SP's with Grounding Issue

David Smyth · Post by **David Smyth** » Sun Feb 05, 2012 5:10 am

Hey there,

I have an LP and 2 SP's for polychaining (SP's in 19" rack behind LP).

I just moved to a new apartment and it appears my 2 SP's (but not the LP) are having the well-documented "dancing-dial syndrome" (encoder LED's moving by themselves).
The LED's do not wildly move around constantly - it seems they just move after a random amount of time (normally between immediately and 2mins or so) on one or both SP's (I set the SP's to preset mode, and one or both units change to panel-active mode by itself and I find one or a few parameters have moved to a different LED position).

I've read various posts here in the Moog forums about the issue and possible fixes, however I am unsure what to do to fix the issue in my case..

The 3 phatties are plugged into a power strip and through a 2m extension lead (all of which have 3 Pins) to the wall outlet.
I have other gear (pedals, kaoss pad, mixer etc.) I use with the phatties, but I have unplugged every lead except power to each phatty, and the problem persists. I have also tried swapping the power leads for both SP's, the power strip, extension lead and I've tried a different wall outlet.

I've also tried running the phatties in different configurations of one, two or all three going at once and the problem seems to remain.

Is there anything else I could try? Or is the whole apartment building's power not grounded enough or something?!

Thanks for your help!

Regards,
David Smyth
NZ

petrveliky · Post by **petrveliky** » Thu Mar 01, 2012 4:08 pm

I am having a similar problem with my LP; when I am plugged into any sort of soundboard or mixer it will cause the dials to dance, but the moment I unplug it the instability stops. And when I plug it into any amp, no matter how nice or cheap, the dials are fine. It's something about plugging into a soundboard, but I can't figure out if it's the wrong instrument cables, or whatever. I'm very confused. Could anybody help?

Voltor07 · Post by **Voltor07** » Thu Mar 01, 2012 11:30 pm

petrveliky wrote:I am having a similar problem with my LP; when I am plugged into any sort of soundboard or mixer it will cause the dials to dance, but the moment I unplug it the instability stops. And when I plug it into any amp, no matter how nice or cheap, the dials are fine. It's something about plugging into a soundboard, but I can't figure out if it's the wrong instrument cables, or whatever. I'm very confused. Could anybody help?

The sound boards must not be properly grounded, they're likely causing a ground loop.

Portamental · Post by **Portamental** » Thu Mar 01, 2012 11:49 pm

I read these report from time to time. Often no solutions is found.I can not help, not having the same hardware, but I am curious.

I have two suggestions :

1- Use a superior quality power bar with surge protectors

2- Regarding sound boards : try a TRS cable if you are using a TS cable (and vice versa).

Who knows? Maybe you will

David Smyth · Post by **David Smyth** » Thu Mar 01, 2012 11:54 pm

petrveliky wrote:I am having a similar problem with my LP; when I am plugged into any sort of soundboard or mixer it will cause the dials to dance, but the moment I unplug it the instability stops. And when I plug it into any amp, no matter how nice or cheap, the dials are fine. It's something about plugging into a soundboard, but I can't figure out if it's the wrong instrument cables, or whatever. I'm very confused. Could anybody help?

Hey there,

In my case, the dials dance even if nothing but power is plugged in, so they simply don't like my power it seems (one of my three phattys is currently with a tech getting a "ground modification" to reduce the sensitivity to grounding issues - if it works for that phatty, I'll be sending the other two for the same mod).

In your case there is the possibility that plugging both devices (LP and mixer) into the same power outlet, or different power outlets may fix it, but if not, I think a ground loop isolator would work between the LP and the soundboard/mixer. Look them up - you can get ones that accept different types of audio cables (you'd be after mono 1/4" jack connections). The connection would be: LP -> Audio Cable -> Isolator -> Audio Cable -> Soundboard/Mixer.

I hope this info helps!

Regards,
David Smyth
NZ

Sir Nose · Post by **Sir Nose** » Fri Mar 02, 2012 12:42 pm

There are two separate causes. Something in the audio chain grounding through a well grounded phatty or the phatty itself is not grounded.

You can try a plug adapter that has 3 prongs in and two prongs out with a place to tie into ground.
something like:

It may be different depending on your location, but the external braket to access the ground prong is needed.

Connect a wire to the ground tab, for the other end you have a couple of choices:
1) connect it to 12+ inch conductive spike and run it out a window and hammer it into firm dry earth
2) use a hose clamp to attach it to a conductive (copper with oxidation removed) piece of plumbing (a cold water line usually will run into the earth without an interruption, a hot water or drain line may have an interruption before the charge could flow into the earth)
3) Only if you have a clue or hire a pro, tie it into the ground at the junction where the power is brought into the building (if you hire a pro, might as well ground the actual outlet and not an adapter)

jeepo · Post by **jeepo** » Fri Mar 02, 2012 1:40 pm

One work around that I have used when I have encountered this problem is to switch the analog mode to pass-through, this makes the grounding issue a lot less problematic.

philip morris · Post by **philip morris** » Thu Mar 29, 2012 4:12 pm

I am getting this problem with my brand new LP

Like others, only when i plug the LP into my analog mixer or audio interface do i get the dreaded dial dance...

I've noticed using separate wall socket for the mixer & LP attenuates the problem, even weirder is depending on the preset the dials move at different speeds (on a few they are even completely stable, others they go total bezerk )

I'm going to try buying some TRS cable (using regular mono patch cables atm) and perhaps some kind of isolator / quality surge protector

If anyone has any further suggestions...

jeepo · Post by **jeepo** » Thu Mar 29, 2012 5:05 pm

Using the same outlet usually solves the problem. Try setting the pots to analog pass-thru mode. When I run into issues that setting tames the beast. Also passive transformer DI boxes have been recomended because they isolate the phatty's audio output from the mixer.

philip morris · Post by **philip morris** » Fri Mar 30, 2012 5:02 am

thanks, can you suggest any "passive transformer DI boxes" ? i'm not even sure where to find that in my country...guitar shop??

Voltor07 · Post by **Voltor07** » Fri Mar 30, 2012 5:08 am

philip morris wrote:thanks, can you suggest any "passive transformer DI boxes" ? i'm not even sure where to find that in my country...guitar shop??

Try to find one of these. http://www.sweetwater.com/store/detail/JDI/

If outside the US or Philippines, you'll need one with 50Hz compatibility.

philip morris · Post by **philip morris** » Fri Mar 30, 2012 5:40 am

^^ just checked my local guitar shop carries it but wow too expensive

jeepo · Post by **jeepo** » Fri Mar 30, 2012 8:25 pm

philip morris wrote:^^ just checked my local guitar shop carries it but wow too expensive

this one http://www.sweetwater.com/store/detail/EDB1/ is considerably less exspensive. There are many others priced between these two.

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