See https://forum.rme-audio.de/viewto … 23#p219923

1. The same ground, pin 1 of the D-sub, is connected to AES in and out.
This is even linked to ADI-2 chassis ground internally.

The XLR plugs‘ casings should be connected to ground either, for blocking HF.

2. On short interconnections, less than a few meters, the impedance matching isn‘t critical.
Typical microphone cable is close to 110 Ohm and can be used for AES.
Video cable had 75 Ohm and fits to Coax digital anyway.

WC isn‘t present on the 9-pin D-sub.
ADI-2 FS-clock perfectly recovers WC out of the selected source.

75 Ohm cable is video standard.

You find those cables everywhere: coax antenna and satellite cables for FM radio and tv sets, inside Scart cables, domestic video cables with (typically yellow colored) RCA plugs etc.

As mentioned, for short interlinks it’s not mission critical at all, bare wires would do (not that I recommend this).
But typical cheap accessory RCA cables for audio do fit too.
The plugs in between don’t represent a problem either.

The mentioned WC cabling is another story, it is about end-termination, which indeed is very important to avoid reflections AND reach the correct electrical signal level.
But, in your case end-termination is already built into each device, you don’t need and by no means should care about it.

So don’t worry too much, use what you have or find, it will do.

Final tip:
SPDIF digital Coax for distances beyond specs can be achieved with cables for digital satellite dish connection, I’ve done 25 m with no problems.
These 75 Ohm cables have ultra-low loss, as the are made for 2 GHz, almost 100 times more than the ca. 25 MHz you find in SPDIF Coax.
These cables are readily available in tv stores and very cheap.

Ive been building a parts list for an ideal transmission, mostly for personal education, as these components are expensive. Im gonna go for your @KaiS advice to use what I have. with some minor upgrades.

Is short what Ive come up with: DB-9 contact with 5-pin and two 75ohm coax inserts (*4 for ADIpro and UCXII). Special solder for thick gold plating. Micro coax cable. Just for coax inserts its €40, so this is just a rabbit hole of expenses. Like I said this box wont see more than a few meter spdif anyway. It would be to maintain impedance, but the most benefit would be a professional look.

Good idea though. I can test the system with cheap TV 75ohm cabling. I think I have some(alot) stashed. Just to run bittests and get some idea of the quality.

Most intelligent solution, I think would be to drive a whole length of cable from ADI2pro DB9 to output and use a rubber gasket and stoppers through BO-chassi, At least this does not subtract from original BO-968 solution. Then again I have the standard db-9 contacts and kinda looked forward to solder and build that stuff.

-A lot of overkill in your list

You think so? These contacts are for labs and hospitals. Overkill is kind of the intention, but its also functional even too much.

-Coax inserts??

These are something like usual DB contacts, and there is a whole range of them. They have some big through holes plus pins. These holes can be use to transmit high power, coax and even pneumatics. Its just standard parts. I found the perfect parts for my use; a DB9 sized 2 holes and 5 pins. Which eqals 2 coax + AES I/O in one contact, with 75ohm impedance all the way.

Naturally these cost more than standard DB, maybe €30+/contact, this is for asembled contact, esp coax is expensive with 2/3 of that. The coax look good quality with solder pot and crimp.

About solder I read a some papers about soldering gold plate, the problem arises with tin mix solders and gold layer above 1.5 micron. Search for "gold scavenging" + "solder". The contacts have au layer right at threshold. This doesnt worry me so much as I could use indium and led pellets for a lots of cool stuff, not that expensive either. You can solder glass to metal with Indium, and it even sticks in cryogenic temp.
Thought was to make InPb 50/50 and use that. This is some milspec stuff and certainely because of mechanical properties of the joint. As gold - tin intermetallics can progressively degrade the joint, above 1.5 micron.

The cable is recomended for the coax contacts and typically come in 100m rolls at €3000. Its about size of jacket and insulation not magic. If I could just find a few meters.

-Digital bits either come through or not, there are no “better sounding bits”, whatever you can read in some esoteric audiophile forums.
Imagine, the bits are not even transferred in the order they are converted to analog, but have to be “sorted” in the converter when received, and internally in the converters there are a number of digital processing intersteps!-

I know that drill! Totally agree. I dont expect any special or magic sound or recovered bits. No rabbits from the hat

Now that you described it, I remember having some of those DB/coax plugs lying around.
But - where do you use them in your configuration?
Thought you’re going from the DB-9 at ADI-2’s back directly to the patchfield with XLR and RCA outlets.

Maybe I misunderstood what exactly you’re about to build.

BTW: coax isn’t ideal for AES, as coax is not balanced, and you miss the screen contact.

About failed soldering joint - whenever that happened here, it was:
• Due to mechanical stress, when the solder itself broke on circuit boards.
• Simply the copper wire broke.

I’ve never seen solder joints to gold plated plug contacts fail or come loose.
This all with standard 60/40/0.5 SN/PB/CU or lead-free SN 96.5 AG 3.5 CU 0.5 electronics solder.

Typically the wire sticks inside a little hole in the back of the contact, filled up with solder. This is a very strong connection.
When correctly done, additionally the flux from inside the solder wire covers the metal for very good environmental protection.

What fails over decades are the litz wires inside the cables, long before the solder joints have a chance to do so.

Interesting remark about soldering with Indium, I’ll have a look.
For electronics normal solder will do, but I occasionally have other tasks.

Why do you insert another connector in between ADI-2 and your patchfield?

I’m not quite getting what you decribe how you do the soldering, but what I understand raises the hair in my neck.

