JP Internal Grounding Issue?

[Etudica]

I finally got around to using my JPXI in a studio situation, which forced me to focus on my tone a bit more than usual. What I began to notice is that there is a subtle, but noticeable, interference type hum coming from my mags in my JP. It disappears the instant I touch either metal PU selector switch (or any metal part for that matter) with my hand, and does not occur when using piezo position only.

I can confirm I am not getting this same interference with any of my other guitars (using exact same setup and cables of course). However, I only have one JP at the moment so I can only compare signal noise to other brands on my own.

Does this sound like a poor ground issue? If so, where should I start looking for the root cause?

 

[DrKev]

If with a distorted guitar tone, I would not be in the slightest bit surprised or worried. Firstly, a poor ground issue would usually be very noticeable - so I don't think that's it. Second, remember that distortion makes any noise or hum much more obvious (as anybody with single coil guitars knows all too well). Thirdly, Humbuckers cannot remove hum absolutely perfectly, especially if the coils are not identical. Sometimes a very small amount of hum is totally normal.

 

[Etudica]

Right, forgot to mention it is noticeable on clean presets as well. Actually, it's not pervasive enough to even pick out on hi gain presets. Only really noticeable on clean presets.

On other guitars I've had that have had some interference/hum noise going on, I don't remember it disappearing when touching metal switches or bridge. This is the part that has me wondering...

 

[Sigvard90]

Interesting...

I've been having the same issue with my JP6 since the beginning. At least your description sounds very similar to what I keep hearing. It is definitely not the usual hum sound/noise coming from pickups/amp.
I try to ignore it and when I play I tend to forget about but as soon as I stop playing it starts humming. And it's quite loud, even on a clean channel. As soon as I simply touch the strings it stops.

I've had the guitar at multiple guitar techs/builders to try and solve it, but so far no one can explain to me what it is. They keep saying it's probably your cable or your amp input (and their wear-out), but all my other guitars don't have it (same cable/amp).

 

[Etudica]

Exactly Sigvard... touching any metal piece (including strings) silences it immediately. And you are probably hearing the same thing - not a standard pickup/interefence type hum. It's more of a static hiss than a hum.

It is noticeable on all pickup positions at all volumes.

 

[Etudica]

Update- It's definitely external interference. Most likely coming from lighting. Found that it slightly fluctuates with position; both position of the guitar relative to the interference source and position relative to myself (standing/sitting - surface area of guitar touching my body). Never had this issue in my home studio though. Perhaps I'll try to shield it better the next time I do a complete setup.

 

[Sigvard90]

Thanks for the update Etudica. I will try and see if I would come to the same conclusion (external interference).