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Help! Problem with amp last satuday

Discussion in 'Amps and Cabs [BG]' started by soulgroovn, Jan 21, 2003.

  1. soulgroovn


    Oct 25, 2002
    New Haven CT

    Last saturday my amp developed a loud hum when going direct through to the PA. It's an Ashdown EVO 500, it does not have a ground lift switch, and it's the first time that this has ever happened with this amp. So, I changed mic cables with a brand new one and the hum was there. Next, I took my Aphex 402, wireless, and rack tuner out of the mix and the hum was there. Next, I unplugged the amp from the wall and the hum was still there when I connected to the DI--> board. Does this mean that the club just had a serious grounding problem and I'm lucky to be alive or is my amp fried?


  2. ZuluFunk

    ZuluFunk Supporting Member

    Apr 14, 2001
    Next time you play the same club, run through a DI box.
    If you still get the hum, it may not be your amp.
  3. dsmith


    Mar 29, 2001
    Mt. Vernon, KY
    Had the same problem a little while back. Changed cables, batteries, changed everything. Then I went directly to the amp (no wireless) and found that solved the problem.
  4. soulgroovn


    Oct 25, 2002
    New Haven CT
    Thanks guys.

    I actually went direct and the same thing happened but what really got me is that I unplugged the amp and it happened. I think it was a bad ground.
  5. my Mesa m-2000 has the same problem. This cures it:

  6. soulgroovn


    Oct 25, 2002
    New Haven CT
    Thanks not78! I'll look to get one of those for this friday's show.
  7. monkfill


    Jan 1, 2003
    Kansas City
    Are you saying that you completely bypassed your amp, going bass > DI > PA and heard the hum through the PA? If your amp is completely out of the loop, then the amp obviously isn't the problem. . .
  8. soulgroovn


    Oct 25, 2002
    New Haven CT

    What I did was I physically unplugged the amp with nothing connected to it. Just a plain unplugged amp. When I placed the mic cable in the amp's DI and the connected it to the board, I still got an aweful hum.
  9. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    You also might want to carry in your bag a simple three prong to two prong electric cord adaptor. Sometimes using one of those will remedy a bad hum. A good 69 cent item can come in handy . . .
  10. Petebass


    Dec 22, 2002
    QLD Australia
    Monk's right, it's not your gear causing the hum. I've had this situation plenty of times and it's usually fixed by getting the sound guy to change his DI lead. They're not always happy to oblige but stick to your guns. And prove it to him by unplugging his dodgy lead and the hum will disappear instantly.
  11. That's a potentially deadly solution. The third prong is on the power cord to carry any excess voltage to ground in the event of a fault. If the power ground lift fixes your hum, disconnecting the audio ground (pin 1) will accomplish the same thing without putting you in danger of electrocution.
  12. soulgroovn


    Oct 25, 2002
    New Haven CT
    I may be wrong but isn't that what a ground lift switch does on most direct boxes? My amp doesn't have one and I called the guys from bassNW where I purchased it and they recommended doing the same thing.
  13. thats what the item taht I suggested does: its a ground lift. ;) I have no Idea why hi-dollar amp manufacturers think that we can get around having one for our DI.
  14. soulgroovn


    Oct 25, 2002
    New Haven CT
    Hey people,

    Just a little followup post here. It turns out that my freakn' guitar player put phantom power across the entire board to accomodate the one mic for his talkbox. Grrrr..... I asked him to take the phantom power off of my channel and it fixed the problem. After that, I seriously thought about using extra wide vibrato and totally abusing the use of fills during every guitar solo for the night, but I didn't. :D