ground at one end. These cables are usually marked directional with the connected end at the sending end of the cable.

3. A cable with both signal/+, ground/-, and shield, but the shield has it's own ground connection that eventually plugs into the power distributor. A few high end cables use a system like this. every signal cable needs it's own ground cable, so not exactly cheap and it's more complicated, it may be the best option. I've been looking into this and it might be an option in the future.

Bob2

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Re: RCA interconnect with shield soldered at one end only
« Reply #4 on: 9 Feb 2017, 11:32 am »
..
« Last Edit: 9 Feb 2017, 03:10 pm by Bob2 »

Armaegis

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Re: RCA interconnect with shield soldered at one end only
« Reply #5 on: 9 Feb 2017, 05:27 pm »
Oops, sorry Dave, I thought this was in the general area and didn't realize it was in your industry circle. I wouldn't have piped up otherwise.

DaveC113

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Re: RCA interconnect with shield soldered at one end only
« Reply #6 on: 9 Feb 2017, 06:13 pm »
Oops, sorry Dave, I thought this was in the general area and didn't realize it was in your industry circle. I wouldn't have piped up otherwise.

No problem, I don't mind discussion and comments.  :thumb:   There's usually some confusion on this subject as there are different ways to implement shields on single ended cables.

Also, I forgot to mention the highest end Siltech cables actually have switches on the cable to connect or disconnect the shield, so that's another option and not a bad idea, but I'd go with option #3 a couple posts above instead.

Armaegis

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Re: RCA interconnect with shield soldered at one end only
« Reply #7 on: 9 Feb 2017, 07:58 pm »
No problem, I don't mind discussion and comments.  :thumb:

but I'd go with option #3 a couple posts above instead.

Yeah, that's what I was alluding to with using a chassis screw to ground down a shield, though connecting all the way back to the power distribution panel is the better option, albeit more finagled with wiring.

I deal a lot more with pro audio so it's all XLR's for me, although even there the "pin 1 problem" never fully goes away.

edwyun

Re: RCA interconnect with shield soldered at one end only
« Reply #8 on: 9 Feb 2017, 08:55 pm »
3. A cable with both signal/+, ground/-, and shield, but the shield has it's own ground connection that eventually plugs into the power distributor. A few high end cables use a system like this. every signal cable needs it's own ground cable, so not exactly cheap and it's more complicated, it may be the best option. I've been looking into this and it might be an option in the future.

Very interesting.

Speedskater

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Re: RCA interconnect with shield soldered at one end only
« Reply #9 on: 10 Feb 2017, 02:42 am »
Yeah, that's what I was alluding to with using a chassis screw to ground down a shield, though connecting all the way back to the power distribution panel is the better option, albeit more finagled with wiring............................
A better plan would be to connect the shield to the chassis with a very short wire (1cm/½inch). Anything longer will act as a noise/interference antenna. Connecting way back to the AC power panel will add a huge ground loop. Even connecting to an nearby AC Safety Ground will add the noise/interference/leakage currents associated with the ground system to the shield.

Early B.

Re: RCA interconnect with shield soldered at one end only
« Reply #10 on: 10 Feb 2017, 03:25 am »
I used to own several Synergistic Research cables with "active shielding." Imagine all of your speaker cables, ICs, and power cords needing to be plugged in. I think it created more problems than it attempted to solve. For instance, I upgraded all of the wall warts on the cables because it made a noticeable improvement. (I'll bet the wiring from the cables to the wall warts could be improved, as well.) Second, there was a need for extra outlets (i.e., larger power conditioners ) that contributed to the total overall cost. Third, the extra cables created a veritable rats nest. I also owned a power cord with battery powered active shielding that suffered from some of the same issues.

Even though the active shielding clearly resulted in better sounding cables, I was glad to get rid of them. "Keep it simple" is my vote.

 

DaveC113

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Re: RCA interconnect with shield soldered at one end only
« Reply #11 on: 10 Feb 2017, 03:02 pm »
A better plan would be to connect the shield to the chassis with a very short wire (1cm/½inch). Anything longer will act as a noise/interference antenna. Connecting way back to the AC power panel will add a huge ground loop. Even connecting to an nearby AC Safety Ground will add the noise/interference/leakage currents associated with the ground system to the shield.

You wouldn't connect the shields "all the way back at the power panel", but right near the components at the power distributor. Ground loops won't be an issue because the ground wire would be the only electrical connection to the shield. Several cable manufacturers currently use this type of shielding, and a ground filter could also be inserted in between the shields and the ground connection point at the power distributor.

All of this goes against the fact I like to keep things simple, and this isn't simple. It's a lot of extra complexity and parts, in a great majority of home environments there is nothing to be gained by shielding anyways. IME, <1% of folks have issues that require shielding, but it does happen occasionally. I am 99.9% sure you have a different opinion, that's fine but lets not argue the merits of shielding or single ended vs balanced systems.   :wink:



DaveC113

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Re: RCA interconnect with shield soldered at one end only
« Reply #12 on: 10 Feb 2017, 03:07 pm »
I used to own several Synergistic Research cables with "active shielding." Imagine all of your speaker cables, ICs, and power cords needing to be plugged in. I think it created more problems than it attempted to solve. For instance, I upgraded all of the wall warts on the cables because it made a noticeable improvement. (I'll bet the wiring from the cables to the wall warts could be improved, as well.) Second, there was a need for extra outlets (i.e., larger power conditioners ) that contributed to the total overall cost. Third, the extra cables created a veritable rats nest. I also owned a power cord with battery powered active shielding that suffered from some of the same issues.

