Mbox 2 high pitch whine

[Doner005]

Hey guys! I'm new to the site and i'm hoping you can give me some advice on a problem with my digidesign Mbox 2. I'm running it with usb into my imac 2.6, and monitoring with active mackie monitors. I get a really bad high pitch whine from the monitors when monitoring music through protools, itunes, or anything else. The odd thing is that monitoring through headphones via the headphone output, is completely clean.

I've try balanced and unbalanced cables like the digi site says, even though mackie says it shouldn't matter. I've read that it is a usb noise problem. Ok, seems plausible, but could someone explain why headphone monitoring is clean?

Yesterday, I dug out my old lexicon audio interface to try and help diagnose this problem. I plugged it in with all the exact same connections, these being the same usb cable and same 1/4 inch to the monitors. I fired it up and it's quiet as a mouse and perfectly clear.

Now the digi site explains that it's almost never a problem with mbox, which i expect them to say. I just can't seem to prove it's not the mbox. After countless hours and numerous threads of this same problem, I've been advised to buy a monster usb cable in most occasions. Thanks, but No Thanks. This mbox should work with the components it comes with, especially when a 5 yr. old interface works perfectly with the same usb cable.

Sorry for the long post fellas but as you can probably tell i'm just frustrated that my brand new product isn't performing how it should be. I appreciate any advice you can give me and thank you in advance for taking time to try to help me sort this out.

Chris

[gtrbob]

I have been using th Mbox 2 for about 2 years now. I don't use it with powered monitors, I usually run the monitor outs to a separate power amp, and then to the speakers. I do hear some high pitch whine, but not a distracting amount. Do your mackie monitors have a unity gain notch on the volume pots? If so, try setting that to unity, then adjusting your listening level with the Mbox monitor knob. Try not to turn up the level control any more than you need on the monitors themselves. I know that this is a longshot, but I can't judge exactly how loud this noise is for you.

[Doner005]

I finally solved it. I wouldn't have expected this to be an issue, but isolating the grounds for my monitor speakers dun did it. I just took a 3 to 2 prong adapter and shazaam, shaquille oneal appeared in a genie suit and granted me one wish. Which obviously i chose to get rid of the high pitch whine. Hope this can help other people who have this problem.

On another note, I am a little unimpressed with the pops and clicks this thing makes when switching between the buttons on the front panel. Well at least it' working now.

[Doner005]

Originally Posted by gtrbob

I have been using th Mbox 2 for about 2 years now. I don't use it with powered monitors, I usually run the monitor outs to a separate power amp, and then to the speakers. I do hear some high pitch whine, but not a distracting amount. Do your mackie monitors have a unity gain notch on the volume pots? If so, try setting that to unity, then adjusting your listening level with the Mbox monitor knob. Try not to turn up the level control any more than you need on the monitors themselves. I know that this is a longshot, but I can't judge exactly how loud this noise is for you.

Hey gtrbob thanks for the input. It was a loud whine, un-maskable with gain controls. Now with the grounds isolated i can crank up the gain and not hear a thing.