Portland, Michigan, USA
•Tektronix CFG253 Function Generator
•Extact Model 129 AM/FM Function Generator
•Audio Technica p615 mic
•Used Guitar (previous owner sanded off all the names and model #\\\'s, it might be a Strat)
•Akai X-330 Reel to Reel
•M-Audio Mobile-Pre USB audio interface
•M-Audio Studiophile Monitors
•Edirol PCR-30 Midi Key+Ctrl
•MSI Wind Hackint0sh
•Ableton Live 7
Electronic Music studio: Ground loop Buzz, Arrrgh!
Written April 10 2011 , Tags: monitors, buzz, interference, hum
I've got a little problem.
Once every few hours, a terrible buzz will begin emanating from my monitors. They are powered monitors, Mackie HR624.
They are running into my old M-Audio Mobile-Pre USB interface, which then goes to my computer via usb.
I never had this problem at my pervious apartment. The house I'm living in now must have had a nut job for an electrician, circuit breakers go off pretty regularly and only a few wall outlets throughout the house have ground plugs on them.
So does anyone have a simple solution to this problem? My computer and Monitors are both running off the same circuit. I assume it stems from the generally crappy wiring job in the house and perhaps it's related to a large appliance turning on, like the refrigerator, since the buzz only happens periodically for a few hours throughout the day.
I've researched a bit about fixing ground loop problems but the solutions seemed overly complicated or unreasonably expensive.
...In other News, Mexican Pointy Bootz!
Yes, it can be very expensive. What mobo do you have? Is the soundcard usb powered or via adapter too. (firewaire available?)
You can read horror stories on gearslutz about studio's with the same problem. A friend of mine fixed it by replacing a part on his mobo, if you want I can ask the details.
Thanks for the reply, Fant00m.
The interface I'm using can only be powered via USB. It is the first generation of the M-Audio MobilePre USB units, as seen here:
Now that you mentioned it, I tried disconnecting the USB cable that connects the audio interface to the computer and it resulted in no more buzz! So... i'm guessing that my USB audio interface does not have proper grounding or shielding. The only strange thing is that this problem started once I setup my studio in this house, never had this problem in my old apartment.
But then again, I bought the M-Audio MobilePre USB interface in 2004 and it was one of the cheapest audio interfaces on the market at the time, so it could be near the end of its days.
I have had my eye on the Apogee Duet for some time now so maybe it's just time to upgrade.
Firewire and adapter powered will help. This way it's (less) not depending on mobo power. Taxas instruments make decent usb in's
From what I understand ground loop buzzes usually occur when one device is grounded differently to another. So, running both devices off the same power strip will usually solve the problem.
Have you tried plugging your computer into the same power strip as your monitors?
Using a different bus powered device might not help. A powered USB hub on the same power strip as your monitors might do the trick. If you have one available it's probably worth a try.
I don't suppose that the buzz occurs when your refrigerator/heater/some other electric device turns on? In that case it's a different kind of problem than a ground loop issue.
My Mackie mixer started that same thing. It was random times then got worse until I just don't use it anymore. Not sure if it really applies to this situation, but you might try some other speakers just to test to see which component it's coming from before going nuts on solving some unsolved groundloop mystery.
Thanks for all the responses.
Selling the mobile pre is definitely something I should do, if only someone would actually want to buy it hah.
As soon as I have the ca$h, it's getting the boot and being replaced by an Apogee Duet.
My computer and monitors are plugged into the same power strip, all my gear is running off the same circuit.
But...I never thought of trying a USB hub! I've had one stuffed away in a drawer full of misc. wires so I'll give that a shot!
is this a notebook computer or tower? If the former can you achieve this behavior when it runs on batteries? Always had this problem with older Dell inspirons...
It is an iMac, which is akin to a tower since it needs to be plugged into the wall all the time. The buzz stops as soon as I turn the computer off or unplug the USB interface.
Some interesting updates: I connected my USB interface to a powered USB hub and the buzz is much less severe, in fact it just completely dissipated but it might just be "that time of day" when the buzz decided to fade out.
Also, as noted in the image of the Mobile Pre USB in the link I posted, it has 4 outs; Two 1/4" outs (L and R) that my monitors are plugged into, a 1/8" stereo line out on the back, and a 1/8" headphone out on the front. The buzz is present when going out from the 1/4" out and the 1/8" stero line out BUT not from the 1/8" headphone output.
...the mystery deepens but this powered USB hub seems to be helping!
I humbly suggest you to entwine (is that the verb? I mean twist together) the power cables so the ground loop has the lesser cross section, according to Maxwell's / Lenz's law. Furthermore, I have also a noisy ac power and it was improved by putting a 10nF capacitor from live to neutral cable (yes, like trying to electrocute it, ha ha) This reduced the radio frequency noise a little more. Do you have your gear near high voltage transmission lines? Those are awfully noisy sometimes because of losses in old/damaged isolators.
Wish you success.
Hey, I forgot about that the refrigerator may have an electric motor that may produce some electrical noise. I'm no specialist on fridges, but I can listen to them on some of my ruined recordings.
Hey, I had a lot of problems with souncards and ground. I resolved It buying a "ground loop isolator" like this one (It was made for cars but worked to me)
Also, you can read something about it here
Hope to help you. This issue was a pain in my ass for more than a year : )
So far, I've tried just about all the suggestions. I have my USB sound card being powered by an external USB hub, my whole setup is running from on powerstrip, and I entwined all the cables, but I still have The Buzz.
sumidero: Yes, in fact there are high voltage power lines outside about 10 feet from my bedroom window...I wonder if that has anything to do with it?
djalankin: Thanks for the info! I think my last resort is buying a "ground loop isolator" and I've tried everything else so I'll probably be picking one up after my next freelance gig. I'll let everyone know how that works out.
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