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Ground Hum?

Discussion in 'Amps and Cabs [BG]' started by TrooperFarva, Oct 7, 2006.


  1. TrooperFarva

    TrooperFarva

    Nov 25, 2004
    New City, NY
    I think I have a ground hum problem, but I'm not sure what to do about it. I just picked up a used Valenti from Nino himself earlier today (that's another thread entirely) but that's when I started to suspect that I had a ground problem. Before, when I used my Fender w/ J-Retro, if I boosted the treble, or used the bright switch, there would be a hum, which would stop when I touched the strings, or anything metal on the bass. I assumed that it was a ground problem with the bass itself, and since I usually roll off the treble anyway, it wasn't a big deal. So I tried out the new Valenti, and it sounds awesome, but there is a hum problem. I didn't experience it when I tried it out at Ninos house. It has a Sadowsky preamp, no VTC, so it's boost only. When the treble is flat, the hum is slight, but it's pretty annoying when I turn the treble all the way up. Again, not the end of the world, since I like to leave the treble off and add some bass. The hum stops when I touch the strings, or anything metal on the bass. But, the hum also stops if I touch anything metal on the amp, without touching anything metal on the bass, which makes me think that it's a ground problem with the amp itself. The same thing happens with my Fretless, when the Tone control is wide open. But it doesn't happen with my Sterling, at least not in Parallel mode, I didn't try single coil. It also happens with the Kern, not just the Aguilar. And when it happens, the amp is not touching any other electrical devices. The Aguilar is in it's rack bag, by itself, plugged into the wall, connected to the speaker cab (it happens with both cabs), and the bass. No DI or anything like that. Is this a ground problem? What can I do to stop it? I find it weird that it doesn't happen with the Sterling, is this just something that happens with Single Coils? In the case of the Fender and the Valenti, the blend control is centered, and in the case of the Fretless, both volumes are wide open. The ground lifts don't do anything. Any ideas? Should I use an isolation transformer? My friend has a 'Hum Eliminator' which essentially is an isolation transformer, I can try it later. I searched the forum, but didn't find anything relevant. Thanks.
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    It's normal. If the hum didn't go away when you touch the bass then you'd have a problem. Humbuckers have less hum than single coils. Otherwise they couldn't call them humbuckers.
     
  3. TrooperFarva

    TrooperFarva

    Nov 25, 2004
    New City, NY
    What causes it exactly? Will an isolation transformer stop it?
     
  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    It's caused by RFI and EMI and is perfectly normal. I don't think a transformer will stop it but I've never tried one to find out.
     
  5. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Jan 16, 2021

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