MBOX INTERFACE NOISE PROBLEM

Hi guys,

Have a slight problem with a friends mbox mini which we're trying to get to work in conjunction with his existing setup. The problem is a high pitched wine (almost sine wave) accompanying the audio when using the main outs into the inputs on his yamaha 01v96 desk. If I patch his mackie monitors straight in to the mbox, then the noise goes away.
I can't think of any reason why we would be getting this noise, but rather than bypassing the desk completely I would like to get this sorted so he can monitor his rack synths etc along with the mbox. I know that the mbox is not 'high end', but is this a no no? Thoughts please?

cheers
Chris

Hi Chris,

Are you using the analog outs/ins?  Why not go SPDIF?

Cheers,
Ruairi

Thanks for the reply Ruairi,

This isn't 'pro' version so no spdif, just analog outs. I've updated usb drivers now which have helped a bit and with some carefull gain setting have reached a useable compromise for the time being. At least it's no longer just a 'paper weight'!  ;D
He's used cubase for many years, so this will be cool for getting used to PT. I think though that given a bit of time, the rack synths will gradually loose favour to soft synths so we can hook up monitors directly and bypass the desk.

cheers

Chris

I had this sort of problem with my Mbox mini using this laptop.  I think it was because this laptop PAU has an earth connection.  The answer was to use a couple of passive DI boxes to isolate the 2 pieces of gear.

I have similar problems with my mbox1. I found that the amount of noise can vary with the USB cable used. Unfortunately the problem  seems to get worse, so I can't exclude a software problem.... 

Sounds like motor noise from a hard drive. Does the pitch change when seeking data?

i've almost always "patched" this problem by using isolation transformers. I'm even using a couple right now to get rid of the high end buzz from my laptop to my Hifi.

greetings,

Thomas

Thanks for all the info and advice so far. Seems like my friend is not the only one to have this problem.
Yes thought about isolating tx's, but just annoys me to think that someone would have to occur the extra expense. Oh well, I suppose its a case of you get what you pay for sometimes. 

My original Mbox 1 does this with my PC... but not with my mac.

There IS no external connection... just headphones, so no isolation transformers can do any good.

Just one more reason for me to use the mac, I suppose!  ;D

with my Mbox mini plugged into my QUAD hifi isolating transformers (in the form of 2 DOD DI boxes) eliminated this problem completely.  I guess it's just different from system to system