Ground loop problem?

[HobGoblyn]

I suppose Presonus is as interested in the particular fault pattern as I am, especially if the fault current bypasses a ground break and is thus coupled to the monitor inputs –– without affecting the actual sound generated.

Just received the following from Presonus

 “ Just updating you. I've tested these speakers on 3 setups and have no issues as described in this ticket. I assume the new speakers arrived and are working ok?”

As I said in my previous post, with the extension lead from Apple that grounds the lug, I didn’t have the problem anymore.

Still waiting for replacements, they’re coming through customs, will do a quick test without using the Apple extension lead, I suspect the tingle will be there, will be very odd if it isn't though, will let you know.

Many thanks everyone

[wraper]

So it looks like buying the cable will fix it, although I didn’t really want the MacBook plugged in all the time, still it’s no big deal, now all I’ve got to do is find one, extension leads on Apple UK have plastic for the ground lug to slot into.

And what’s inside that slot is two metal spring contacts that firmly contact the ground stud. That’s how this system works. Apple has been using this system for over 20 years, not sure why you seem so skeptical of it.

FWIW in 2016/2019 Apple recalled apparently nearly all regional variants of this plug adapter except US sold since 2003
https://support.apple.com/ac-wallplug-adapter
https://www.apple.com/uk/newsroom/2019/04/important-notice-for-certain-ac-wall-plug-adapters-and-apple-world-travel-adapter-kits/