Connecting DB25 to Open Neutrik?

[Luci_Musix2003]

If I had a 8 input plate with 8 XLR/TRS combo neutriks (which all come open and requiring soldering) how would I be able to connect them to a DB25 Cable?
I know you can get a DB25 to XLR (or TRS) which splits off into 8 channels, but for each of the tendrils, the wire looks too narrow to cut open and attempt soldering surgery on, and at a price between 50-80 I don't want to waste buying one in order to find out.
I could wire the neutrik onto an XLR cable and then connect the XLR and the adjoining end of the DB25 cable to each other, but that runs the risk of the cable changing affecting the sound and its just more places for stuff to go wrong. Ideally if there is a way to connect the Neutriks directly to an 8 channel split DB25 cable that would be perfect, but I don't know how realistic that is.

Let me know if you guys know any cool solutions

 

[ecc83]

Not entirely sure what you are about here Luci? You can't wire an 8 way XLR3 COMBI plate to DB25 because there are not enough pins in the plug. Maybe you mean to have XLR on one DB and the TRS on another?

I have not stripped a DB25 cable but I doubt it would be beyond a decent hobbyist to break out the wires and solder them. You would need to be VERY meticulous in your wiring and testing.

Another solution is to buy a drum of 3mm OD foil screened two core cable and make the whole thing from scratch. What I would have done. That way you get a cable of just the length you want.

Oh! And by the way...NOTHING you do to the way that system is wired is going to affect the sound quality. Unless the cable is extremely long and the sources crap.

Dave.

 

[bouldersoundguy]

Well, if the TRS are all parallel with the XLR, there are enough pins.

 

[ecc83]

Well, if the TRS are all parallel with the XLR, there are enough pins.

That would potentially put phantom power on the TRS, a big no-no. In any case, surely XLR pins and TRS pins go to different destinations in equipment?

Dave.

 

[rob aylestone]

The question is what is the equipment that has the 25 pin connectors? Audio DB25 is 8 channels, balanced audio NOT 8 channels of line level and 8 of mic level? What are you connecting?

 

[Luci_Musix2003]

Not entirely sure what you are about here Luci? You can't wire an 8 way XLR3 COMBI plate to DB25 because there are not enough pins in the plug. Maybe you mean to have XLR on one DB and the TRS on another?

I have not stripped a DB25 cable but I doubt it would be beyond a decent hobbyist to break out the wires and solder them. You would need to be VERY meticulous in your wiring and testing.

Another solution is to buy a drum of 3mm OD foil screened two core cable and make the whole thing from scratch. What I would have done. That way you get a cable of just the length you want.

Oh! And by the way...NOTHING you do to the way that system is wired is going to affect the sound quality. Unless the cable is extremely long and the sources crap.

Dave.

My powers of descriptions are awful, so I'm going to attach some pics to help me describe what I'm getting at.






Basically I want to have my 8 inputs connected to a DB25 that runs into my patchbay. Which would be easy enough if they were either XLR or TRS, since I could use a DB25 to XLR cable, or a DB25 to TRS in order to do that. But to do so would require me to choose whether my inputs are XLR or Quarter inch connections. But I want to find a way to have my inputs be through these Combi neutrals that are wired for both XLR and Quarter inch inputs, and then find out if it is possible to connect a DB25 cable in some way to one of these connections. The Combi Neutrik as far as I can tell I still a 3 pin connection. Since the DB25 can carry 8 XLR connections, as is displayed by the image above, surely it should be possible to connect those 3 pin signals on each of the 8 channels to the Combi Neutrik if I was to cut the cable open and isolate the 3 wires... right? It sounds logical to me, but I have no experience with any of this so I don't know how far fetched it is.

 

[Luci_Musix2003]

The question is what is the equipment that has the 25 pin connectors? Audio DB25 is 8 channels, balanced audio NOT 8 channels of line level and 8 of mic level? What are you connecting?

check my comment above, I think it might help answer, maybe?
I'm trying to connect from my input plate (8ins) to my patchbay which is all DB25 connections

 

[ecc83]

check my comment above, I think it might help answer, maybe?
I'm trying to connect from my input plate (8ins) to my patchbay which is all DB25 connections

Then you will need at least 2 DB25s per 8 combis. The Neutrik NCJ9FI-H has no fewer than ten pins. That is a TRS switched jack so you could go simpler but you still need 3 for XLR and 2 for balanced TRS and at least one ground, better two.
AFAICT.
Actually the setup would be more versatile with separate XLRs and jacks but I guess space is an issue?
Dave.

 

[Luci_Musix2003]

Then you will need at least 2 DB25s per 8 combis. The Neutrik NCJ9FI-H has no fewer than ten pins. That is a TRS switched jack so you could go simpler but you still need 3 for XLR and 2 for balanced TRS and at least one ground, better two.
AFAICT.
Actually the setup would be more versatile with separate XLRs and jacks but I guess space is an issue?
Dave.

I'm not sure I follow you. The combo has 3 pins no? I'm not sure I follow you on why it would require 2 DB25s. How many DB25s would I need if I was connecting to a standard xlr neutrik, like the na3fdm?

 

[rob aylestone]

Combos by convention have mic level on the XLR pins and line level on the trs pins. If we also assume your patch bay is line level only, then you wire xlr 1 to sleeve, 2 to tip and 3 to ring, which works for 38 connections on the db25. If you wish to mix line and mic levels, you need 2 db25 connectors, with 6 connections to the combo. This is what we are trying to get out of you! You could link the jack and xlr connections, and then just remember which of the jackfield sockets is in use at each level, but thats a bit prone to mistakes, and feeding phantom through a patch is an accident waiting to happen. Most gear is capacitor decoupled so they block the DC, but you can bet some poor keyboard or cheaper sound device will not like it. Hence why many people never put mic level through a patch.

 

[ecc83]

"Most gear is capacitor decoupled so they block the DC,"
Rob ^ is quite correct but the protection is rarely up to stopping phantom power for several reasons,...
One is that the capacitors involved will rarely be rated above 22V since few devices have internal rails above +&- 18V.
Next the caps will almost certainly be 'the wrong way around' i.e. presenting the negative side to the +ve ppower. That will almost certainly allow enough leakage current through to destroy the output device. And lastly, even if the above did not obtain then there would be a charging current through the cap and potential destruction.

There is also the added factor that many AIs now sport a DC path to their outputs so that they can output CV. I HOPE such things can cope with 48V but I have seen no evidence that they can so far.

N.B. this is NOT scaremongering about phantom power! The energy involved is tiny and KEPT TO THE RIGHT DEVICES and inputs there is no danger to connected devices nor the mixer/pre/AI supplying the power.

Bottom line IMHO. IF you want an XLR mic patch, make or buy one. IF you want a TRS patch do the same but never the twain!

Dave.