different kind of cable thread (maybe?) - DIY unbalanced 'interconnect' strategy & tactics

mhardy6647

I am interested in folks' opinions and experiences with respect to rollin' your own
unbalanced ("RCA" plug) audio cables for line-level use.

• Favored type (brand/model and/or configuration) of cable?
• Favored RCA plugs (brand/model)
• Shielding scheme (if any)

you know, stuff like that.

I've been reading a little (e.g., Rane note 151, rane.com/note151.html) and just getting myself completely confused.

As a potential way to break my analysis paralysis, I figured it couldn't hurt to ask about
some empirical experience (is that redundant?)... but I'll definitely settle for some conjectural opinions.

Thanks.

delkal

I am very proud of the 999 silver interconnects I made, Its a very simple design. Pure solid silver wire in a teflon tube. Cut it to size and solder on a mid priced RCA. I didn't have any true high end interconnects to compare it to but the improvement from my mid priced interconnect was noticed immediately first time I tried them. I also made a matching pair with mil spec silver coated hookup wire with teflon insulation. They also sounded good but I have mostly been using the pure silver ones.

I used this site as a guide. The only problem I had is I couldnt figure out how to secure the teflon tubes securely in the RCA body (they are slippery!). You don't want to pull these cables out by the wires. The pair I made look similar to these.



laventure.net/tourist/cables.htm

msg

I like the Douglas Connection "kits" I ordered from Doug. So far I've only managed to get one set made, but I think they sound pretty good.

I used the Furez FZ162AA Analog IC. I'd probably look at some Mogami shielded stuff as well.

I like locking RCA connectors. Doug has a bunch of different ones.
I used the DC Locking RCA; $12.50/pr. These are affordable and work well enough, but I prefer the locking functionality of other connectors a smidge better. These ones don't get quite as tight as I'd like, but there's a little trick to help that a bit.

(Just picked up some Furez R10BCS Silver Plated Copper Core to use to refresh the connectors on my Technics SL-1200); $35/pr

Also picked up some time ago some Parts Express Locking RCA Connectors; $20/2pr. These are similar to the Vampire Wire ones, though I've not handled the VW's personally.


I once tried to bulk order some GLS Audio Locking RCAs, which look similar to the Parts Express ones, but the connector is thin and cheap, so back those went. With this style of locking connector, I was trying to find something similar to the ones MIT uses, but couldn't really find them. Most will be gold plated brass core, but I think Ideally I'd want gold plated copper core. WBT makes some, but spendy. Watch out for fakes on Ebay.

Check out RCA Cables and Connectors at The Cable Company
and at Parts Connexion.

Re: shielding, for me, as I was "taught", I go with the shielding terminated along with the ground to the body of the source side connector only, and trim and tuck the braid on the destination end. I was reading that some companies don't use shielding, and instead rely on conductor geometry for interference rejection? Dynamique is a company that does this, iirc?

Here's a link to my ugly first build with embarrassing solder work. Yeesh. Haven't done any serious critical listening with these. Was mostly just for the project fun with some nice quality materials.

pitdogg2

delkal wrote: »

The only problem I had is I couldnt figure out how to secure the teflon tubes securely in the RCA body (they are slippery!).

How about color coordinated shrink tubing with adhesive??

Works..... still remove by RCA as you should always anyway.

[Deleted User]

Low capacity RG62A/U and Pomona 6881 RCA plugs. Also Switchcraft SWC-3502A RCA plugs work fine.

msg

Ken, that's coax, right? How do you wire/build it with a single conductor?

mhardy6647

msg wrote: »

Ken, that's coax, right? How do you wire/build it with a single conductor?

Are you asking coax for unbalanced I/Cs? Center conductor is "hot" (center pin); braid (shield) is "return" (outer connector) is the usual way IMO/IME (ahem, it's what I do). I

Coax makes nice signal cables but (at least the cables I've used) are stiff and somewhat tedious to work with in the real world. I will admit that I've never (knowingly) encountered RG62, though

92 ohm cable... it appears.

Thanks to all for the input so far; I much appreciate it@!

[Deleted User]

I don't believe the characteristic impedance will make any difference except for digital device connections. It is the cable's geometry that caught my attention, the center conductor is held in the middle of a flexible plastic tube by a spiraling plastic form. The air between the conductor and the centering tube is the dielectric material (air has a good reputation for sound quality when used as a dielectric). This cable is used in scientific and test equipment when low capacitance is needed. Also early computer network connections.
You have to use a little care to maintain the shape of the cable when attaching the RCA's ground return so as not to change the relationship between the conductor and the supporting structure. Of course any coaxial cable needs this care when attaching any kind of connector.

pitdogg2

KennethSwauger wrote: »

Low capacity RG62A/U and Pomona 6881 RCA plugs. Also Switchcraft SWC-3502A RCA plugs work fine.

