Kef T2 Subwoofer Humming.. - AVS Forum
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post #1 of 26 Old 03-30-2013, 03:42 AM - Thread Starter
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I finally got my Kefs hooked up and the T2 hums when plugged in.what cab I do to stop this or could it be a defective sub?

Thanks
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post #2 of 26 Old 04-01-2013, 09:23 AM
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Have you tried a different cable?

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post #3 of 26 Old 04-02-2013, 06:03 PM - Thread Starter
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Unfortunately there is 16g speaker wire run so I had to adapt to RCA ends. The only ones I could find at the time had 24g wire for pigtails. As soon as I find some decent ones with screw down contacts ill change them. I really hope that is the problem but I doubt it.
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post #4 of 26 Old 04-03-2013, 09:28 AM
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Do you still get the hum with the cable disconnected? If not, it's the cable. If so, it's something else.

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post #5 of 26 Old 04-03-2013, 10:19 AM
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Quote:
Originally Posted by Alan P View Post

Do you still get the hum with the cable disconnected? If not, it's the cable.
Not if it's a ground loop, which is the number one source of subwoofer hum.

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post #6 of 26 Old 04-03-2013, 10:45 AM
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^^^^

I know Bill, that's why I said "If not, it's the cable. If so, it's something else." wink.gif

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post #7 of 26 Old 04-03-2013, 12:31 PM
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Quote:
Originally Posted by Alan P View Post

^^^^

I know Bill, that's why I said "If not, it's the cable. If so, it's something else." wink.gif
You said Do you still get the hum with the cable disconnected? If not, it's the cable That infers that if the hum stops with the cable disconnected that the cable is the problem. It may be, but not if it's a ground loop, which also will cease if the cable is disconnected.

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post #8 of 26 Old 04-03-2013, 01:06 PM
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Once again, you are correct Bill....never mind me. rolleyes.gif

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post #9 of 26 Old 04-03-2013, 01:12 PM
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Originally Posted by Alan P View Post

Once again, you are correct Bill....never mind me. rolleyes.gif
No biggy. BTW, OP, have you tried disconnecting the TV cable? That's a prime source of ground looping, and can be fixed with transformer isolation of the TV cable.

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post #10 of 26 Old 04-03-2013, 05:35 PM - Thread Starter
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When I disconnect the speaker wire to the sub the humming stops. Are you guts talking about disconnecting the coax cable?
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post #11 of 26 Old 04-03-2013, 07:17 PM
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Originally Posted by Salty Dog View Post

When I disconnect the speaker wire to the sub the humming stops. Are you guts talking about disconnecting the coax cable?
Yes. If disconnecting that from the system stops the hum you need to transformer isolate it. This link explains why ground loops happen. The culprit is unbalanced consumer grade connections and on-board sub amps. On-board, because it makes the interconnect long and the distance from where the sub amp and receiver plug into the AC outlets long, and the hum level goes up by the square of the total ground wire length. TV cables compound the problem by introducing another ground path, and as this one extends all the way back to where the TV cable enters the building it's even worse than the interconnects as a noise source.
http://www.rane.com/note110.html

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post #12 of 26 Old 04-03-2013, 10:49 PM - Thread Starter
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Ok, so what exactly do I need to get and where do I install it

Thanks
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post #13 of 26 Old 04-04-2013, 05:34 AM
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Originally Posted by Salty Dog View Post

Ok, so what exactly do I need to get and where do I install it

Thanks
You haven't told us yet if disconnecting the TV cable stops the hum.

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post #14 of 26 Old 04-04-2013, 05:58 PM - Thread Starter
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Ok, I disconnected every cable in and out of the cable box, still hums. I took the subwoofer wire off of the amp, still hums. I reconnected everything, still hums. I took the wire off the bottom of the sub, stops humming.

My local ADI guy says I should run coaxial to the sub with RCA adapters...
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post #15 of 26 Old 04-04-2013, 07:02 PM
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Quote:
Originally Posted by Salty Dog View Post

. I took the wire off the bottom of the sub, stops humming.
What is the wire on the bottom of the sub?

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post #16 of 26 Old 04-04-2013, 07:25 PM - Thread Starter
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It's a 16g speaker wire with a 24g RCA pigtailed on to it.
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post #17 of 26 Old 04-05-2013, 01:16 AM - Thread Starter
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It's the good 16g wire that is double insulated
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post #18 of 26 Old 04-05-2013, 05:22 AM
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Quote:
Originally Posted by Salty Dog View Post

It's a 16g speaker wire with a 24g RCA pigtailed on to it.
You've lost me. If you have a powered sub there is no speaker wire, it's inside the cabinet.

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post #19 of 26 Old 04-05-2013, 06:24 AM - Thread Starter
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Now we are even, both lost smile.gif

This is what I have

http://www.kefdirect.com/t2-subwoofer.html

There is 16g speaker wire going to it with 24g RCA adapters on each end.
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post #20 of 26 Old 04-05-2013, 06:25 AM
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If Im reading this right (doubtful tongue.gif) he's adapting speaker out from the receiver into RCA inputs on the sub confused.gif
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post #21 of 26 Old 04-05-2013, 06:34 AM
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Originally Posted by Salty Dog View Post

Now we are even, both lost smile.gif

This is what I have

http://www.kefdirect.com/t2-subwoofer.html

There is 16g speaker wire going to it with 24g RCA adapters on each end.
A sub should be connected to the receiver LFE output with a shielded interconnect, not an unshielded speaker wire.

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post #22 of 26 Old 04-05-2013, 07:26 AM
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Quote:
Originally Posted by Alan P View Post

Have you tried a different cable?

Quote:
Originally Posted by Salty Dog View Post

Unfortunately there is 16g speaker wire run so I had to adapt to RCA ends. The only ones I could find at the time had 24g wire for pigtails. As soon as I find some decent ones with screw down contacts ill change them. I really hope that is the problem but I doubt it.

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It's a 16g speaker wire with a 24g RCA pigtailed on to it.

Soooo....you still haven't tried a different cable?? This would have been the very first thing I would have done, especially with that cobbled together cable you are using. Hit up Monoprice, they got good sub cables for cheap.

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post #23 of 26 Old 04-05-2013, 09:35 AM - Thread Starter
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I'm a little bit afraid the if I try and pull the new cable through the walls that it might get stuck or come apart and then I have no wires going to the sub. The hole drilled in the one stud in the closet that I can see definitely wont fit a cable with an RCA type end on it so I doubt the other 8 studs will either.

I may be able to fit a coaxial cable and then put ends on it if you guys think that it would solve my problem.
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post #24 of 26 Old 04-05-2013, 09:38 AM
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Quote:
Originally Posted by Salty Dog View Post

I'm a little bit afraid the if I try and pull the new cable through the walls that it might get stuck or come apart and then I have no wires going to the sub. The hole drilled in the one stud in the closet that I can see definitely wont fit a cable with an RCA type end on it so I doubt the other 8 studs will either.

I may be able to fit a coaxial cable and then put ends on it if you guys think that it would solve my problem.

It should, if the cable is shielded and you terminate and connect the plugs to the shielding properly. (which means connect to the shielding on one side or both sides, guys?)
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post #25 of 26 Old 04-05-2013, 10:25 AM
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I would just try a different cable strung across the floor first before fishing one through the wall. Then you would know if that's the problem or not before going through all that hassle.

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post #26 of 26 Old 04-05-2013, 11:23 AM - Thread Starter
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Good idea. I'm on my war to ADI now to get the cable ends
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