Hi Gang...

I just discovered that the nasty buzz I thought was from the internal soundcards on my 2 new machines is actually being created by the DVI monitor I'm using. If I unplug the monitor the noise (buzz) goes away...

I've been sharing this monitor manually re-connecting it between the 2 new machines and discovered that when I unplugged the monitor (Old Apple Cinema circa 2010) the moise disappears.

Any info regarding this type of situation would be appreciated.

Do you think it's the monitor itself and purchase of a new monitor will solve it or is it in the use of DVI format itself?

Might converting the DVI to vga (adapter) fix the issue? this would allow me to use one of the monitors I already own as the Apple Cinema is the only DVI I have and I'm really too broke to buy the adapter let alone a new monitor ;-(

Many thanks for any thoughts/ideas/info any of you can help with...

Keni

I have two PC's with DVI interface LCD monitors and no noise. Have you tried a new DVI cable? (that's cheaper than a new monitor).

Thanks... but this monitor has a built-in cable that runs into the power supply (external)...

That helps tho. At least it's not something specific to DVI...

I wonder if simply using a DVI2VGA adapter would work? I might be able to get one of those here in town in the morning.... So I might try it as that's the cheapest solution...

Too bad as the DVI monitor I'm using is my only widescreen of any sort (tho not true widescreen - It's an old Apple Cinema 22" display)...

Thanks again...
Keni

Another possibility is the power supply needs opposite polarity (if it is not a polarized plug) or it needs to be plugged into the same circuit as your computer.

Strange that the video cable would be connected to the external power supply. But, Apple does tend to do things "their way". That's probably where the buzz is being introduced since its in the same housing as the power supply. Or its a "ground loop hum". If it has a 3 prong AC power plug, use a 2 prong adapter to lift the ground and see if the buzz goes away.

Thanks firebird...

I hadn't thought of lifting the ground. It's been a long time since I had to but I know I've got some lifters around...

It sounds like high speed digital bleeding into the ground... The monitor as well as the computers are all on a common battery backup... But now that I think of it, it's also wired to my pat bay which has gear running on the same line, but not the backup....

Hmmm... Something else to try before I spend

Thanks again...
Keni

Thanks Gang...

It did turn out to be a ground loop. I don't understand how/why as they are all plugged into the same battery backup... I'll have to research it some more but for now, I'm running the monitor with a ground lift adapter....

<whew>... I was worried where I'd find cash to buy a new monitor... What a relief!

Keni

Ground loops (a different in AC potential on the ground) can and often does occur with both devices connected to the same AC power point. Its caused by how the ground is treated/handled internally in the devices.

fireberd


Ground loops (a different in AC potential on the ground) can and often does occur with both devices connected to the same AC power point. Its caused by how the ground is treated/handled internally in the devices.

Thanks again firebird... I've spent far too much of my live searching out ground issues as a studio builder most of my life...


Do you feel it's "safe" to simply leave it running with the ground lifted? My studio is so old and over-run with cables everywhere it's become a nightmare for me at times... Trying to trace/remember how/why I did things.... I'm too old! ;-)


Thanks again for taking time to try helping me...
Keni

As long as the monitor is grounded via some other device (e.g. connected to the PC) its OK. 

Its like using two guitar amplifiers at the same time and lifting the ground on one.  As long as they are both connected together through a guitar cord (or whatever ground) they are both grounded.  
 
Speaking of "building" studios.  I rebuilt a studio in Kansas City. MO (Big K Records) that was located about a block from an AM radio station transmitter site.  RF everywhere, along with grounding problems. I was able to get the radio station out (or at least attenuated to a point that was useable) of the recording system but I could never get it completely out of the headsets.