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What's the difference between a mic preamp and an interface? Dual-Channel Preamps
Old 12th July 2018
  #1
Here for the gear
 

What's the difference between a mic preamp and an interface?

Maybe a dumb question, but I'm curious... I'll try to use examples to the best of my knowledge.

I use a Scarlett 18i20 AD/DA converter and my understanding is that the main 8 inputs are actually preamps and the rest of the equipment takes the signal and does the AD/DA conversion work so I can record in my DAW.

Sometimes I like to browse gear I can't afford (lol) and today I was looking at Tube Tech's MP2A. As far as I can tell, I can't directly interface this with my DAW. It looks like it just has an output and you'd have to send the signal to something that can record.

So, in my case would that be the 18i20 interface? Would that somehow mess up the signal if I recorded the MP2A output through the lower quality preamps in the interface? I'll probably never get such an expensive preamp cause I'm just doing small home studio stuff, but if I ever find a different/cheaper/used preamp maybe I'd go for it.

Thanks!
Old 13th July 2018
  #2
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Quote:
Originally Posted by dtx3yamaha View Post
Quote:
Originally Posted by dtx3yamaha View Post
What's the difference between a mic preamp and an interface?
Maybe a dumb question, but I'm curious...
The interface is a connection between your computer (DAW) and other gear.

The microphone preamp takes a mic level signal (the mic output) and amplifies it, typically to line level.

Some mic preamps have digital outputs, and thus perform conversion as well. If your computer has a similar digital input the interface can be bypassed (or you could argue that the interface is 'built into' the mic pre, although few would use the terms that way).

Some interfaces have mic preamps, like your Scarlett.

Quote:
Originally Posted by dtx3yamaha View Post
I use a Scarlett 18i20 AD/DA converter and my understanding is that the main 8 inputs are actually preamps and the rest of the equipment takes the signal and does the AD/DA conversion work so I can record in my DAW.
I'm not trying to be annoyingly nit-picking, but it's not correct to say that the "inputs are actually preamps". The inputs are just inputs, and inside the box those inputs go somewhere. In the case of your Scarlett they do go to mic pres. After the mic pres the signal goes to analog-to-digital converters. Then the digital signal goes to some sort of output.

Quote:
Originally Posted by dtx3yamaha View Post
Sometimes I like to browse gear I can't afford (lol) and today I was looking at Tube Tech's MP2A. As far as I can tell, I can't directly interface this with my DAW. It looks like it just has an output and you'd have to send the signal to something that can record.

So, in my case would that be the 18i20 interface?
That's correct. If you look at the back of your interface the inputs actually say "mic/line". So this tells me that they're meant for both. You would connect a mic obviously in order to use the built-in preamp, but you could also plug in a cable that carries a line-level signal. The TubeTec would output a line level signal. So, mic goes into TubeTec preamp, goes out of it at line-level into the Scarlett, and the Scarlett then converts that to digital.

Quote:
Originally Posted by dtx3yamaha View Post
Would that somehow mess up the signal if I recorded the MP2A output through the lower quality preamps in the interface?
I'm sure a fair amount of people would argue that it does. "Mess up" is a strong word, but of course the more components you add to the signal chain the more you change the signal, even if they don't seem to 'do' anything.

Some interfaces have mic pres that can be bypassed, and some don't. So if you have one that can be bypassed that would then arguably maybe be better.
Old 13th July 2018
  #3
Here for the gear
 

Quote:
Originally Posted by mattiasnyc View Post
The interface is a connection between your computer (DAW) and other gear.

The microphone preamp takes a mic level signal (the mic output) and amplifies it, typically to line level.

Some mic preamps have digital outputs, and thus perform conversion as well. If your computer has a similar digital input the interface can be bypassed (or you could argue that the interface is 'built into' the mic pre, although few would use the terms that way).

Some interfaces have mic preamps, like your Scarlett.



I'm not trying to be annoyingly nit-picking, but it's not correct to say that the "inputs are actually preamps". The inputs are just inputs, and inside the box those inputs go somewhere. In the case of your Scarlett they do go to mic pres. After the mic pres the signal goes to analog-to-digital converters. Then the digital signal goes to some sort of output.



That's correct. If you look at the back of your interface the inputs actually say "mic/line". So this tells me that they're meant for both. You would connect a mic obviously in order to use the built-in preamp, but you could also plug in a cable that carries a line-level signal. The TubeTec would output a line level signal. So, mic goes into TubeTec preamp, goes out of it at line-level into the Scarlett, and the Scarlett then converts that to digital.



I'm sure a fair amount of people would argue that it does. "Mess up" is a strong word, but of course the more components you add to the signal chain the more you change the signal, even if they don't seem to 'do' anything.

Some interfaces have mic pres that can be bypassed, and some don't. So if you have one that can be bypassed that would then arguably maybe be better.
Nice, thanks man. Don't mind the nit-picking. I think the details are important and I appreciate the detailed response.
Old 13th July 2018
  #4
Lives for gear
Msync is correct.
Just to add a couple of things... Newbies need to be careful when using an outboard preamp that they don’t overdrive the interface pre (or line) input.
Also, and this is a personal opinion shared by some and not by others, an EXTREMELY mediocre interface can be so blah and slow on transients that it will give every input a dose of that, no matter what preamp you put in front of it. The good news is that most interfaces these days are reasonably good at passing audio without negatively impacting that audio. So they will do a good vanilla job with their own preamps or line inputs, but they will also do a good job capturing any measure of tube, transformer, vintage, saturated, or whatever special sauce a great external preamp sends.
If you think about it, even a very average audio system can reveal the quality differences between Abbey Road product and a garage band with a Zoom. The quality of the capture translates fairly faithfully.
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