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  #41  
Old 10-26-2017, 07:38 PM
KarlDB KarlDB is offline
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Default Re: Eleven Rack Output to Amp buzz

Okay, this is totally weird.

I ordered a new RF/EMI filter and installed it, and it was no change. Noise still there. Then in the process of ruling out other things, I happened to unplug the Eleven Rack from AC power altogether and the noise is still there.

If I just have the 1/4 inch guitar cable plugged into the input of the Bugera, no noise, unless I grab the tip with my hand, which is normal. But, as soon as I plug that guitar cable into the OUTPUT to AMP jack on the (unplugged from AC power) Eleven Rack, the noise is back.

I don't know if the Eleven Rack is generating the noise somehow, or if it is just acting as an antenna and picking up RF or EMI noise somehow. I do have LED lightbulbs in the studio, and if I turn the lights off the noise gets slightly quieter, but it is still there.

Not sure what to think at this point.
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  #42  
Old 10-26-2017, 07:50 PM
Darryl Ramm Darryl Ramm is offline
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Default Eleven Rack Output to Amp buzz

uh as I have pointed out before here it is likely a ground loop caused by the single sided Amp 1/2 outputs from the Eleven Rack. (and ground loop does not just mean you get AC line frequency hum, it means you are building an antenna)... and/or it’s just being an antenna... which is what your test shows.

The way to break the ground loop is to use a balun or passive revamp box. And if needed lift the ground there. And run balanced proper cables where you can.

If you do have better behavior on the Main Outs why not use them?

I keep hearing you say stuff that is not the “best” way to do this. So yet again, start with the best way and get that working. Get your output from the Eleven Rack going into the V22 FX Loop return, not the V22 guitar input. Ideally take that from the Main Out L over a balanced XLR cable into a passive revamp box like a Radial Reamp JCR and a very short 1/4” instrument cable into the FX Loop Return. Play with gain staging on that to reduce noise.

This must be the third time I have said much of this stuff...

Beyond that you should do all the usual things chasing ground loops and noise. Check power outlet ground, move equipment to a single common known grounded outlet, check signal and power cables, turn off computers, fluorescent lights, motors, refrigerators etc. Turn off all other electrical circuits nearby, try carefully lifting grounds, check all the TRS connections are making proper contact etc.

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Last edited by Darryl Ramm; 10-26-2017 at 10:46 PM.
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  #43  
Old 10-27-2017, 09:31 AM
Darryl Ramm Darryl Ramm is offline
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Default Re: Eleven Rack Output to Amp buzz

One thing that is not clear is is there a computer connected to the Eleven Rack, if so what happens when it is disconnected. If it is needed and a problem you can look at a USB opto isolator and placing it away from the Eleven Rack.

You want to disconnect everything you can, all other devices, guitars, unused cables. Unused power strips/adapters, extension cords, etc.


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  #44  
Old 10-27-2017, 05:38 PM
KarlDB KarlDB is offline
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Default Re: Eleven Rack Output to Amp buzz

It is a ground loop, you are right. It doesn't matter if nothing else is plugged into the Eleven Rack, no USB, no mains, no exp. pedal, no power cord, it is still acting like an antenna. I finally started thinking about it like old school, and just lifted the ground on the amp and that solved the problem.

Thanks for all the help. It wasn't related to the Eleven Rack really at all.

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  #45  
Old 10-27-2017, 09:11 PM
Darryl Ramm Darryl Ramm is offline
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Default Re: Eleven Rack Output to Amp buzz

Quote:
Originally Posted by KarlDB View Post
It is a ground loop, you are right. It doesn't matter if nothing else is plugged into the Eleven Rack, no USB, no mains, no exp. pedal, no power cord, it is still acting like an antenna. I finally started thinking about it like old school, and just lifted the ground on the amp and that solved the problem.

Thanks for all the help. It wasn't related to the Eleven Rack really at all.

Great! Not to say there were not power filter issues on some Eleven Racks, I just didn't want folks to leap to the conclusion that it would cause most problems.
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  #46  
Old 10-31-2017, 06:59 AM
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panamajack panamajack is offline
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Default Re: Eleven Rack Output to Amp buzz

Quote:
Originally Posted by KarlDB View Post
. . . I finally started thinking about it like old school, and just lifted the ground on the amp and that solved the problem. . .
Does the Bugera have a power switch with three positions (i.e., on-off-on) so you can switch the polarity easily?
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