# understanding the REW measurement SPL graph



## skypickle (Dec 13, 2016)

So I successfully attached a UMIK-1 mic, downloaded the calibration file and the latest beta of REW 5.17 beta 14.
I set the mic to unity gain in the audio midi devices and to 48khz input. Since I am a stereo listener I just have two speakers - about 10 feet apart toed in to point to the listening position which is at the apex of an equilateral triangle. The mic is pointed to the center between the two speakers. When I run the measurements, I get a dialog that pops up saying the impulse peak is not where it should be....I attached a screen capture-it's attached below. What does that mean?

Anyway, the sweep was configured to go from 40hhz to 20khz over 5 secs and the result is posted below. I was confused as to why the signal drops off at 4khz. So I ran the measurements twice more but this time I pointed the mic to the right speaker and then the left speaker. These curves are shown in the third image.again there is a drop-off. I was investigating on why one curve seems to drop off sooner than the other and it appears that the headphone connection that sends the audio to the preamp is flaky. Anyway that doesn't explain why I am missing everything above 8 khz. Is this a problem with the UMIK-1? I know my tweeters are ok because I can play a 12khz tone and they sound the same. 

Finally it looks like there are a few nulls that I have to figure out 50 hz, 58hz, 400 hz, 600hz, 1100hz and 1800hz.
What's the best way to figure out why I am losing those frequencies?


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## skypickle (Dec 13, 2016)

I set up the UMIK in a different room with a different macbook pro measuring a sonos connect:amp driving a pair of duevel speakers. Again the SPL curve drops off abruptly by 2k. I don't get it. Is there any way to MISCONFIGURE REW to get this kind of result or is my umik-1 broken?


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## JohnM (Apr 11, 2006)

Try setting the replay buffer size on REW's soundcard preferences to 16k. I suspect there is too much buffering delay in replay.


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## Mariam.1938 (Apr 12, 2015)

Hello SKYPICKLE, please carefully studying the new documentary about the use of this wonderful software REW:

"A Step by Step Guide (Rev 5.2, August 10 2016)".
Jeanm


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## FargateOne (Mar 3, 2015)

Mariam.1938 said:


> Hello SKYPICKLE, please carefully studying the new documentary about the use of this wonderful software REW:
> 
> "A Step by Step Guide (Rev 5.2, August 10 2016)".
> Jeanm


follow to the letter this guide, don't give up, first place your speakers at the best place available, second, treat your room as far as you can with waf , third eq if possible and enjoy! 3 years later, I have the best sound I ever had. It is not the perfection but wow, good!


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