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Ground loop - Korg DTR1

Posted: Sat Feb 09, 2019 11:13 am
by bettsaj
I have a very annoying ground loop on my rack, it's being caused by a korg DTR1 rack tuner. I've looked on the internet and it appears to be a common issue with the DTR1 and DTR2 tuners.

I've connected the send on loop 1 of the GCX to the input of the tuner and not connected the return of loop 1, therefore I'll have silent tuning when loop 1 is engaged, also this ensures no audio signal through the tuner unless loop 1 is engaged. Unfortunately I'm still getting this ground loop issue, even when the tuner is out of the audio path. If I unplug the power cable to the tuner the ground loop disappears.

Is there a way to safely lift the ground on the tuner? Everything in the rack is currently being powered by a Samson Power brite power conditioner, and being in the UK all the plugs into the power conditioner are male IEC plugs. Can I just remove the ground wire from inside the IEC plug??

Re: Ground loop - Korg DTR1

Posted: Sun Feb 10, 2019 5:36 am
by Marlboro05
I’d not remove the earth from a power cable. Can you open it up and see if there is an earth jumper to remove the earth to chassis from the signal? Or make a patch cable without an earth for the tuner? Run the patch cable through the buffer on your GCX then to your tuner? Run the patch cable through an isolator?
It may be safe to do so but I wouldn’t take a power earth away.

The newer Pitch Black rackmount tuners are just 9v, maybe get one of them🤷‍♂️

Re: Ground loop - Korg DTR1

Posted: Sun Feb 10, 2019 11:31 pm
by bettsaj
I've done the sensible thing and got a Behringer HD400 Hum Destroyer HD400.... I had a fiddle with the DTR1 and pulled the cable from GCX loop 1 send to the DTR1 input and the ground loop disappeared. I'll place the hum eliminator between the DTR1 input and the GCX send, that should solve my problem.


Re: Ground loop - Korg DTR1

Posted: Mon Feb 11, 2019 11:42 am
by JohnClark
You may be able to get away with isolating the tuner fro the Rack Rails. You can use HumFrees rack isolation tabs, or plastic shoulder washers (you need to insulate between the rack ears and the rack rails, as well as insulate the rack screw from the mounting hole in the rack ears).

...or the isolation transformer you have will likely also work!

Let us know how it goes!

Re: Ground loop - Korg DTR1

Posted: Tue Feb 12, 2019 1:10 pm
by bettsaj
John, the ISO transformer works perfectly, I plugged it in and it cleaned up the signal so all I have is the sound of a guitar. The rack rails are already isolated from the ears, with nylon washers. I've tried everything and after i looked on the net it's quite apparent that the DTR1 is a ground loop nightmare. It's affected loads of rigs, and most have had to be isolated. Anyway, i'm good to go now.

There have been some changes since we last spoke, so I may as well bring you up to date.

I bought the System Mix Plus, tried it for 3 weeks and couldn't get on with it. I hate having parallel effects, when i added the SM+ I realised that so sold it on. I lost a lot of the effects on the G-Force because they're optimised for a serial FX loop not parallel, so i now have the rig in series and love it. I have the G-Force in loop 8 of the GCX so I can bypass it, and my rig is really good now. I've also sold the Triaxis, and gone back to my old faithful Marshall JMP1, I love them and they're so easy to use. I found the Triaxis just overly complicated for me, I needed a PHD in sound and electronics to program it. Also I couldn't get a good sound out of it.... It was just too, Mesa sounding if that makes sense. OK if you want to sound like every other Hetfield and Petrucci wannabe out there but not good for me when all I want is a good clean sound, and a couple of good drives.

I'll post some pics soon as soon as I get it to a studio, and also some video too...