# ECM8000 placement for calibration



## apilon (May 18, 2006)

Good evening 

I was trying to get some measurement to determine the best placement for my sub and for seating location and during the last attempt i somehow hit the ecm8000 mic and it ended up 90 degree straight up (toward ceiling) instead of toward speakers and i got better measurement 

So just to make sure should the mic be pointing toward the ceiling or toward the speakers when taling measurement with REW? 

Alain


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## SAC (Dec 3, 2009)

Good question!

Checking the various Behringer docs...who knows?

I guess that is just one of the many perks(sic) of going with a cheap measurement mic. 

I find it a bit odd that so many will pay for calibration and go to all the trouble of tweaking this mic without this basic information. Information that is normally standard with a measurement mic - or any quality mic, for that matter.

Typically the optimal orientation is stated in terms of 0, 45 or 90 degrees to source.

I would suggest contacting Behringer. Good luck finding anyone with a clue as to what you are talking about,as considering their business model, I doubt you will find anyone technical.


For comparison sake, the reference orientation of a few additional measurements mics are:

Earthworks M30 & M30 BX - 90 deg
TEF 04 - 45 deg
TEF 05 - 0 deg
SoundFirst SF101 - 0 deg
Audio Toolbox - 90 deg
DPA 4007 - 45 deg
DPA 4090 - 0 deg

And while some are worrying about this, let me assuage your concerns a bit.

As far as low frequency response relative to evaluating modal issues and establishing equalization filters, it really doesn't matter, as issues of orientation are significant primarily to the high frequencies. 

And above ~250 Hz the frequency response serves little practical purpose aside from verifying that you do indeed have comb filtering in the frequency response due to the superposition of direct and indirect energies (which is a given!). 
Above ~250 Hz, Here you want to be dealing with the impulse and ETC response in order to evaluate the specular energy behavior. And one is fortunate that the wavelengths above ~10,000 Hz contain relatively little energy and we generally do not worry to much about this. 

So this issue, while indeed valid, is actually rather trivial with regards to the vast majority of practical purposes and applications often cited here on the forum. But it is a good question and one whose answer is worth at least knowing!


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## apilon (May 18, 2006)

SAC said:


> Good question!
> 
> Checking the various Behringer docs...who knows?
> 
> ...


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## SAC (Dec 3, 2009)

Don't worry, you will be fine.

A VERY simple indication of the best orientation might be to play an REW test tone and measure it on axis at 0, 45 and 90 degrees and note any deviations in response and use the orientation with the best response.

But in any case, the lower octaves will be fine regardless if you are using the mic for modal equalization, and above that the frequency response is not that critical - as you either have comb filtering, or...well you are in an anechoic chamber!


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