# Whats the purpose of an SPL meter when using calibrated Mic with REW?



## Exocer (Apr 19, 2006)

I never understood the connection between the RS spl meter and the calibrated mics with use in REW. It is my understanding that even with a calibrated mic, you will still need the SPL meter. What purpose will it serve?


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## RollsRoyce (Apr 20, 2006)

To correctly set levels on the processor, mic/mic amp combo, and in REW itself. The ECM 8K is a good mic, but it does not tell you whether it's seeing 65 dB or 105 dB. Only a sound level meter can tell you that.

Hope this helps!

Royce


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## Exocer (Apr 19, 2006)

Thanks, it does help!
One more question though. The RS spl meter needs calibration. Since they vary unit to unit, and aren't the most accurate means to measuring SPL, how would it be used to correctly set levels?


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## Sonnie (Apr 11, 2006)

It would need correction values if you used it to measure your full response, but as far as setting and calibrating your SPL levels with the pink noise supplied with REW, no correction is needed.


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## Guest (Oct 14, 2007)

Has REW changed since this thread started? My version of REW does have an SPL meter, or am I way off-base with this somehow.

Also, when running a .cal file on the ECM8000, do you then get accurate measurements up to 20kHz or is this mic just not good for measurements that high?


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## Otto (May 18, 2006)

dave7 said:


> Has REW changed since this thread started? My version of REW does have an SPL meter, or am I way off-base with this somehow.
> 
> Also, when running a .cal file on the ECM8000, do you then get accurate measurements up to 20kHz or is this mic just not good for measurements that high?


Hi Dave,

REW does have an SPL meter, but you have to calibrate it by using an external SPL meter. The "meter" in REW doesn't know what it's seeing unless you tell it a relative value, which comes from the RS meter.

As to measurements up to 20 kHz, I'm not sure about the mic's response itself. However, room reflections and such make it difficult to measure that high. I think you'll get a pretty raggedy response even if you had the best and most-accurate mic in the world.


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## Guest (Oct 14, 2007)

Thanks Otto -



Otto said:


> As to measurements up to 20 kHz, I'm not sure about the mic's response itself. However, room reflections and such make it difficult to measure that high. I think you'll get a pretty raggedy response even if you had the best and most-accurate mic in the world.



I know room response is a big factor, but I consider this as part of the system. Terry Montlick has certified my room, but I still like playing around with things...my top end response included.

It looks as though the ECM8000 rolls off a ton at 10kHz. I think just like 10Hz, not many of us hear that much higher/lower than this, nevertheless I am curious.


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## Otto (May 18, 2006)

Right, but I'm thinking that the reflections make it such that the measurement is so erratic that you won't be able to target any changes. But there's certainly no harm in trying! You may be able to smooth it and see gross trends that you will be able to address.


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## Guest (Oct 15, 2007)

Actually what I see in my graph follows the cal file for the ECM8000 on the download page quite well. But is that because the mic isn't picking anything up anymore so just about anything would look the same (over 10kHz)? I guess that's my question. And - what is the "next better" full range mic that will do a legitimate 10Hz - 20kHz measurement?

Thanks for the help BTW.


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