Subwoofer noise...

Discussion in 'Speakers & Subwoofers' started by Mike L., Apr 13, 2004.

  1. Mike L.

    Mike L. Auditioning

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    Hey gang. I came across this forum and am glad I did. I need some advice.

    I have a older Velodyne subwoofer (model CT 80). I bought it as an open box item from Circuit City about 5-6 years ago. Its in good condition and works fine except for the fact that it has always given a lasting low frequency thud until it receives a signal from the receiver. (My receiver is a Sony STR DE 825)

    If I haven't made myself clear here's an example of what I mean:

    I have my subwoofer power cord plugged into the back of my receiver. When I turn my receiver on (either radio tuner or tv audio) there are a few seconds in which there is no audio (this also happens when switching between audio sources). But while the subwoofer is waiting those few seconds to receive an audio signal from the receiver, it gives a low frequency thud that is REALLY annoying until the tuner or tv audio kicks in. This happens whether I have the sub power cord plugged into the back of the receiver or not. I think its a problem with the subwoofer that I can't fix myself.

    Is anyone familiar with this type of issue? Can anything be done? I've had people tell me it may be a grounding issue with the power cord, but their suggestion of putting an extension on it has not worked.
     
  2. Ernest Yee

    Ernest Yee Supporting Actor

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    I'm not sure about your specific issue but as for resolving the grounding issue by extension cord - it's not actually the extension cord that will solve the problem, it's that you want to convert the 3 prong grounded plug into a 2 prong ungrounded. If you use a orange type heavy duty extension cord w/ 3 prongs, it won't change the setup at all.
     
  3. Mike L.

    Mike L. Auditioning

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    Come again?

    What should I do?[​IMG]
     
  4. Ernest Yee

    Ernest Yee Supporting Actor

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    I was saying that if it is a grounding issue, make sure that the extension cord that you're using extends to a 2 prong.

    l
    l Subwoofer Cord
    l
    lll 3 Prong grounded end of sub

    lll
    l
    l Extension Cord
    l
    l
    ll 2 Pronged end coming out to connect to outlet
     
  5. Ernest Yee

    Ernest Yee Supporting Actor

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    Or just use a 3 prong to 2 prong adapter... [​IMG]
     
  6. Mike L.

    Mike L. Auditioning

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    Ok, that's what I thought. Yeah, I've tried those things before and it didn't work. Still get the feedback.

    Any other suggestions?
     
  7. Cees Alons

    Cees Alons Moderator
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    Mike,

    Welcome to the forum. What you described as a "thud" is most probably the power frequency (60 Hz). It means that your sub's input isn't properly connected while there is no signal. This is known as a grounding problem.

    This may be a particular problem of the sub - but more likely has something to do with either the wire connection or the receiver (or decoder or amp) you connect it to.

    Sometimes it's even a power problem: try turning the power connector of the sub around in the outlet (switching the pins in the outlet, which is only possible, of course, if they're symmetrical). Make sure the sub is connected to the same outlet as the receiver/decoder.

    Test the signal path: Did you try another connecting wire to the input of the sub already? And another source (receiver/decoder/amp)?

    Cees
     
  8. Marc H

    Marc H Second Unit

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    Never plug the sub power cord plugged into the AC outlet on a Sony receiver; not enough current delivery.

    I'd guess it's a problem with the auto on/off muting circuit but best have a service centre have a look at it.
     

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