in an audion interface - isn't phantom power a type of mic pre-amp

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diannaZ

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Hi
I want to buy an audio interface and I want to boost the mic signal.
I will record electric and acoustic guitar, and vocals.

I'm a little confused about this the phantom power\preamp thing.
in an audio interface - isn't phantom power a gain used to boost signal? isn't that called pre-amping ?
are there other ways an audio interface boost the signal of a mic ?
 
Nope, that's not what phantom power is.

Preamps can be bought as standalone units, or built into to an interface.
Many, but not all preamps will have preamps built in.

Generally speaking, an XLR input means there's a microphone preamp in there.


Phantom power is a type of power source that some microphones require to work.
It's often supplied by the preamps and is 'invisible' to most microphones that don't require it.

Dynamic mics don't need it, condenser mics do.

Some ribbon mics can be damaged by it in certain circumstances, and *I think* some active ribbon mics might need it.

Hope that helps.
 
Steenamaroo said:
Preamps can be bought as standalone units, or built into to an interface.
Many, but not all preamps will have preamps built in.
Click to expand...

you meant "Many, but not all audio interfaces will have preamps built in." , right?

Steenamaroo said:
Generally speaking, an XLR input means there's a microphone preamp in there.

Phantom power is a type of power source that some microphones require to work.
Click to expand...

so basically, any audio interface that has an XLR input means there's a microphone preamp in there and in addition if it has a "48db+" button or a "phantom power" button on it - than is also has phantom power?
 
diannaZ said:
you meant "Many, but not all audio interfaces will have preamps built in." , right?



so basically, any audio interface that has an XLR input means there's a microphone preamp in there and in addition if it has a "48db+" button or a "phantom power" button on it - than is also has phantom power?
Click to expand...

Yes. That is what he meant to say. And no, not ALL audio interfaces that have an XLR input means there is a mic pre.

Not "48db+," but "48v."

Decibels (db) is not voltage (v). But to answer your question, yes. If you see that button, it means it has phantom power.
 
in an audio interface - are there other ways an audio interface boost the signal of a mic other than "phantom power" ? what are they?

CrowsofFritz said:
not ALL audio interfaces that have an XLR input means there is a mic pre.
Click to expand...

what should I be looking for at the specs to make sure the audio interface I'm buying has a good mic pre built in it?
 
There are several things here.

Phantom power provides power to condenser microphones and other devices which require it to operate. That's all it does.

A preamplifier boosts the signal of a microphone, condenser, dynamic, ribbon, whatever.... to a usable level. You can't record anything without a preamplifier - you just may not be aware that you're using one.

Audio is analogue - to get it into a computer via USB or Firewire the signal has to be digitised. That requires an AD converter (audio to digital).

An audio interface provides some, or all, of these services/components - as well as the physical inputs and outputs to plug mic and other cables into and out from, often with audio outputs as well as the USB, for monitoring purposes.

Most people will recommend, if you don't have any other of the bits in standalone form, that you get an audio interface that does all these functions.

Some also have MIDI capability, as well.

Depends what you want to do... horses for courses.

Read some of those STICKYs up the top and things will be much clearer.
 
diannaZ said:
in an audio interface - are there other ways an audio interface boost the signal of a mic other than "phantom power" ? what are they?



what should I be looking for at the specs to make sure the audio interface I'm buying has a good mic pre built in it?
Click to expand...

As Armistice has said, phantom power only makes condenser microphones work. It don't boost the signal. It just gives the mic the voltage for them to work.

I haven't read any specs that mention the quality of the preamp in an interface. I know some companies boast that the interface "has this preamp built in." I would just say as a general rule: the higher the price, the better the quality. Now obviously this doesn't apply to everything (especially used gear). But there is a correlation.
 
Yes, i meant not all audio interfaces have microphone preamps built in.

As said, phantom power/+48 doesn't boost any signals. It's a power supply, just like a battery or whatever.
 
Ok, I'm a bit confused now. Let me use actual examples... Focusrite Scarlett has two pre-amp inputs - are those phantom power inputs as well? Will I have no problems when sticking in an AKG condenser mic via XLR into one of those? What about my electric guitar? If I wanted to plug it straight into the audio interface will I need to use the pre-amp input or can I use one of the regular inputs?
 
Okay, let's go back to basics here.

Some items of audio equipment need an electrical source to operate--condenser microphones are the most common of these but there are also some other bits and pieces like DI boxes that need power as well.

