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#300219 - 04/04/10 01:09 AM Maximum Sub Cable Run
SatKartr Offline
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Registered: 09/19/08
Posts: 612
Loc: Dallas
Is there a theoretical maximum for running a sub cable to ensure the integrity of the signal? I have to go at least 48 feet if I want to run the cable via the ceiling, longer if I want to approximate something like a true diagonal, I assume 48 feet wouldn't be an issue but just wondered if there are known numbers regarding recommended maximum length as there are with networking cables.
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#300224 - 04/04/10 02:26 AM Re: Maximum Sub Cable Run [Re: SatKartr]
JohnK Online   content
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Sat, there might be a theoretical maximum which would be many miles in magnitude, but of course that wouldn't have any relevance to home audio use. The effect of capacitance in connecting cables(typically around 20pF per foot)can result in small losses at very high audio frequencies above 10kHz if the cables are on the order of hundreds of feet long, but at subwoofer frequencies below 100Hz the distances required for any significant loss are beyond anything that would be contemplated.

A less remote possibility, although still not likely in typical home environments, is that external interference would be picked up in the course of a long run, causing an audible noise level.
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#300258 - 04/04/10 09:41 AM Re: Maximum Sub Cable Run [Re: JohnK]
MarkSJohnson Offline
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I'm not sure what sub you're using, but at that distance I would be using a balanced XLR if possible...
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#300266 - 04/04/10 10:19 AM Re: Maximum Sub Cable Run [Re: MarkSJohnson]
SatKartr Offline
aficionado

Registered: 09/19/08
Posts: 612
Loc: Dallas
John thanks for the info, Mark the sub is an ep800 which does have an XLR input but the receiver is the Denon 3808 so I'm stuck with an unbalanced cable run. What I can do is run the cable outside of the wall and if there's no noise hopefully/it sounds like most likely there will be no interference when I run the cable through the ceiling/wall.
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#300270 - 04/04/10 10:39 AM Re: Maximum Sub Cable Run [Re: SatKartr]
alan Offline

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Registered: 01/29/02
Posts: 3264
Loc: Toronto/New York/parry Sound
Hi SatKartr,

As JohnK has noted, you should be good for several hundred feet of unbalanced cable run with no problems, and there is no need to use balanced XLR runs.

It's very rare that a long run of coaxial cable will pick up RF unless your place is nearby a big commercial transmitter. Even then, in my experience, it's usually unshielded speaker cables that will be susceptible to RF pickup, feeding a signal back into an amplifier or receiver where it's rectified and heard in the background (I speak from personal experience here; when I worked for CBC television, I lived a few blocks from the downtown Toronto transmitter, and had bad RF pickup of the TV audio on my stereo system. I traced it to the speaker cables. When I replaced them with shielded cable, the RF TV audio disappeared.)

Regards,
Alan
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#300333 - 04/04/10 05:57 PM Re: Maximum Sub Cable Run [Re: alan]
jakewash Offline
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Registered: 12/26/03
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Loc: Calgary, Alberta
I would use a coax RG6 terminated with an RCA for a run of that length, you should be well shielded from interference and the signal will still be strong at the sub.
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#300379 - 04/05/10 12:00 AM Re: Maximum Sub Cable Run [Re: jakewash]
oldskoolboarder Offline
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Registered: 05/25/03
Posts: 2181
Loc: Menlo Park, CA
 Originally Posted By: jakewash
I would use a coax RG6 terminated with an RCA for a run of that length, you should be well shielded from interference and the signal will still be strong at the sub.


I'm doing the same thing in a new setup w/ about 100'. I expect it to be fine w/ my RG6 cable and adapters.

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