# Newbie question



## mtavares (Dec 13, 2011)

We are trying to calibrate our DIY subwoofer using the a Radioshack SPL and the soundcard of an Asus notebook. We are observing a big discrepancy between each procedure below 30Hz (more than 7dB). Is it normal?

Based on the comments here, the Radioshack SPL is only indicated for subwoofer. We would like to know if the combination below is adequate to run the REW for the entire audio frequency range:
a) MXL Micmatec XLR 
b) Dayton EMM-6

Is there any other similar price option better that this one?

Thanks in advance by your cooperation.

Marcos

Q.J.A


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## JohnM (Apr 11, 2006)

An alternative would be to use a Xenyx 502 instead of the MicMate, would give you a bit more control. The ECM8000 is an alternative to the EMM-6, either would be fine but both need calibration. Cross Spectrum offer calibrated ECM8000 and EMM-6. For general info see the Information Index and Cabling and Connection Basics threads.


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## rocksure (Mar 4, 2012)

Expensive mics will generally give more accurate results than cheaper ones. But the cheap ones are still in the ballpark for calibration. However, the main thing is that whatever mic you choose it should be a small diaphram condensor mic with an omni capsule rather than a cardiod or hyper cardiod one.


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## mtavares (Dec 13, 2011)

JohnM and rocksure

Thanks by the response.

The Xenyx 502 seems to be a better option. We will change our spec accordingly. For the mic we are still considering the EMM-6 because it come with its calibration file.

We tried to repeat the measurements during the wekeend using the RS SPL and the results were very different from the first day. We really need to have a better measurement setup.

Q.J.A


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## JohnM (Apr 11, 2006)

The RS meter may not be particularly accurate, but it should be quite repeatable. If you get different results from successive measurements with the meter in the same place there may be a problem with the soundcard configuration, unless you are seeing variations only below the lower limit of the sub in which case it is likely to be noise. Might be worth posting some example measurements.


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## mtavares (Dec 13, 2011)

An additional information. Our notebook does not have LINE IN input, only the MIC IN. After some research, we verified that I will need an USB soundcard or something like a Xenyx 502. Am I right?

Q.J.A


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## Wayne A. Pflughaupt (Apr 13, 2006)

Many laptops these days can switch the input between a mic in or a line in. If yours only does mic in, then yes you’ll need a USB soundcard. 

The XENYX 502 is not a USB sound card. It is merely a small mixer that has a mic pre-amp, and it would have to connect to a separate USB sound card. Alternately, there are other soundcards that have built-in mic pre amps – i.e. an “all in one” package.

Wayne


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## mtavares (Dec 13, 2011)

Thanks Wayne,

Unfortunately, our notebook does not allow the switch between MIC IN and LINE IN. It seems that the only solution is an USB sound card or something like an M-Audio Fast Track Pro, that it will be what you consider an ""all in one"" package.

Marcos

Q.J.A


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## SAC (Dec 3, 2009)

mtavares said:


> It seems that the only solution is an USB sound card or something like an M-Audio Fast Track Pro, that it will be what you consider an ""all in one"" package.


Or an ART Dual USB Pre(amp) available at B&HPhoto for 1/3 the price.


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## mtavares (Dec 13, 2011)

SAC

Thanks by your suggestion. We will evaluate this solution.

Marcos

Q.J.A


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