dad311 Posted November 20, 2011 Share Posted November 20, 2011 Spent this weekend moving the subs around looking for the best sound. Found the sound, but now I have a hum. Ive found the problem, just dont know the best way to fix it. My 2nd sub is 30 feet away from the amp. If I use my cable from Monoprice, I get a hum. If I use my Monster cable with the little directional arrow, I get NO hum. From my research, Ive found that the arrow on the Monster cable means the shield is only connected at one end (I think). How do I make a sub cable with the shield disconnected on one end? As far as I know, a coax cable has two conductors (core and shield). If I disconnect the shield on one end, I will loose the one conductor resulting in no sound. thx. Quote Link to comment Share on other sites More sharing options...
wuzzzer Posted November 20, 2011 Share Posted November 20, 2011 Did you try flipping your monoprice cable around? I think all the RCA cables I've bought from them have been shielded. Quote Link to comment Share on other sites More sharing options...
dad311 Posted November 20, 2011 Author Share Posted November 20, 2011 Did you try flipping your monoprice cable around? I think all the RCA cables I've bought from them have been shielded. Yeah, tried that. Funny thing is the sub continues to hum when the cable is disconnected from the processor. Its only when I disconnect the cable from the sub the hum stops. The cable should be shielded, but now Im have doubts. Maybe its just a crappy cable and 50 foot is why to long for a crappy cable. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted November 20, 2011 Share Posted November 20, 2011 Sounds like a ground loop hum. Try a cheater plug on your sub amp. Quote Link to comment Share on other sites More sharing options...
dad311 Posted November 20, 2011 Author Share Posted November 20, 2011 Sub AC plug only had 2 prongs, no ground. At this point I believe Im a victom of a bad/cheap cable. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted November 20, 2011 Share Posted November 20, 2011 Sounds like you are picking up RF noise. I would complain to monoprice and see what they say. Quote Link to comment Share on other sites More sharing options...
LarryC Posted November 21, 2011 Share Posted November 21, 2011 If I use my cable from Monoprice, I get a hum. If I use my Monster cable with the little directional arrow, I get NO hum. From my research, Ive found that the arrow on the Monster cable means the shield is only connected at one end (I think). I think I can help answer your Monster cable question. But first I wonder if you don't have a faulty ground connection in your monoprice cable. This break could be between a braided wire around the central wire, and a "shield" that surrounds the pin of the connector jack, if it's an RCA jack. In that case, a typical 2-wire RCA-type cable has a central axial wire that goes to the "positive" pin of an RCA jack, and a braided wire that connects to the shield around the pin: In all cases, a signal requires two conductors. In the above example, one is the central wire and the other a braided "shield" wire that connects to the shield of the RCA jack. I've seen cases of terrible hum where the connection is broken between the braided wire and the shield cylinder surrounding the central pin of the connector. I'd carefully look there, unscrewing the back part of the plug if necessary. If there is a visible break, soldering will take care of the hum in my limited experience. If you can't see a break, turn it on and jiggle the wire on each side to see if the hum abruptly comes and goes. The Monster cable is a three-conductor cable. Two central wires carry the signal, one each for the "positive" and the "negative" signals. The 3rd conductor, a braided wire, is a shield against hum and RF, but must be connected at only ONE end. I believe Monster connects it at the outgoing, or signal-receiving, end. That's the reason for the arrows, to orient the cable in the appropriate direction and put the disconnected end at the signal input end. Monster makes quality cables and connectors IMO. Quote Link to comment Share on other sites More sharing options...
dad311 Posted November 21, 2011 Author Share Posted November 21, 2011 I believe you are correct. The Sub does not hum unitl I plug the RCA cable into it (with the other end disconnected). Its acting like a antenna. Last night I ordered a much better cable from Blue Jean Cables, I believe this will solve my issue. Although Ive always had good luck with Monoprice cables, but Ive had two bad cables in two weeks. Im thinking about swapping out all my Monoprice cables with DYI interconnect cables, but thats for a different post. Oh, LarryC nice drawings! thx Quote Link to comment Share on other sites More sharing options...
LarryC Posted November 21, 2011 Share Posted November 21, 2011 Oh, LarryC nice drawings! thx http://searchnetworking.techtarget.com/definition/RCA-connector Quote Link to comment Share on other sites More sharing options...
dad311 Posted November 25, 2011 Author Share Posted November 25, 2011 Received my new BJC sub cable today, ZERO HUM! Quote Link to comment Share on other sites More sharing options...
mustang guy Posted November 25, 2011 Share Posted November 25, 2011 Received my new BJC sub cable today, ZERO HUM! Awesome! Quote Link to comment Share on other sites More sharing options...
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