# Live sound RTA help.



## dysharm (Sep 12, 2014)

Hi guys, 

I know a bit to get around in live sound & need help in doing RTA for a system in a small hall. I'm using an M-Audio Fast Track interface with a Behringer ECM 8000 measurement microphone & RTA program from a laptop to generate pink noice. Basically from what I understand & read is the ECM 8000 mic goes in the Mic input of the M-Audio & from the RCA out (Stereo L/R) from the M-Audio interface to any of the XLR (mono) channel on the mixer.

Is this correct or how is the connections suppose to be? I read something about the reference signal, how to do the connections for this setup?
:dontknow::dontknow:


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

You’ve basically got the right idea. You didn’t mention what RTA program you’re using, or you what you intend to do with the measurements (presumably equalize the system?), but they are only as good as the hardware in use. Particularly, unless you have a custom calibration file for your mic, your measurements won’t be accurate. As the graph below shows, there is considerable deviation in response from one ECM8000 sample to the next (as is the case with any budget mic).










Regards, 
Wayne


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## dysharm (Sep 12, 2014)

Thanks for replying. Basically using a 31 band EQ to equalize the speakers in the hall. Im using Smaartlive 5.4, how about the reference signal? Do I use the Matrix out to return the signal back to the M-Audio Line in?

By the way, do you have the calibration file for the ECM 8000?


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

dysharm said:


> how about the reference signal? Do I use the Matrix out to return the signal back to the M-Audio Line in?


If you’re talking about a loopback measurement, it really isn’t necessary. Most audio interfaces these days have ruler flat response. Just make sure whatever channel you plug the pink noise signal into on the console has all EQ set for flat, all filters bypassed with no compression or EFX processing engaged.




> By the way, do you have the calibration file for the ECM 8000?


We have one on our Downloads Page, but it’s generic. As noted on the Downloads page, generic files are not for critical measurements and should not be relied on as a perfect standard. Based on the graph in my previous post, I wouldn’t do any equalizing above 2kHz or below 100 Hz with a generic file.

Regards, 
Wayne


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## Jee-Bee (Feb 17, 2009)

maybe a littlebit off topic.
How do i create a calibration file? i have a superlux ECM 888 and want make a calibration file from it...


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

http://www.hometheatershack.com/forums/rew-forum/24615-eqsetup.html#post225666

Regards,
Wayne


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