Loud Whine/Hum Noise In Studio Monitors...NEED HELP!!!!

F

FiveFamily

New member
Hey, I recently purchased a pair of KRK Rokit 8 studio monitors and I am havin' a whining/hummin problem with them. Only when I load up Pro Tools or Logic. I have them plugged into an MBOX MINI 3G, BUT I am usin' instrument cables to connect them. I have tried different TRS cables, both balanced but I am not sure if both are instrument cables or not as I found the other pair in my garage randomly. I thought it might be a grounding issue so I was lookin' in to gettin' a 3 prong to 2 prong adaptor but whenever I start to plug the cable into my MBOX MINI 3G, as soon as the ring touches the port I get a LOUD whining noise, then when I plug it in all the way it limits it, but it's still there. I originally tried using unbalanced RCA cables but the noise was even worse, so I switched to the TRS cables. I have been using the MBOX for a while now and I did not have a problem with my old reference monitors. Does anyone know if it would be the cables causing this, a grounding issue or possibly something in my iMac? Maybe even the MBOX? If some one could help that would be great as this is killin' me and I can't seem to find an answer.

Thanks.

21.5" iMAC 10.8.4, 2.5Ghz Intel Core i5 Processor, 4 GB 1333 MHz DDr3 Ram, Macintosh HD.
Avid MBOX MINI 3G
KRK Rokit 8 Studio Monitors
Yorkville Balanced Instrument Cables
Pro Tools 10
 
given that you cannot power your MBOX MINI 3G from an exterior source, I would hazard a guess that your interface is not getting enough current from the USB power buss. Most devices that USB Buss powered expect to see 2A (2000mA) @ 5v being available. If they get a fraction of that current (mostly due to poor implementations of the USB Power Buss supply lines), then you get noise induced as the device tries to suck more current than it can be provided with.

You also do not state whether your mac is a laptop or a desktop model.

In either case, you need to use a powered USB hub top connect your MBOX to the mac. Make sure that the hub is being powered by a 2A (2000mA) power supply.

Good luck (if in doubt also ask foggy about this in a PM)
 
Hey, thanks for the reply. I am a little confused though. I have a USB hub, but I have the MBOX going straight to a USB hub on my mac. Are you saying I need to go buy a USB hub that also plugs into the wall? If so would you have any links for ebay, amazon etc to give me an idea? Also I am using a 21.5" iMac, not a macbook or mac pro.


Thanks.
 
what I am saying is that you need to make sure that mbox is getting enough current - the only sure way to do this is to connect it to a powered usb hub that is supplying the full 2A current specified by the usb specc.
 
If you have checked everything and still get that annoying bis in the line make sure you only have incandescent lighting on the same power circut. The florescent lighting have ballast that have internal grown loops that are transparent in your audio chain. Might wanna check for that as well... :)
 
I guess that different countries have different codes as to how lighting is connected; but in Australia lighting has its own circuit.

Of course if you are talking about have desk lamp tiype situations then yes, you may get power hash on the circuit and possibly in your audio lines
 
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