Subwoofer noise w no input??

[lancestapp]

<font color='#000000'>I had a DCM powered sub connected to my system with an RCA cable. &nbsp;I get a double or triple thump every now and then for no reason. During a movie or even during the day when the sub is not being used. I switched recievers from Sony to Denon with no change. I went and bought a Velodyne sub thinking the sub was the problem and I still get thumping maybe every 20-60 minutes. Usually a double or triple thump. I took the RCA cable off and still get noise so it must be coming through the AC wall outlet. I have used it with a surge protector and with out with no change. Even tried running a ground wire from my reciever to the sub to make sure they had the same ground with no change. Maybe the electric company has some voltage surges or maybe somthing in my house? Not sure what the problem is. I could sure use some help after two recievers and two subs. All input welcome. Do they make inexpensive line conditioners to smooth out ac peaks? I called Velodyne thinking they would have some experts that would help me but the tech was convinced it was a bad sub. No way could two subs of different brands be bad with the same problem. Please help.</font>

 

[Yamahaluver]

<font color='#0000FF'>I would look into the option of a voltage line stabilizer from the likes of Tripp Lite. Looks like so real heavy machinery is nearby your house.</font>

 

[gene]

<font color='#000000'>Question: &nbsp;When you hear this thump, is it your sub turning off/on and vice versa? &nbsp;Try disabling the auto on feature and leave it on the whole time to see if the problem persists.</font>

 

[lancestapp]

<font color='#000000'>I will try both of these solutions starting with checking the auto on/off switch. &nbsp;Thanks and all input still welcome.</font>

 

[Audioholics]

<font color='#008080'>Just a thought - this doesn't correspond to your cell phone ringing does it? I had this problem in my vehicle. Kinda cool, cause I had a 3-second warning every time my phone was going to ring...</font>

 

[Guest]

<font color='#000000'>I would suggest trying some power conditioners.  Start with the cheapest thing that might work and try it in your home if it works, great, if not, you need to spend more money.  Make sure you go to a dealer that has a good return policy.  Trial and error is the best way to go.</font>

 

[lancestapp]

<font color='#000000'>I turned off the auto on switch and turned it on manually. It had no effect, still thumps even without rca input. I will try a cheap line conditioner next. If I could just minimize the thump that would be a plus. My daughter thinks some one is knocking on the door. &nbsp;Thanks for all input and more is welcome. &nbsp;Lance</font>

 

[lancestapp]

<font color='#000000'>Hawke, I will check about the cell phone. My wife charges her cell phone close to the sub. Thanks</font>

 

[cschang]

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>

lancestapp : Hawke, I will check about the cell phone. My wife charges her cell phone close to the sub. Thanks

I was going to ask the same about a cellphone, in particular, a Nextel phone.  Nextel phones are notorious for this noise in speakers/audio equipment.

If my Nextel phone is too close to my sub, I get a &quot;thumping&quot; noise once in a while. &nbsp;Just before it was going to ring, and at random times.</font>

 

[lancestapp]

<font color='#000000'>Hawke and cschang got it. My wife has been charging her cell phone on top of the sub. I turned the cell phone on and got a triple thump and turned it of and also got noise so this must be the problem. Thanks so much for all the input. I wonder why I never suspected the cell phone. It must send out signals even when not being used (stand by)and they are picked up by the amplifier.</font>

 

[cschang]

<font color='#000000'>Was it a Nextel phone by any chance?</font>

 

[Audioholics]

<font color='#008080'>I'm betting AT&amp;T.</font>

 

[lancestapp]

<font color='#000000'>It was a cellular one phone.</font>

 

[tdeuce]

I know this a really old thread, but I am having the same problem with a velodyne sub. The outlet is dedicated soley to this sub and it is not cellular phone related. It is very annoying!!! I am going to try a voltage line stabilizer. This sub belonged to a friend who never experienced this problem. Any new suggestions please let me know.

 

[steveimage]

Subwoofer thump

Looks like this old thread has been restarted!
I have a DefTech Supercube II - same thumping problem! I'll be watching a TV program and it will start and after disconnecting the RCA it continues until I unplug the AC. I sent the unit back for repair and they replaced the entire Hi level Amp. I bring it back home a month later and the same problem... I now have a call into DefTech waiting a response. Reading the previous threads, I can't see how this could be cell or land line phone related.

 

[bandit]

I have had similiar occassional thump in my system since its inception. I finally traced it to actually two sources. One - my refrigerator two - my sump pump. Both have electric motors that cause noise on my electrical system. (electric motors have always done this) I notice that the thump happens as they turn on - or sometimes off.

You could try having someone turn off and on some of the major electrial appliances in your house as you listen for the thump.

Bandit

 

[mtrycrafts]

<font color='#000000'>Hawke and cschang got it. My wife has been charging her cell phone on top of the sub. I turned the cell phone on and got a triple thump and turned it of and also got noise so this must be the problem. Thanks so much for all the input. I wonder why I never suspected the cell phone. It must send out signals even when not being used (stand by)and they are picked up by the amplifier.</font>

That's great news to find the problem. Who would think of a cell phone causing this, wow. And, being on top of the sub, disconnecting the interconnect would obviously not matter. Interesting.

 

[steveimage]

Subwoofer thump

I found out the problem with my sub... after reading all your emails about cell phones, refrigerators and pumps it turns out I simply had a bad amp in the sub. Although I've had my Supercube II for nearly 2 yrs, they gave me a brand new one. Now that is what I call a terrific manufacturer that backs up their product! Thank You Magnolia Audio Video!

 

[mtrycrafts]

I found out the problem with my sub... after reading all your emails about cell phones, refrigerators and pumps it turns out I simply had a bad amp in the sub. Although I've had my Supercube II for nearly 2 yrs, they gave me a brand new one. Now that is what I call a terrific manufacturer that backs up their product! Thank You Magnolia Audio Video!

And that new amp cured the problem? Great.

 

[steveimage]

So far so good! if it had been a cell phone or a motor, I would had the problem since I first bought it. This started happening a year later...
thanks to all for the past info as it's good to know other possible causes...
Regards