FYI for mic/pres plugged into Audio interfaces that have Built in Mic-pres.

malcolm123

New member
My son went to record last night at a friends house. I guess he been listening to me about having a clean signal chain for mics.

He told his friend that there was too much noise in the mic. So his friend then put a gate on it. My son then told him
that there is still noise whenever the gate if off while speaking into the mic. So he called me. I told him I would have
to come see it and listen. I never had to listen because he was running a mic/preamp plugged into the audio interface's
mic/pre. They keyboard player had a extra DI-Box. Simple. Mic>Mic/pre>DI>audio interface mic in.

For those who may not know.
 
Well, technically, he should have gone from the mic to the interface mic in. But, if there's a mic pre, it goes to a LINE IN, not the Mic in. There should be no need for a DI.
 
Well, technically, he should have gone from the mic to the interface mic in. But, if there's a mic pre, it goes to a LINE IN, not the Mic in. There should be no need for a DI.

Mic Pre is better than the Audio Interface's mic/pres. DI

If I am wrong, then please explain it. I learn something new everyday.
 
i was told going into to the Mic IN is ok too, the 2nd preamp becomes a pad like thing.
It works, but Line In is the first choice in most diagrams Ive seen.

some pro's I was reading today mention the weaker less desirable preamp can hinder the sounds a bit e the Line In would bypass. I dont know how old some of this folklore is based off of though. My personal experience I couldnt hear a big difference going into one or the other.
 
Mic Pre is better than the Audio Interface's mic/pres. DI

If I am wrong, then please explain it. I learn something new everyday.
Well, first you have to define better. Some can be better, but it's nothing I'd take for granted. It depends on the mic pre and the interface. I probably wouldn't put a cheap mic pre between a good mic and a Focusrite Clarett, for instance, but in any case, I'd always suggest actually recording both ways to compare.

And, with the pieces you've strung together, you're going through the interface's mic preamp anyway.

But, if we just assume this is a good preamp and it makes the mic'd performance sound better (edit, or perhaps it was necessary because the i/f didn't have sufficient gain), then it will be better to plug it into the line input of the interface.

I'm assuming, of course, that the interface has a line input!
 
Well, technically, he should have gone from the mic to the interface mic in. But, if there's a mic pre, it goes to a LINE IN, not the Mic in. There should be no need for a DI.
Mic Pre is better than the Audio Interface's mic/pres. DI

If I am wrong, then please explain it. I learn something new everyday.

It would be interesting to know the original I/F -mic pre situation to cause excess noise. Likely gain had to be jacked up perhaps? Yet if it was ok with the external pre (and D/I), I'd bet what happened was the I/F pre saw higher level, and worked better set lower.
A mic pre can do ok seeing a 'line out', as long as the level up stream is tamed and input it isn't clipped.
Might could have done the same w/o the D/I, but maybe the D/I helped loose some level to make it happen?
 
i was told going into to the Mic IN is ok too, the 2nd preamp becomes a pad like thing.
It works, but Line In is the first choice in most diagrams Ive seen.

some pro's I was reading today mention the weaker less desirable preamp can hinder the sounds a bit e the Line In would bypass. I dont know how old some of this folklore is based off of though. My personal experience I couldnt hear a big difference going into one or the other.
You have a link to what you were reading?
 
You have a link to what you were reading?

Some people may have only 1 Mic/line and 1 input on the audio interface.

Active bass guitar, etc>Passive DI>Audio Interface's input..
Passive bass guitar, etc/Non condenser mic (No Phantom)>Audio Interface's input.
Condenser mic (Phantom)>Mic preamp>Passive DI>Audio Interface's input... XLR or Input.

If Audio Interface's "Input" has a "Line/Inst" switch,, then switch to line and forget about a DI Box.
 
RME-QuadMic-II running to some type of M-Audio box. He say he got the RME from his Dad's friend.

That RME preamp is rubbish unless modified in a secret way known only to ME! PM me IMMEDIATELY and I will pay shipping plus a nifty for your trouble.....

Heh! Does his dad's friend KNOW he has it? Over 1/2 a bag's worth of kit in the hands of noobs!

Dave.
 
That RME preamp is rubbish unless modified in a secret way known only to ME! PM me IMMEDIATELY and I will pay shipping plus a nifty for your trouble.....

Heh! Does his dad's friend KNOW he has it? Over 1/2 a bag's worth of kit in the hands of noobs!

Dave.

LOL,, I'm sure he does. Or he may not as well. They all have ties to James Brown in some type of way. Could have been
Jame's engineer or something. That's highly possible here. We all are from Augusta Ga. He doesn't know what he has though. I even saw a old
Studer 24 track recorder. LOL
 
You have a link to what you were reading?

the use of it as a pad was told on the forum here. back when I was running a ISA One into a Tascam Frontier USB (their first usb unit the silver with blue rubber on it! lol funny looking)

the weakest link comment was on another forum in a high end section. I usually dont doubt those guys hearing more in a room thats tweaked and near perfect, but can HR hear the tiny subtle differences? I dont know. Makes sense in theory too. Weakest Link theory.
 
There's two truths in this problem.

If you have average gear that has a true line input, use it.

BUT better gear, and any recent gear that follows the electronics handbook, has a mic input that is also the line input. That's because these mic preamps have such a wide gain range, that you can use them as a line input, simply by reducing the gain.

The only thing that might not be ideal, is the impedance. But the days of impedance matching have long gone. Your typical mic preamp has a 2 to 5 kOhm impedance at the input. A "true" line imput should be 10 to 100 kOhm. But modern gear doesn't care, so it really is a moot point.

If you're running real vintage tube stuff, it becomes a real problem, technically. But that's just the kind of stuff they do, those who own the real vintage stuff. To add colour, warmth, depth, or whatever they like to hear in harmonic distortion.

A way to check in the specs if the gear you're eying works well with a combined line/mic input, is to check the overall gain. Anything below 60 dB gain will be mediocre. Anything above should work.

If we take the example of an RME interface, it has 80 dB overall gain. In theory, the output would produce 10 V from a 1 mV input at full gain. Of course, the output can do 10 V, but the following input might not be able to take that without a bit of distortion. It's just spare gain, for those mics that don't even reach 1 mV. At 0 dB gain, there's a number that's not often in the specs. It's the minimal gain. In this example, it's 20 dB. Eg, a 1V at the input still results in 10V at the output.

It's also why good gear has a headroom of at least 20 dB over 0 dB;

Where do you encounter the problem? Any battery fed recorders. Except stuff like Sound Devices etc.

Because the mic inputs run on low voltage, low current, the design isn't by the book. And these usually distort a lot a 1V, 0 dB input. The better ones have line inputs, unfortunately often it's just a -40 dB pad, which adds a litlle noise.

There are a real 32 bit interfaces. >15.000 €, sans options. These don't even need to adjust gain. Their range is so big it doesn't matter if the signal is 1V or 1 mV.

To us, mere mortals with a mortgage, RME with it's digital gain is the closest we can get to 32 bit heaven. It's only 24 bit, but with a true digital gain. 0,5 dB is precisely 0,5 dB. Every time, not dependent on mains power or moon phase.
 
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