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Thread: Help! New Amp Hum

  1. #1
    Forum Member OldStrummer's Avatar
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    Help! New Amp Hum

    I am in the process of moving, and I took my Monoprice tube amp over to the new place by myself, to avoid potential punishment by the movers. I set it up in what will be my guitar practice room, plugged in one of my SGs, and flipped the switch.

    Holy racket, Batman! The audible hum emanating from this box is astounding. I swear it didn't make that noise when I had it in the old home. I must have bumped something (so much for the movers, hey?), but what, and how to rectify it is beyond me. I know I've been distracted with all the things that go into a move, but is there a simple fix?

  2. #2
    Forum Member chuckocaster's Avatar
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    Re: Help! New Amp Hum

    Try plugging it in somewhere else and see if it still makes that noise. If it's an older house it might be the electrical wiring. Sometimes amps make noises when they're on the same circuit as florescent lighting and dimmers, stuff like that. Unless it was dropped, I think it's more likely the power in the house and not the amp.
    "don't worry, i'm a professional!"

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    Forum Member Don's Avatar
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    Re: Help! New Amp Hum

    Chuck's right. Also check that all of the tubes are completely seated in their sockets. One of them might've gotten jarred loose in the move.

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    Forum Member OldStrummer's Avatar
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    Re: Help! New Amp Hum

    Thanks, I will do both of the above. The house isn't that old (1999) and the condominium I'm leaving is even older (1991). There aren't any fluorescent bulbs (that I know of), but I have multiple electrical outlets in the room, so I can check them all. If nothing's loose (I was careful moving it, but still, road bumps or such...) Is there a filter I can put between the outlet and the amp's power supply?

  5. #5
    Forum Member chuckocaster's Avatar
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    Re: Help! New Amp Hum

    Yep, it's called a power conditioner and there's several companies that make them.

    I just highly doubt that YOU did something in your travels to make the amp hum. That's usually a case of a cap or resistor going bad, and that's usually from use not transporting.
    "don't worry, i'm a professional!"

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    Re: Help! New Amp Hum

    I agree-house electrics,tubes,or both.In my last house ,in one room i could pick up radio shows and what sounded like some foreign dictator addressing the nation!(Cheap stock valves],upgraded to mesas,amp sounded amazing,stopped picking up random stations,kind of missed them for a while;)

  7. #7
    Forum Member OldStrummer's Avatar
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    Re: Help! New Amp Hum

    Quote Originally Posted by chuckocaster View Post
    Yep, it's called a power conditioner and there's several companies that make them.

    I just highly doubt that YOU did something in your travels to make the amp hum. That's usually a case of a cap or resistor going bad, and that's usually from use not transporting.

    Well, that's a relief. The trip from old to new houses is only six miles.

  8. #8
    Forum Member Don's Avatar
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    Re: Help! New Amp Hum

    Quote Originally Posted by chuckocaster View Post
    I just highly doubt that YOU did something in your travels to make the amp hum. That's usually a case of a cap or resistor going bad, and that's usually from use not transporting.
    Once again, I agree with Chuck (that happens pretty often). These amps get moved around a lot with no issues and a loose tube isn't likely to cause a hum, but it's worth it just to make sure they're all seated. The issue is most likely related to something outside the amp.

  9. #9
    Forum Member chuckocaster's Avatar
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    Re: Help! New Amp Hum

    It is possible that you have a microphonic tube, might've been on the edge and the move exacerbated it. Reseat the tubes like Don said, then flick each tube with a fingernail. You'll hear a "plunk" through the speakers when you hit the bad tube.

    How bad a hum we talking here? And does it change if you point different directions? This kind of stuff is hard to diagnose over the internet. But I'm hoping it's something easy. I'm sure you can find a used Furman power conditioner on CL or at a local music store. They're not too expensive new, but it's always nice saving a couple bucks.
    "don't worry, i'm a professional!"

  10. #10
    Forum Member DanTheBluesMan's Avatar
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    Re: Help! New Amp Hum

    I wouldn't let the age of the house be a factor, it's more like the competency of the crew building it. I would definitely think it's the wiring and not the amp.

  11. #11
    Forum Member Don's Avatar
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    Re: Help! New Amp Hum

    Modern wiring can sometimes be worse. CFL lighting, electronic dimmers...

  12. #12
    Forum Member OldStrummer's Avatar
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    Re: Help! New Amp Hum

    It's too early to tell, but last night during my last trek to the new home, I moved the amp, plugged it in and let it warm up. Sure enough, the hum returned, even though I had moved the plug to a different outlet. I turned the power off, plugged in my SG and hit the switch again -- no hum! I only played for a few minutes, but there was no evidence of hum during the time I made the strings vibrate. Go figure?!

    Since it's a guitar amp, if it doesn't hum when a guitar is plugged into it, I should be okay with it.

  13. #13
    Forum Member CoyotesGator's Avatar
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    Re: Help! New Amp Hum

    Get one of the cheap polarity testers they sell at the home places.

    It'll quickly tell you if the outlet is wired correctly.
    What happend?
    Who let the magic smoke out?

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