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Done something stupid and created a feedback loop. Please help!!!

Discussion in 'AV Receivers & Amplifiers' started by Jamesv, May 13, 2005.

  1. Jamesv

    Jamesv
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    Hi,
    a friend of mine has done something stupid and created a feedback loop. He is now worried he may have damaged one of his components. His setup is as follows:

    Decks into mixer (analogue)
    mixer into amp (analogue)
    amp into computer line in (analogue) and also to Kef Eggs
    computer spdif out (digital) into amp


    Decks
    |
    Mixer
    |
    Amp--Kef Eggs
    ||
    Computer


    This is so live mix sets can be recorded onto his pc. If his pc wasnt connecting back into the amp then this setup works fine (this is needed to listen to audio from his pc), but because it is its creating a feedback loop. As the signal from the pc is digital the amp prioritises this and overrides the analogue signal from the mixer.
    This caused major feedback and sound distortion. Could this have damaged the pc motherboard/ amp or speakers?
    He is concerned the sound is grainier than it used to be. If damage occurred could it be negligable like this or is it more likely to have been more obvious ie blown speaker or crackling noises (meaning he can relax as its probably just his imagination?!)

    Any advice is much appreciated.
     
  2. pragmatic

    pragmatic
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    What amp is being used, also just turn the pc sound off i.e. mute it, or is that not an option?
     
  3. lee789

    lee789
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    Would it be better to take the mixer direct to the pc then from pc to amp ?

    When not using the pc to record you could take a line from the mixer direct to the amp?

    Not sure of exactly what kit he has, but I used to have a couple of synths which I hooked up to a Folio Notepad mixer direct to pc, then sent this to my amp, so the amp only got one signal.

    Not 100% on this as I am no dj expert but something to have a think on.
     
  4. Jamesv

    Jamesv
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    Cheers for the info guys. He is using a Yamaha AX750SE amp.
    Originally the mixer was routed to the pc then to the amp, but for some reason this caused a delay of about half a second throught the speakers. This became a problem when mixing because the headphones plugged into the mixer were playing half a second ahead!!

    He has now resolved the issue by unplugging the digital out from pc to amp when mixing/ recording. The main reason for the post was to find out if the feedback loop could have caused damage.
     
  5. pragmatic

    pragmatic
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    If you press the source button multiple times for a particular source you can select between anolouge and digital.
     
  6. Jamesv

    Jamesv
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    Problem has been resolved! Feedback was not down to feedback loop but down to using the phono sockets for the mixer. Apparently these are dedicated to phono only and cannot be used as a generic input. Switched to the cd in socket and everything ok now!!
     

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