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Subwoofer thud... Help

Discussion in 'Subwoofers' started by pandrew, Feb 3, 2003.

  1. pandrew

    pandrew
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    I've recently connected my speakers (Elac Cinema 2) to my receiver (Yamaha RX-V630) and have this annoying problem.

    Whenever I change from one DSP program to another (i.e Prologic to Prologic II) I get a thud sound from the subwoofer.

    The subwoofer is connected via the LFE jack on the receiver.

    Does anyone know what could be causing this and could the sub or amp get damaged ?

    Also can someone explain what a RCA ground loop is?
     
  2. Tim1968

    Tim1968
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    I have a Yamaha AX620 and a philips sub and have exactly the same problem, like you i would appreciate any advise out there that could help..
     
  3. Ken

    Ken
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    I had a similar thing happen with a Denon about a year ago, the LFE channel eventual stopped working. The thump could damage your driver, it tore mine apart in the end. You may have a different problem, feel how much it is moving the cone.

    Ken
     
  4. Andywilliams

    Andywilliams
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    The problem is caused by pulling the sub cable out of the sub or receiver while powered up.There is a capacitor that you damage (in the receiver)by doing this it isnt much though to get it repaired or if your amp is under warranty shouldnt cost you anything so long has you dont mention pulling any cables out while switched on.From memory yamahas suffer most with this happening.
     
  5. IanLongstaff

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    Was about to post a question on exactly the same issue and saw this thread, so here's my experience.
    I bought a set of Mission FS-1 speakers and a Panasonic SAXR55 amp. Both are brand new and I have EXACTLY the same symptoms that you have. Changing function on the amp causes a thump.
    I went back to Panny and they said "Sorry Guv, nothing wrong with our kit"
    I went to Mission and got the same response, only a bit shorter.
    In the end I took it to a local repair shop and commissioned them to do me a report. After 6 weeks of poking and prodding, they said they located it to an incompatibility of the 2 components and that it was caused by the "floating earth" The act of physically change a function, required that the signal be earthed and as both components have a floating earth, the receiver dumps it to the sub.
    They tried earthing out the receiver to no avail, though they said that if they could have (without damaging the equipment) they would have earthed the 2 together to see what happened.
    In conclusion, they said that I needed to find a receiver that by trial and error, works with my speakers.
    I am therefore quite interested to understand more about this "unplugging of the sub" that has been mentioned on the thread and how I get this checked, just as a sanity check so to speak.
    Finally, the repair man said that although that Panasonic didn't own up to anything, the way that the techie was talking to him, it was his best guess that this is much more widespread than people might think and that the manufacturers don't want to own up to the problem coz as they say, "If you acknowledge a problem, you own it!"
    Thoughts?
     
  6. Andywilliams

    Andywilliams
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  7. IanLongstaff

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    Many thanks Gozo for the link, I hope that Pandrew also gets a resolution!
    Best regards
    Ian
     
  8. 4Real

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    Yes if you connect and fiddle with cables and wires while amp/dvd etc. are still on it could damage something inside!!

    1 - ALWAYS switch off everything COMPLETELY from the MAINS (not standby mode) - tedious but worth it.
    2 - It is a good idea to remove any static build-up on your hands by touching a metal surface - (PC case, C/H radiator etc.)
    3 - NEVER EVER touch the inner/center pins/plugs on phono, component, coaxial, Scart, HDMI, DVI, Firewire RGB, Audio cables etc. (even when system is swtiched off completely)
    4 - DO NOT yank cables in haste to get system up and running again
    5 - DO NOT push cabls in by FORCE because you are in a hurry to hear your new system
    6 - Make sure all wire connections are secure and not loose
    7 - It's a good idea to switch on one component system at a time gradually (Amps then... DVD then... Active Sub... etc.)
    8 - Make sure volume on all connected components are turned down very low before switching on.
    9 - It's good practice to turn volume down "reasonably" before switching off
    10 - Avoid using really old degraded cables -(years old) if you can; Don't fold cables too rigedly/tightly when storing away. Better to wind it up in a circle.

    Yes, most on the list are common sense but hey... :cool:
     

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