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Old November 28th, 2003, 08:00 AM   #1
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Balanced input question

Anyone know if there would be any problem connecting an unbalanced XLR cable to a mic input that's designed for balanced cables?
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Old November 28th, 2003, 02:42 PM   #2
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Marco,
I think you've got some terms confused here. The XLR is by make a balanced cable. So your question doesn't really make that much sense.

but:

I made a quick search on the web, and found the term "unbalanced XLR" a couple of places, but this doesn't really make sense since XLR in name and nature is a balanced cable. May be that they use the name XLR for some similar design. Does anyone have some clarifying input on the subject?
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Old November 28th, 2003, 02:46 PM   #3
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Eivind, XLR is not necessarily balanced - it usually is but doesn't have to be and also non XLR adapters are not necessarily balanced. It is simply a connector that is used on the cables. You can have balanced TRS plugs.

Go here

http://dplay.com/dv/balance/balance.html#conn for information.


Marco, if you go to that site you can see how to connect up your balanced and unbalanced connectors.

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Old November 28th, 2003, 03:54 PM   #4
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Yeah, maybe I should have included a few more details. Coresounds has an adapter that takes an unbalanced stereo mini-plug, and splits it into two XLR cables for plugging into the balanced mic inputs of one of their A/D converters. I wasn't sure if that would actually work.

Aaron, thanks for the link. Lot of information to digest. I'll see if I can absorb it.
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Old December 1st, 2003, 07:01 PM   #5
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Unbalanced-to-balanced can work... the disadvantage is that you lose the benefit of balanced lines, which is the ability to make long cable runs without fear of hum & noise pickup. Therefore, it is best to keep as much of your run length as possible in the balanced mode. Using a transformer (or a direct inject box, which usually contains transformers) is the surest way to stay out of trouble.

XLR can be deceptive: the Sennheiser EW100 ENG receiver comes with a camera connection cable which is unbalanced but has an XLR plug on the camera end. Since it is less than two feet long, it is works fine.
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Old December 2nd, 2003, 07:39 AM   #6
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<<<-- Originally posted by Mike Butler : Unbalanced-to-balanced can work... the disadvantage is that you lose the benefit of balanced lines, which is the ability to make long cable runs without fear of hum & noise pickup. Therefore, it is best to keep as much of your run length as possible in the balanced mode. Using a transformer (or a direct inject box, which usually contains transformers) is the surest way to stay out of trouble. -->>>

XLR connectors are just that. They can be wired balanced or unbalanced.

You probably mean balanced to unbalanced can work, and it does. The key is to have a low impedance input, a good voltage output and keep cables to less than 33 ft. If anything from that formula changes you may have noise or high frequency drop.

Cables should be good quality, with proper shielding.

Staying balanced as much as you can, using something like a Beachtek or similar, is certainly more healthy. Amplifying the signal is also very good.


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Old December 2nd, 2003, 05:11 PM   #7
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True, Carlos. Good quality cables mean a lot. I have had good success with Pro-Co. In another thread I recently described a new use I found for cheap XLR cables--just cut the plugs off and use them as ropes to tie down a weather cover on my tractor! :-)

If running unbalanced, I don't even like to go 33 ft. even if I know the circuit to be low impedance. 25 is the max i'll go on RCA cables before getting nervous.

One problem is that I have so much DJ and Karaoke equipment, where most of the mics are 1/4" mono phone plug and most of the rest of the inputs and outputs are RCA. Well, my Numark mixer has a Neutrik for the main mic so you can go XLR or 1/4" but how much will you bet that the preamp is wired unbablanced? :-)

Interfacing with this kind of stuff doesn't make me feel all warm and fuzzy. Meanwhile, I have used 150 ft. snakes with no hum or noise at all because thay are all balanced lines from beginning to end.
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