# Calibration for DBX RTA-M measurement mic



## John 57

I am knew to this site. I joined after visiting the REW site. I have a small home recoding studio but also design custom acoustic treatments. Most of my knowledge outside of about 30 years of live sound and 8 recording comes from the book "Master Handbook of Acoustics, 5th Edition" by Everest and Pohlman. This is a rather complex book that goes into extreme detail about all things acoustic and has formulas for designing essentially any kind of treatment, both reflective and absorptive, including formulas for advanced root mean square diffusion panels, Helmholtz resonators, etc. I highly recommend it to anyone that is interested in everything acoustic. You can use the book to effectively design a space from the ground up. My question concerns calibration files for the DBX RTA-M. Although it costs $100, I chose this mic over the Behringer because it has a lower noise floor. I have a dwg file that is supposed to be the basic calibration files but am wondering if anyone has basic calibration files in a different format for the mic and/or will REW read the dwg files? Thanx!


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## JohnM

There are a few threads for this, including ones with calibration files, though the files may not match your particular mic since mics vary, individual calibration is the best route.

DBX RTA-M Calibration Curve?
dbx RTA-M
dbx rta-m mic


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## John 57

Thanx! I ended up finding the threads you referred me to. I got a response from DBX on the mic. They sent the same cal files but also referred me to AV Leader, the company that actually makes the mic. They sent me PDF's that show the mic to be essentially flat all the way down to 0 hz.


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## AudiocRaver

John 57 said:


> Thanx! I ended up finding the threads you referred me to. I got a response from DBX on the mic. They sent the same cal files but also referred me to AV Leader, the company that actually makes the mic. They sent me PDF's that show the mic to be essentially flat all the way down to 0 hz.


First, welcome to Home Theater Shack.

I kinda doubt (meaning NO WAY!) the flat to 0 Hz claim in the first link. The +/- 5 dB at 50 Hz as shown in the second link looks about right. Like JohmM says, for getting a rough idea where you stand, a generic cal file is a starting point, but for serious work you will need an individually calibrated mic.


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## Phillips

Would/has Herb (Cross - Spectrum) calibrated these mics?


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## AudiocRaver

According to this page at the CSL web site, they will calibrate whatever you want to send them, assuming no outlandish mechanical or electrical configuration funnies that they can not handle (and I can not imagine what that would be).


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## Anechoic

Phillips said:


> Would/has Herb (Cross - Spectrum) calibrated these mics?


Yes/Yes.

That "spec sheet" is certainly... interesting. Not realistic, but interesting.


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## JohnM

John 57 said:


> Thanx! I ended up finding the threads you referred me to. I got a response from DBX on the mic. They sent the same cal files but also referred me to AV Leader, the company that actually makes the mic. They sent me PDF's that show the mic to be essentially flat all the way down to 0 hz.


The DBX plot missed the "2" from the "20" that should have appeared on the left hand side of their graph, though they seem to have extended the AVL measurement somewhat arbitrarily. The AVL graph seems more honest in showing the expected tolerance band around the idealised nominal and stopping short of making any claims about behaviour below 50 Hz.


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