Ground Loops/HELP!

[NancyJohnson]

About a year ago my old PC carked it and I bought a HP Pavilion mini-tower thing.  I set everything up, my chosen playback softwares (Winamp and Spotify) installed my DAW and an Audiobox USB interface, speakers (M-Audio BX5).  I noticed almost immediately that when I played back audio, either through the onboard soundcard or the Audiobox USB I was getting a pre and post-roll whistling sound (the Audiobox connected via a USB cable, speakers plugged into that).  If you watch/listen to the following, this will make sense:

The sound didn't manifest itself on recordings, so that was a blessing.  The issue was posted to the HP Support forums (https://h30434.www3.hp.com/t5/Desktop-Audio/High-pitched-tone-whistle-from-studio-monitors-and/td-p/5975715), but despite a lengthy amount of trying to fix things it never went away.

Anyhow, fast foward to the now.  Over the last couple of weeks we've had some power issues locally; the power fluctuations were very short and not long enough to throw the cooker or microwave time off, but long enough for the PC to go down, which irritatingly caused some lost work, so I bought and installed an APC UPS. 

I fired up the PC this morning and now I've got a ground loop rumble coming from speakers, so clearly the UPS is causing an issue.  I've installed a thing in-line with USB cable that's supposed to filter out the grounding noise, but while the noise dissipates and becomes barely discernable at first, it just builds until you can hear it behind what's playing (the sound is almost like someone drumming their fingers on a box!  Just for good measure, when I use the roller on the mouse, I can also hear that too!

I'm at a loss. 

Anyone had anything similar?  Or can help?

 

 

 

[Skol303]

Your probably need a compressor in the signal chain!  (yeah, that's going to get old very quickly...).

But in all seriousness, it's hard to advise on fixing ground loops over the internet, 'cos the problems are often very localised. I had a significant ground loop at home - constant buzz through my monitors - that I was unable to localise even after a good deal of faffing around.

In the end I capitulated and bought one of these on recommendation of a friend:

Ebtech HE-2 Hum Eliminator

It sits at the end of the signal chain between my mixer and active monitors... and it has completely killed my ground loop. Like, quite literally silenced it.

The Ebtech box is quite expensive new but can usually be found second hand on eBay, which is where I got mine.You might otherwise be able to buy one on a 14-day returns policy and just try it out.

I'm sure others will also be along with better advice...

 

[SpondonBassed]

I dramatically reduced induced noise from the PS in the analogue output from a laptop using a ground loop isolator:

One of the first search results  here

[operative451]

I get running a Dell mini tower thingy into a mixer and then bass amp (never mind why).  A DI box with a ground lift button in between the computer and the everything else sorts it...

[SH73]

I unplug the laptop when I record. It solved my problems.Ibought behringer hd400 but was useless so I sent it back.

Ola Englud recommends this

https://www.amazon.com/dp/B003PJ6NPO/?tag=dnulgn-20

[BigRedX]

If you need a power conditioner in the UK then there is something fundamentally wrong with your mains wiring and you should get a proper electrician in ASAP.

[NancyJohnson]

I should point out that until recently the supply here is clean, but everyone I know in the street is experiencing these short blips, so the UPS was a way around this.

[taunton-hobbit]

Worth a nose around the neighbourhood to see if you have any new industry locally - their kit could be causing problems - I had this with EMI in hayes a few years ago.............