Hum/buzz from computer equipment thru my 388

[WhinyLittleRunt]

I just pulled apart all my wiring tonight to try and isolate a buzz I've been getting but have been too lazy to attack. I'm posting it here because of the 388 being the central hub and though I'm sure it probably has nothing to do with it, I figured most of you have computers in your setup at some point in the chain.

The problem was most apparent when I recently got a Drobo (backup hard drive). I noticed that when the device would boot up or wake up, I could hear the hard drives and the whistling i.e.: when your car alternator picks up the radio, through my monitors. It was one of those wtf moments. So I finally took everything apart and started isolating. The 388, as is, with my monitors hooked up and my 8 channels patched to an XLR bay, is very quiet. Then I turned on my audio interface (Firepod). There's the noise. Even inactive, it was producing a nasty buzz. It is patched back and fourth (stereo outs of the 388 to the inputs on the Firepod and the outs of the Firepod patched into the stereo ins on the 388). I can't see any other way to get the audio back into my 388 for listening so that's what I've got. But I don't really remember the thing being that bad in the past. Anyway, moving on I also found that my LCD (older Apple cinema display) created a buzz in the monitors when on. So the speakers (active) are clearly picking up some frequencies somewhere.

So the question is, how do I avoid this stuff? It isn't affecting the actual recorded output that I can tell but it's extremely annoying to listen to if I have the monitoring up somewhat loud. I thought about a power conditioner but that isn't going to help the LCD issue. I'd rather get a rack mount power conditioner just for my rack gear at the least, but not to solve this problem. What are my options?

 

[gentlejohn]

I had a similar problem. Traced it back to an old Dell monitor screen. When I took this out of the equation the hum went. Turned out to be a ground loop. I just lifted the ground on the monitor screen's plug and the hum went away. Good luck!

 

[famous beagle]

I've had similar issues with hum/buzz being present only when monitoring and not recording. The most recent was a Tascam US122 USB interface causing it.

It only had RCA outputs, so I was running those to my RCA monitor inputs. On a whim, I decided to try using an adapter to run from the interface's RCA outputs to the XLR inputs on my speakers, and that did it. Noise is totally gone.

So if you haven't tried running balanced cables, I'd try that. I'd always heard that, unless both ends of the connection is balanced, then it won't make a difference. But that's obviously not true, as my case has proven. Good luck; I know how f-ing annoying that can be!

 

[WhinyLittleRunt]

I guess as long as it's not picking up in my recordings it's not a huge problem, but it's annoying as hell. The drobo is the worst offender; there must be a magnetic field issue with the speaker coils and the hard drives or something because as long as they're turned on, it amplifies the drive noise, spinups, etc. Even if I move them away it doesn't get better, it's crazy. I'll have to just play around with everything.

I will try to change the monitor cables; they are just cheap RCA cables right now because the monitor outs are RCA so I just have some 1/4 adapters on them. Maybe I'll try that half-balanced idea and use XLR to RCA or something and see. But I have had all of this equipment all along and only started noticing the drobo noise recently, haven't changed anything else that I can recall. The monitor, same thing, just didn't realize the buzz is coming from that.