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personthingy
26-12-2006, 12:13 PM
Having realized that the blue and brown pair in standard cat5 cable don't actually do anything under normal use, i some time ago found a use for some of them, and started using them for phones.

Then, faced with the prospect of buying 2 lengths of balanced audio cable, and threading them through where cat5 should be anyway, i found myself thinking "Why not use the 2 redundant twisted pairs for audio?"

So here's a pic:
http://something.orcon.net.nz/abuse_of_cat5.jpg

Can anyone throw a spanner in the works, and tell me what, if anything is wrong with this idea?

winmacguy
26-12-2006, 12:19 PM
Cool setup. I take it you like to make your own music @ home.

personthingy
26-12-2006, 12:27 PM
Cool setup. I take it you like to make your own music @ home. Not quite. I help other people inflict their musical offerings on others in public places. The home stereo is the minimal version of my concert PA system. The music that i'm running into it when it's back in the cave is simply my music collection, which these days lives purely on HDD.

Ta for the compliment tho :D

winmacguy
26-12-2006, 12:35 PM
Your welcome. Although I am more of a creative ideas person than a technical one I still like the look of the set up. I am still hanging out to get into DV editing.

Have you ever heard of or tried Logic Pro?

somebody
26-12-2006, 12:39 PM
While I don't know the exact physics involved, I recall either Godfather or GrahamL mentioning in response to another post that sending another signal (be it audio or whatever) down those pairs of wire will interfere with data which is sent through the (used) pairs of the CAT5 cable. You'd be best to wait for one of them to reply for an accurate answer to the question.

In the meantime, it's worth a shot I suppose - it shouldn't break anything.

winmacguy
26-12-2006, 02:10 PM
Well good luck personthingy I hope you get it sorted out.

pheonix
26-12-2006, 02:13 PM
Normally would not be a problem as long as the audio line is low-level audio.
If it is of too higher level, it will induce into other pairs and cause either the data to be corrupted. Definitely NO speaker level audio.
That principle has been used before in businesses of using the spare pair/s as the telephone extension connection, along with the computer data connection without problems.

personthingy
26-12-2006, 02:41 PM
I'd not be running speaker level signals. Apart from anything else, with a 3,500wRMS system it would melt the cable. :D
I use spare pairs in other Cat5 cables for phone purposes. That works well.

I suppose what i'm worried about is if i am going to get noise induced on the audio, all though, seeing many microphone cables are an untwisted pair running along side an earth for the body of the mic, i hope i'll be alright so long as i keep the pairs truly balanced.

Renmoo
26-12-2006, 04:47 PM
Having realized that the blue and brown pair in standard cat5 cable don't actually do anything under normal use, i some time ago found a use for some of them, and started using them for phones.

Then, faced with the prospect of buying 2 lengths of balanced audio cable, and threading them through where cat5 should be anyway, i found myself thinking "Why not use the 2 redundant twisted pairs for audio?"

So here's a pic:
http://something.orcon.net.nz/abuse_of_cat5.jpg

Can anyone throw a spanner in the works, and tell me what, if anything is wrong with this idea?
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The requested URL /abuse_of_cat5.jpg was not found on this server.

TGoddard
26-12-2006, 05:27 PM
Use of the extra pair in this way will generate additional noise, slowing the possible transmission speed of the ethernet link. If this is not a problem, go ahead. If it could be a problem, extra cable would be much better.

personthingy
26-12-2006, 05:39 PM
Not Found

The requested URL /abuse_of_cat5.jpg was not found on this server.
I just tried to browse every.orcon.net.nz site i know, seems Orcons webserver is having a bad day :(

I put the pic here as well, on a registerdirect server


http://millerton.co.nz/images/f1/abuse_of_cat5.jpg

plod
26-12-2006, 05:44 PM
I just tried to browse every.orcon.net.nz site i know, seems Orcons webserver is having a bad day :(

I put the pic here as well, on a registerdirect server


http://millerton.co.nz/images/f1/abuse_of_cat5.jpg

Glad to see you let the neighbourhood kids draw for you LOL.
but pretty impressive

personthingy
26-12-2006, 05:50 PM
Use of the extra pair in this way will generate additional noise, slowing the possible transmission speed of the ethernet link. If this is not a problem, go ahead. If it could be a problem, extra cable would be much better.I'm not too worried about the transmission speed to the lounge, there's no lounge computer, and if there ever was to be one, i cant see it moving much data, thats what the server and the office computer is for.

What i am worried about is the quality of the Audio feed

Thanks plod :) No child labor was exploited in the drawing of what i have in mind, i can draw that good all by my self! :p

pheonix
26-12-2006, 06:13 PM
I mentioned the speaker level in case any other readers got the idea they could and so cause themselves/others some grief.

