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Long cable run


d.breeze

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Just a quicky, what do people reckon is the best way to get a stereo audio signal going one hell of a long way? Talking 500-700m cable run. I'm hoping there's a better solution than just a mega long run of XLR...

 

Any ideas?

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There are various passive adapters available to send stereo unbalanced audio down Cat5 (which is cheap), and with a balanced line it's even easier, just use one pair for left, one for right and ground the other two at one end. Use STP cable rather than UTP and I don't think you'll get any appreciable noise issues or signal loss over that distance. Only thing to be careful of is accidentally linking the grounds of different electrical environments so 1:1 isolation transformers may be a good idea.

 

I imagine you're also looking at analogue or digital wireless options, not got much experience with those over such distances I'm afraid!

 

Good luck

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1425668918[/url]' post='518466']
1425668464[/url]' post='518465']

I thought CAT5 was only good for 100m...

 

for 1's & 0's there will be dropouts for digital.

 

analogue its just copper

 

Yeh fair enough, just worried about signal strength loss over such a long run of analogue.

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I thought CAT5 was only good for 100m...

http://www.kenable.co.uk/product_info.php?products_id=6506&gclid=CJvC94GxlMQCFenJtAod2loA_A

This one quotes 305m maximum length but I suspect that might be because that's the maximum length you can get in one piece of cable. The DC resistance of copper over that distance is not going to cause significant voltage drop (and hence signal strength reduction) in a typical low-impedance audio line of that length. Think of the length of analogue phone cables from exchange to your house, to put things in perspective!

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1425670478[/url]' post='518469']

Think of the length of analogue phone cables from exchange to your house, to put things in perspective!

 

I figured there were clever boosters and things involved with that!

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Line level balanced analogue will go miles over twisted pairs but the thicker the copper the better. A kilometer of mic cable would be OK, UTP should be fine as well - or even BT type drop cable. Over a couple of km you'll notice a drop in level and HF content but it's recoverable.
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1425670478[/url]' post='518469']

Think of the length of analogue phone cables from exchange to your house, to put things in perspective!

 

I figured there were clever boosters and things involved with that!

Surprisingly not apart from very extreme cases. There's typically miles of cable from exchange to house, and that's just twisted pairs without shielding.

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IIRC phone lines can be 35Km without amplification. In your situation put plenty of signal into either balanced mic cable, or separate pairs down a cat5 cable or even use starquad if you are short of signal level.

 

At least part of the skill is putting enough signal level into the cable that noise is minimal and any upper audio frequency attenuation is recoverable. Having the least number of potential failures is good so one long length would be better than lots of connected 20m lengths of cable.

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Fair enough. Looks like 500m of XLR then!

 

I hope you mean 2 runs of 500m. You need a balanced signal and a balanced cable for each channel. A single run of CAT5 would work as well and be easier to run and pick up at load out. You could use a commercial connector box or an adapter like the Studio Hub. Studio Hub has a variety of adapters to CAT5 that they use in studio wiring.

 

Mac

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We've successfully done 500m on several occasions.

 

Aword of advice though keep your number of joints as low as possible both for reliability and also if you're doing outdoors less joints to suffer from water ingress.

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