Home › Forums › Help/Technical Questions › Hum when using other than supplied 9V power supply

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  • December 10, 2009 at 10:55 am #79496
    HansHumblet
    Member

    I recently bought a Memory Man with Hazarai and a Voice Box. 2 great pedals, however, only when I use them with the 9V power supplies that came with them.
    When I try to power them using my T-rex Fuel Tank Classic, Fuel Tank Junior or Visual Sound One-spot adapter (1700mA), they start humming. Not very loud, but too loud to use them in a live situation.
    Has anyone experienced anything similar? Is there any way to solve this?

    Thanks in advance!

    December 10, 2009 at 1:17 pm #105116
    electro-melx
    Moderator

    ‘Yes’ is the short answer.

    The way to solve it is to use the 9V supllies that come with them or use a multi supply with isolated outputs … if the T-rex has isolated outputs then it probably isn’t putting out enough mA for these pedals.

    December 10, 2009 at 2:29 pm #105119
    Kevin Demuth
    Member

    i’ve had the same issue here with a Hazarai and some other pedals (Akai Headrush being one).
    there can be added background noise or a high pitched whine when running these pedals from a daisy chain (such as the One-Spot) or power supply with un-isolated outputs.
    however, i have found that some combinations of pedals work fine – i have around 50 pedals and there are only a handful which the Hazarai doesn’t like sharing power with.

    after looking at the specs for the T-Rex power supplies your using, it looks like the 9v outputs on the Fuel Tank Classic are not isolated and only output 500ma in total, so running the two named EHX pedals alone could already be straining the power supply. that could lead to noise in itself, even more so if the either (or both) of pedals object to sharing power.

    the Fuel Tank Junior HAS isolated outputs, but they only supply 120ma… so that could well be under-powering the EHX pedals.

    “Is there any way to solve this?”

    well, you’ve found the solution already: use the supplied PSU.

    the other option would be to buy another power supply, which has isolated 9v outputs providing 200ma (or more)… but obviously you don’t want to do that after already investing in the Fuel Tanks and One-Spot.

    December 10, 2009 at 10:01 pm #105161
    Mr.Grim
    Member

    there are many factors that go into the noise, power supply being the main one, so everyone’s experience with multi power units are different.

    in my case i currently have about 16 pedals on the board im using (more on the shelf of course) and i use 2 VS one Spots on all the pedals i can (9v ones that is) including the SMMWH, and i get no noise whatsoever!

    December 11, 2009 at 12:24 am #105168
    JackOtrades
    Member

    http://www.uniquesquared.com/servlet/the-63/Furman-SPB-8-Pedal/Detail
    I have an XO Polyphase, Hazarai, and a Riddle would this board work to power those 3 (amongst others) without their native power supplies? I also have a 1-spot with extra mini cables.
    Thanks, Jack

    January 29, 2010 at 9:16 pm #106929
    kaptainkaffeine
    Member

    Oh my, yes. This is what I registered here to ask about. It is very inconvenient to have to run a second power adapter from my pedal board just to satisfy the voice box’s finickiness. The adapter says 9.6v, but is the same amperage as my standard Boss style adapters and actually has printed on it that it is a replacement. The hum in the guitar amp is quite annoying and present when the VB is plugged into a different power supply, or is daisy chained with other pedals using the VB’s own PS. I have also noticed that at some clubs, the hum is awful even when using the VB with its own PS by itself. It has all the symptoms of a ground loop, but no lift on the unit. Does anyone have any ideas on how to deal with this live?

    August 1, 2010 at 6:15 pm #110602
    nyirijesse
    Member

    so im looking to buy the voodoo lab pedal power +2. just the 9v setting would work fine for ehx pedals? ive been under the impression that they required some very specific power deal

    August 2, 2010 at 2:19 pm #110612
    TheGhostMachina
    Member

    I to have had the hum from my Voice Box at certain clubs. I keep my Voice Box in my keyboard rig, and power it with it’s own adaptor.

    I also keep 2 Radial JDIs in my rig for trouble shooting purposes. When my Voice Box hums at a club, I’ll put a DI in between the output of my sound card (used to send the carrier to the Voice box) and the input of the VB. Basically, I’m using the DI backwards to take advantage of the ground lift. You’ll need some 1/4 TRS to XLR adaptors to do this.

    I also keep some 6″ XLR pin lifts in my rig, so I can lift the output of the Voice box if needed. Every club is different. And you may have to try a variety of things until you find something that works for each place you’re gig’n.

    Hope that helps!

    TGM

    May 5, 2016 at 4:59 pm #121496
    MisterRider
    Member

    I know I’m arriving late to this party, but…

    I too have the same problem with the Voice Box “whining” or humming. It’s only in certain conditions, at certain clubs – and I can’t figure out what those conditions are. Regardless, it hums in about 50% of cases, so it’s unuseable in those circumstances. I too am use the standard “Boss replacement” power adapter that is alledgedly compatible.

    Did anyone manage to solve the Voice Box whine/hum problem by changing adapters?

    Thanks!
    T

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