0

A very simple question before I purchase an online UPS.

I have a ground loop problem with an audio workstation, I temporarily removed the earth (to test only) and the noise went away, so I am considering an online UPS with this PC to isolate the circuits.

Is the ground from the mains plug of the online UPS also isolated from the PSU's outlets? I've read that online UPSs are a good electrical firewalls.

JRE
  • 71,321
  • 10
  • 107
  • 188
Oliver M Grech
  • 121
  • 3
  • Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. – Community Oct 01 '21 at 15:14

1 Answers1

2

The ground on your UPS input and the ground on the UPS output should be connected together inside the UPS. That is how they are supposed to be.

Ground is for your safety, and the safety of anyone who touches the equipment.

Do not defeat the safety ground on your UPS, or on the equipment directly.

Plug the equipment into one outlet so that all devices are connected to the same ground. If that doesn't help, get an audio isolation transformer to put in line between the audio devices.

You can often get away with defeating the safety ground. As long as the equipment and cables are all good, nothing bad will happen - until some day, something does go wrong and the safety ground isn't there to save your bacon.

Don't break the ground.

JRE
  • 71,321
  • 10
  • 107
  • 188
  • The ground was defeated just to rule out any other problems, just to test and then connected it back in. – Oliver M Grech Oct 01 '21 at 15:11
  • 1
    Right. Your plan, though, was to use a UPS to break the ground permanently. – JRE Oct 01 '21 at 15:12
  • Everything is into one outlet. The previous PC did not have this problem, so for sure there's a ground issue inside the PC – Oliver M Grech Oct 01 '21 at 15:13
  • So I'm back after several tests.... I used a normal UPS (WITHOUT connected to the wall .ie on battery)... PC alone on UPS solved the ground loop, and also the poweramp alone solved the ground loop, but both connected to UPS (again, on battery not wall outlet) had the ground loop... am I correct to say that the PC is most probably not grounded properly and the shortest route is through the audio cable (its a balanced XLR). – Oliver M Grech Oct 01 '21 at 20:58
  • 1
    Solved. I put a passive DI box in series between the PA and PC audio cable with ground lift on and voila all sorted and no ground pins removed :) DI Box used is a Radial Engineering Pro DI – Oliver M Grech Oct 02 '21 at 14:46