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Discussion Starter · #1 ·
Hi, we are going to use REW to setup general PA and conference room audio systems. Our laptops have an audio jack that is both input and output(lame!) depending on pc settings. Since we want to use the test patern outputs within REW I need this jack to be an output. So....can anyone recommend a USB mic and is it even recommended? -Rob
 

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So....can anyone recommend a USB mic and is it even recommended?
No, REW won't operate with a USB mic. For laptops, most people require an external USB soundcard that has a line-in and a line-out, or a line-out and a mic preamp for condenser microphones.

brucek
 

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Discussion Starter · #3 ·
thanks Bruce, I'll look into the external USB soundcards.
or do you think I should use my laptops mic input connector for REW and get an external white noise generator?
 

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You can use a USB mic, but the same caveats apply as when using a laptop or desktop mic input: the frequency response may be optimised for voice use (and so roll off at LF and perhaps at HF also) and the signal/noise performance may be poor. Without something to compare the results against it is hard to know whether a mic input is useful or not, though on a USB mic the frequency response (or at least its extents) should be in the spec somewhere.
 

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So you DID get this to work well with REW?
yes, Micmate works fine with REW

on a USB mic the frequency response should be in the spec
the Micmate and equivalent products are not usb mics : it's just an external soundboard with phantom power supply. Before using the Micmate, I measured the frequency response for my calibration : it was good enough for acoustic measurements. So the measurement quality depends only on the mic you use.
 

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"So the measurement quality depends only on the mic you use."

It's probably been told before but
Why can't i use, for example, an AKG perception 100, a MXL 2001 or overhead mics with the REW software instead of those pencil shaped measuring mic?
Aren't these flat enough?
What's the difference?
 

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How are you able to do a soundcard calibration when using USB as the input?
I connected a measurement generator (Audio Precision, Prism or equivalent) on the input of the mixmate and recorded a wav file. Then I analysed this file (frequency response, distortion). This response added to the cal file of the mic itself gives me the global cal file to use.
 

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Why can't i use, for example, an AKG perception 100, a MXL 2001 or overhead mics with the REW software instead of those pencil shaped measuring mic?
The main difference between a measurement mic and a studio mic is usually the polar response. Measurement mics are omnidirectional, which allows them to capture the whole soundfield and makes them (fairly) insensitive to orientation. Studio mics are typically directional to varying degrees (cardiod, commonly) which means measurements taken with them will be very sensitive to the direction the mic is pointed and the contributions of the room coming from other directions will be atttenuated.
 

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Wouldnt you want a microphone that emilates a persons ears? They have these dummy heads that have testing microhpnes in them for headphone testing i would think somthign similar to this would be ideal/ Even if its just 2 microphones in mono.
 

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I think with REW and general room acoustics you are looking to measure how the sound is behaving in the room and not how you perceive it with your ears. You could then make mathematical assumptions geared towards how it would be heard. It would be much harder, if not impossible, to do it the other way around with a directional mic.
 

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I think with REW and general room acoustics you are looking to measure how the sound is behaving in the room and not how you perceive it with your ears. You could then make mathematical assumptions geared towards how it would be heard. It would be much harder, if not impossible, to do it the other way around with a directional mic.
Yeah maybe thats being a little to critical?

Somthing like that might be better for the full range speakers? *shrugs*
 

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Wouldnt you want a microphone that emilates a persons ears? They have these dummy heads that have testing microhpnes in them for headphone testing i would think somthign similar to this would be ideal/ Even if its just 2 microphones in mono.
Not really. Everyone hears slightly differently. If only because everyone's had different events in their lives that have damaged or not their hearing accordingly. If the idea is, first and foremost, accuracy, you want the test equipment to be as neutral as possible. Ears, are anything but.

It sounds like you're wandering (unintentionally) towards the old loudness switches, that tried to contour the FR to mimic the the equal loudness curves... not necessarily a bad goal, but not exactly easy to implement...
 
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