"Phantom Power" is a clever way to provide this electricity. It feeds 48 volts (at a fairly low amperage) out of the same XLR socket that you plug the microphone (or other devices) into. It does this safely by putting the same +48 volts on the two active pins (2 and 3) of the XLR. This is safe because of the way a balanced audio signal works: the actual audio is fed at opposite polarities down the two conductors. This means that, when the signal on one of these pins is inverted, the 48 volt phantom power is also inverted, cancelling out the voltage. Gear that needs phantom can grab it before the polarity reversal happens; anything else can safely ignore it.

Phantom is pretty much always restricted to XLRs because be physical layout means that pins 2 and 3 connect at the same instant. It is rarely, if ever, provided on quarter inch TRS sockets because, as you plug in the conductors click past each other and can cause short circuits.

On the Focusrite you mention, there are combined XLR/TRS sockets but the phantom power is only present on the XLR (and only when switched on) so you can still safely use the centre quarter inch sockets for instruments or other sources.

Microphone pre amps are very different things. The signal from a microphone is a very, very low level compared to powered items like CD players, mixers, etc. A mic signal is something like 40 to 60dB quieter than the standard "line level" signal that most audio gear processes. The solution to this is to amplify the microphone with a mic pre amp. A mic pre amp is a clever device that raises the signal by 40-60dB without adding significantly to the noise level.

As has been said, USUALLY inputs to interfaces or mixers including a mic pre amp are the ones with XLRs, the same as the ones that provide phantom power but the two functions are totally separate. Always check the manual for the gear you're using because there can be exceptions to the "XLR = microphone" guideline--for example, a lot of broadcast TV gear uses XLRs for everything.

However, in the case of the Focusrite you plan to buy, the XLRs are, indeed, the mic inputs. However, just to add confusion, the quarter inch jacks in the centre are set up for line or instrument level and don't carry phantom power.
 
Steenamaroo said:
Read all the stickies and noob guides, really.
Click to expand...
I really want to find a sticky that answers if an audio interface has a certain amount of signal boosting, but there is so much info and links to more info on those stickies that I can't find what I'm searching for there
 
diannaZ said:
I really want to find a sticky that answers this , but there is so much info and links to more info on those stickies that I can't find what I'm searching for there
Click to expand...

Ok, read bobbsy's reply instead then. ;)
 
ok, let's forget about phantom power for a minute.
some audio interfaces have built-in preamps, right?
ok, so I want an audio interface with a built-in preamp, strong enough to boost the signal of a c606 shure mic with minimal noise.
(I know there are preamps as a stand alone unit - those I don't want right now)

what should I be looking for at the specs of an audio interface to make sure the audio interface I'm buying has a reasonable mic preamp built in it?
 
That's a karaoke mic, it has a 1/4 plug instead of an XLR. Not sure which interface will run the 1/4 through the mic pre. Most interfaces will expect the 1/4 jack to be supplied at line level or instrument level which is much more voltage than what a mic will put out. That means the interface won't send the 1/4" jack input through the mic pre.

Do yourself a favor and don't use that mic. From the quick search, it seems that mic is one step above a toy. You can certainly find much better mics for not a lot more money.

Check out this mic, it's my go-to mic for my vocals. On eBay, it's a great deal. I just might have to pick up another...
MXL V57M Large Diaphragm Condenser Microphone | eBay
 
Chili said:
That's a karaoke mic, it has a 1/4 plug instead of an XLR. Not sure which interface will run the 1/4 through the mic pre. Most interfaces will expect the 1/4 jack to be supplied at line level or instrument level which is much more voltage than what a mic will put out. That means the interface won't send the 1/4" jack input through the mic pre.

Do yourself a favor and don't use that mic. From the quick search, it seems that mic is one step above a toy. You can certainly find much better mics for not a lot more money.

Check out this mic, it's my go-to mic for my vocals. On eBay, it's a great deal. I just might have to pick up another...
MXL V57M Large Diaphragm Condenser Microphone | eBay
Click to expand...
oh I forgot, I already decided to buy a new mic (i'm thinking the shure sm57 or sm58, they are XLR - right ?) so forget I mentioned the c606...we are talking XLR input
 
Chili said:
So, back to your "which interface" question.... You should be looking at something like this or an equivalent to get you started:

PreSonus AudioBox USB | Sweetwater.com
Click to expand...

thanks but the question is not "which" interface is right for me but what should I be looking for at the specs of an audio interface to make sure the audio interface I'm buying has a reasonable mic preamp built in it? are there different types of built-in audio interface preamps ?
 
I think diannaZ is asking for something that gives a list of audio interfaces, and describes the pres that are built into them. I have seen nothing of the sort.
 
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