Line level, mic level, direct box... ?

[Umlaaat]

ok.. i know this is one of the more basic questions..

what is line level and mic level?

i know that mic level has something to do with phantom power, but after putting a condenser mic thru a pre, does it then become line level?

also, i had put a keyboard directly into an input of my motu 828 mk2, but there was very faint signal. then i put it into an input of a mackie mixer, then the direct output into the motu, and it was ok.. why does the outs of an electric keyboard (nord lead 2) need to be amplified?

does that change the signal to line level? why doesn't it work if you go directly out of the keys (nord lead) into the input of the motu?

also - i put the bass thru a direct box (sansamp bass di) into an input of the motu, very faint signal. but when it went into the di of my great river, it was good.. shouldn't that be the same?

thanks for the input, y'all...

[Jack Ruston]

I'm not really very technical so I cant really explain the finer details but...

Line level refers to either +4dbu (professional level) or -10dbv (consumer level).

Mic level is very much lower than that which is why a microphone needs to be amplified. A mic amp input accepts mic level, and outputs line level.

Phantom power can be supplied to mics that require power (eg condensors), but this does not convert the mic signal to line level.

Tube mics often have their own external power supply, which outputs mic level (it is not a pre) but removes the need for supplying phantom power.

The keyboard is giving you a consumer level unbalanced signal, whereas the motu is expecting professional level balanced signals. You need to use a direct box to convert, or as you have discovered, use a mixer to perform that task.

I'm not familiar with the sans amp or the great river, so I couldnt say where the level mismatch is coming from.

J

[eberrong]

Sansamp Bass Driver DI outputs at MIC level. You need to connect it to a mic preamp using a mic cable. Otherwise you will get a very low signal if you try to plug into a line input (even a -10dB input).

[steins]

Originally posted by Umlaaat
also - i put the bass thru a direct box (sansamp bass di) into an input of the motu, very faint signal. but when it went into the di of my great river, it was good.. shouldn't that be the same?

thanks for the input, y'all...

A DI box, unless it has some kind of gain pot like the Avalon U5 DI, just converts your signal to a balanced, low-impedance signal suitable for preamp inputs. It doesn't amplify the signal.

On the Great River, you can use the gain pot to get the correct output level.

You typical signal path for Bass would be:

Bass->DI->Preamp->Motu

Stein Tore

[steins]

Sorry eberrong, you beat me to it...

Stein Tore

[Umlaaat]

Originally posted by steins
A DI box, unless it has some kind of gain pot like the Avalon U5 DI, just converts your signal to a balanced, low-impedance signal suitable for preamp inputs. It doesn't amplify the signal.

On the Great River, you can use the gain pot to get the correct output level.

You typical signal path for Bass would be:

Bass->DI->Preamp->Motu

Stein Tore

hmm.. thats a bit illogical to me. isnt the purpose of a DI to get it to a correct ouput?

(sorry.. i've got to digress for a sec. "Correct input Level" is Line level? if so, does that mean that everything that enters an a/d has to be at line level?)

if not, then can't you go directly to a preamp instead of a DI?

a *dynamic* mic preamp and a preamp that a synth would go into is the same thing?



thanks for the help...

[djui5]

Originally posted by Sly
Mic level is very much lower than that which is why a microphone needs to be amplified. A mic amp input accepts mic level, and outputs line level.

The level (or voltage) of signal generated by a microphone. Typically around 2 millivolts. Compare this with the two normal line levels (1.23 volts and .316 volts),

[djui5]

Originally posted by Umlaaat
hmm.. thats a bit illogical to me. isnt the purpose of a DI to get it to a correct ouput?

Actually the purpose of the DI is to switch the output signal of the instrument to balanced mic level for a number or reasons, one is the ability to use a pre-amp and another is to balance the signal for long cable runs.

Some pre's have an instrument input that you could plug the instrument (bass, key's, whatever) into without a di, but the instrument level is different than a line level so plugging an instrument into a line level input won't work properly.


Yes...all pre amp's are the "same type of thing". There's no dedicated "keyboard preamp".

(please don't flame me for saying pre amps are the same...I was refering to their general use...)