What is a DI box?

[digmudvayne4lif]

I heard that a DI box is a good way to record a guitar into the computer.
1. What is a DI box?
2. Does it really make a difference than just plugging your guitar into the computer?

 

[jkokura]

DI stands for Direct injection...

Basically, one of these puppy's turns an unbalanced signal into a balanced signal. The electronics can be complicated, but there are two kinds. Passive (unpowered) and active (phantom powered).

Unbalanced signals are those found in acoustic guitar pickups and keyboards. The thing with unbalanced signals is that they lose power over long distances - after 10 or 12 feet in your average guitar cable you'll start to lose signal strength and therefore 'tone'. You don't want to lose your tone do you?

A balanced signal can be run a much, much longer distance. I've run cables 100 feet and haven't noticed signal differences on the same source with a 10 foot cable. If you look at 250 foot snakes and you'll see that a balanced signal can be sent a long way. Preamps and Mics put out a balanced signal, and many types of gear use it simply because signal integrity is crucial in recording.

However, to answer your 2nd question, a DI box will turn an unbalanced signal into a balanced one, but it will not make a signal line level - something different. You need a preamp to make a 'guitar' signal go into your soundcard's line in. You would plug your guitar into a DI and then the DI into the Preamp, and then the preamp into the soundcard.

jacob

 

[MessianicDreams]

Basically, one of these puppy's turns an unbalanced signal into a balanced signal. The electronics can be complicated, but there are two kinds. Passive (unpowered) and active (phantom powered).

exactly. an unbalanced signal is also subject to noise, while a balanced signal has a form of noise cancelation.and while what jacob wrote is correct, it's only half the story: a DI box also matches impedence.

are you familiar with impedence and how it relates to audio work? i suggest you try to read up about it, it's not all that complicated but it will help you get a much better sound (or at least understand why you're getting a crappy sound ).

the whole impedance thing is a bit complex, but if you think of the analogy of water in a pipe its a bit simpler: the guitars output has a small pipe full of water, whereas the input of your mixer as a very fat pipe. the same amount of water is still there, its just not as full.

For impedence matching, remember the following:

"High-to-low won't go"
"Low-to-high will fly"

if you're plugging any sort of instrument, such as an electric guitar, bass, keys, straight into a mixer you really should put a DI between the instrument and mixer.