Direct Box

[paulbeteivaz]

I'd like to know what is the pupose of using a direct box in recording, what are the applications of this device?

Regards,

 

[Nick98338]

One main purpose is to convert an unbalanced signal to a balanced signal. Some recording equipment will only accept a balanced signal. Or, a balanced signal is otherwise desired. But, some instrunents (guitars) only output an unbalaced signal. So, you need to convert before going into the recording equipment. Along with converting the signal, a DI often converts to a certain kind of cabling.

 

[up-fiddler]

It will also give you more gain to your input. You don't need to run you boards inputs as hot and typically get less noise as a result.

 

[easychair]

DIs actually drop signal level, or at best are unity gain. They don't add gain. There are a couple that have gain circuits, but that's not part of what DIs really do. You end up plugging into a mic input, which is more sensitive. So it takes less signal to get the same level as plugging into a line input. It seems like your signal has more gain, but it's not what's happening.

 

[paulbeteivaz]

How do I know which instrument needs to be connected through a DI and which does not? How I can find more technical/practical resources for this device?

 

[mawtangent]

paulbeteivaz...I think I need a DI box because when I tried to record an electric bass guitar recently (through the line-in of my mixer) it sounded weak and noisy (with a low buzzing noise)...I am looking to buy a DI soon to get a better bass guitar recording.

I have been reading some audio recording textbooks as part of a college class called "Music Technology" and I remember reading a refreshing comment about DI boxes which basically said that if you are getting a weak and noisy signal (without a DI box) then you probably need a DI box...it seemed to be saying to use your ears to determine if your signal/sound is acceptable, and then determine if a DI is necessary (this is not always easy, I am still learning to discriminate between what sounds good and what sounds bad)...a DI seems to be the solution to an obvious (in your face) problem, a weak and noisy signal from a high impedence instrument.

Of course a DI may improve an "acceptable" signal also (I don't know, I've never used one, and am not really qualified to comment on this topic). In general a DI seems to be a good thing to use when recording an electric bass or an electric guitar directly (without micing an instrument's amplifier) into the mixer (from my readings here, most prefer to record electric guitar by placing a microphone in front of the guitar's connected amplifier/speaker), but I have also seen mention of using a DI with a keyboard also.

 

[travelin travis]

a DI box converts instrument level to line level. that's all.

 

[Dags]

but I have also seen mention of using a DI with a keyboard also.

That was probably my addition. In context, that was for stage use only when you need to get the sound from the synth to the main mixing desk.
If you're in a room no more than 20 feet away from the recording console, your average decent quality unbalanced jack to jack cable will be good enough for carrying the signal.
If you're further away then you'll be wanting to use a D.I. to enable you to run longer *balanced* leads to the recording console to maintain signal strength and minimise unwanted noise from the lengths of cable involved.

Dags

 

[Farview]

A DI will balance the signal and change the impedance from hi to low. When you plug a bass into the line in of your mixer, it is the impedance mismatch that makes it sound weak. (if your bass has passive electronics, they also don't have enough gain)

A passive DI is good for active basses but for guitars and basses with passive pickups, you need an active DI. The active DI will not load down the passive pickups and muddy things up.

DI boxes do not change the gain of the signal.
DI boxes do not turn a line level signal into a mic level signal
DI boxes do not turn an instrument level signal into line level

DI boxes do balance the signal
DI boxes do match impedance

 

[Nick98338]

How do I know which instrument needs to be connected through a DI and which does not? How I can find more technical/practical resources for this device?

Most electric guitars output an unbalanced signal. I won't say all. There are some exceptions. Any instrument that has a 1/4" or 1/8" TS (2-wire) output will be unbalanced. Any instrument that uses an RCA type plug will have an output that is unbalanced. That includes many keyboards, but not all.

Most instruments that use an XLR plug and cable will be balanced. Again, there are exceptions. Instruments that use a 1/4" or 1/8" TRS (3-wire) *might* be balanced. More likely they will actually carry two different unbalanced signals (stereo).

Search the web. There's gobs of stuff out there to explain all of this.

 

[mawtangent]

How do I know which instrument needs to be connected through a DI and which does not? How I can find more technical/practical resources for this device?

You might find this helpful:

http://psbg.emusician.com/ar/emusic_going_direct/

 

[giraffe]

A DI will balance the signal and change the impedance from hi to low. When you plug a bass into the line in of your mixer, it is the impedance mismatch that makes it sound weak. (if your bass has passive electronics, they also don't have enough gain)

A passive DI is good for active basses but for guitars and basses with passive pickups, you need an active DI. The active DI will not load down the passive pickups and muddy things up.

DI boxes do not change the gain of the signal.
DI boxes do not turn a line level signal into a mic level signal
DI boxes do not turn an instrument level signal into line level

DI boxes do balance the signal
DI boxes do match impedance

with the exception of this post, this thread is dog-fucked madness.

 

[easychair]

with the exception of this post, this thread is dog-fucked madness.

And even that one is off the mark, in some ways. (no offense, Farview)

DIs do change signal level, downwards. Passive DIs use step-down transformers. So they don't convert line level to mic level per se, but step down the gain of the input by a certain amount by nature of the transformer. 20db is pretty common, as many passives use 10:1 step-down transformers. Good thing, really, as most mic inputs can't handle a line or instrument signal without some kind of padding.

Active DIs have losses as well, all circuits do. A zero-loss or boosting active DI has some kind of amplifier inside. No getting around it.

 

[fazil]

Just see it as a sort of box that simulates a microphone output. Then connect it, just like a mic, to the preamp.

A DI box wants to see a high output impedance device on its inputs and converts it to a low output impedance and balances the unbalanced signal. -> so you get pretty much what a mic output looks like.


If you connect a low output Z device to a high input Z device you generaly get less noise/loss/hum/crap ....
Balancing the signal also cancells unwanted crap like noise etc...

As you can see DI's provide you the ability to send a very "weak" signal such as a guitar pickup over much longer distances.

 

[paulbeteivaz]

Direct Box Application

In a home studio project, and in order to connect a workstation/arranger keyboard to a multitrack recording software, is it necessary and or a plus to use a DI?

 

[MessianicDreams]

i think the most important feature of the DI box is impedance matching..as it is that which'll make your guitar sound like crap when plugged straight into a mic input etc..

 

[up-fiddler]

DIs actually drop signal level, or at best are unity gain. They don't add gain. There are a couple that have gain circuits, but that's not part of what DIs really do. You end up plugging into a mic input, which is more sensitive. So it takes less signal to get the same level as plugging into a line input. It seems like your signal has more gain, but it's not what's happening.

Right. Sorry. Most mike input strips are multifunction and have a gain boost perhaps a simple compressor, a de-esser, etc. A true DI typically doesn't boost gain. I was using the terms interchangably. Dave

 

[up-fiddler]

Like this! Dave.

 

[easychair]

Just see it as a sort of box that simulates a microphone output. Then connect it, just like a mic, to the preamp.

That's beautiful, man.

 

[noisedude]

with the exception of this post, this thread is dog-fucked madness.

I agree. WTF happened to this website?