If you used the 1Volt line levels, I can't see a problem. I have used the spare pairs also for digital phones and neither the phones or the data connection had any problems at all. The digital phones were real bast**ds when it came to any noise being induced.

pctek
27-12-2006, 08:28 AM
Having realized that the blue and brown pair in standard cat5 cable don't actually do anything under normal use, ?

I used to do structured cabling at Akld Uni. Under normal use means thats fine for a 10Mb connection, but for 100mb you did need all 8.

personthingy
27-12-2006, 09:51 AM
I used to do structured cabling at Akld Uni. Under normal use means thats fine for a 10Mb connection, but for 100mb you did need all 8.Cool!
I didn't actually realize this, but fortunately this won't make any real difference as there is no lounge computer, and the socket will probably only ever be used for someone checking their email via their laptop on my connection. As my Internet connection is limited to 10Mb/sec, there's not much to be gained with a 100Mb/sec feed to that room.

However that's a good point to keep in mind with future work.
:D

Billy T
27-12-2006, 12:34 PM
I don't see a problem at all. It should be OK for audio provided that the cable doesn't run too close to power wiring in the walls. Twisted audio pairs do cancel-out induced noise, but that cancellation is not perfect and depends on how well the Cat 5 was run in the first instance. If it has any kinks, sharp ends or is compressed under clamps that could cause impedance variations and create other issues.

The audio won't interfere with your data, but I'd check that the data doesn't cause a problem for the audio by turning the volume up with no signal on that input, then sending some data down the ethernet line and checking for noise from your speakers.

Cheers

Billy *<8-{)=

personthingy
27-12-2006, 12:42 PM
Thank you Billy,

Thats exactly what i was hoping, so i'm now ready to go and buy a little cat5 cable to gently mutilate so that i can run amarok of the central server, and use it to feed the ever varying main house sound machine.

pheonix
27-12-2006, 03:20 PM
PCtek , why does the 100mb use all 8?

It still only has a send pair and a receive pair. Thats 4 of the 8 wires.

I know that with the telephone over the same cable, the data still runs at 100Mb/s.

Graham L
27-12-2006, 04:15 PM
There have been a number of 100 MHz twisted pair Ethernet systems. :D One did use all 4 pairs. The commonly used system uses only the two pairs 1+2, 3+6.

Even volts of audio won't bother the Ethernet. It's at megahertz, not audio frequencies. Even the other way shouldn't give problems, as long as the audio is a true balanced system, and at reasonable levels "0 dBm"). Otherwise, you might get rectification of the RF Ethernet signals in the amplifiers (detection, as in an AM receiver). There will be slight coupling ("leakage") because no balanced system is perfect but the frequencies are so widely different there should be no problems. If you were dependent on millivolt level signals in one of the systems, it might be different.

pctek
27-12-2006, 04:44 PM
PCtek , why does the 100mb use all 8?


Dunno, I only got to the Krone Master Installer level, not the Designer.
I lost interest then.......

pctek
27-12-2006, 04:50 PM
Here we go......
Whats the difference between 100base-T4 and 100base-TX.

100base-T4 wiring uses all 4 pairs (8 wires) and allows for the use of Cat 3, Cat 4 OR Cat 5(e) cables. If you have ANY Cat 3 or Cat 4 cabling in your network you MUST use this standard. Most telephony cables (including 25, 50 or 100 pairs) are rated Cat 3. If your LAN uses these cables ANYWHERE you must use 100base-T4 wiring (see diagram). 100base-TX wiring uses only 2 pairs (4 wires or conductors) but can only be used with Cat 5, Cat 5e or higher cables.

w.zytrax.com/tech/layer_1/cables/cables_faq.htm

pheonix
27-12-2006, 06:07 PM
Never come across that at all.
CAT3 was always rated as 10Mb, and all the places I dealt had changed out for CAT5e. Some are now moving to CAT6.

Greven
27-12-2006, 06:41 PM
According to the information I found from a google search, 100mb cat5 only uses 2 pairs & you can safely use the other 2 pairs for different applications, but 1000mb Cat6 uses all 4 pairs.

pheonix
27-12-2006, 07:09 PM
CAT3 = 10Mb/s
CAT5 and CAT5e = 100Mb/s
CAT6 = 1000Mb/s

All above use 2 pair only (send and receive), for the standard 100% over a length of 100Metres horizontally.

So you can use say 1 metre of CAT3 at 100Mb/s as the losses are not bad for the length. It's just normal practice to comply with the above CAT standards.

Anyway, time to move on as the original poster has had his fears assuaged.