Need help with confounded humming!! - AVS Forum
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post #1 of 5 Old 04-07-2013, 03:01 PM - Thread Starter
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I searched the forum and haven't found an answer to this specific problem. I have a fairly simple setup: professionally modified Jolida integrated tube amp (a sub-out was wired to the aux jacks, caps were improved etc.), a meridian cd player, custom mtm 2way speakers, and powered 12" subwoofer. I've noticed two problems I can't get rid of.

1. The sub has a ~60hz hum (that's not present in the 2ways). The hum is there even when I disconnect the line-level cables from the Jolida and it is not effected by the volume level on the sub-amp. I've taken the sub-amp to a shop to have it tested and they say it's fine. I currently have it plugged into a different circuit than the rest of the system, and when I move the plug over to the outlet where the Jolida is plugged in, the hum is almost but not entirely gone. The outlet for the Jolida is waaay across the room and my wife won't let me run another power cable from the sub-amp to the outlet. My house is not grounded so I made a ground for the Jolida outlet by sinking a copper pipe into the dirt and wiring it to the ground on the outlet, so that plug is grounded. Grounding the plug didn't seem to make much difference. Is there a way to leave the sub-amp plugged in where it originally was and eliminate the humming? maybe grounding that plug the same way I did the other or running a ground wire from that plug to the ground I just put in or using something like this http://www.zzounds.com/productreview--EBTHUMX, or do I have to plug it into the same circuit?

2. I have the sub-amp connected to the Jolida via the sub-out on the Jolida to the line-in on the amp. I get a low frequency hum through the 2way speakers whenever I touch either the positive terminals on the speaker level on the sub-amp or the ends of the right channel cable from the Jolida. This is not effected by any of the things I did in 1. above. If I disconnect the positive cable from the line-level in on the sub-amp while everything is on I get a loud popping noise from the 2way speakers. What could be causing this? It doesn't seem to effect the quality of the sound while I'm playing something so I've tended to ignore it so far.

Any help is greatly appreciated. Thanks, Jim
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post #2 of 5 Old 04-07-2013, 04:35 PM
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Have you investigated your RCA cables as a potential culprit? Are they properly shielded? Are they bundled with the power cables for cable management?

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post #3 of 5 Old 04-08-2013, 03:01 PM - Thread Starter
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Quote:
Originally Posted by postrokfan View Post

Have you investigated your RCA cables as a potential culprit? Are they properly shielded? Are they bundled with the power cables for cable management?

Thanks for your help. The cables are supposed to be properly shielded but I don't know how to check this out for myself. They are not bundled with the power cables although they run close to the sub-amp power cable for about a foot.
Jim
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post #4 of 5 Old 04-08-2013, 09:05 PM
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If you have some extra RCAs laying around that would be a simple way to test.

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post #5 of 5 Old 04-09-2013, 10:19 AM
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Is there a cable or sat box connected? These are common cuplrits, usually means the connection from service and/or dish was not really done correctly.
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