ECM8000 microphone measuring techniques and usage discussion - Page 15 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #141 of 170 Old 10-21-11, 08:40 AM
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Re: ECM8000 microphone measuring techniques and usage discussion

Thanks LastButNotLeast, I ended up muddling around the site last month when I posted this and finding that link.

I've ended up with 2 of the ECM8000's that I've had professionally calibrated, 2 boom stands and an Alesis iO2 USB interface. I'm experimenting with ARTA, REWv.5, TrueRTA and ETFv.5 software.

I do a bit of speaker modding as well as solving mode problems, and with 2 mics I'm able to take Stereo Listening Position measurments as well as standard Nearfield and 1Meter/1Watt measurements. I'm having a blast experimenting with this gear and am really pleased with the cost/performance ratio.
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post #142 of 170 Old 12-08-11, 07:34 AM
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Re: ECM8000 microphone measuring techniques and usage discussion

Great thread! Just got myself an ECM8000, I can't wait to start measuring!
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post #143 of 170 Old 12-11-11, 04:42 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

hi im looking for a mic for a mini lap acer.. im trying to use it in car audio.. i live in mexico and my lap burns when i try to use it with the mic it has... but then i read i cant use it with it... so i need one.. has anyone a mic it wont use anymore?.. i cant pay much for it.. but if you tell me how much i save the money to get it... thnks..
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post #144 of 170 Old 12-11-11, 05:49 PM
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Re: ECM8000 microphone measuring techniques and usage discussion


Hi Beto,

The only cheap mic that can be used with REW (assuming that’s what you want it for) is the Radio Shack SPL meter. If your computer has a line input. If it doesn’t you’ll also need a USB sound card.

But the Radio Shack meter is only good for low frequency (subwoofer) measurements. If you want full range measurements, there is no cheap option. Even if you use our generic calibration file, the ECM8000 mic with a suitable sound card that has a pre-amp and phantom power will cost at least $100.

Regards,
Wayne



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post #145 of 170 Old 02-26-12, 03:02 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

Hi again.. thanks for the info.. look i dont know english so much but i just read abouot be a moderator.. what this mean? i dont under stand.. besides..how can i help you if you are kings in this work? you are the bible fro all knowlege.. i dont even know how to fix my pc.. or how to calibrate a car.. sorry i cant help you because i dont know all you do know.. thnks..
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post #146 of 170 Old 03-20-12, 03:44 AM
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What happens if you use the ECM8000 Basic Mic 'not Basic +' with Cal file for measuring your rooms response?
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post #147 of 170 Old 03-20-12, 05:56 PM
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Re: ECM8000 microphone measuring techniques and usage discussion


The Basic + adds calibration for 45° and 90° mic orientations, in addition to the 0° orientation of the Basic calibration package. However, for frequency response measurements you typically want 0° orientation – i.e., pointed at the signal source. More reading as to the “whys” and “wherefores” here.

Regards,
Wayne



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post #148 of 170 Old 03-21-12, 03:37 AM
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Re: ECM8000 microphone measuring techniques and usage discussion

Quote:
Wayne A. Pflughaupt wrote: View Post

The Basic + adds calibration for 45° and 90° mic orientations, in addition to the 0° orientation of the Basic calibration package. However, for frequency response measurements you typically want 0° orientation – i.e., pointed at the signal source. More reading as to the “whys” and “wherefores” here.

Regards,
Wayne
Thanks Wayne.

The more you go into EQ the deeper it gets that's for sure, it's like, just as you learn how to open one door another comes along with a bigger lock, 'so to speak'.



The short answer for subwoofer measurements is, it doesn’t matter.

If you’re doing full-range measurements (your main-channel speakers), the short answer is, you only point the mic towards the ceiling if you’re using a 90-degree incident (vertical) calibration file.

Horizontal orientation with the mic on-axis to the sound source (0-degrees incident) has been the traditional method for full-range, free-field measurement, where the room was an open space relatively free of reflections. However, that’s mainly because most stand-alone RTAs (which until several years ago was about the only thing available) came with mics that were calibrated for on-axis measurements.

Some RTA manufacturers offered the option of 90-degree orientation for random incident measurements (aka diffuse field), where the sound arrives from all directions more or less simultaneously, with equal probability and level. In other words, an exceedingly reverberant environment. Random-incident measurements required a different capsule for the measurement mic (which the manufacturer made available), for reason of the specific calibration as well as a housing better suited for 90-degree orientation.

That just refers to the mic’s position during its calibration, however. Everything I’ve seen for actual “in the field” measurements says the standard protocol for horizontal (on-axis) measuring is 20 degrees, and 70 degrees for vertical (i.e., angled slightly forwards towards the sound source). This may have something to do with compensating for interference from the mic’s housing with the sound waves, I forget exactly why.

The ready availability these days of mics with 90-degree calibration certainly opens up more measurement options. Others have their opinions, and maybe they’ll weigh in, but mine is that you will generally get the best results with on-axis measurements. It should be a no brainer to figure out that the home theater environment, while certainly not totally free of reflections and reverberation, more closely resembles a free-field environment than a random-incident environment.

Vertical orientation may add more upper-frequency information from ceiling reflections than you’d get with on-axis, and as such will probably influence what the RTA displays. How much so will depend on your particular room – how “live” it is, the height of the ceiling in relation to the distance between the sound source (speaker) and measurement mic (i.e. inside or outside the “first reflection” zone), etc. Even though the ECM8000 is omnidirectional, its capsule is rather large for a measurement mic. As a result, its off-axis response (compared to on-axis) starts skewing as low as 3 kHz. So differences >3 kHz are what you might see with horizontal vs. vertical readings. (Smaller-capsule omni mics typically retain uniform 0 vs. 90-degree response at least an octave higher.)

Regards,
Wayne
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post #149 of 170 Old 04-04-12, 12:07 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

Hi.

I have just received my ECM800 'Basic' Mic from Cross Spectrum. It comes with two Mic Cal files. I was wandering which Cal file I load into REW, either the 'narrow band response 0 degree', or the 'one third octave band response 0 degree'.
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post #150 of 170 Old 04-04-12, 12:30 PM
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Re: ECM8000 microphone measuring techniques and usage discussion


There should have been a “Read me” file on the calibration disc that includes the following:

Quote:
The narrow-band-response.FRD files are designed for use with measurement and analysis programs like Room EQ Wizard, ARTA, and FuzzMeasure Pro that can make use of fine-tuned correction curves. The one-third-octave-response.FRD files are designed for applications where additional smoothing is warranted or for comparision with criteria given in terms of 1/3-octave bands.
Regards,
Wayne



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