ECM8000 microphone measuring techniques and usage discussion - Page 12 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #111 of 170 Old 02-03-10, 05:14 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

Hi,

Just a quick query regarding the ECM8000. My ECM8000 came with a response curve, provided by the manufaturer. The response curve is to within 2db from 15hz to 20khz.
I've noticed that calibration files(provided onthis sie) and response curves, taken for the calibration files, show that the mike requires up to 5db correction, above frequencies of 2khz. This somewhat makes it seem no more accurate than a bog standard spl RS meter.However, it appears accurate at lower frequencies, better than the RS spl meter using the calibration files. My questions is, is the ECM8000 useable above 2khz, even with the calibration files?

Thanks

Delphi
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post #112 of 170 Old 02-03-10, 05:26 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

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delphiplasma wrote: View Post
Hi,

Just a quick query regarding the ECM8000. My ECM8000 came with a response curve, provided by the manufaturer. The response curve is to within 2db from 15hz to 20khz.
If you're talking about the curve on the box, that curve has no basis in reality. It may have at one time, but not anymore.

Quote:
I've noticed that calibration files(provided onthis sie) and response curves, taken for the calibration files, show that the mike requires up to 5db correction, above frequencies of 2khz. This somewhat makes it seem no more accurate than a bog standard spl RS meter.However, it appears accurate at lower frequencies, better than the RS spl meter using the calibration files. My questions is, is the ECM8000 useable above 2khz, even with the calibration files?
It's perfectly fine as long as you're using the calibration file and you're not trying to measure very high SPL's (over ~ 115 dB).
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post #113 of 170 Old 02-03-10, 05:54 PM
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Re: ECM8000 microphone measuring techniques and usage discussion


What Anechoic said. The graph you see on the ECM8000 box is useless. Here is a graph that shows the response of a few dozen mics as measured by Cross Spectrum. You can see that the deviations are pretty severe.




Regards,
Wayne



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post #114 of 170 Old 02-03-10, 08:17 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

I'll third what Anechoic said. But rather than use the curve on the box, you'll be better off using our generic cal file, or having Cross Spectrum created one for you based on your particular sample.

-Greg

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post #115 of 170 Old 02-08-10, 06:50 AM
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Re: ECM8000 microphone measuring techniques and usage discussion

Thanks for the responses. I did a comparison between the ecm8000 and my RS meter. The RS meter is pretty good. However, there is the typical 3 to 5 db increase from 3khz up to 8khz and a quick roll off after 10khz. This would lead me to believe that the ECM mic, is flat from around 40hz up to around 9khz. Above 9khz there would appear to be a dramatic increase of a few dbs up to around 20khz. I sent a question to Beringer (see below):

"My question is have you any calibration files? I have been advised that the microphone I purchased, 2-3 years ago does not have the linear frequency response curve as seen on the box, instead there is a rise in frequency from 2khz to a peak of 5db at 10khz. I've been told that the curve may have been accurate for microphones made when the response curve was taken. Therefore, is it possible for a re-test to be done on these microphones and a calibration file, or calibration details provided?"


Thanks for writing to BEHRINGER technical support.

"No, there are no other calibration files for the ECM8000. The users manual and what is on the box is all that is available for this. There have been no changes in production to the ECM8000 since its introduction. As these mics are manufactured in China, it is not possible to be sent back to the factory for a retest. You could always have a local service center, studio, or production company test the mic for you. Honestly, for the $40 dollar price of the ECM8000, it would be less expensive to buy a new one if your current one is no longer accurate.


We hope that we have been able to help you with this information"
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post #116 of 170 Old 02-08-10, 09:34 AM
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Re: ECM8000 microphone measuring techniques and usage discussion

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delphiplasma wrote: View Post
There have been no changes in production to the ECM8000 since its introduction.
This is sheer fantasy, there are any number of sites that have documented changes in the capsule and pre-amp circuits of the ECM8000 over the years.
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post #117 of 170 Old 02-08-10, 09:44 AM
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Re: ECM8000 microphone measuring techniques and usage discussion

And the bottom line is that our data on multiple ECM8000's say that some have a rise at HF and some drop off. Hence the desire to get a custom cal file generated if you're that concerned with accuracy.

-Greg

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post #118 of 170 Old 03-13-10, 11:47 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

When creating a sound card calibration file for my MobilePre, is it okay to use an XLR (using the XLR balanced in jack) to 1/4" (using the 1/4" unbalanced out jack) cable as long as I don't turn on the phantom power? Or should I use a 1/4" to 1/4" cable (which I currently don't own). I don't want to fry my MobilePre.
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post #119 of 170 Old 03-14-10, 12:06 AM
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Re: ECM8000 microphone measuring techniques and usage discussion


No, you have to use the 1/4" jacks only. The XLR jack puts the mic pre-amp in the loop, and that should be avoided because they're so sensative.

Regards,
Wayne



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post #120 of 170 Old 03-14-10, 07:43 AM Thread Starter
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Re: ECM8000 microphone measuring techniques and usage discussion

I did it both ways to see if there was a difference. There was nothing major that I could see. A few little changes here and there, but tough to see. The mic cal is much more important. Images below:

Top one should be the Quarter to Mic. Bottom is Quarter to Quarter.

Quarter to quarter is easier and you can get the cable at any guitar shop (or Radio Shack)
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ECM8000 microphone measuring techniques and usage discussion-soundcard_cal_q_to_m.jpg  

ECM8000 microphone measuring techniques and usage discussion-soundcard_cal_q_to_q.jpg  

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