Even though the active shielding clearly resulted in better sounding cables, I was glad to get rid of them. "Keep it simple" is my vote.

 

I forgot about the active shield cables, I remember that thread on DIY Audio... if I was going to think of one company that would run with it, it's SR.  :lol:  I think AudioQuest has some active cables too.

Armaegis

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Re: RCA interconnect with shield soldered at one end only
« Reply #13 on: 10 Feb 2017, 04:39 pm »
I've always wanted my own personal Faraday cage...  :green:

DaveC113

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Re: RCA interconnect with shield soldered at one end only
« Reply #14 on: 12 Feb 2017, 04:23 pm »
I've always wanted my own personal Faraday cage...  :green:

Sounds like a great business idea.  :thumb:

It seems like it would be easy to come up with a bunch of hyperbolic marketing speak about a "refuge from technology in this day and age", or something...  :)

WireNut

Re: RCA interconnect with shield soldered at one end only
« Reply #15 on: 12 Feb 2017, 06:03 pm »
I'm glad I didn't start making my interconnects yet before reading this thread.
I'm getting ready to make 7 pairs of interconnects using Belden 9207 Twinax Cable with shield and RCA connectors.
I was planning on connecting the shield at both ends along with the negative wire.
Why wouldn't I want to do it that way?

I'm currently using Belden 89259 (75 ohm) coax cable for my interconnects and it works great.
Just want to try Belden 9207 (100 ohm) cable as an experiment in SQ.

I was going to start on them today.


There's an interesting artical here at Jeff's Place about using Belden 8402 twinax with shield at both ends.
http://jeffsplace.me/wordpress/?p=7325

Here's another artical about Enhanced wire termination for twinax wires US patent 6380485 B1.
It's a bit deep for me at this point but it may be interesting to those more technical than me.
http://www.google.com/patents/US6380485


This artical is called noise reduction techniques in electronic systems.
http://www.physics.utah.edu/~jui/3620-6620/Files/ott.pdf

 

WireNut

Re: RCA interconnect with shield soldered at one end only
« Reply #16 on: 12 Feb 2017, 10:07 pm »
DaveC113,

 When using a twinax cable (Belden 9207) with a shield and RCA's
would connecting both the positive and negative wires together to the center pin and
then only using the shield as a ground/negative connection work?

This was mentioned on Jeff Day's blog but was never followed up.

DaveC113

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Re: RCA interconnect with shield soldered at one end only
« Reply #17 on: 12 Feb 2017, 11:44 pm »
I think the shield connected at one end is best, it takes the shield out of the signal path and the shield doesn't do triple duty as signal return, ground connection + shield. The main idea is the shield is connected on the sending end so any noise picked up by the shield doesn't make it to the next component.

In some circumstances you may have better results with the shield connected at both ends, especially if the ground wire is small. Reducing resistance reduces noise voltage as a result of potential differences between component grounds, Ohm's law is V=IR, reduce R, V is reduced as well. Hopefully I is small to begin with, if it is then reducing R may not make much of a difference. But in any case, it's best to reduce R. I do this by making the ground leg much larger than the signal leg and then add shielding if necessary. 99.9% of the time shielding isn't needed with short cables in home systems, it just adds capacitance and dulls the sound. I'd be willing to bet a simple twisted pair of 24g UPOCC copper/teflon would beat out any of the Belden cables easily.


WireNut

Re: RCA interconnect with shield soldered at one end only
« Reply #18 on: 13 Feb 2017, 01:08 am »
99.9% of the time shielding isn't needed with short cables in home systems, it just adds capacitance and dulls the sound. I'd be willing to bet a simple twisted pair of 24g UPOCC copper/teflon would beat out any of the Belden cables easily.


 Makes since. I have 7 pairs of IC's in my system but none of them are longer than 3 feet. Most are 1.5 to 2 feet long.
Referencing the Belden 9207 twinax that I already have, would combining the 2 inner wires to the center pin of both RCA'S and just using the
braided shield connected to the ground of both RCA's be a good idea or would that induce problems?

Nothing that I have read discusses doing this except an entry in Jeff Day's blog with no further comments.

I don't have a distribution outlet as you stated above. My equipment is connected to 3 different circuits on my main panel.
My Turn table, phono stage, and preamp DO NOT have ground connections. Come to think of it either do my 2 power amps.
My system is Bi-ampped. Only my Marchand XM-44 crossover  and my DAC have a ground connection.


WireNut

Re: RCA interconnect with shield soldered at one end only
« Reply #19 on: 13 Feb 2017, 01:39 am »
Bump for more input from more technical savvy people then me.