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Old 24th February 2014, 04:49 PM   #321
gedlee is offline gedlee  United States
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Quote:
Originally Posted by Greebster View Post
Your use of low quality measurement equipment not designed for the task is appalling. Do you know anything other than sensitivity and response of your non traceable uncertified microphones? If you repeat with they are calibrated, I will laugh, as they would be considered inadmissable in court for even SPL measurements. I at least understand the limitations of the UMIK-1's I own and what calibration means having run a NIST traceable cal lab on hundreds of equipment of all shape and form.
This attack is unfounded. Just because a court requires a calibration trace is no support for not using "typical microphones" in tests like this. The calibration is almost exclusively to calibrate sensitivity, which is irrelevant in these discussions. Unless the microphone is actually broken its frequency response will be sufficient to study any and all issues being discussed here. I find this attack to be precisely what you are claiming about Markus (who is also quite often guilty of obscuring the issues to win the argument.)
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Old 24th February 2014, 10:21 PM   #322
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Whats that stupid noise about the calibration of the microphone? It is completely irrelevant for this topic.

Instead we should talk about why barleywater is wrong and why PEQs work for room equalization (or why not).
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Old 24th February 2014, 10:32 PM   #323
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Originally Posted by Baseballbat View Post
Instead we should talk about why barleywater is wrong and why PEQs work for room equalization (or why not).
I'd appreciate that.
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Old 25th February 2014, 12:52 AM   #324
gedlee is offline gedlee  United States
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Somehow all of the DIY Audio E-mails are getting "junked". So I have been out of the loop.

Quote:
why PEQs work for room equalization (or why not).
Are we talking about room EQ above Schroeder, or below, or both? The answers are all quite different.
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Old 25th February 2014, 01:54 AM   #325
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Originally Posted by markus76 View Post
Greebster, you're digging a pretty deep hole here.
One of my mics was calibrated by Herb Singleton of Cross Spectrum Labs and another one by a German vendor. I compare them from time to time just to make sure I'm not fooling myself. It's your claim that I'm using "measurement equipment not designed for the task" that is "appalling".
The point that is all they tested, frequency response and nothing else. Not that the quality of how they tested is at question if you understand the limitations. Would be saying mine and your elcheapo's are as good as true high end instrumentation mic's that cost thousands. I would never draw that conclusion, nor should you.

My first mic was something I made 28years ago and used a panasonic electret element with a phantom ps. It worked very well, but reference was missing. This did not stop me from using it, quite the contrary, proved quite useful especially in the low mids to near 10k, flat on axis, despite being "Omni". Wasn't the first or the last mic I made, some including ribbon mics as I was just as interested in all this as you are today. Difference was digital wasn't there yet and even when it did show up on scene cost a fortune. So old school analog ruled supreme. When understanding test parameters you also accept the limitations of the test. I do not know of any place on the planet that does these types of tests for under a grand, you supply the lab grade mic.

Here is a brand I am very familar with Microphones and preamplifiers - Brel & Kjr
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Old 25th February 2014, 07:33 AM   #326
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Originally Posted by gedlee View Post
Are we talking about room EQ above Schroeder, or below, or both? The answers are all quite different.
Above AND below.

I've made my point already somewhere in this thread, first page or so.
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Old 25th February 2014, 02:33 PM   #327
Juhazi is offline Juhazi  Finland
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This is from Dirac link (Above)
"Multiple measurements
Dirac Live uses several measurement positions (9 typically) in the listening room.This way, it is possible to find consistent acoustic problems. Only these should be corrected.

Click the image to open in full size.In terms of the impulse response, this means the direct wave and very early reflections. Generally, at higher frequencies there is less consistent time-domain behavior. Dirac Live automatically finds consistent problems in a frequency-dependent way and corrects for them. After finding consistent time-domain behavior, there may still be some late reverberation in the room that causes a gentle coloration. This is corrected in the frequency domain with just the right resolution.

Impulse response correction
The impulse response of a loudspeaker affects clarity, tightness and all spatial aspects of the sound, such as location and distinctness. Dirac Live is unique in actually correcting the impulse response in a large listening area, not just a single point. By focusing on consistent problems across the measurement positions, and correcting only these, a faster decay time is achieved. Typically, the power ratio between the direct wave and the tail is improved by 6 dB or more, representing a vastly tighter sound."
---

This is common and sane procedure. Still I am stupid enough to not understand how time-domain correction is possible in signal level, but I guess it is - and I relly would like to see measurements before/after.

I use REW and I like to look at amplitude response and short/long decay in many ways and with different analysis parameters. I have been doing this for half a year now weekly, total hundreds of hours - and I am sill puzzled with many things! It is very difficult to get "touch" of these things. Automatic correction like Dirac is very useful, if it really works.

This topic is about PEQ and as a minidsp user with 4-way speakers, I can do it for each "way" L/R separately and even for the full signal for L/R. The problem lies with measurements in a small room! Even some 10-25cm (4-10") move of the microphone makes wiggles to mirror images! As stated earlier and in many other threads, below schroeder this is a little easier. One general rule is to avoid high Q (sharp) corrections because they are too space-spesific. Half-octave accuracy is practical maximum, but there are some exceptions.

This morning I had a measurement session with AINOs, about 4 hours of hardcore tuning and parameter setting. Result will be shown later here, they are in my laptop now.
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Old 25th February 2014, 02:39 PM   #328
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Quote:
Originally Posted by Juhazi View Post
Still I am stupid enough to not understand how time-domain correction is possible in signal level
Good read: http://www.dirac.se/media/12044/on_room_correction.pdf
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Old 25th February 2014, 02:53 PM   #329
gedlee is offline gedlee  United States
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Originally Posted by Greebster View Post
Another fine example of blinders on is like when Columbia burned up and all the NASA engineering geniuses said that piece of foam was of no concern. Standing in the back was one engineer that stood out and said you are all wrong.
That was Richard Feynman, a physicist, like me, and not an engineer. And he was at the front of the room, not the back. Anecdotes are always better when they are actually said correctly.
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Old 25th February 2014, 02:55 PM   #330
gedlee is offline gedlee  United States
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Originally Posted by Baseballbat View Post
Above AND below.
Anyone who believes that the solutions or approaches above and below are not completely different does not understand the problem.
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