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Getting HUM w/ my M-2000! HELP!!!!!

Discussion in 'Amps and Cabs [BG]' started by QTraXQ, Mar 1, 2004.


  1. QTraXQ

    QTraXQ Guest

    Aug 16, 2002
    San Antonio, TX
    1.) I've tried several configurations to connect a DBX 166XL and a DBX 1231 to my Mesa/Boogie M-2000.. IF I use the Send and Return, I get a constant 60hz HUM without a groundlift adaptor, but with a ground lift I get noise which will amplify as i adjust the Volume..

    *Above scenario:IN a RACK and without Rack :bawl:*


    2.) If I connect my Bass into either device(DBX1231 or 166xl) and go straight into the Active Instrument Input I get Noise which amplifies up as I adjust the Volume on the M-2000.. If I use a Ground Lift adaptor I get a Lower amount of Noise which amplifies as i turn the gain and Output Volume Up..

    *Above Scenario:Out of Rack..*

    If I use the Active Instrument Input but in the rack I get more Noise..


    I Obviously Believe its a Ground Issue but cannot figure how to rid myself of this Hum. Hasn't anyone else use an M-2000 with Other Gear like a Compressor or an EQ or Rackmounted Equipment..???

    :help: :crying:


    PS:I can use my BOSS Chorus, SansAmp Bass DI, and Ibanez Phat-Hed without any of the above noted Problems and in any Configuration.. If I remove the connection from the M-2000 I do not get any noise even though they were in the same rack..

    I have since taken back the rack and may get 2 seperate rack but logically thinking I feel as though the hum and/or Noise will probably Continue.

    Edit: I also tried removing the ground wire at several points on the cables and tried connecting each DBX component 1 at a time...
     
  2. natrab

    natrab

    Dec 9, 2003
    Bay Area, CA
    Call Mesa Boogie and see what they can figure out over the phone. (707) 778-6565

    When I had trouble with my M-2000 pedal not working, I called up and their bass amp tech spent an hour with me on the phone testing each individual strand in the cable as well as the sockets on the back of the amp. In the end he had me open up the jack and low and behold a wire had come undone. I desoldered and resoldered them all and it worked like new. Their tech guys are really nice and can usually help you out a lot over the phone.
     
  3. QTraXQ

    QTraXQ Guest

    Aug 16, 2002
    San Antonio, TX
    I am definitely going to call tomorrow.

    Have you ever hooked up any equipment requiring a 3 Prong Plug or any rack equipment with your Mesa either through Send/Reurn or through Instrument Input?
     
  4. Benjamin Strange

    Benjamin Strange Commercial User

    Dec 25, 2002
    New Orleans, LA
    Owner / Tech: Strange Guitarworks
    Did you try the ground lift on both items, or just the amp?

    Does the DBX make noise on it's own? Odd that it makes the hum and a pedal doesn't. Could that be the issue?
     
  5. QTraXQ

    QTraXQ Guest

    Aug 16, 2002
    San Antonio, TX
    I tried lifting the ground using a 3prong - 2 prong adaptor on both dbx's but not on the mesa.. I feel the power the M-2000 is pulling is a little to dangerous to play the Ground-Lift Game.. I may try that after work tonight but will leave the ground on 1 of the dbx's..

    I will never run my setup with out one piece of equipment grounded somewhere throughout. Anyone disagree with this? :meh:


    PS: There is no Ground-Lift Switch on any of the Gear so I am using an Adaptor.. Also the Foot Pedals are using batteries not 3 prong plugs..

    Ive read that the supposed "Ground Loop" problem is caused by a difference in ground Potential somewhere through out and could be cause if a piece of equipment is chassis ground and one is signal Grounded.
     
  6. natrab

    natrab

    Dec 9, 2003
    Bay Area, CA
    Well the effects loop on the mesa isn't grounded (I don't think) so the problem shouldn't be ground lift. If you were using the DI out on the Mesa (which is the 3 prong XLR), then you should definately put the ground lift on that side and let the DBX ground that circuit.
     
  7. TimmyP

    TimmyP

    Nov 4, 2003
    Indianapolis, IN
    First, it's not a good idea to float the AC ground of a component, other than as a temporary troubleshooting test.

    If you connect the loop out to the loop in with a cable, does it add any hum or noise? If yes, disconnect the shield at one end of the cable. Did this solve the problem? If it was noise and it did not solve it, the noise is in the loop circuitry. If it hummed and disconnecting the shield it solved it, add in the first outboard piece. If it hums, disconnect the shield on one end of the second cable. If that fixes it, add in the second outboard unit. If it hums, disconnect the shield at one end of the third cable.

    Hope this works for you.
     
  8. QTraXQ

    QTraXQ Guest

    Aug 16, 2002
    San Antonio, TX
    Sorry Timmy but I'm way ahead of you on what you wrote in.. I've tried those.. Believe me I wouldn't want to Lift a Ground on any piece of equipment whether the equipment is being grounded together thru the chassis/rackmount or Cables..

    A guy at my local music store says that lifting a ground wouldn't hurt me unless it was raining and I was standing in the Water. He then said that I was still protected because of my Rubbersole shoes, the connection to the rack and the cable connections.. LOL


    I have already tried detaching the ground wire on each cable and with out the rack.

    Thanks for posting