Quad L-ITE subwoofer rustling sound

Discussion in 'Subwoofers' started by playedalive, May 6, 2012.

  1. playedalive

    playedalive
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    Hi
    Recently my Quad L-ITE subwoofer has started to make a sort or rustling sound.

    This will occur even when just the power lead is attached and powered on. Even when I disconnect the power lead it will continue making the sound for around 10 seconds. It works when i attach it to the amp but will continue making the noise along with what is being fed to it.

    I have tried the normal procedure of different power leads and even turned off everything around it in case it was interference.

    To make it easier to undersand what is going on I have filmed it and poped it on youtube:




    This just me sliding my phone underneath it with just the power lead attached.

    The amp is now around 4 years old so well out of warranty.
    Is there anything that can be done to repair this? I myself am not competent at electronics repair but I know others who are.

    Thanks
     
  2. hifix

    hifix
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    Sounds like it'll need to be serviced. Something on the amp board isn't happy.
     
  3. bigsta

    bigsta
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    Did you get this fixed? My sub (again about 4yrs old) has started doing this at 3am the other night, initially very loudly! I've called quad and they suggested sending them the amp part of the sub to them to check but no idea of cost etc?
    So be great if you could let me know how you got on?
     
  4. mavice

    mavice
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    Mine too.

    3am in the morning I had a massive thunderstorm in the front room that turned out to be the sub.
    Now it either rustles or starts to pop and boom progressively louder regardless of input.

    I have the maintenence manual for the system from Quad and amp circuit diagram & parts list if anyone is interested and IAG (Quad) support suggested it could be a failing transistor - but which one - there are loads !
     
  5. Oxide

    Oxide
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    My sub has started doing the same thing. I contacted IAG and they said to send them just the amp unit off the sub however when I unscrewed it, the power cord and power switch don't appear to be easily disconnectable.

    Anyone please know how I can detach these?
     
  6. mavice

    mavice
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    As an update. I experienced this problem after the sub was in storage for several months. I persevered with it, using it occasionally but making sure powered off at night, and the problem 'seemed' to have gone away.
    So possibly could be a capacitor issue ? ...anyway, regular use and turning off at rear switch when finished seemed to improve.
    We still own it and it regularly has no use for months on end as now resides at a holiday home....so will report back if it occurs again after inactivity.
     
  7. lumagaco

    lumagaco
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    Hi mavice,

    I have the same issue with my Quad Lite Subwoofer and after open it seems be a failing transistor. Please, could you provide me the maintenance manual and the amp circuit diagram & parts?... Without that it's very complicated try to fix the problem.

    Thanks.

    Luis
     
  8. lxplmo

    lxplmo
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    I'm having the same issue too. !! I've opened the sub and manage to extend the cabling to be able to measure voltages. There are two boards inside (pre-amp & display control) and ( psu & amp), ac transformer is inside the box there is no need to reach it.
    The noise cames from the psu&amp board, I've checked the system without the pre-amp and the rustling sound persists. DC voltages looks fine to me so I'm afraid there is one or several transistors in the amp part the ones who causes the problem.
    >>>>@mavice
    >>>>I have the maintenence manual for the system from Quad and amp circuit diagram & >>>>parts list if anyone is interested and IAG (Quad) support suggested it could be a failing >>>>transistor - but which one - there are loads !

    If you don´t mind sharing the manuals and schematics it will save me a lot of time of blind tests. If I fix the sub I will post the results od the faulty parts.
    Thanks in advance.
    Alex.
     

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