How to correctly connect balanced XLR to unbalanced stereo AUX on headphones amp

  • Thread starter Thread starter husle
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husle

husle

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Hello everyone,

I've searched a lot, but it'is difficult to search since it gives me only basic answers or unrelated cable options...

Situation:
- I have mixer (SQ 5) with AUX outputs (XLR balanced).
- I have a headphone amplifier (mackiee XM 400) with AUX inputs (1/4 jack stereo unbalanced)

I want to connect mix balanced output to headphones amp AUX (stereo unbalanced) without hum(noise/buzzing). I can do that with XLR to 1/4 stereo jack and it works, but it gives a lot of noise (PC mouse moving can be heard).


Is there some kind of D.I. box that do this? Am I missing something?


Thanks
 
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On cheap thing you can try is to take advantage of the mixer balanced outputs. They’re probably differential outputs, so the mouse noise, indicative of the computer ground being ‘contaminated’rather than a simple ground loop, might be sortable. The unbalanced 3 circuit jack could be wired like this. wire the xlr plug without using pin 1. Take pin 2 as your signal, so that goes to jack tip. Take xlr pin 3 to the jack sleeve. This also goes to the other xlr pin 3, while in that one, pin 2 goes to the jack ring. This leaves the ground broken. This can often get you out of trouble.
 
Thank you, I'll deffinetely try this.

But it makes me think: Has this been already solved with some easy solution (special cable, some sort of box)?
 
Yes. You make the special cable. Check the specs on your mixer to confirm the pinout. Most are 1= Ground, 2=+ and 3=-. I also have a StudioMaster mixer where the XLRs are jst the opposite.
 
Behringer makes such a box. I used it all the time between my PA sytem and separate mixer for cranking stuff up. Worked great! I gotta find it to show you exactly, but it is something like a 'noise eliminator'.

I'll be back.
 
Nope, it was more for hum elimination now that I think about it.

Behri Hum Destroyer


I had similar noise from computer in an early setup between two computers input through a monitor controller. Balanced cables solve it.

But if you don't have the ability, I bet the guys above are giving the best solutions. :)
 
The ideal would be to use a transformer to interface between a balanced output and an unbalanced input. But there are ways to do it with a simple cable, if you do it right.

Definitely pin 2 to tip (or ring if it's the right channel of a stereo TRS). What goes to sleeve may depend on the type of balanced output.

For standard active balanced outputs, connect pin 1 via the shield to sleeve, and connect pin 2 via the conductor to the tip (or ring...). Leave pin 3 unconnected. You can use an unbalanced cable for this.

For transformer balanced output, connect pin 1 to the cable shield, pin 2 via the + (typically red) conductor to tip (or ring...), pin 3 via the - conductor (typically black) to the sleeve. You need a balanced cable for this. You're basically just skipping the shield to ground connection at the input device end.

For cross-coupled active outputs use the transformer method but also connect pins 1 and 3 at the output device end, and set the ground switch (if provided) to grounded.

This might be why there aren't a lot of "off the shelf" solutions.

My source for this: https://www.ranecommercial.com/kb_article.php?article=2107
 
husle said:
Thank you, I'll deffinetely try this.

But it makes me think: Has this been already solved with some easy solution (special cable, some sort of box)?
Click to expand...

I install AV gear professionally and with the adoption of Teams and Zoom via a PC this is a pretty common issue with a number of room integrations. My son even had an issue with his game streaming rig and needed to isolate his audio.

RDL makes a number of products in both transformer and active buffering amplification to isolate and convert balanced and unbalanced signals. Good quality products but will come at a cost. The RDL TX-1A is a transformer balanced to unbalanced converter that is $36.49 each on B&H. There are also a lot of other transformer products geared to isolating ground issues with both captive screw and RCA to 1/8th inch. Just search for a balanced to unbalanced converter online.

Edit. Sometimes it helps to RTFM. In looking at the manual it is easy to confuse unbalanced for mono input but the Aux input is unbalanced stereo. The balanced Aux outputs of your mixer is single channel. Here it makes sense to wire T & R to the + of the balanced output and sleeve to ground if you want to make your own cable. I'd try this configuration first without a transformer.

Screen Shot 07-21-22 at 08.21 AM.webp
 
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Hello,
so I've ordered microphone cable and Neutric connectors and after long work i managed to make some cables. And: it works! No more mouse sounds in headphones! Thanks everyone.
 
When you make a cable for the first time and it fixes your problem, there’s a real satisfaction, isn’t there!
 
Well, it wasn't my first cable :D I have it opposite: cables made by me are horrible and I feel a lot of frustration when I am making them :D So that's why I was asking for ready solution at the beginning...
 
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