ECM8000 microphone measuring techniques and usage discussion - Page 14 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #131 of 170 Old 03-03-11, 11:53 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

Great dialog, but not clear to me if there is a conclusion wrt microphone angle, the original topic of discussion.

Is it fair to say the conclusion is now that ECM8000 microphone should be best pointed at speaker for full range measurements UNLESS you only have a calibration that was done otherwise? It sounded like Anechoic does calibrations at both 0 and 90 degrees. Does 0 degrees means pointed at speaker? 0 degrees seemed to show HF peak between 10k and 20k (2-10 dB, average around 5) but extended response to 20khz. 90 degrees (vertical) gives flatter response at first, then drops 10dB or so at 20khz.

But even if it is "best" it may not be worth the trouble, given you have vertical calibration it's far easier to do vertical orientation measurements (and particularly if you need to do several).

One problem might be if microphone becomes more orientation/position sensitive when pointed at speaker. Perhaps vertical orientation would reduce that, for one thing, there would be less issue regarding how exactly you are aiming it, and therefore more repeatable results. Plus, it would be a whole lot easier for measuring multiple channels to use vertical orientation.

Another question in my mind is "what does vertical mean"? Is vertical pointing at ceiling or pointing at floor?

Now a question no one has mentioned here. Is it better to measure with listening chair in position? It would seem to me better to remove listening chair from room, otherwise gating will be ineffective, lots of early reflections. Human listeners, from what little I understand, can to some degree compensate for the early reflections from something like chair.

And how about this question: if you choose to use just one capsule position or vertical orientation, what part of listener's head should microphone capsule be positioned at? It would seem to me that for best accuracy, left-side channels should have microphone capsule positioned at left ear (where it would be during listening), and vice versa. I don't think I've ever seen anyone do this. If you choose not to take the trouble to do it, would it be better to position capsule at nose position or midway between the ears?
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post #132 of 170 Old 03-04-11, 01:01 PM
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Re: ECM8000 microphone measuring techniques and usage discussion


Welcome to the Forum, Charles! These links should answer most of your mic orientation questions.

http://www.hometheatershack.com/foru...tml#post184039
http://www.hometheatershack.com/foru...tml#post263849

There’s no good reason to get worked up about the listening-position furniture being in the room. The main thing is to keep the mic away from adjacent surfaces, especially the front and sides of the capsule. Just position the mic about a foot or so in front of where your head would be (i.e., giving it some distance from the back of the seat, especially if it’s high) and you’ll get good results.

Regards,
Wayne



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post #133 of 170 Old 03-05-11, 04:15 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

Hey i dont speak english so much as you do.. But i have a question im new in this thing i cant get working the rew program.. Mi question is doews this program works with my mini laptop microphone? Because non sistem goes higher than 94 db or 98 db please help..
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post #134 of 170 Old 03-06-11, 08:47 AM
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Re: ECM8000 microphone measuring techniques and usage discussion


Hi Beto,

Any mic used with REW requires a calibration file. Without a calibration file, the measurements will not be accurate.

Regards,
Wayne



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post #135 of 170 Old 06-14-11, 04:16 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

Just got a new, calibrated ECM8000 from Spectrum. I thought I'd ask a few, probably redundant, questions before taking some readings.

In particular, I wish to measure the performance of each of my drivers in my room, hence the problem. I don't have an anechoic chamber and taking the speakers outside is a no go due to their size.

I understand the best way to get a reasonable reading is to use the gating function to exclude room interaction. If that is correct, what are the recommendations for the gates? How far from the driver should the mic be placed? My speakers are two way DIY products with 15" ported bass bins and Tractrix horn HF.

If this has been covered in another thread, my apologies and could you post a link? I'm still searching.

DIY Mains, Oris 150 and Oris 250 horns, actively crossed with Ashly 4.8SP. QSC and Behringer pro amps. Integra DHC 9.9 Pre/Pro, Oppo BD-93 Blu Ray. Side Effects - Klipsch Pro Cinema, 4 LFE Subs - Full Marty DIY build. 7.1 setup, Projector - Panasonic PT-AE4000U, Dalite HP screen. HTPC for lossles .flac audio.
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post #136 of 170 Old 06-14-11, 05:18 PM Thread Starter
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Re: ECM8000 microphone measuring techniques and usage discussion

I used to do "Distance to first reflection point"/1100ft/s = Time to First reflection.

This is from memory, but I think that's right. Set the first gate to a few ms before the wave would even arrive (to minimize noise) and then the second gate after the first reflection.

For me, that was usually the floor and was really close, so I couldn't get any bass measurements. I would cover the floor with pillows and fluffy blankets and then use the next reflection (ceiling) measurement for the gate. This was for when I was getting measurments from the listening position.

For actual driver tests, I had a stick that was exactly 1m long that used to space the mic on axis at that distance. No early gate, but I set the late gate the same way as above.

If you can see the time/pulse waveform, you can actually see spikes when the first wave arrives plus all the reflections. This can give you a better idea of where to set the gates.

It's been a while, so this may be a bit rusty. Good luck, and let us know how it goes.
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post #137 of 170 Old 06-14-11, 10:55 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

Anthony, thank you and I will post results when I get going on this. Likely sometime next week.

DIY Mains, Oris 150 and Oris 250 horns, actively crossed with Ashly 4.8SP. QSC and Behringer pro amps. Integra DHC 9.9 Pre/Pro, Oppo BD-93 Blu Ray. Side Effects - Klipsch Pro Cinema, 4 LFE Subs - Full Marty DIY build. 7.1 setup, Projector - Panasonic PT-AE4000U, Dalite HP screen. HTPC for lossles .flac audio.
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post #138 of 170 Old 10-04-11, 08:56 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

I've just purchased a pair of Behringer ECM-8000's that I will eventually have calibrated, but would like to download "Sonny's (Sonnie's?) calibration file" for some immediate measurements.

I've used the search function and can't seem to locate the Behringer ECM-8000 calibration file that I've seen mentioned in several threads here.

Where can I find it?
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post #139 of 170 Old 10-04-11, 11:30 PM
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Talking Re: ECM8000 microphone measuring techniques and usage discussion

thnks for your help.. my computer fail ad until ow i got it workimg.. im trying to use the rew program for car audio.. i don´t know where to find a mic for made my mini lap acer workig.. can you please tel me where to uy one ad send it here to mexico? im triying to get my self into the spl comp.. as you know im new in this.. thnks so much for your ..
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post #140 of 170 Old 10-20-11, 11:30 PM
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Re: ECM8000 microphone measuring techniques and usage discussion

Quote:
inspired wrote: View Post
I've just purchased a pair of Behringer ECM-8000's that I will eventually have calibrated, but would like to download "Sonny's (Sonnie's?) calibration file" for some immediate measurements.

I've used the search function and can't seem to locate the Behringer ECM-8000 calibration file that I've seen mentioned in several threads here.

Where can I find it?
http://www.hometheatershack.com/foru...oads-page.html
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