Interconnects Using DH Labs Pro Studio - How To Use Twisted Pair for Unbalanced?

[bhjazz]

So some parts are rolling in. I'm excited to finally get the solder iron up and running again. I'll jump on the balanced connections in a week or so, but I bought some extra wire and RCA connectors to build a pair of interconnects. I'll be using:

DH Labs Pro Studio for the wire. Twisted pair inside with a shield outside (pretty standard)

DH Labs RCA-3 connector.

Now, the RCA-3 connector is a little different than what I have used in the past. It looks like this:

It looks very much like these would be great for a digital cable (and they are 75 ohm as well). For audio, though, I have a twisted pair inside the cable with the shield outside. I'm fairly sure their idea would be that (in the pic above) the part second from the left would directly contact the shield. That makes sense. But should I just use a single wire of the twisted pair inside, or strip both 22ga wires, tie them together, and solder them as one to the center pin? I'm thinkin that would be the best use of the twisted pair, and I'm fairly sure two 22ga wires will fit down the tube.

Many thanks!

[cetoole]

First, they can't be 75ohm, exact same spacing from the pin to the ground as any other RCA. As for how to use them, I would go one wire of the pair to the center pin, the other to the outer ring, and the shield connected only on one side.

[n_maher]

Colin's advice sounds good to me.

[Pars]

I'd 3rd Colin's advice, and elaborate slightly. Connect the shield to the outer ring on one end only. The end with the shield connected is normally used on the source end of the cable. Looks like a nicely constructed plug.

[bhjazz]

I double checked their site. The connector says, "optimized" for 75ohm. Hm.

Might be a problem connecting the second wire to the outer ring. These fit pretty tightly together and there appears to be no facility for doing that...no gap or place to do it. I need to sit down the the DMM and check one other thing out: I think when these are assembled, part 2 contacts part 4. I'll post later today.

Thanks, all!

[bhjazz]

Confirmed. Part 2 does, in fact, contact part 4. I took a quick look at Rane (as was suggested in my other post) and they seem to think that using the shield from end to end is their absolute best right way to do it, or words to that effect. I'll have to figure out if I can get anything connected to that sleeve inside. Maybe some time with a dremel is in order...

[Pars]

I double checked their site. The connector says, "optimized" for 75ohm. <snip>

Marketing likes saying such things

[bhjazz]

No kidding. What does that even mean?

So, just for fun, I've dispatched an email to DH Labs asking them how these two products should be paired. No, seriously.

[nikongod]

Confirmed. Part 2 does, in fact, contact part 4.

I think you are supposed to actually crimp the shield between those 2 parts when using a coax cable to achieve 100% shielding from end to end.

I took a quick look at Rane (as was suggested in my other post) and they seem to think that using the shield from end to end is their absolute best right way to do it, or words to that effect.

They sort of do and sort of dont say that

The "absolute best right way to do it" only applies to balanced interconnects because that is simply the best and right way to send signal any more than 3 meters. Below 3M you are probably not going to have a problem with noise pickup in even a consumer "standard" 2v nominal signal no mater how you connect the shield - even if you dont have one at all! When you *need* an interconnect longer than 3M things start to get weird for any number of reasons, and that is where having the rane article is key. To add, the rane article la-la-loves transformers to isolate various pieces of single ended gear which makes sense because transformers are awesome and so is whoever wrote that article. Too much awesome simply does not exist.

Anyways, if you look at the "not so right ways to do things, but how its going to be because the world is an imperfect place and you have to hook that piece of crap Rane didnt build to some shit someone else from Rane built" chart at the bottom of the page they say hook the shield up at both ends in certain cases, but not others.

The general theme is that if there is only 1 conductor you make do with what you have and use the shield as signal ground. If there are 2 dedicated signal conductors the shield is connected at only 1 end if floating the shield like that solves a problem. If the 2 ends are of similar termination (balanced to balanced) the shield is connected at the source end when problems arise. Im not sure why they dont touch on what to do with twisted pair cables for RCA-RCA use but other people do hook the shield up at the source end only.

[bhjazz]

The general theme is that...

Thanks for that. Makes sense. And (dun tada dun!) it's very similar to Darren's reply to me this morning. Nice job! Here is his reply:

Brian

Termination instructions for the Pro Studio are below. Do not connect both wires to the center pin. The RCA-3 is a very good connector, but it was designed for the D-75 digital cable. It might be more difficult to use this plug with the Pro Studio. We usually use our Ultimate RCA plugs with the Pro Studio.

If you need more specific information, please call.

Darren

DH Labs

Termination instructions for Pro Studio interconnect cable.

RCA Plugs

Source end:

1. The red wire connects to the center pin of the RCA plug.

2. The white wire and the shield connect to ground on the RCA plug.

Load end:

1. The red wire connects to the center pin of the RCA plug.

2. The white wire connects to ground on the RCA plug.

3. Cut the braided shield (do not connect it) and insulate it if necessary.

So you can see I'm a dork of an online shopper. D'oh! In my defense, I bought these at different times over the last month. Like that matters. Anyway, now I'm at a good point to decide if I want to just build the cables this way, or grab a few feet of D-75 wire and build some digital cables. I will continue to complicate my life further with each passing day.