Why should i use a direct box instead of plugging directly in to a PA?

Question

i'm not exactly sure what a DI box is used for, but i was told to use one if i am going to plug a bass guitar into the mixing amp... rather than just plugging the bass directly into the input on the mixing amp... why?

http://www.arx.com.au/FAQ_DI_boxes.htm

in simplified terms.. what does this mean?

i just don't understand why a DI box is better than plugging the instrument into the mixer..

audio noob

Answer 1

Why SHOULD you?  No reason.  They're good to have on hand in case you need one.  A direct box serves a few purposes, such as an adapter for different plug types, especially if you'r working with a combination of 3-pin Balanced connectors and 2-pin Unbalanced connectors.  Even then, it only matters IF you need to convert from one plug type to another.

Probably most important, though, is the capacity to be a 'ground-lifter' when you get HUM in your system.  Hum can be due to a variety of situations, one of which is called a 'ground-loop' where the ground pin of one piece of equipment is not truly at ground.  By 'lifting' the ground pin from the rest of the circuits, you've effectively removed the loop and the hum.

Use it when it's needed, otherwise, you'll have direct boxes  for every single device you're plugging into your mixer.