Grounding issues with my rack switching rig. Help please :)

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lolzgreg

lolzgreg

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I put together my Rack Gizmo controlled switching rig today. I am using an EVH 5150 III with the rig.

The issue I'm having is: Whenever I turn any effect on in the effects loop of the amp, I'm getting insanely loud ground hum.

I have the effects hooked up all in inserts 5-8; one pedal, my ISP Decimator G-String, is both in front of the amp and in the loop.

The effects in front of the amp do not have any hum issues.

I am using a Voodoo Labs PP2+

This is what I can say about my problem.

-I tested all of my cables through a guitar amp prior to hooking them up, and everything works without a doubt, and no leads are reversed, nor are there any poor connections.
-I tried lifting the ground on one side of the cable going from the effect return of the amp to the Rack Gizmo OUT 8/NO ; it did not work.
-I tried lifting the ground on one side of the cable going from the Rack Gizmo In 5 to the amp's effect send; it did not work.
-I tried pressing the ground lift on the back of the Rack Gizmo; it did not work.
-I tried moving the unit in the rack case/floating it with my hands to make sure it wasn't a rack ground issue; it was not.
-By turning the power off to a pedal while the respective loop was on in the effects loop, the noise went away
-The hum is not minor, but so loud the amp would be unplayable

If you have any suggestions, it would be very very welcome.

Cheers,

Greg

EDIT: PROBLEM SOLVED! Thanks guys!
 
Hey Greg, I'm doing the exact same thing today only I have the effects gizmo and a blueface VH4. What pedals are going into the loop? Have you systematically tried removing the pedals one by one? Do any of the pedals use and AC powered wallwart, I am having hum issues in my setup thanks to the ac power cube that comes with the effects gizmo that I'm also using to phantom power the midi board. The ac wall wart seems to cycle hum into the rig going into my furman 1215 power conditioner.
 
Hey Greg,

Have you tried removing each pedal from the system one-by-one? I'd start with the ISP since it connects the loop to the front end...
 
Have you tried plugging in your effects that go in the loop into seperater outlet. Ive had this happen to me before and the solution was to isolate the power. I found that if I plugged my effects and my amp into the same power or like a PL8 type unit I got a nasty ground loop/hum. I was able to isolate the hum by using different power sources which is why a lot of guys use those ebtech hum elimination plugs.
 
If none of these previous ideas work, post this in the Racksystems Sub Forum, I have seen a lot of posts there where Dave helps people out with these kind of issues.
 
Have you tried running the pedals on batteries? That may help isolate where the issue is, then start adding things back till you find the hum. Also try nothing in front of the amp. Use one main power source with its ground connected. Like a rackmount power deal with everything plugged into that. Leave the ground hooked up to the power deal but lift whatever is plugged into it.

It could also be an open loop somewhere.

These things can be a pita to find.
 
Hey mate

Are you using the PP2 to power pedals before the amp as well as in the loop? I had an issue where it created a ground loop due to this reason. I then used a seperate power source for my pre - pedals and a seperate one for my loop pedals. Cost a bit more but it worked.
 
What are the pedals you are using and where? Most likely its the g string in front and in back. List your stuff and Ill tell you how to hook it up.
 
Hey everyone. Thanks so much for your quick advice. This forum is full of great people :)

Dave, Ron over at RJM has been great help so far. He told me to hook up my stuff like this:

With my Rack Gizmo:

"Guitar into loop 7 input
Loop 7 output into loop 8 input
Loop 8 output to front of amp

Amp's loop send into In 1-4
Out 1-4 to In 5
Out 5 to amp's loop return

Connect effects to loop sends/returns as required"

I'm positive it's the G-string causing the noise.

When I turn up the threshold on the G-string, it becomes active, and that's when the hum becomes audible.

The question is, how do I prevent it from making the noise?

Is there a way to clip one of the grounds on the cables going to and fro the switcher?

Any other suggestions.

Thanks so much.
 
steve_k":3bb1ngr2 said:
Remove the G-String.
Click to expand...

:lol: :LOL: :doh:


When I remove the G-String from the loop and run it in front only, the hum goes away.

I want the noise reduction in the loop though :(

EDIT: There's still more hum present when all the switcher/rig is hooked up than when it isn't, even with the Decimator out of the picture.
 
Seems like you can jump a spare send and spare return jack and solve this problem. Someone else on here had a quick fix.
 
Reza,

It actually only fixed half of the problem. It was in the effects send from the decimator to the amp. I honestly think I'm just going to need to get rid of the pedal in the loop.

Steve,

What should I jumper?
 
Greg,
Ditch the G String and upgrade to the Prorack Decimator G. The current edition of those units has ground loop switches on the back, plus it does a better job of noise reduction than the pedal.
 
Hey dude,

Thanks for the advice. I was just about to go that route when...

I actually just figured it out with an isolation transformer. I'm done! WOO HOO!
 
Hey everyone, I'm also having a hum issue. Seems like a lot of people on here actually know what they are talking about so maybe you can help me as well.. I have a 5150 iii and all i'm running into it is a rack mount bbe sonic maximizer and a rocktron hush super c both into the effects loop, I also have everything plugged into my furman power conditioner (Which I know may be the problem). The hum doesn't really disrupt anything while playing but I imagine it's not supposed to be there. I saw some other info on here that may be useful but I would really appreciate some advice because no one on here is running the bbe or the super c.. If it helps at all I may have narrowed it down to something that the bbe is producing but im not positive. Either way it would be very helpful if someone can tell me how to eliminate what I believe to be a ground hum. Thanks a lot guys! hope to hear back :)
 
220px-Cheater_plug_edited.jpg


put either your head plugged into that, or your effects unit.

as long as one is grounded, even if the other isn't you wont die from shock, in the rare occurrance that you'd get shocked anyway.
 
I don't miss those days......hours of tweaking. Then change it up again!

Glad you got sorted though. Ron's good people for customer service.


Steve
 
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