Ken made some of these for me a few years back. It surprised me how well this cable worked.

delkal

KennethSwauger wrote: »

Low capacity RG62A/U and Pomona 6881 RCA plugs. Also Switchcraft SWC-3502A RCA plugs work fine.

RG62A/U coax is the only wire I know of that used a copper coated STEEL conductor. Most "experts" say you need to use the purest copper or silver availible and to avoid all ferrous material like the plague .

But I can't argue if it works. The "experts" don't know everything.

https://catalog.belden.com/techdata/EN/9269_techdata.pdf

pitdogg2

delkal wrote: »

KennethSwauger wrote: »

Low capacity RG62A/U and Pomona 6881 RCA plugs. Also Switchcraft SWC-3502A RCA plugs work fine.

RG62A/U coax is the only wire I know of that used a copper coated STEEL conductor. Most "experts" say you need to use the purest copper or silver availible and to avoid all ferrous material like the plague .

But I can't argue if it works. The "experts" don't know everything.

https://catalog.belden.com/techdata/EN/9269_techdata.pdf

Many (most) coax is now copper coated steel. This that Ken used was 100% copper. I believe his was an much older stock because when i tried to find some to buy i ran up against the fact i could no longer find 100% copper. Canare and a few others still make 100% copper coax and it costs more of course unfortunately none is RG62a/u

machone

I used Mogami w2549 microphone cable with Neutrik gold RCA's.

The Mogami has very low capacitance and a great shield.
The Neutrik have superior strain reliefs and the ground makes contact before the center pin.
I connected the shield to the case on one end only (the source I think?).

https://www.parts-express.com/mogami-w2549-neglex-long-run-microphone-signal-cable-1-ft--103-1012

https://www.parts-express.com/neutrik-nf2c-b-2-profi-professional-rca-plug-pair--092-114

msg

Yeah, I was wondering how a cable like this is physically terminated.
I presume in this case, the shielding has to be terminated on both ends, whereas a 2-conductor cable, the return (not ground; dehr me) is the second conductor, and then the braid only terminated on the source side?

I don't know how noise/interference gets into a cable, so this has me wondering
1. How coax sounds when used as an analog IC constructed as above wrt noise rejection, and
2. How digital cables built from coax are constructed/terminated.

Good info up there on the build design/geometry, Ken. Neat to see what goes into selection of the wire, other uses, etc.

mhardy6647 wrote: »

Are you asking coax for unbalanced I/Cs? Center conductor is "hot" (center pin); braid (shield) is "return" (outer connector) is the usual way IMO/IME (ahem, it's what I do).

mikeyb128

delkal wrote: »

I am very proud of the 999 silver interconnects I made, Its a very simple design. Pure solid silver wire in a teflon tube. Cut it to size and solder on a mid priced RCA. I didn't have any true high end interconnects to compare it to but the improvement from my mid priced interconnect was noticed immediately first time I tried them. I also made a matching pair with mil spec silver coated hookup wire with teflon insulation. They also sounded good but I have mostly been using the pure silver ones.

I used this site as a guide. The only problem I had is I couldnt figure out how to secure the teflon tubes securely in the RCA body (they are slippery!). You don't want to pull these cables out by the wires. The pair I made look similar to these.



laventure.net/tourist/cables.htm

A friend of mine builds RCA’s similar to this design, and they sound dam fine. They sound almost as good as name brand cables in the 900 range.

delkal

If you do have a shielded cable one end MUST be terminated. If not the shield can act as an antenna and pick up interference. With shielded speaker cables (not sure about interconnects) you only want to have the shield grounded to the source end. Supposedly bad thing happen if you terminate the shield at both ends. Ever wonder why you have directional speaker wires when the AC current just moves back and forth? This is why.

Unless you live next to a radio tower or are using extremely long runs I think shielded interconnects are over hyped. They add capacitance to the wire.

mhardy6647

msg wrote: »

Yeah, I was wondering how a cable like this is physically terminated.
I presume in this case, the shielding has to be terminated on both ends, whereas a 2-conductor cable, the return (not ground; dehr me) is the second conductor, and then the braid only terminated on the source side?

I don't know how noise/interference gets into a cable, so this has me wondering
1. How coax sounds when used as an analog IC constructed as above wrt noise rejection, and
2. How digital cables built from coax are constructed/terminated.

Good info up there on the build design/geometry, Ken. Neat to see what goes into selection of the wire, other uses, etc.

mhardy6647 wrote: »

Are you asking coax for unbalanced I/Cs? Center conductor is "hot" (center pin); braid (shield) is "return" (outer connector) is the usual way IMO/IME (ahem, it's what I do).

