Cat 6 STP as subwoofer line level cable

creek · 24th October 2004, 07:05 AM

I have an unused run of cat6 stp (shielded) run through the wall that goes from where the reciever is to the other side of the room right where I want to put a new sub.
My question is - Can I convert this cat6 run to a subwoofer line level cable, and what is the best way of going about it? The run is about 45'.

Brent Welke · 24th October 2004, 10:03 AM

I bet it will sound great. I use Cat5e for speaker cable and interconnects. I have not done a 45' run but that should not be a problem. Try it and see.

Something to keep in mind. There are 4 twisted pairs. Two pairs (blue and orange) are tightly twisted.

The lenght of the wire will be different between the two types of twists. So just use one type of twist.

I would use blue for Left and orange for Right. If you only need one channel then I would combine the blue and orange.

I can't say I have actually heard a difference between the twists but it can't hurt to take that into consideration.

I actually took 10 feet of my Cat5e and untwisted a blue pair and green pair and mesured a 28mm difference in length beteen the two. Knowing that you can cut the tightly twisted pairs shorter and then all 4 pairs are actually the same length.

Sometimes attention to details like that can make a difference and thats what its all about.

pinkmouse · 24th October 2004, 10:09 AM

For a line level run of that length, you will need to run it balanced to avoid noise problems.

falcott · 24th October 2004, 10:35 AM

Quote:

Originally posted by brentw
...There are 4 twisted pairs. Two pairs (blue and orange) are tightly twisted....

The CAT5e cable I have here has the blue and green pairs twisted slightly tighter than the orange and brown... Maybe there are different specs for CAT5 cable??

Brent Welke · 24th October 2004, 07:05 PM

Also the sheild on that Cat6 cable... connect only one end to ground. I would ground the input end of the cable. Balanced would be nice if you have the stuff to do it that way but give it a try unbalanced anyway. I know it is just for a sub, but test it with a full band audio signal and I bet it will sound great.

If I have some time to kill I will make a 45' interconnect and see how it sounds unbalanced.

Twisted pairs... if you expose a foot of the pairs you should be able to see which pairs are tightly twisted.

If it is all in the wall with wall plates and jacks on the wall then that makes it harder. I have seen about 5 different makes of cable and blue and orange were the tightly twisted pairs. So if you have to guess that would be the guess to make. You would have to take the wall plate off the wall and see what wire goes where and match it up on the plug that you are plugging into the jack. Best is not to use the RJ45 jacks at all and solder RCA jacks right on the wire. Second best would be to solder on extentions to the wire at the wall plate. Third is to make patch cables that have RCAs on one end and RJ45s on the other to plug into the wall.

creek · 24th October 2004, 08:30 PM

Thanks brentw, great explanation. I will try your suggestions. The cable is sticking out of the wall about 3 ft on each end so I will be able to experiment some. I am away from home for another week so it will be a little while before I get to try it, but I will report back here when I do.

jwb · 24th October 2004, 08:50 PM

I'd leave the shield unconnected and run it balanced, if possible, or connect the shield on the transmitting end directly, and on the receiving end with a capacitor. Leaving one end completely disconnected is just as bad as leaving both ends disconnected. But STP is notorious for noise pickup problems. UTP is preferred if you can do differential transmission.

24th October 2004, 07:05 AM	#1
creek diyAudio Member Join Date: Sep 2003 Location: Ohio	Cat 6 STP as subwoofer line level cable I have an unused run of cat6 stp (shielded) run through the wall that goes from where the reciever is to the other side of the room right where I want to put a new sub. My question is - Can I convert this cat6 run to a subwoofer line level cable, and what is the best way of going about it? The run is about 45'.

24th October 2004, 10:09 AM	#3
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	For a line level run of that length, you will need to run it balanced to avoid noise problems. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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24th October 2004, 10:03 AM	#2
Brent Welke diyAudio Member Join Date: Jun 2004 Location: Victoria, BC	I bet it will sound great. I use Cat5e for speaker cable and interconnects. I have not done a 45' run but that should not be a problem. Try it and see. Something to keep in mind. There are 4 twisted pairs. Two pairs (blue and orange) are tightly twisted. The lenght of the wire will be different between the two types of twists. So just use one type of twist. I would use blue for Left and orange for Right. If you only need one channel then I would combine the blue and orange. I can't say I have actually heard a difference between the twists but it can't hurt to take that into consideration. I actually took 10 feet of my Cat5e and untwisted a blue pair and green pair and mesured a 28mm difference in length beteen the two. Knowing that you can cut the tightly twisted pairs shorter and then all 4 pairs are actually the same length. Sometimes attention to details like that can make a difference and thats what its all about.

24th October 2004, 07:05 PM	#5
Brent Welke diyAudio Member Join Date: Jun 2004 Location: Victoria, BC	Also the sheild on that Cat6 cable... connect only one end to ground. I would ground the input end of the cable. Balanced would be nice if you have the stuff to do it that way but give it a try unbalanced anyway. I know it is just for a sub, but test it with a full band audio signal and I bet it will sound great. If I have some time to kill I will make a 45' interconnect and see how it sounds unbalanced. Twisted pairs... if you expose a foot of the pairs you should be able to see which pairs are tightly twisted. If it is all in the wall with wall plates and jacks on the wall then that makes it harder. I have seen about 5 different makes of cable and blue and orange were the tightly twisted pairs. So if you have to guess that would be the guess to make. You would have to take the wall plate off the wall and see what wire goes where and match it up on the plug that you are plugging into the jack. Best is not to use the RJ45 jacks at all and solder RCA jacks right on the wire. Second best would be to solder on extentions to the wire at the wall plate. Third is to make patch cables that have RCAs on one end and RJ45s on the other to plug into the wall.

24th October 2004, 08:30 PM	#6
creek diyAudio Member Join Date: Sep 2003 Location: Ohio	Thanks brentw, great explanation. I will try your suggestions. The cable is sticking out of the wall about 3 ft on each end so I will be able to experiment some. I am away from home for another week so it will be a little while before I get to try it, but I will report back here when I do.

24th October 2004, 08:50 PM	#7
jwb diyAudio Member Join Date: Mar 2002 Location: San Francisco, USA	I'd leave the shield unconnected and run it balanced, if possible, or connect the shield on the transmitting end directly, and on the receiving end with a capacitor. Leaving one end completely disconnected is just as bad as leaving both ends disconnected. But STP is notorious for noise pickup problems. UTP is preferred if you can do differential transmission.

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