Advice on my noise issue with MK-IV rig

[phrygiandom]

In a nutshell, I moved to Germany some time ago and now use a 1600w stepdown transformer to power my entire rig. I have a USA voltage Mark-IVA, this pedalboard (with a Pedal Pad effects loop module not pictured):

http://www.musiciansfriend.com/guitars/pedal-pad-mps-xl-ii-tour-series-powered-pedalboard

I get a constant hum through the rig. I don't hear it at all on R1, it's barely noticeable on R2 but becomes really annoying on channel 3. I get absolutely NO noise when using the MK-IV alone, so it's all coming through the pedalboard. The transformer itself emits a humming noise, and I suspect that this is seeping into the signal chain. I've tried many options, including lifting the ground on the MK-IV, then the pedalboard, then the transformer. No luck. I've also used different step-down transformers, in the 1000-2000w range....all the same with regards to humming noises.

When using my M13 with the MK-IV, 4-cable, it's dead silent. But sonically I prefer to just use my other pedals, so I'm stuck.

Would a ISP Decimator or Boss NS-2 get rid of this hum? The nearest store doesn't have them in stock, so I would have to blindly order it.

Any suggestions? Thanks.

 

[cho]

I recommend to add only one pedal at time, to see which pedal is the offender. Once you find it, try swapping the last patch cable added, as well, in case the problem is with a cable. Good luck!

 

[DaveP]

Are your effects send and return cables near the right side of the amp? (where the AC cord is)
I had a terrible hum with the effects loop on and discovered if you route the cables away from the AC the hum will disappear.
Give it a shot. It may be the issue.

 

[phrygiandom]

Earlier this year, I replaced all the patch cables to no avail.

This evening I will double-check to make sure that the loop cables aren't crossing the AC cord.

I've read conflicting stories about Decimators removing hum from the signal chain, so I'm hesitant to blindly purchase one. Gut instinct tells me the hum is originating from the step-down transformer, leaking into the signal path.

I appreciate the responses.

 

[MrMarkIII]

Google "ground loop".
This is an interesting article:
http://www.rane.com/note110.html
I have used an Ebtech Hum-X:
http://www.sweetwater.com/store/detail/HumX
You need to experiment, but generally the best practice is to plug *either* the amp or the pedal board into the Hum-X, then the A/C source.