# Groove Tubes Brick preamp > EMU 0404 PCI...is this calib file correct?



## jlird808 (Nov 2, 2010)

So I guess there's a debate whether or not to include a preamp in a soundcard calibration file. In my case, I have an EMU 0404 PCI interface and a GT Brick preamp. According to REW instructions, I'm supposed to just plug the output of the soundcard directly into its input. However, I'm certain the the EQ "characteristics" of the preamp affect the way that REW analyzes my readings....so I send the output of the soundcard to the input OF THE PREAMP instead. 

Here's two images of my calibration files....the first is without the preamp, the second is with.

















When I run a sound card calib using the preamp in the chain I get a message saying something like...

"The soundcard measurement varies by 7 db between 20hz and 20khz. The calibration file may not be valid and should not be used".

So what gives? The Brick preamp is a tube preamp and has a "warm tone"...is that why there's the huge dip past 10k? Can I still use this calib file?

THX!!!!


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## EarlK (Jan 1, 2010)

> "The soundcard measurement varies by 7 db between 20hz and 20khz. The calibration file may not be valid and should not be used".
> 
> So what gives? The Brick preamp is a tube preamp and has a "warm tone"...is that why there's the huge dip past 10k? Can I still use this calib file?


Yes, I would use the "pre-amp included" calibration file ( but only when using that tube preamp ) . It looks to be accurate .

When that tube preamp is used , the electronic chain obviously needs some HF correction applied for REWs' measurements to be useful ( 20 - 20K ) .

( In your case ) ignore that warning ( it's a case of a program feature whose intent was to be informative but has instead misled you ) .



<> EarlK


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## jlird808 (Nov 2, 2010)

Awesome thanks! That's what I was kinda figuring...though the warning was difficult to ignore without someone else saying to do so lol.

One other thing when doing the soundcard calib is that the EMU PCI card is 1/4" out so I send it to the Brick's 1/4" in. Obviously an ECM is XLR so my calib file is running thru the 1/4" but I measure the room using the Brick's XLR (Brick has both).

Any significant diff? I guess I could get a 1/4" to XLR adapter but Im so sick of spending $ on adapters lol...

THX!!


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## EarlK (Jan 1, 2010)

> Any significant diff?


I doubt there's much difference ( in this case ) from your XLR in ( though I wouldn't really know without seeing it scoped out via a loopback measurement ) .

I'd just start measuring things if I were you .

<> EarlK


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## jlird808 (Nov 2, 2010)

EarlK said:


> I'd just start measuring things if I were you .


Lol good call!


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