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XLR to TRS Stereo wiring. How to... Headphone Amps
Old 1st March 2014
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Digibear's Avatar
XLR to TRS Stereo wiring. How to...

A client wants to hear IN STEREO in his IEM. The sends from the live console are mono XLR (balanced). What's the best way to get from 2 XLR outputs (L and R) into his headphones (unbalanced, stereo TRS)?

I'm thinking that simple Y-cables would work. Here's an example I worked up on the Redco site. Would this work (and work well)?

OK, I can't upload the pdf, but any thoughts in general? Thanks.
Old 1st March 2014
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Richard Crowley's Avatar

The conventional answer would be to use a headphone amplifier.
That provides you with
1) Proper separate inputs for Left and Right channels
2) Capability of handling balanced or unbalanced sources with a variety of connectors
3) Output impedance and power compatible with a variety of headphones.
4) Properly combining Left and Right channels into the TRS plug format.

If you are confident that BOTH
1) Your console sends have enough power to drive the headphones directly
2) Your console sends can be safely "unbalanced" by grounding the "cold" side
THEN yes, you could wire a simple Y-cable to feed the headphones directly from the Left and Right console XLR outputs.
Old 1st March 2014
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Digibear's Avatar
Thank you for the reply. I should clarify: we need 3 separate headphone mixes with identical xlr to trs conversion.

All the headphone amps I can find have only 1 pair of xlr inputs. Some have aux inputs, but those are already on trs, so we still have the conversion issue.

How does that change your advice?
Old 1st March 2014
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Richard Crowley's Avatar

What does "3 separate headphone mixes" mean?
Does that mean the same mix to three different headphones?
Or does that mean different mixes for three different users?

What does "identical XLR to TRS conversion" mean?
Does that mean there are actually six different XLR outputs, L & R for each of three users/mixers?
Or does that mean something else (that I can't figure out)?

There ARE monitor systems that have this all worked out (several inputs to choose from, and customizable mixes for each user/headphone).
Some even have little control panels for the users to create their own mixes for themselves in the studio.

If you are doing all these monitor mixes in the console, and you have six different XLR outputs (Left and Right for headphone users 1, 2 and 3), then three simple "Y-cables" like this would do it (assuming those XLR outputs will drive the headphones adequately)

Old 1st March 2014
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Digibear's Avatar
Hi again, Richard. Yes, it's 6 XLR into 3 separate TRS headphones. I am aware of the personal monitor options, but they are expensive overkill, I think. Assuming that the board can output enough level.
Old 2nd April 2014
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I don't know about you guys, but I've never seen a mixer that its line outputs could drive a set of headphones. Pick up a Behringer PowerPlay Pro-8 or an Alesis MultiMix 6 cue, buy or make XLR to TRS cables or a snake, and buy or make dual 1/4" TS male to 1/8" or 1/4" TRS female y-cables (depending on your headphones).
Old 2nd April 2014
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Richard Crowley's Avatar

I have never had a problem trying to drive headphones with a line-level output.
There may be some very low-end consumer gear that is too wimpy to drive headphones.
Or there may be headphones/earbuds with very low impedance, but I have never encountered either of those.
Old 2nd April 2014
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I should rephrase my statement. I've never been able to get a usable signal without using an headphone amp. Usable being something I would be comfortable leaving the client with saying it works. Granted, everyone's setup is different. But using an headphone amp is the right way to do it, there wouldn't be as big of a market for them if they weren't needed.
Old 2nd April 2014
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Richard Crowley's Avatar

Remember that connecting headphones/earbuds/whatever DIRECTLY into a typical "Line Output" will result in poor results because you are trying to use a balanced monaural source to drive an unbalanced stereo load.
That is why you need a special wiring arrangement such as shown in my post #4.
Certainly plugging headphones directly into a line-output connector will probably result in the kind of results kevlar557 is suggesting.
Old 27th November 2014
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Hello. I have a similar question. Using the xlr outputs on a Beringer X32 to run an IEM monitor mix through a Roland TD20, which the input is stereo. Left and right are not balanced (I get more volume from the right side). I'm using an xlr to TRS. In being told, from the guy who owns the board, that going from high impedance to low impedance is why I'm getting the in-balance.

The reason why I'm questioning what he's saying is because the x32 has had several problems. He rejected two because of issues and is sending this board back for service after 6 months. I plugged into to another out put and it was balanced for me. The guy who owns the board days he checked all the outputs and the impedance is the same. The problem is that he won't migrate my mix, controlled by the iPhone app, to another output.

It probably doesn't matter because I'll have to figure it out on my own, is he correct in his technical reasoning and am I going to have to use some other mixer or transformer to get what I need?

Old 27th November 2014
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Richard Crowley's Avatar

We have no clue what you mean exactly by " I'm using an xlr to TRS." That could mean literally a dozen different things, most of them improper.
There are so many unknowns here, it is almost impossible to answer your question. But it seems pretty clear that if your connection works with ONE of the mixer outputs, and not with the OTHER (presumably identical) outputs, then there is a problem with the mixer.

It is extraordinarily unlikely that you have a "high impedance to low impedance" problem. And even if you DID, it would not cause an "in-balance".
If the connection WORKS with ONE of the mixer outputs, then you don't need another mixer or a transformer.
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