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ground loop in 4CM when connecting the ext. amp jack: any news?


rudomat
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hi!

i´ve still found no solution for my ground loop issue i have with my orange dual terror amp...when i plug in the external amp switch cable, i get a terrible ground loop...

 

has there been any solution for problems like this...?

thanks!

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Iso box between helix and amp in, fixed. One should always have an isolator box for such issues. Switching and audio on common ground is normal for amps really.

Did/do you have the expression pedal issue too? http://line6.com/sup...pedal-position/ Still the same after your iso box? Got a link to where I can get one of them at all?

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Front input. You have to break the loop at one point, this is the easiest one. If you isolate at the fx loop you need a dual box to isolate both, send and return.

ok...i´ve got an ebtech hum eliminator here...and it says line level only...so that won´t work, right?

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ok...i´ve got an ebtech hum eliminator here...and it says line level only...so that won´t work, right?

That one is specially designed for fx loops. I think it has two iso chains, one for send, one for return. So it should work in the loop.

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  • 1 year later...
  • 2 weeks later...

Ebtech did not work for me.  There is another thread on the forum that says to disconnect the "sleeve" cable on the Helix end.  My Mesa needs to close the connection between ring and sleeve, so I'm not sure what will do.  RJM makes a box that will receive midi and channel switch using relays.

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Update:

 

I tried many combinations of cable modifications, swapping the shield to tip, disconnecting one end etc, etc, and nothing made the hum go away.  My Mesa Royal Atlantic needs to see Ring/Sleeve closed in order to switch.

 

I tested the RJM Amp Gizmo which I have in a larger rack setup.  It worked perfectly.  RJM makes a few different switching units.  Their smaller "Switch Gizmo" features TRS amp switching, so I am ordering one of those.  Average price is $159.00. 

 

I'm guessing this is a hardware design issue, in that the relays seem to be grounded instead of isolated.  If you can't modify a cable to make this work, I recommend RJM.

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