Flux paste - igitt!!!
Soldering pot???

Here’s how to do it correctly:

• Use thin solder wire for electronics, with flux core.

• Heat up a soldering iron, with a fine but no too fine tip, enough that the soldering process itself is done within a few seconds.

• Get a “third hand”-tool (see below) to hold connector and cable exactly in position.
The free end of the not pre-tinned wire fully sticks in the empty hole of the connector pin.

• Soldering tip and solder wire touch the joint almost at the same time (opposed to the picture below, I didn‘t find a better one), melting just enough solder to fill the hole.
Pull away the solder wire, and continue heating for ca. 2-3 seconds, to make sure wire and pin are heated enough to make a good tinning and joint.
This is a one-step process, no pre-tinning necessary.

• After cooling down a nice tin-surface should exist, with the tin visibly linked to wire and pin.
The excess flux creates an almost invisible skin on the metal, protecting it from environmental influence.

• BTW: to remove the lacquer isolation on e.g. headphones cables, heat, not burn it away with a gas lighter.
Alternatively the soldering iron at 380 °C melts it away while (only in this case) tinning the ends.

Not the best, but the classical “third hand tool”, lots of usable variants exist.
I even have a board made with the most common connector’s conterparts mounted, to stick the connector to be soldered into.
On this one I usually remove the loupe and use strong reading glasses or a working microscope instead:

I didnt mean I have nothing to learn, but basic soldering maybe isnt for RME forum? ,but why not ppl talk about some other crazy stuff here so.

Im gonna put my money there my mouth is, so you trash can my project after I built it Thnx again for advice and sparring

"put 2-3mm solder in cup, heat, reheat, put in wire." In this description I have pre tinned the wire. Beacuse its easier to handle than loose copper threads. Thats about right

What you are saying is all the re/heating evaporates the (protective)flux and the quicker, and with lesser steps I do this is the better?

The protective flux? I actually thought the opposite, that the flux was destructive to the joint and washed the joints with isopropyl. You are talking about the rosin core here. And the advice is to do nothing after solder has cooled. Seems I do need some basic soldering lesson. I did study those RolO charts, but this information has evaded me. Alot of metals form their own protective oxide layer, like titanium which is actually very reactive to oxygen.

I have the third hand, and tons of vices and clamps. With mostly one offs that I do positioning can be, well. This part is directly tied to the result. I worked a lot of production in my youth, so if I would do like 10 chassi XLR a day or whatever really. I would have made fixed jigs for speed and convenience. I have learned to put some effort here. Nice to hear you got off on a good start, I can honestly say I did soldering in the past that didnt last 24 hours. I did some simple LED circiuts for plastic models. That soldering was pesky stuff. Now I have a relly nice Weller station, digital temperature is good to have.

Another question: The BO adapter that came with the UCXII(I belive). It has a ferrite bead. Do you know of recomended target frequenzy and resistance for this. And is placement of the bead important, like must it be placed closed to output from ADI2pro. I ask because I have found a series of ferrite meant to be screwed to the chassi, but this solution will put the ring roughly on the middle of cable. If this is no good I will order standard clamp on bead.

I think I see. I have a box of rosin flux. Rosin as in natural product colofonium. I knew this was in standard solder wire and meant to give flow. ,but this stuff has protective/anti-corrosive properties you say. I have heared of tin-pest before, but only for antique tin smith stuff. It makes sense, tin is tin.

The other stuff I have is synthetic paste flux, but these came with directions to clean even though they where labeled as noclean, I remember that confused me a bit. They were meant for SMD´s. There where others to even more corrosive.

You can always learn alot by yourself, but whitout schools, courses and mentoring. You are bound to miss things i guess.

Ill put those rf-beads on ice. Im gonna have E14 tubeform led bulbs close to audio electronics. If that becomes a problem I wil take it from there. No use seeing ghosts in broad daylight.

Now your making me look foolish Its not that bad. This is just another paste recomended for some solder I bought. Its not the metal-packed kind. Its also at the lower end of those corrosive, acidic or whatever they put in there. Basicly synthetic rosin. Its meant for SMD and other board work. Its creators maybe didnt have audio adapters in mind. Just like that

The other rosin I have, the colofonium kind. It works good, but its also really gluey and nasty stuff. The synthetic is much swifter and cleaner to use.
The pentaconn I mentioned. Solder area are rings inside the contact. I used a small amount of extra flux and soldered from underside to get some gravitational help, instead of letting solder flow over the ring from top. Wires were alternated from left and right. I feel I couldnt have done this operation whitout the extra flux. Its just not enough in the rosin core of wire, and some of my solders dont have flux-core at all. Low-temp solder also really helped. The process was also very quick, no messing around.

About the coaxial adapters, I just need to adjust ambition from time to time. I thank you for that!

The wiring should:

Go like a daisy chain:
ADI-2——OUT2——OUT1.

NOT like a Y-split:
ADI-2——OUT2
        |___OUT1.

The red line cable needs needs to be as short as ever possibly, few cm only.

If only one out is used, it should preferably be OUT1, the one at the end of the Daisy-chain, as this is 100% correct termination.

For AES, although impedance termination is incorrect , feeding two or more destinations from one source does work if relatively short cables are used.

For SPDIF usually it doesn’t work, the electrical signal level mostly gets too low when feeding two destinations from one source.

Idiot-proof does not exist, the idiots are too inventive
But - no toasting ahead, the outputs are short-circuit-proof.

If you really need distribution of digital signals, an active digital matrix switch-box would be a good idea.