iMac 27" Static Noise through external monitors

Same problem. Using M-audio Bx5a and Subwoofer. Tried ground lift adaptor, Hum X and other fixes. Final solution was to add audio interface usb adaptor. This solved the problem and added benefit of more clearer and dynamic sound. Good luck.

I want to report the same thing-- recently purchased iMac i7 (27in) and running a pair of KRK - Rokit 8 G2 Powered Studio Monitors out. When I'm not sending any signal through, I here static interference coming through both. Very concerned about this. When I unplug from the headphone jack, the interference stops. Also, volume controls do not control the interference, so its an interference signal coming from the port directly, climbing up the cable to the monitor speakers. Arg@!

I bought a iMac 21" at the end of last year and have the same problems. it seems to be coming through the firewire 800 port.

I've asked and checked out loads of threads on here and no-one seems to have an answer, in the US they use a guitar type earth protector gizmo on the main plug to stop it, but it looks like that can't be done in the UK.

Considering i'm trying to use my imac for producing music and I only went mac cos of logic, i really want to get this sorted, but no-one at apple seems to care!!

Just bought a 27" i5 for Logic and my active Samson monitors are giving me the same grief. I, too, bought the rig for Logic.

Searching around and found this: http://support.apple.com/kb/HT2743?viewlocale=en_US

Haven't tried any of the suggestions yet though.

I had this problem, but from my Windows computer. What I did to solve it was purchase an inexpensive ground loop isolator from the local Radio Shack. The 'buzz' was gone.

Hi guys,

well i've managed to solve my noise problem.

I purchased this from amazon, cheapest i could find.

http://www.amazon.co.uk/gp/product/B000NVWB9O/ref=oss_product

and put it between my monitors and external soundcard, now it's completely silent, brilliant. Just sounds weird without noise now lol.

Well I found an answer! If you're okay with using RCA (unbalanced) cables, Radio Shack's Ground Loop Isolator (#270-054) completely got rid of the noise to my Mackie MR5 reference monitors. I mean, it is *dead silent*! Best of all, it cost me all of $16.99.

http://www.radioshack.com/product/index.jsp?productId=2062214

This product provides a 1/8" gold plated connector for the computer output, then stereo RCA cables to go to RCA ports on your speakers. Originally I wanted XLR (balanced) to the monitors at first, and was thinking of spending far more money on the Whirlwind pcDI box, but I'm very pleased with this solution. No way could anything else make it as quiet as this.

Now record music without hearing static every time I scroll a web page with my Magic Mouse (along with the other ground-loop noise)!

Brilliant!

A Ground Loop Isolator worked perfectly! And way cheaper than using a piece of hardware like an audio card etc.

Love it.

Same problem with a friend of mine. Managed to resolve the problem by connecting the speakers to another power-point in the room. No additional/external hardware needed.

I have an imac i5 running audio out into a vestax pmc mixer. The mixer goes into yamaha powered speakers. When I move the mouse or move a window (and basically any other operation but scroll and moving windows accentuates noises the most) there's a very loud buzzing noise. I run my system loud because there's too much content on the internet which has poor/quiet audio.

It could be RF interference.... but probably not. I have a wireless mouse and keyboard. BUT... RF interference would happen randomly wether you're scrolling or not. The noise that i'm hearing only happens when I do ****. (actually there's a consistent noise that's ALWAYS there.. but it's accentuated much louder when I do stuff, so I don't think it has anything to do with RF).

Could be a sound card thing, but I'm not a computer guy and couldn't say.

The problem seemed to be solved when I went out of my computer through the usb, into an DAC (digital analog converter) then from the DAC into the speakers. (a DAC is basically what your soundcard would do).

In conclusion: I think that Apple has ****** audio components. These machines are in some really great studios... And they have sound problems like this? ***?

This is caused by a faulty dimmer regulator on the 27". It will get worse when you dim the screen. Eventually the unit will fail and require repair. If within warranty, take it back asap. This is a very common fault unfortunately! See http://www.listenupsteve.com/fixtheimac/

Message was edited by: BOFHMAN

-= Guaranteed Solution =-

Hi, I have a Quick and nasty solution. It will work, it's a good test also if this is not the case, however, I bet it is.

The problem is technically a ground loop ( http://en.wikipedia.org/wiki/Groundloop%28electricity%29).

The 'Quick and Dirty' solution is to buy a normal cheap double adapter, cut off the earth (I just used pliers) and plug the power of your iMac into this and then your socket, effectively, removing the ground plug to the Mac.

I have messed around ALOT. This is the cheapest complete fix. Be careful when you plug USB's into the computer. I now use a hub for USB, as without the earth you will get some sparks from the ungrounded mac aluminum frame, If this happens don't worry but yeah its not ideal.

If this test works I would then recommend getting a decent RCA Ground noise filter, I don't know if it will cut frequency's of the audio or not, I guess the other option is to try a fully reconditioning UPC unit I haven't tested this yet, I just assume it would work. (cost $200-$600+)

You can also try plugging the Monitors and iMac into the same power board or even better same split power cable. this might have some effect until you really increase power output as the earths are as close to each other. This works for me until I turn my Mackie MR8's up to about 75%. if they are plugged into different power supply I can hear the noise at around 25%-30%.

The iMac actually has an impressive sound card, I have a feeling either it or something on the USB is leaking earth onto the aluminum frame. maybe even the sound card itself isn't earthed properly and runs through the USB earth. It annoys me mac won't provide any kind of solution or admit any of this. ****, I would be happy if they at least sold a ground loop filter on there shop. I know I'm not the only person with Monitor setup and iMac 27" !!!!

The "Quick and Dirty" solution is also a "Quick and Deadly" solution.

There's a reason you are getting sparks from the iMac's aluminum frame. The chassis of most electrical products, including computers, is connected to the ground pin on the AC power cable. This provides a safe path to ground for any high voltage currents from inside the product in the event they come into contact with the chassis. Removing the ground pin from the power cable disconnects this safety path, leaving the high voltage at the chassis. If you come into contact with the chassis, you become the grounding path for the current. If this happens, you will not have any further noise problems, but the fix will not be cheap.