Audio out for macbook, for live work?

A

akpcep

New member
Hi all,

Quick one - I've got a macbook which I'm planning on using with my live band for sequencing/percussion etc. I need some kind of interface/cable so I can get the audio out from either the USB or headphone outputs to 2 x 1/4inch jacks, which will go into stage DI boxes for left and right stereo.

Can anyone recommend anything that will do this?

Cheers!
 
Hi,

I have used one of these, they work fine and are very cheap, you then connect to the DI's (left and right) with 2 Jack to RCA leads.
http://www.behringer.com/EN/Products/UCA202.aspx

If you get a ground loop through the USB cable, as happens with laptops sometimes, you will also need one of these in between the DI and UCA202.
http://www.behringer.com/EN/Products/HD400.aspx

And whiles you are at it, if you get one of these as well you could have the whole thing made up with short cables and taped together so that it is ready to plug into the PA without fiddling around with connectors at the gig or having the sound guy telling you he has not got any DI boxes left.
http://www.behringer.com/EN/Products/DI20.aspx


Cheers

Alan.
 
Wow, thanks Alan what a tremendous reply!

That all looks nice and compact, I'm familiar with Behringer's gear, a bit cheap and cheerful but it always looks rugged enough.

One question though, I've noticed the DI box has a ground lift switch, wouldn't this make the hum cancelling box redundant?
 
Hi,

It may fix any problems with balanced inputs like XLR pin 1 earth, pin 2 + pin 3 -, where the earth lift lifts pin 1 (I have not tried this) but you may still have trouble if you plugged into a unbalanced input direct from the UCA202 if you had to plug into a line input on a mixer for some reason.

You may not have problems anyway so I would try it before buying the hum eliminator.

Earth loop problems happen on laptops because on later laptops the power supply has a mains earth, this is linked to the - side of the lap top power so that you cannot be electrocuted from a metal part of a lap top. What happens then is that if there is a mains earth loop problem, the loop is via the USB cable, this shows up as bad sound quality / whining noise etc. The 2 ways to fix it is the hum eliminator or use a double insulated power supply on the lap top that has no mains earth (older lap tops had this). If you run the laptop on the battery with the power supply unplugged there won't be a problem either, this has got me out of trouble in the past.

My old laptop (which was stolen) did not have a problem, but my new one does. It only happens when using USB sound cards, my firewire sound cards don't have a problem with the earthing.

Cheers

Alan.
 
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