OT: noise thru Powered Sub Woofer

Trex · #1 07-12-2005, 10:31 AM

I get an occasional staccato hum (sounds like low freq. Morse code) through my Klipsch powered sub woofer. At the last East Meet 05 at my place, one of you guys said I should test it by playing something while the TV cable is disconnected. So, I played a DVD the other night with the TV cable removed and no hum. Thus, it is a problem with the ground for the TV cable. I was too fizzed at the time to remember who told me to do the test, but they also said it is common for a cable ground to not be doing its job properly and there are better ways to ground the cable coming into the house or to add a special grounding adaptor for the cable. Tommy - was that you with the sane and sober advice? What device can I buy to provide a better ground? Right now, the cable comes into the basement and it goes to a splitter (not a Radio Shack splitter, but a fancy one I bought from an Audio specialty shop. WooHoo, it's got gold connectors). That splitter has a bare ground wire which I have going over to a water pipe with one of those old school strap/nut devices. I cleaned all the surfaces on the pipe where it makes contact with the strap and cleaned up the ends of the wire from the splitter to the ground nut on the strap and the strap is all cleaned up, but that has not stopped the hum.

Help appreciated.

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ncx · #2 07-12-2005, 11:46 AM

Plug them all into a good clean power conditioner. You should have any good equipment going through a line conditioning device anyway. Besides the obvious benefit of common grounds, you can also filter cable (coax) noise in many of those devices. I use them in both my my home theaters and will swear by the benefits of clean power. (Plus you get surge control, etc). Also make sure your sub cable is properly shielded and not parallel to other signal or power wires. Good luck.

Chris F. · #3 07-12-2005, 12:36 PM

This is a great topic. While a power conditioner helped my hum a little bit, it didn't kill all of it. I'd be curious to hear other peoples approach to this as well. I'll have to try a different ground location for cable and see if that helps.

Trex · #4 07-12-2005, 01:36 PM

ncx - School me. You mention a line conditioner. I take it that is not the same thing as just a surge control device - or is it the same thing? You say that "you can also filter (coax) noise in many of those devices.", but you don't mean that a coax cable goes through (connects to) the conditioning device, do you? My sub cable is a Monster and crosses perpendicular to the coax cable, but they are some distance apart: the sub cable down along the floor over to the sub and the coax coming out of the floor and up to the separate input box for a Sharp Aquus LCD screen.

Would it be possible that my current surge box is not properly grounded? From what I can tell, you are implying that the coax grounding is probably good, but it is the shielding (and possibly the ground) for all the plug-ins that is the problem (or might lead to the solution).

Is Monster cable really good or really hype? What line conditioner do you recommend?

Trex · #5 07-12-2005, 01:40 PM

BTW - Chris, you mention a hum. As you might know, a constant hum from a powered sub woofer can be eliminated by adding one of the ground adaptors ($.25 at Radio Shack in either yellow or orange) between the power plug and the outlet.

The hum I am referring to is not a constant hum at a constant cycle. It is off and on, like Morse code with a low frequency, as mentioned above.

BlueX5guy · #6 07-12-2005, 02:17 PM

A line conditioner is a fancy surge protector that will provide cleaner power along with surge protection/grounding for cable and phone lines and might help with your problem.

I would also look at the audio connection from your reciever/pre-amp to the subwoofer. You mentioned a "Monster" cable for this connection. Is this a shielded coax type cable or a standard audio type cable. For long runs ( over 15 feet) it is generally recommended that quad shielded rg-6 coax cable be used with rca connectors fitted to the ends. This will prevent unwanted signals from getting into the audio source of the subwoofer.

BTW I have the Monster Power HTS 3600 on my system and it works great.
http://www.monstercable.com/power/pr...erence%20Power

Dennis

Quote:

Originally Posted by Trex

ncx - School me. You mention a line conditioner. I take it that is not the same thing as just a surge control device - or is it the same thing? You say that "you can also filter (coax) noise in many of those devices.", but you don't mean that a coax cable goes through (connects to) the conditioning device, do you? My sub cable is a Monster and crosses perpendicular to the coax cable, but they are some distance apart: the sub cable down along the floor over to the sub and the coax coming out of the floor and up to the separate input box for a Sharp Aquus LCD screen.

Would it be possible that my current surge box is not properly grounded? From what I can tell, you are implying that the coax grounding is probably good, but it is the shielding (and possibly the ground) for all the plug-ins that is the problem (or might lead to the solution).

Is Monster cable really good or really hype? What line conditioner do you recommend?

MiCkEy · #7 07-12-2005, 02:48 PM

Leaky capacitor on your sub Power Supply. Get it checked out.

Oh and also STFU

ncx · #8 07-12-2005, 04:15 PM

Trex -
I am no expert at all but yes, a line conditioner is a lot more then just a surge control. A surge is just going to clamp power at some predetermined rate and kill itself in order to try to save your equipment from frying during a huge surge. A conditioner is constantly cleaning up the power signal from minute spikes and dips and stray noise that is all residential power. If you ever hook up good test equipment to an AC outlet in your house you will see how poor your power really is. Constant fluctuation and terrible noise in the line. Also you are setting up a single ground for all your devices on the conditioner. For all you know, a bad computer power supply or your refrigerator is crapping junk on to your power line and your sub (which can play 60Hz ((the exact frequency of AC power)) is amplifying that noise. A line conditioner would filter out that noise before it gets to any of the device's power supply. That is just one scenario. Just from your description it sounds like an electrical issue and not a sub signal issue. But who knows.

Many line conditioners also have coax in and out so you can try to clean up a video signal and provide surge control on that cable as well. Some actually filter the video to remove all kinds of stray junk and noise. You can also get separate gear just for the video portion. I think much of Monster's higher end cables are over rated (well, at least over priced). That said, I use their HTS5000 power centers and think they are great. I have used the 2500 too and it was solid. Panamax, Triplitte, Audience, PS Audio... etc all make them but I cannot give you personal opinion of them. I can tell you that my system's overall noise floor dropped to non-existent when I installed the conditioner and my cable is rock solid. Check this page for a lot of reviews http://search.ecoustics.com/Editoria...r-Conditioner/

Also as BlueX5guy states, long runs for a sub work better with quad-shield RG6 for the reason stated.

As Mickey stated you could just have a problem with a cap in your sub amp which would not be that hard to fix. If it only makes the noise it in that room, on that one AC circuit, on that one stereo, it must be something else. Maybe the ground for that whole circuit is not good. Do some eliminating of possibilities (different sub cable, or different room/AC circuit, etc).

Nice screen by the way

Trex · #9 07-12-2005, 04:33 PM

Tonight I'll take a look at the Monster cable I have for the sub. The distance between the sub and the receiver is small - maybe 3-4 feet (Mickey, you saw the set-up, remember?), but I might start with a better shielded cable. I might plug the sub into an outlet that is not used by all of the other components. The line conditioning sounds interesting and I looked at a couple of them, but YIKES the new Monster 3600 is, like $500. And some are $3,000. What's the best bang for the buck with a line conditioner?

ncx · #10 07-12-2005, 05:30 PM

You can get a decent power conditioner for $200+- from Panamax, Monster, and others. You can find Monster Power 3500 for about $280. The 2500 is under $200. You don't "need" the refernce series (2600/3600/5100/7000) unless you have some high end stuff or you just like overkill. Good luck! I hope you get it fixed.

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