AC adapter hum

Discussion in 'Effects, Pedals, Strings & Things' started by HarryJ, Sep 22, 2005.


  1. HarryJ

    HarryJ Member

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    Hi,

    I am getting hum from both the Boss adapter (used for 4 devices) and the dedicated adapter for my Boss SE 70 multi effects.

    If I move both adapters out of my pedalboard, it goes away, and works just fine

    I use George L's in the board, and Lava's for the guitar and amp

    Does anyone have any idea how to reduce the hum and keep the adapters in the board?

    Thx

    HJ
     
  2. dosmun

    dosmun Member

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    Are they regulated?
     
  3. HarryJ

    HarryJ Member

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    Boss PSA120T
    I think so, couldn't see it in writing, but it certainly was designed for audio

    HJ
     
  4. stinkfoot

    stinkfoot Member

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    One (or more) of your pedals is sensitive to the electro-magnetic fields emitted by the adapters. When this happens, a wah pedals is usually involved (those are notoriously sensitive to EMI fields). Try running the wah pedal on battery power, and see if it helps.

    Of course, if you don't have a wah pedal (or if battery power didn't help), you will simply have to move the adapters to a location where they won't disturb the pedals.

    /Andreas
     
  5. HarryJ

    HarryJ Member

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    Humm... no wah

    The hum also seems to change in intensity. Some gigs it's hardly there. Some I can simply rotate the adapters, while some I have to move them away from the board

    I'll have to try one at a time to see if there is one effect that is causing this.

    Can the adapters be shielded any better?

    Thx

    HJ
     
  6. HarryJ

    HarryJ Member

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    Looks like the adapter for my SE-70 is the main offender.

    It is a 14V AC output. Sooo... that kinna brings me back to the extra shielding option? Since the Voodoo Lab won't help here

    It seems to react when near my beloved Barber Tone Press and Sans Amp. These are both in steel cases, I assume grounded?

    What is so strange is that on some days it doesn't seem to hum. It also seems to be affected by different clubs.
     
  7. dosmun

    dosmun Member

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    Is there a ground pin on the AC adapter? I have an old MXR AC powered Flanger and I had to ground lift it to keep it from humming.
     
  8. dosmun

    dosmun Member

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    Make sure you have your Amp and pedalboard both plugged into the same circuit.
     
  9. HarryJ

    HarryJ Member

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    Thanks, No it's 2 prong
    I don't think it's any kind of ground loop issue. If it were the hum would not go away when moved away from the devices.

    I believe that it is the magnetic fields from the transformer in the power supply reacting with the devices.

    I want to see if it can be shielded, and how

    Thx

    HJ
     
  10. jaymeister

    jaymeister Supporting Member

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    It sounds like the proximity of the transformers to the signal cable. You need to keep them apart.
     
  11. HarryJ

    HarryJ Member

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    Thx Jay,

    I realize that. My question is can it be shielded to minimize the problem?

    Someone had mentioned putting it in a steel box

    How would I ground the box?

    Thx

    HJ

    P.S I just also took someone elses advice and ordered the Visual Sound 1 Spot adapter. Apparently it is the same as the Godlyke adapter

    HJ
     
  12. drolling

    drolling Member

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    Boss PSA is a regulated power supply, don't know about the other one. Don't know why they don't indicate on the adaptor whether it's regulated or not. Some digital circuitry (like the Strobostomp's, for example) can be damaged by an unregulated power supply.

    The OneSpot's a good one, but some users claim that it is noisy with certain pedals. I've got the Godlyke Power-All, which is supposedly a bit more reliable in this regard.
     
  13. DK207

    DK207 Member

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    I've got the onespot and don't have any problems with noise. I'm really happy with it for the low price tag. And you can just add on more of the daisy chain cords if you get crazy and buy more pedals.

    :cool:
     

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