Tube preamp hum

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Comments

  • rubin
    rubin Posts: 565
    edited October 2010
    I have 2 panamax conditioners. One of them makes a humming sound.When I unplug it the speaker hum stops. So I found the culprit.

    Strange thing is that the preamp is plugged into the other panamax unit, as was the ss pre (same hookup) and everything was quiet with the ss unit.

    Each panamax is on its own 15 amp circuit. However the humming p-max is very close to the preamp transformer. I will move it and see what happens.

    Thanks to all for their suggestions.
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  • fishbones
    fishbones Posts: 947
    edited October 2010
    Glad you found it!

    A lot of good info ended up on this thread for future reference. :D

    EDIT: My future reference.
    ..... ><////(*>
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  • rubin
    rubin Posts: 565
    edited October 2010
    Called Panamax, here's what they said....Because I'm using 2 surge protectors, the combination is causing ground loop hum, even though each protector is plugged into it's own dedicated 15 amp circuit.

    I mentioned that when I unplug the noisy one all is good. Their reply was, unplugging one unit resolves the ground loop issue caused by using both protectors at the same time.

    I'm no engineer so I couldn't argue to point. I was advised to plug all components into just one surge unit and if the hum is gone, then that shows there is a ground loop issue when using both protectors....DOES THAT SOUND REASONABLE?

    My only concern is if there is any possibility that the humming can damage anything. It's really not that bad/loud.
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  • rubin
    rubin Posts: 565
    edited October 2010
    Been switching power cords and ic's, can't get rid of the hum. Pulled the cover off the surge protector, it seems to have a slightly noisy transformer. It's probably been that way all along and became audible after swapping in the tube pre.
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  • george daniel
    george daniel Posts: 12,096
    edited October 2010
    jumping in this one kinda late,, but do you have your amp and pre connected to the same power surge unit? If so,,have you tried the amp straight to the wall?
    JC approves....he told me so. (F-1 nut)
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  • rubin
    rubin Posts: 565
    edited October 2010
    george daniel wrote: »
    jumping in this one kinda late,, but do you have your amp and pre connected to the same power surge unit? If so,,have you tried the amp straight to the wall?

    I had them plugged in both ways, no difference.The amp has a little bit of noise but with the preamp off I have to put my ear right on the speaker to hear it.

    The tube preamp adds a little more noise and the protector adds a little more. I never noticed any noise before the tube pre was swapped in, but I guess there always was some.
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  • rubin
    rubin Posts: 565
    edited October 2010
    THe noisey surge unit also has a usb port for charging cell phones etc. so the hum is always there, even when it's switched off
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  • rubin
    rubin Posts: 565
    edited October 2010
    Update....I've had the "new" tube preamp on for over 24 hours, the hum is almost gone. What's going on? The music/sound is really good also. I don't know what to think. Neil Young never sounded better. Tube audio is nice.
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