Weighting measurement with Omni Mic - AVS Forum
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post #1 of 8 Old 03-30-2012, 03:39 PM - Thread Starter
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In a discussion with another forum member there was some interest in seeing some measurements taken with Omni Mic, specifically the SPL tap and the use of the “C” weighting and the use of “none” for weighting.

What I did first was to make sure the subs were reading 75db with my Onkyo internal test tone.

Microphone was never moved and all measurements were taken at -20 master volume.

I than ran How To Train Your Dragon from 1:14:25 – 1:15:00. In the screen shots as “HT”.

This was done with all speakers and subs playing and then with just the subs playing.

Screenshots shots show with the “C” weighting and “none” weighting.

I also did this with the XBOX 360 game Mass Effect 3 when the ship goes through the Mass Relay. I know, I know but it was very easy to reproduce in a quick manner and I did not have any other “known” movies sitting around.

PLEASE note that I could not catch the graphs fast enough in the screen shots but what was in question was the “Peak” and “Max” values.

Screen shots in order are:

1) 75db_cal_c_weighting
2) 75db_cal_no_weighting
3) HT_20_allspeakers_subs_c_weighting
4) HT_20_allspeakers_subs_no_weighting
5) HT_20_subs_only_c_weighting
6) HT_20_subs_only_no_weighting
7) ME3_20_allspeakers_subs_c_weighting
8) ME3_20_allspeakers_subs_no_weighting
9) ME3_20_subs_only_c_weighting
10) ME3_20_subs_only_no_weighting
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post #2 of 8 Old 03-30-2012, 03:40 PM - Thread Starter
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Last 5 measurements.

Also, I did hit the "reset" button that is below the "Peal", "Max", etc before taking each reading.
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post #3 of 8 Old 03-30-2012, 04:33 PM - Thread Starter
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Peak and Max values from the screenshots in an easier to read way.

75db cal C weighting:
Peak 84.7
Max 75.4

75db cal no weighting:
Peak 87.2
Max 77.9

HT Speakers-Sub C weighting:
Peak 104.6
Max 93.9

HT Speakers-Sub no weighting:
Peak 105.2
Max: 96.0

HT Subs C weighting:
Peak 100.1
Max 92.0

HT Subs no weighting:
Peak 104.3
Max 95.9

ME3 Speakers-Subs C weighting:
Peak 98.7
Max 89.4

ME3 Speakers-Subs no weighting:
Peak 102.2
Max 91.2

ME3 Subs C weighting:
Peak 96.0
Max 88.0

ME3 Subs no weighting:
Peak 99.0
Max 90.1
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post #4 of 8 Old 04-01-2012, 02:14 PM
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Quote:
Originally Posted by exojam View Post

In a discussion with another forum member there was some interest in seeing some measurements taken with Omni Mic, specifically the SPL tap and the use of the C weighting and the use of none for weighting.

What I did first was to make sure the subs were reading 75db with my Onkyo internal test tone.



What kind of dB reading was that 75 dB test tone?

Average?

Max?

Peak?

SPL C scale?

No weighting?

You should show all of those numbers to see if your 75 dB SPL calibration number makes any sense at all relative to your test results. The SPL C scale average reading is used in calibration.

Your measured test results shows about a 9 dB +/- difference between all of your MAX and PEAK readings.
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post #5 of 8 Old 04-01-2012, 02:20 PM - Thread Starter
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JPC,

The screen shots in the first post and information in the second post should answer your questions. Let me know if they do not. Thanks.

James
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post #6 of 8 Old 04-01-2012, 02:56 PM
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Quote:
Originally Posted by exojam View Post

JPC,

The screen shots in the first post and information in the second post should answer your questions. Let me know if they do not. Thanks.

James



Yup, everything is there. I guess I am getting a bit lazy these days.

The calibration screen shot shows the same difference between MAX and PEAK as your playback sample shows.

So a 75 dB SPL S scale calibration level is about 77 dB SPL C scale MAX and 87 dB SPL C scale PEAK.

Not sure why PEAK levels are of much use in that no one mentions the 87 dB SPL C scale PEAK calibration level for an apples to apples comparison. All PEAK levels seem to scale just fine from the MAX values.
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post #7 of 8 Old 04-01-2012, 03:27 PM - Thread Starter
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JPC,

No problem at all, I miss more than I catch now a day.

Since you are here maybe you could assist me on something. One of the tests I was using was from the Mass Effect 3 video game. I did not think it had super low bass or anything it was just very easy to recreate and measure.

Now my question is, I used the link below which shows the part I measured, just as a reference; I actually had the game running through my system.
Now I made that video into a wav file and played it through Spec Labs. Does the attached screen shot appear as I did that correctly? I hope this makes sense. Thanks.

Video just showing what I was recording.
http://www.youtube.com/watch?v=95luOuLOTNQ

James
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post #8 of 8 Old 04-01-2012, 08:00 PM
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Good stuff! Thanks for taking the time to run the tests and post your findings.
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