Ground loop noise (I think...) from P6. Help!

Ground loop noise (I think...) from P6. Help!
« on: May 19, 2017, 02:08:54 PM »
(I posted about this same problem a while back, but I think it's better if I cut to the updated chase in hope that someone here can help translate my technical no-how into actual know-how!)

My Prophet 6 is generating unwanted noise. I've sent it in to Thomann, but they found no fault. The noise is intermittent, and is affected by the Master Volume - if I jiggle it or push the knob upward, the noise ceases, sometimes completely, sometimes for a moment before flaring back up. Thomann replaced the Master Volume knob, just in case, I guess, and the synth seemed fine for the first week after it was returned to me. The noise, however, has flared up again. DSI has been great - they've helped me do enough troubleshooting that we're left assuming it must be some sort of ground-loop noise. My studio is such a mess and I'm so non-tech (despite being surrounded by gear, right?!), so my troubleshooting technique is more "mad scientist" than anything. Still, maybe there's simply something I can buy - an adaptor or a noise-eating bug or such. If I keep typing, I'll just make as much mess as the gear surrounding me, so I'll turn it over to anyone who might have an answer or further questions. Hope someone can help! Cheers!

chysn

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Re: Ground loop noise (I think...) from P6. Help!
« Reply #1 on: May 20, 2017, 03:43:35 AM »
If you've ruled out a ground loop, how about RF interference? Do you live near a radio station?

I live a few hundred meters from a 50 kilowatt AM radio tower, and sometimes it causes problems.
Prophet 5 Rev 4 #2711

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Re: Ground loop noise (I think...) from P6. Help!
« Reply #2 on: May 20, 2017, 06:40:16 AM »
I might have misrepresented the problem, but I'm actually pretty sure it is a ground loop problem. I've plugged the P6 into a basic universal adaptor, converting it "from EU to EU" and that seems to be doing the trick. I didn't have this problem in the room I previously had my gear set up in, so perhaps it's to do with different electrical lines running in the house. No idea, me! My Juno 6 was noisy as hell until I ran it also through the same converter, though in that case it was "UK to EU." I don't know what magic is in these converters - it's a basic €10 thing that offers US/UK/EU inputs/outputs. I don't know what it's doing that suppresses the ground loop noise, but if it works, I'm happy...!

This is probably not the most riveting or even useful post, so if any moderators want to delete, have at it!


Re: Ground loop noise (I think...) from P6. Help!
« Reply #3 on: May 20, 2017, 09:47:01 AM »
...or maybe a grounding issue in general?

I'd bet that a plug-in outlet tester would probably give you a pretty good idea (when the symptoms actually occur).
Sequential / DSI stuff: Prophet-6 Keyboard with Yorick Tech LFE, Prophet 12 Keyboard, Mono Evolver Keyboard, Split-Eight, Six-Trak, Prophet 2000

Re: Ground loop noise (I think...) from P6. Help!
« Reply #4 on: May 21, 2017, 02:12:41 AM »
...or maybe a grounding issue in general?

I'd bet that a plug-in outlet tester would probably give you a pretty good idea (when the symptoms actually occur).

This sounds like a wise idea, cheers! 

Thankfully, I've solved the problem by running the P6 into a universal travel adaptor. No idea what magic lives inside this €8 piece of plastic, but it's doing the trick, just as it does for my Juno 6. I had the noise issue with the Juno in my previous studio room next door, but the Prophet noise issue has only been a problem in here.