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Audio over cat 5??

#1 User is offline   brownstuff 

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Posted 01 February 2006 - 12:56 PM

does any one know if you get a bad sound from running XLR signal over cat 5 ?
as I have some 100m cable runs to do and its like 1000 times cheeper that mic cable.
jason

#2 User is offline   Mr.Si 

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Posted 01 February 2006 - 01:01 PM

We have a 30mtr multicore at church which (before my time) was made from network cable, however, I think it is PTP (Partially-Screened Twisted Pair) as some of the channels don't work.

When we try using phantom, 2 or 3 channels crackle, so that's no good. But other churches with similar multi's (made by the same guy) seem to be ok.

I wouldn't choose it by any means, but it sounds fine over the shorter distance at least.

I know it's not 100mtrs, but hey, I hope it helps in some way. :unsure:

#3 User is online   mackerr 

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Posted 01 February 2006 - 01:02 PM

View Postbrownstuff, on 1 Feb 2006, 7:56 AM, said:

does any one know if you get a bad sound from running XLR signal over cat 5 ?
as I have some 100m cable runs to do and its like 1000 times cheeper that mic cable.
jason
It depends on what you mean by "XLR signal." If you are talking about mic level signals, you should be sure to use real shielded twisted pair like mic cable.If you are talking about balanced line level, you should be fine as long as you connect pins 2 and 3 to to one of the 4 twisted pairs in the CAT5. Because of it's tight and controlled twist, CAT5 has very good noise rejection, and line level should be fine without the shielding of mic cable. Do not pick arbitrary wires in the CAT5, it must be one of the 4 pairs.

Mac

#4 User is offline   Simon Lewis 

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Posted 01 February 2006 - 01:31 PM

Mac is spot on...

Much of the noise rejection in audio systems is achieved through balanced circuits and twisted pair cable. The screen part is effective against RF (subject to various conditions being met). It is quite possible to use CAT5 for line level work, but passing 48V for mics needs a return 0V path.

Obviously, the other benefits of mic or multicore cable (handleability, low noise construction, cotton fillers, low temp jackets, stranded flexible conductors, ease of termination etc., etc.) may mean that we don't rush out and rewire our systems with network cable!

For further details, have a look at Tony Waldron's excellent site! Quite technical in parts, but you'll start to understand the problems....


Simon

This post has been edited by Simon Lewis: 01 February 2006 - 01:34 PM

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#5 User is offline   Yorkie 

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Posted 01 February 2006 - 04:25 PM

View Postbrownstuff, on 1 Feb 2006, 12:56 PM, said:

Does any one know if you get a bad sound from running XLR signal over Cat5?
I have some 100m cable runs to do and it's 1000 times cheaper that mic cable.


Not only do Cat5 and Mic cable have a completely different price, they also have a completely different application.

#6 User is offline   Rich newby 

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Posted 01 February 2006 - 05:06 PM

Yep exactly, Like wiring your house with bell wire. What gig are you doing that requires 100m cable, but is on a really really tight budget?
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#7 User is offline   Bobbsy 

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Posted 01 February 2006 - 05:15 PM

Are we talking a permanent install here? There are lots of cables designed for audio use but much cheaper than microphone cable (which has to be specifically rugged, flexible and "non-kinky"). These are much cheaper than mic cable and more suitable than Cat 5.

A bit more about your application maybe?

Bob
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#8 User is offline   dbuckley 

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Posted 01 February 2006 - 05:46 PM

It doesnt come across from the above posts: you can use all four pairs in a cat5 for line level audio simultaneously, you can also use pairs out of ethernet or telecoms circuits for line audio, but this requires a bit of care to ensure that its physically wired correctly!

But you have to have a twisted pair!!! Random cores will be terrible...
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Website: http://www.davidbuckley.name, a good place to go for PCStage tips and techniques

#9 User is offline   J Pearce 

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Posted 01 February 2006 - 09:19 PM

That site Simon posted is very good. Hurts my head tho...

Definitely worth a read.
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#10 User is offline   Chubby 

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Posted 02 February 2006 - 09:25 PM

We sometimes use Balum boxes to transmit stereo line level audio down a CAT 5 cable. We have sucessfully run audio down 300m of cable using this boxes which we brought from canford audio. You can also run video down using these boxes but I haven't ever tried this so can't coment on the performance but for line level audio they proved very usefull.

#11 User is offline   robertnisbet 

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Posted 03 February 2006 - 03:25 PM

Audio over cat5 is fine.

Audio has a bandwidth of 20kHz, cat5's bandwidth is 100MHz.
Cat5's inherent impedance is 100ohms +/- 15%, however, this is of little consequence in this application.
The extremely accurate twist in cat5 should reject the majority of noise.

If you use a screened cat5 (STP) type cable, you could use the screen as a return for phantom power.

I'm in the process of writing my dissertation on audio over cat5, and can supply you with references for these figures, plus real world examples of analogue or digital audio and video being sent via cat5, should you really wish to see them.

So in essence, yes, audio over Cat5 is not only possible, its very much emerging technology and in some work (installation especially) has the power to revolutionise.

#12 User is offline   Simon Lewis 

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Posted 03 February 2006 - 04:49 PM

So you must have Sam Wise's paper on this subject? ;-)
"Ignorance more frequently begets confidence than does knowledge"

#13 User is offline   robertnisbet 

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Posted 03 February 2006 - 06:51 PM

Simon: Thats not one I've come across yet - could you provide a link?

Just for the record, as part of this project I'm building a self-mix monitor system, with analogue I/P and O/P, and some signal processing in DSP in the middle.

#14 User is offline   Diarmuid 

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Posted 01 April 2006 - 09:59 PM

Hiya,
Has anyone had any experience using CAT5 cable for mic lines?
Because, I am trying to install all the mic lines, video runs and Cans for a prompt desk that is being built, and wondered whether it would pick up a lot of interference as the cable, doesnt have a shield. Or at least I dont think it has one.

Thanks

Diarmuid


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#15 User is offline   Beanzy 

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Posted 04 April 2006 - 05:51 AM

I'd rather get the mics to line level with a local pre-amp first, then use something like PSN20 or 40 to do a run between krone blocks to do your 'trunk' and hook up locally to that using FST. You'll get stacks of interference and attenuation on the poor old mic signal if you try to send that over the distance on small wires.

What kind of budget are you looking at for the hardware?

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