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Pedalboard grounding problem...it's my AC-'Tron

Discussion in 'Effects [BG]' started by Mad Subwoofer, Jul 15, 2002.


  1. Finally got my huge pedal board all wired up with a Voodoo labs power supply and Morgan Miller three-loop CPR bypass switcher; it's a great setup. BUT...their is of course that evil 60 cycle hum we know all to well. I have like three transformers and it's none of them...the only AC powered unit in my setup is my vintage Mutron III, the AC powered model. It's a terrific box, plugs right into the power bar, no weird bipolar power supply of anything. It is the cause of the hum. I unplug it from the AC...no hum. It's true bypass..it has a three prong plug so is grounded to the wall or something. I never had this hassle when it was just in my regular floor setup, I've had it for about a year; no 60 hz hum at all. This grounding problem is only with my new board.
    So.....do I lift the ground??? What d'ya all think? Risk death for a smooth quite tone? The "Pedal Power" is three prong but the DC outputs are seperated..the three-prong FX box in my setup is the Mutron. Maybe I should just trade one of you who has a vintage model with the Mutron bi-polar power supply for this AC-model.
    I dunno.....help!
     
  2. Josh Ryan

    Josh Ryan - that dog won't hunt, Monsignor. Staff Member Supporting Member

    Mar 24, 2001
    I'd hate to tell you to risk death and then find out you'd been turned into a chicken nugget at a gig somewhere. That said, I hate that hum. Can post a pic of your setup?
     
  3. Here's a shot B4 I wired it all up..the AC-Tron is on the far right...

    [​IMG]

    This is the actual pedal board, split level.

    [​IMG]

    I have the Morgan Miller, three loop CPR as the "brain."

    1st loop>Korg G5

    2nd loop>EBS oct>Mutron III+>Mutron III>DOD FX25>Chunk fuzz>EBS BassIQ> P+C>

    3rd loop>MXR Phase 90

    Then to my Akai Headrush>Mesa M-2000>BBE>DBX120XP>EB/MM2x12's.
    The CPR means i can turn any or all my FX off/on at once...and it's true bypass!
     
  4. Josh Ryan

    Josh Ryan - that dog won't hunt, Monsignor. Staff Member Supporting Member

    Mar 24, 2001
    So you can use loop 1 + 2 +3, OR 1 OR 2 OR 3 , 1+2 but not 3 etc. and any permutation of? Very cool! I think I'm going to get that just for those times when I play through a P.A. and can't bring the rack. Actually, that would be really advantageous.
     
  5. Thanks...I still don't know what to do. My connections are all unbalanced of course. I guess I need to "transformer isolate" my AC-Mutron III, how the hell I do that I wouldn't know. It still looks like lifting the ground on the 'Tron is my only option???
     
  6. lneal

    lneal

    Apr 12, 2002
    Lee County, Alabama
    Its confusing, I know. Back in "the good old days" equipment manufacturers put "polarity" switches on things (ala old Fender amps). They were very effective at solving things like your problem. Some questions:
    1) Is the case of the Tron touching the case of anything else?
    2)Is there any other way the case of it could find its way back electrically to any other case other than through the signal cables?
    3)Does that Tron have plastic or metal in/out jacks?
    Not being familiar with that model I don't know. (My re-issue Tron has a "wall wart").
    These problems can be a pain to track down. Let me know, maybe-maybe I can help! Also, read the Rane note a time or two and maybe it will make sense.
     
  7. I'll go over the Rane notes again but from my first time through I didn't see much that applied? It's all unbalanced connectors, the 'Tron is connected via 1/4" plugs to everything else so no isolation is possible, no matter what?

    1) Yes..I'll try isolating it. I should be able to hold it in my hand just to see?
    2)Yes; see (1)
    3)Metal

    Thanks....
     
  8. WOW...I thought that I was FX crazy, but Mad Sub, you take the cake. I sincerely hope that you solve that hum problem tho'.