# Do I need a handheld SPL meter?



## soss (Apr 21, 2014)

I have a 2 way audiophile system with a usb dac. I have a Dayton usb mic on order, and I want to use REW to make an impulse file for JRMC. What I am confused about is the built in software spl meter. Do I need to use a handheld spl meter to calibrate, or can I just rely on the one built into REW? Part of my confusion is that the videos and faq's I have seen deal with two-way pro audio interfaces that require loopback. Obviously, I'm using a separate "out"(usb dac) and "in"(usb mic) for my measurements. Thanks for any help/suggestions.


Oh yeah, what spl level do you suggest for my specific purpose? 90db okay?


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

REW’s built-in SLM requires calibration, but it’s only necessary if you require graphs with accurate dB indications. If not, just run the test signal at a comfortable level and “tell” REW that it’s 75 dB.

Regards, 
Wayne


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## soss (Apr 21, 2014)

Ok, thank you. I will be purchasing a meter then. The graphs are definitely interesting and I would like to learn about this. 



And I now realize that 75db is the standard that dolby labs use. (from REW manual).


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## ajinfla (May 10, 2009)

soss said:


> Ok, thank you. I will be purchasing a meter then.


If you already have a smartphone, the Dayton IMM-6 mic and AudioTool software will set you back around $25.

 

cheers


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## tonyvdb (Sep 5, 2007)

I would not even go that far, if you have a smartphone there are plenty of free SPL meter aps that will get you good enough readings to set the correct levels on REW.


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## soss (Apr 21, 2014)

tonyvdb said:


> I would not even go that far, if you have a smartphone there are plenty of free SPL meter aps that will get you good enough readings to set the correct levels on REW.


Really? Even with the cheesy built-in iphone mic? Do you think it could come within 3db accuracy?


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## tonyvdb (Sep 5, 2007)

if all your doing is setting an SPL of 75db so that your graphs are correct using REW then yes. What mic are you using with REW?


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## soss (Apr 21, 2014)

I'm going to start out with a Dayton UMM-6 USB and see how that goes. I use a USB 3.0 PCIe card for my DAC, and will be using a motherboard port for the mic.

I'm guessing a something like the Behringer ecm8000 mic with a good firewire pro audio interface will give more accurate results, but my overall goal is improved sound in JRMC and that UMM-6 just may be accurate enough.

I would think accuracy will be more important with an impulse wav file than it would with manually entering eq filters. I will be trying both of course.


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## tonyvdb (Sep 5, 2007)

For a mic this UMIK-1 Mini would be the best option to use with REW


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## soss (Apr 21, 2014)

tonyvdb said:


> For a mic this would be the best option to use with REW



Oh yeah? My UMM-6 arrives tomorrow so maybe I can do a "Return To Sender". Any particular reason why the UMIK-1 is better for REW?


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## soss (Apr 21, 2014)

Ok, I just downloaded the $1 iphone SPL meter from Andrew Smith. Should I choose "c weighting" and "slow"? Those are the two options, and I remember reading about that in the REW manual. Thanks.


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## tonyvdb (Sep 5, 2007)

Yes C and slow will be ideal.


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## soss (Apr 21, 2014)

tonyvdb said:


> Yes C and slow will be ideal.



And as far as the UMIK-1? See my last post on page 1 in case you missed it.


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