Ableton Forum

Let me just start by saying I have no power conditioner (as of yet), just a surge protector.

I have a two monitor setup (computer monitors that is). When one of them is on, I get an extremely annoying hum/buzz from my left studio monitor. Once that computer monitor is turned off, the hum is gone completely.

I had tried plugging the problem computer monitor into a different outlet but the problem persists. Is this a ground loop problem? The interface has no ground loop lift switch so I'm not sure what to do.

My interface is the PreSonus Firepod connecting via firewire to the computer which then outputs to the two computer monitors.

Try moving the offending monitor?

Buy a ground loop suppressor at Radio Shack or Amazon they cost about $15 usd

I tried moving the offending computer monitor but it doesn't seem to do anything. If I twist it's power plug a little bit, the hum reduces but is still there.

I believe my 1/4 inch cable from the interface to the left monitor is not balanced, and perhaps a balanced plug would solve the issue as well.

try moving all the audio cables away from all the power cables, and if that doesn't work, you could try plugging the offending speaker in to a different power socket to see if its picking up interference with the monitor

I had an old 17" monitor that had to be plugged in separately to all my audio gear as it would make everything hum when it was on standby

balanced cables will only stop so much electrical interference, it wont cure a bad earth somewhere

Liam wrote:Try moving the offending monitor?

Buy a ground loop suppressor at Radio Shack or Amazon they cost about $15 usd

a groud loop supressor? i use the handles from a plastic shopping back as ground loop supressors.

but that only works on german plugs i guess ...

sphinxxx wrote:Let me just start by saying I have no power conditioner (as of yet), just a surge protector.

I have a two monitor setup (computer monitors that is). When one of them is on, I get an extremely annoying hum/buzz from my left studio monitor. Once that computer monitor is turned off, the hum is gone completely.

I had tried plugging the problem computer monitor into a different outlet but the problem persists. Is this a ground loop problem? The interface has no ground loop lift switch so I'm not sure what to do.

My interface is the PreSonus Firepod connecting via firewire to the computer which then outputs to the two computer monitors.

If you're not already doing so, plug in the ac adapter and use that for power. I have a firebox and using the adapter cuts the monitor hum significantly. I get unbearable noise if I use firewire bus power.

scott nathaniel wrote:

sphinxxx wrote:Let me just start by saying I have no power conditioner (as of yet), just a surge protector.

I have a two monitor setup (computer monitors that is). When one of them is on, I get an extremely annoying hum/buzz from my left studio monitor. Once that computer monitor is turned off, the hum is gone completely.

I had tried plugging the problem computer monitor into a different outlet but the problem persists. Is this a ground loop problem? The interface has no ground loop lift switch so I'm not sure what to do.

My interface is the PreSonus Firepod connecting via firewire to the computer which then outputs to the two computer monitors.

If you're not already doing so, plug in the ac adapter and use that for power. I have a firebox and using the adapter cuts the monitor hum significantly. I get unbearable noise if I use firewire bus power.

I thought firewire doesn't have bus power? (only usb). I am using the AC adapter for the firepod.

Also I thought all connected equipment should be on the same outlet in order to minimize differences in ground

A few observations and comments:

There is too much faith put in power conditioners, most problems stem from bad grounding or improper wiring in the gear, not the supply power. So it is better to try all fixes before going to the power conditioner (the most expensive solution).

It would seem your monitor ac plug is the culprit, whether that is inducing noise (via near contact with audio cables) or more likely has a bad ground, this is why when you fidget the cable it's noise character changes.

my $0.02

yeah, try a new power cable and avoid it touching or being near the audio cables as much as possible. if they have to touch/cross, they should do so at a 90 degree angle. you can also get power cords that can address the problem- these use twisted pairs for the power + & - and actually can reduce emi interference pretty substantially in some applications - http://www.middleatlantic.com/power/iec.htm.

is it a CRT monitor? those are notorious for audio interference.

sphinxxx wrote:I believe my 1/4 inch cable from the interface to the left monitor is not balanced, and perhaps a balanced plug would solve the issue as well.

i'd start with balanced cables and go from there. this alone made an enormous difference for me.