Pedalboard ground loop woes

[xtian]

Can't rid my pedal board of ground loop noise. See photo.

All six pedals on the right are powered by a JOYO supply. If I take the output from the last pedal in the chain, the Micro Vibe, and out to the amp, it sounds GREAT. Low noise, no ground loop.

The M9 is powered by its own 9vac supply. If I run the guitar thru the M9 ONLY, it sounds great.

BUT, if I combine ANY pedal and the M9, I get a moderately loud hum.

Solution?

[NickC]

Is the M9 power supply wall-wart unregulated? Also, that wall-wart transformer is close to the wireless transmitter, try moving it away and see if that helps ...... maybe EMF interference?

Are all of the stomp devices center-tip-negative power supply types types?

I note you're not using any Boss pedals. Some of the older style Boss pedals needed an ACA type power supply ..... unregulated 12V. Inside those ACA type pedals there is a resistor and diode to drop the power down to 9V. Oddly enough, if Boss ACA type pedals share in a daisy-chain with other 9V PSA type Boss pedals, they will all work and coexist happily. It's because of some weird grounding scheme when both types of pedals share power through the daisy chain. I don't know if something like that might apply here. I'm grasping at straws.

[Blindog]

Can't rid my pedal board of ground loop noise. See photo.

All six pedals on the right are powered by a JOYO supply. If I take the output from the last pedal in the chain, the Micro Vibe, and out to the amp, it sounds GREAT. Low noise, no ground loop.

The M9 is powered by its own 9vac supply. If I run the guitar thru the M9 ONLY, it sounds great.

BUT, if I combine ANY pedal and the M9, I get a moderately loud hum.

Solution?

I have the M13, and I had a ground loop issue when I used the 4 cable method to be able to patch the distortion/overdrive models to the front of the amp and leave the others in the amps effects loop. I read a number of threads on the Line 6 forum, and it seems the Behringer Microhd HD400 helped most people get rid of the hum. I bought one, it was only like $29, and it did the trick for me. Apparently it has something to do with the way Line 6 supplies power to the unit internally (in/outs vs send/returns) that causes the ground loop situation with these units. Hope this helps!

http://www.behringer.com/EN/Products/HD400.aspx

Mark

[xtian]

Is the M9 power supply wall-wart unregulated? Also, that wall-wart transformer is close to the wireless transmitter, try moving it away and see if that helps ...... maybe EMF interference?

Are all of the stomp devices center-tip-negative power supply types types?

I note you're not using any Boss pedals. Some of the older style Boss pedals needed an ACA type power supply ..... unregulated 12V. Inside those ACA type pedals there is a resistor and diode to drop the power down to 9V. Oddly enough, if Boss ACA type pedals share in a daisy-chain with other 9V PSA type Boss pedals, they will all work and coexist happily. It's because of some weird grounding scheme when both types of pedals share power through the daisy chain. I don't know if something like that might apply here. I'm grasping at straws.

Yes, the M9 has an unregulated wall wart. No, the wireless is not the problem. I had it unplugged during testing.

Yes, all pedals are center neg.

I found the ModTone Power Plant. It has seven 9vdc outs and one 9vac outs. Perfect. I'll let you know how it performs.

[xtian]

The Mod Tone Power Plant solved my problem. It has exactly the right number and kind of outputs for my board, including a 9vac out for the Line 6 M9. The only problem is it won't fit under the board of the Pedal Train 2, and I had to bump the wireless receiver off the board.

But, boy howdy, is this rig quiet! So gratifying.

[donzoid]

So do you think the Joyo power supply was the inherent problem? Curious because I think the Modtone is also Chinese (though I admit that is no longer a catch-all for poor quality, some are better'n others). I was thinking about getting one, they get great reviews, but I'd take your word before all of those. I also wanted to mention that I get similar issues with my Vocalist Live processor, and I have a Behringer Microhd HD400 which is a very handy tool indeed for stopping ground loops cold almost anywhere -- Guitar, multi-amps, PA...it's pretty remarkable.

[donzoid]

I hate to even say it....but if you stick with that layout, and it doesn't give you grief to place it directly on there, y'all could velcro that wireless right to the top of the Modtone supply...heheh!

[xtian]

I don't have an answer for you Donzoid. I just know, with this new unit, both DC and AC supplies are properly ground isolated, and it sounds perfect.

[JazzGuitarGimp]

A power supply with isolated outputs is essential. But it doesn't guarantee it will cure all hum issues. For example, I use the TC G-System as the centerpiece of my effects system. I use a passive Ernie Ball volume pedal between the output of the G-System and my amp. I get a lot of hum from this arrangement, and the volume pedal is passive! If I take the volume pedal out of the chain, plugging the output of the G-System directly into the amp, I have no hum. So I use an audio isolation transformer between the G-System and the volume pedal, and that solves the problem.