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Subwoofer - connection

Discussion in 'Subwoofers' started by Ridcully, Jan 7, 2003.

  1. Ridcully

    Ridcully
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    Right, I think I must be going through a massive stupid moment but here goes.

    Borrowed a sub from a friend to see how much difference it made. I have a Technics DX930 receiver and the sub is a KEF PSW1000. The receiver has a 'sub woofer out' RCA and the sub has a right and left line in RCA. I have tried both / either connection using an rca cable but I get what I would call mains hum as though something isn't grounded.

    Have I
    a) wired it up wrong
    b) got a knackered receiver which I've only just found out about as this is the first time I've tested the sub thing on it
    c) something else

    Anyone, Please
     
  2. jim.rae

    jim.rae
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    All the subs I have used only have one phono in from the amp...

    Sub sound by default, is mono.

    What does it say on the phone in sockets on the sub?
     
  3. Ridcully

    Ridcully
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    The subwoofer rear has the following.

    Speaker input left +&-
    Speaker input right +&-
    Speaker output left +&-
    Speaker output right +&-

    Which look as though they take the main speaker inputs and then feed these to satelite speakers. I am not using this

    Line in left - RCA
    line in right - RCA

    which are the two I mentioned above. The instructions seem to indicte that both are wired when using a pre amp. Or just to line in right when having a subwoofer output from an amp. This what I tried.

    High pass output left - RCA
    High pass output right - RCA

    Looks to be a loop through to a power amp for satellite speakers, if used in this configuration.
     
  4. cybersoga

    cybersoga
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    It should go into the line in on the sub, from the subwoofer pre out on the av reciever.
     
  5. Ridcully

    Ridcully
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    Yep. That's what I did. And I get something similar to a mains hum.
     
  6. DaveP

    DaveP
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    How good is your lead? I had a bad attack of the hums but got a better quality lead and it improved it no end. Also, make sure it doesn't go near any mains cables or plugs!

    DaveP
     
  7. Nobber22

    Nobber22
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    Have you set the sub out (LFE) on the amp to on? If your main speakers are set to large, this may be disabled. Go into the amp's (onscreen) menus......
     
  8. James45

    James45
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    left or right makes no difference... although if you added a y-splitter to the end of your sub lead you could feed both left and right, this apparently improves the sensitivity of the sub's auto-on setting which switches intself off if no signal is detected.
     
  9. neoxp

    neoxp
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    I have a PSW1000 and have it connected from the sub-out on my amp via RCA cable to the right RCA input on the sub. I use QED cable. This appears to be the same way you have. This worked out of the box. I assume the sub is OK?

    Some people actually prefer to use the speaker inputs anyway. To do this you run another set of speaker cables to the sub from your amp (the same outputs that feed your front speakers). If you do this make sure you disable LFE on the amp.
     
  10. Silent Fly

    Silent Fly
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    Ridcully,

    I would suggest you to try the following:

    1. Turn the sub volume to zero. Connect your sub to the DVD player directly using the L (or R) output and play something. Turn up the sub volume (slowly). If you can still hear the hum it is the sub or the cable.

    2. If you cannot hear the hum with another cable, it is the cable.

    3. If you cannot hear any hum after test #1, it might be the amp. Connect the sub out of the amp to another amp line input. If you hear the hum is the amp.

    Silent Fly
     
  11. Ridcully

    Ridcully
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    OK.

    Definately not the cable. Tried turning all speakers to small and that didn't work. Not going to be able to play any more until the weekend so will try the direct feed from the DVD then

    Thanks for the help so far
     
  12. James45

    James45
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    try a search on earth loop and hum
     

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