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Hi,

The REW software looks very well done, thanks to the authors.

I am trying to assemble the parts necessary to take large room measurements and I have some very basic questions.

According to the help pages, it appears that a calibrated microphone can take the place of the SP level meter, so if I go with the following microphone it would serve the same function as having feedback from the SPL meter? (Is this true, it is not so clear.)

I am looking at the Dayton EMM-6, which is currently on sale at parts express. Is the calibration file that is tied to this microphone serial number via downloading, equivalent to sending in the mic in for cal?

Is it worth a few extra $10 to get the Behringer EMC-8000?

If I use the ART-USB-Dual Preamp box, this gets me directly from the XLR with phantom power to the PC USB input. Therefore, does it eliminate the need for the external sound card? I would still be relying on the internal sound card of the laptop for the output audio; is that sufficiently good?

If the above eliminates the need for an external sound card, then it is unclear how to perform the loopback test, unless I go into the XLR input and adjust the gains. This seems like a problem. Am I missing something?

Thanks.
 

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According to the help pages, it appears that a calibrated microphone can take the place of the SP level meter, so if I go with the following microphone it would serve the same function as having feedback from the SPL meter? (Is this true, it is not so clear.)
The input to REW can be from the analog output of an SPL meter or from a mic and preamp. If you use a mic you will need to have an SPL meter handy to calibrate the readings so that the levels shown on the graphs correspond to actual room levels.

I am looking at the Dayton EMM-6, which is currently on sale at parts express. Is the calibration file that is tied to this microphone serial number via downloading, equivalent to sending in the mic in for cal?
It is not as accurate as a proper calibration

Is it worth a few extra $10 to get the Behringer EMC-8000?
The EMM-6 mic seems fine, but it would be worth spending the extra to get it properly calibrated.

If I use the ART-USB-Dual Preamp box, this gets me directly from the XLR with phantom power to the PC USB input. Therefore, does it eliminate the need for the external sound card? I would still be relying on the internal sound card of the laptop for the output audio; is that sufficiently good?
Yes and yes.

If the above eliminates the need for an external sound card, then it is unclear how to perform the loopback test, unless I go into the XLR input and adjust the gains.
Correct, you would need to dial the gain right back to allow for the line level output. In practice most soundcards have sufficient extension that calibration for room measurement is not really necessary, but the calibration loopback measurement does reveal whether there is any unintended feedback/monitoring going on, which would render the measurements useless.
 

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If I use the ART-USB-Dual Preamp box, this gets me directly from the XLR with phantom power to the PC USB input. Therefore, does it eliminate the need for the external sound card? I would still be relying on the internal sound card of the laptop for the output audio; is that sufficiently good?

Yes and yes.
so the art usb is an external soundcard that takes the signal from the mic and sends it through USB to the laptop to the rew software, then the rew software tells the laptop internal soundcard (that depending on what i read should or shouldnt be used as the soundcard at all) what signal to generate and send to the art dual pre which passes it along to my avr?
do i have that all correct?

for some reason i was under the impression the rew software would talk to the art usb pre through the usb line to tell the art pre what output signal to generate and send, thus bypassing the internal soundcard altogether.

can anybody set me straight on this?

also, apparently theres a chance i dont actually understand what a soundcard is/does.
 

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The EMM-6 mic seems fine, but it would be worth spending the extra to get it properly calibrated.
Sorry but i'd say thats a wrong assessment

http://techtalk.parts-express.com/showthread.php?t=225468

Unless the OP is doing below 20hz or needs 45/90 deg angle of incidence measurements then theres no reason to spend a lot more on getting a calibrated one, dayton does a fine job calibrating it themselves

OP, i would suggest checking out my guide, bob_m posted it above

Ive never seen this ART USB Dual Pre before... ill probably add it to the guide. Has anyone actually measured one before? is it flat from 20hz to 20khz?
 

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The ART Dual USB Pre(amp) is commonly used for REW and FuzzMeasure and works fine within the parameters that most need and costs significantly less than the other of comparable measure. ($69 at B&H Photo)

If you need a higher performing pre-amp, none of the ones commonly cited and used here will suffice. If you need information regarding those pre-amps, PM me.
 

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Sorry but i'd say thats a wrong assessment

http://techtalk.parts-express.com/showthread.php?t=225468

Unless the OP is doing below 20hz or needs 45/90 deg angle of incidence measurements then theres no reason to spend a lot more on getting a calibrated one, dayton does a fine job calibrating it themselves
We'll have to agree to disagree on that. In my view, the plots in the post you linked only serve to underline problems in the process used to derive the PE cal data. Microphones by nature have smooth responses, cal data that shows seemingly random fluctuations indicate that the methodology by which they were derived has flaws. Personally I would be happy to use that mic without a cal file rather than load the PE cal file, for measurements that needed greater accuracy than the underlying +/-2dB or so the mic offers I would get it properly calibrated and the extra $30 or thereabouts that adds to the cost looks good value to me.
 

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We'll have to agree to disagree on that. In my view, the plots in the post you linked only serve to underline problems in the process used to derive the PE cal data. Microphones by nature have smooth responses, cal data that shows seemingly random fluctuations indicate that the methodology by which they were derived has flaws. Personally I would be happy to use that mic without a cal file rather than load the PE cal file, for measurements that needed greater accuracy than the underlying +/-2dB or so the mic offers I would get it properly calibrated and the extra $30 or thereabouts that adds to the cost looks good value to me.
No need to agree to disagree...

I see what youre saying now, the dayton cal is jagged as hell, the CSL is much more smooth. Like you said, the CSL cal file implies that theres very little wrong with these mics by default and that the dayton is making WAY too many corrections, and thus it would probably be beneficial just to use the mic without daytons calibration txt altogether. Especially after the 3000hz mark the dayton cal file goes crazy while the CSL is a smooth hill. Realistically i think the dayton mics are "good" from 30hz to 3000hz and dont need much correction, which is where you do most of your EQ for subs, and where you engineer most crossovers for speakers.

What i dont understand is what could be "contaminating" their results? I guess theyre just using an inadequate environment and may be getting reflections from something theyre not aware of.
 
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