Noise in Speakers: Hum

Discussion in 'Beginners, General Questions' started by Jon_Durham, Apr 1, 2003.

  1. Jon_Durham

    Jon_Durham Extra

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    When I connect my Hitachi 57wux20b to my stereo a temendous hum emits from my stereo speakers. I had the same problem with my 29" Hitachi and the only way I could over come this problem on the old TV was to turn off the internal speakers and connect the stereo via the external speaker connection.

    Here's my equipment:

    Dynaco Preamp
    Dynaco Amp by Van Alsine
    Dynaco Passive Home Theater
    Equalizer between preamp and amp
    Sony CD Player
    Harman Kardon Tape Player
    DBX unit
     
  2. Cees Alons

    Cees Alons Moderator
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    Jon,

    A "tremendous" hum signals a missing ground connection in the audio signal. How exactly do you connect your Hitachi to your stereo? What outputs/inputs do you connect and with what? What is your "stereo", BTW? Are your TV and your stereo set on the same power outlet (or at least close)?

    Cees
     
  3. Lee Carbray

    Lee Carbray Second Unit

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  4. Jon_Durham

    Jon_Durham Extra

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    A "tremendous" hum signals a missing ground connection in the audio signal. How exactly do you connect your Hitachi to your stereo? What outputs/inputs do you connect and with what? What is your "stereo", BTW? Are your TV and your stereo set on the same power outlet (or at least close)?

    Cees

    Hi Cees

    The only reason to leave the TV speakers on would be to use them as a center speaker.

    Back to my problem: Hitachi connects to the preamp via RCA cables. So does my CD player, tape player, equalizer (see below), DBX unit, and FM tuner. Stereo and Hitachi are on two separate outlets that are a few feet apart. Output from the preamp goes through the equalizer to the amp.
     
  5. Cees Alons

    Cees Alons Moderator
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    Jon,

    (Trying to get the picture). So all is right until you plug in the TV connection and then HUM? Are you sure (sorry for asking) to connect a regular Stereo-Out from your TV to the receiver input? How do you use your TV speakers as nothing more than a center speaker?

    Again: sorry for asking all these questions, but the problem does sound very interesting and challenging!

    Cees
     
  6. Lee Carbray

    Lee Carbray Second Unit

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    To use the TV as a centre speaker wouldn't the TV be hooked up from an audio out(high level usually) from the receiver to an input on the TV? And it would have to be set up in the TV's audio menu to be a centre speaker. Are we sure that this TV supports this. I could not find it on there web site(or anywhere on the net for that matter).
     
  7. Ted Lee

    Ted Lee Lead Actor

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    do you have cable tv?

    try hooking everything up like normal, then disconnect the cable co-ax feed (for your tv) from the wall. you might be getting a ground-loop hum.

    the fact that everything works until you hook up the tv makes me think this.

    if that is the problem, read this thread. it has some info on some parts you can get from rat-shack that may work to solve your problem.
     
  8. Jon_Durham

    Jon_Durham Extra

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    (Trying to get the picture). So all is right until you plug in the TV connection and then HUM? Are you sure (sorry for asking) to connect a regular Stereo-Out from your TV to the receiver input? How do you use your TV speakers as nothing more than a center speaker?

    Cees,

    Yep, hum goes away when I disconnect the RCA cable from the TV and am using the output audio on the TV.

    Haven't bothered much with the TV speakers other than shutting them down to see if hum goes away. Shutting them down has no effect.

    I have disconnected the coaxial cable and hum is still there.

    My thinking is the TV and audio equipment are not on the same ground.
     
  9. Cees Alons

    Cees Alons Moderator
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    Is it possible to use the same power outlet (with the same ground) for your stereo and your TV (even if it's just once, for testing purposes)? And did you also try another RCA cable (the cable just might be broken or so)?

    Cees
     
  10. Jon_Durham

    Jon_Durham Extra

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    I can use the same outlet with an extension cord. I'll check the RCA.
     
  11. Jon_Durham

    Jon_Durham Extra

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    I unhooked everything and the begun to plug in devices. Viola, no hum with all devices in the circiut EXCEPT the SURGE PROTECT for the cable.
     

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