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GK 150 MB - DI?

Discussion in 'Amps, Mics & Pickups [DB]' started by pdbass, Jul 27, 2007.

  1. pdbass


    Jan 2, 2007
    Did an outdoor gig yesterday at a big ampitheatre. The soundman ran a line out of the DI of my GK combo. The amp started breaking up, especially when I "dug in" on the bass. It was pretty noisy coming out of the amp, as well as the line that the house had. Funny thing, though, when he took the XLR out of the amp, the breakup disappeared(?). My sound was clean as can be, so I went into a direct box instead.

    What gives? Anybody ever have this problem with a GK MB amp before?
  2. Jeff Bonny

    Jeff Bonny

    Nov 20, 2000
    Vancouver, BC
    Sounds like it might have been a problem with the PA system. Have you checked it through another PA yet? FWIW I've heard soundmen comment more than once that they like the DIs in those little GK amps.
  3. pdbass


    Jan 2, 2007
    That sounds totally plausible--and I'm thinking that maybe he had phantom power on the channel, or something. I haven't tried it through another PA, but tomorrow I'm playing a big outdoor jazz festival with both of the festival's headliners (this is what happens when you play bass). I'm not sure if I should bring the GK or the AI (backup amp) yet.
  4. Bishbass


    Jul 13, 2007
    Boston, MA
    Paul, I have had the same problem with both my GK combo ( using both the 1/4 " out on the back of the amp, and the XLR out on the front), and my Walter Woods setup. It always ends up being a problem on the sound company's end (bad cord, bad direct box, etc.).

  5. Bring the GK and don't worry. Killing the soundguy usually solves the problem anyway...
  6. Bishbass


    Jul 13, 2007
    Boston, MA
    Ah yes.........but where to hide the body?:ninja:
  7. Leave it there - just make sure it's properly labeled as soundengineer's body. That's no criminal, I suppose.
  8. Reuben

    Reuben Supporting Member

    Aug 8, 2005
    Brooklyn, NY
    Live sound engineers can be run off 48volt phantom power anyway.
  9. pdbass


    Jan 2, 2007
    Thanks, Dave. I don't feel so nervous about tomorrow now.

    Now about soundmen, I prefer sending them AS LITTLE power as possible, dig?
  10. Bishbass


    Jul 13, 2007
    Boston, MA
    No problem Paul. Hope all goes well. Have a great time tomorrow.
  11. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    This happened to me once with my MB150, and it was at an outdoor gig too. The direct outputs of the MB150 are coupled with capacitors, so it should be able to survive phantom power. But perhaps the problem was caused by some severe ground loop.

    This is not a scientific statement, but I have gradually formed the opinion that outdoor power is always evil.

    A good transformer-coupled direct box is your friend in these situations. Always a good thing to keep in the trunk of the car, I suppose.
  12. I often heard that the di signal out from my mb150 is very (too) hot.
  13. Joe Smithberger

    Joe Smithberger Supporting Member

    Mar 8, 2002
    Canton, Ohio, USA
    The DI is post EQ isn't it? If so the input gain and the eq settings are sent to the house. I always have to turn the bass knob back down when I send to the PA.
  14. Joe Smithberger

    Joe Smithberger Supporting Member

    Mar 8, 2002
    Canton, Ohio, USA
    My bad.
  15. pat.p


    Nov 20, 2004
    Poland, Poznań
  16. speedster


    Aug 19, 2005
    Ontario Canada
    The MB150S XLR output is pre-eq, pre-preamp etc.... The 1/4 " output line out is post eq and post pre-amp and thus the settings can adjust signal to the board.

    I've found that on occassion I've discovered a bad ground loop that the switch on the GK MB150 can solve.

    These amps are awesome electronically but unfortunately according to my local repair guy they have 1000 dollar electronics and 50 cent input & output jacks....

    I've had to have mine cleaned on more than one occassion after having crackling and popping sound problems at large festivals...

    I usually use the 1/4 line out and set my tone and sound on stage and have the sound guy do a little tweaking for the room but board can be left relatively flat otherwise.....

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