The Rane technical note I referenced (I think) in the first post is well worth reading -- even though it may make one's brain hurt if taken too fast. Mine did.

mhardy6647

FWIW -- I think that we've made our own lives more difficult in terms of keeping (analog) signals clean and quiet by the immense amounts of EMI and broad-band RFI "hash" that we've added to our environments with cell phones, WiFi, Bluetooth, etc., etc., etc.

Yeah, I am old and crotchety -- about some things, at any rate.

FestYboy

One could always install a Faraday cage around the rack... IR remotes wouldn't be affected, but any data streams from an outside source would need wired in or have an external antenna (outside the cage) installed.

mhardy6647

delkal

mhardy6647 wrote: »

msg wrote: »

Yeah, I was wondering how a cable like this is physically terminated.
I presume in this case, the shielding has to be terminated on both ends, whereas a 2-conductor cable, the return (not ground; dehr me) is the second conductor, and then the braid only terminated on the source side?

I don't know how noise/interference gets into a cable, so this has me wondering
1. How coax sounds when used as an analog IC constructed as above wrt noise rejection, and
2. How digital cables built from coax are constructed/terminated.

Good info up there on the build design/geometry, Ken. Neat to see what goes into selection of the wire, other uses, etc.

mhardy6647 wrote: »

Are you asking coax for unbalanced I/Cs? Center conductor is "hot" (center pin); braid (shield) is "return" (outer connector) is the usual way IMO/IME (ahem, it's what I do).

The Rane technical note I referenced (I think) in the first post is well worth reading -- even though it may make one's brain hurt if taken too fast. Mine did.

I did make it (mostly) thru your link and it did make my brain hurt a bit..........But it did answer my previous post. For shielded interconnects you want the ends of each shield to be connected to the chassis of each component (see pin 1). This makes a lot more sense than dumping all of the interference the shield picks up into the RCA neutral.

Eureka! All you have to do is connect a wire to each end of the shield and connect that to a screw on each components chassis. Instant balanced connection! I have no clue why interconnect manufacturers don't do this.





http://www.rane.com/note151.html

mhardy6647

grounding is an art and a science (maybe even a philosophy or religion) all to itself.

I am still at the man-ape* scratching at the dirt with a sharp stick stage of understanding proper grounding.



_____________
* I mean, of course, person-ape.

delkal

mhardy6647 wrote: »

grounding is an art and a science (maybe even a philosophy or religion) all to itself.

I am still at the man-ape* scratching at the dirt with a sharp stick stage of understanding proper grounding.



_____________
* I mean, of course, person-ape.

Go ahead and do it........Throw that bone up in the air and see where you end up.

Don't let the other monkeys keep you down.

mhardy6647

voltz

The Doctor is always on Call and here to serve!

Rock on Crazy Diamond!

ken brydson

https://www.youtube.com/watch?v=XcxKIJTb3Hg

delkal

mhardy6647 wrote: »

There you go..........now you are thinking!

delkal

delkal wrote: »

I did make it (mostly) thru your link and it did make my brain hurt a bit..........But it did answer my previous post. For shielded interconnects you want the ends of each shield to be connected to the chassis of each component (see pin 1). This makes a lot more sense than dumping all of the interference the shield picks up into the RCA neutral.

Eureka! All you have to do is connect a wire to each end of the shield and connect that to a screw on each components chassis. Instant balanced connection! I have no clue why interconnect manufacturers don't do this.





http://www.rane.com/note151.html

Maybe I was inspired too but I did a little more thinking about my previous post. If you ground both ends of a shielded RCA interconnect you will NOT get a balanced connection. The above schematic shows 2 op-amps in the pre (giving reverse phase signals) going to one op amp in the amplifier (that "decodes" / combines them).

Grounding both ends of the shielded RCA interconnect to each components chassis will still work though. But only for the signals picked up by the interconnect. It seems like something trivial to try and it has to be much better than grounding these signals into the audio path,

machone

https://www.venhaus1.com/diysilverinterconnects.html

Here is one without a shield that looks interesting.

mhardy6647

machone wrote: »

https://www.venhaus1.com/diysilverinterconnects.html

Here is one without a shield that looks interesting.

That does look cool, thanks for sharing the link.
I like the topology -- not sure I'd go with silver wire, but that's a personal bias thing, you know?

msg

Doc, in the interest of helping keep you on track with your projects/goals/life's desires, howsabout an update?

mhardy6647

heh, been doing too much garden prep (and pickup-truck-purchase equivocating).
That said, some free time is on the horizon; thanks for the kick in the... well... you know.