Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 296 - AVS Forum
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post #8851 of 10749 Old 02-21-2014, 05:54 AM
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Why not ask Parts Express? They sold it so they should know.

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole
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post #8852 of 10749 Old 02-21-2014, 05:55 AM
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Originally Posted by markus767 View Post

^
Why not ask Parts Express? They sold it so they should know.

Funny you asked that...I have an email into them...waiting response...just hoping there was a "faster answer".

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post #8853 of 10749 Old 02-21-2014, 06:07 AM
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I'm fairly certain the PE cal file is for 0 degrees BICBW.  Send it to Herb and he'll calibrate all 3 positions for you.  As I recall, there wasn't a HUGE difference between using the 0 and 90 degree cal files when this question came up about 50 pages ago (at 100 posts per page).

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post #8854 of 10749 Old 02-21-2014, 06:16 AM
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I'd say the difference at high frequencies is quite significant. Here's my EMM-6:


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post #8855 of 10749 Old 02-21-2014, 07:11 AM
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Quote:
Originally Posted by toofast68 View Post

Funny you asked that...I have an email into them...waiting response...just hoping there was a "faster answer".

http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/4920_20#post_23808303
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post #8856 of 10749 Old 02-21-2014, 07:17 AM
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Quote:
Originally Posted by AustinJerry View Post
 

Bookmark this post so you can answer the question, because it is bound to come up over and over again.....

Psychic?

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post #8857 of 10749 Old 02-21-2014, 07:22 AM
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Directly at the speaker being tested, I always aim for the area between tweeter and mid-woofer.
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post #8858 of 10749 Old 02-21-2014, 07:25 AM
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Quote:
Originally Posted by Theresa View Post

Directly at the speaker being tested, I always aim for the area between tweeter and mid-woofer.

 

Ok, but I think you are wrong :eek:

 

At least according to the experts on this thread....or am I more confused than ever.

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post #8859 of 10749 Old 02-21-2014, 07:36 AM
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Mine too is "calibrated" only for on axis so I point it at the speaker being tested.
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post #8860 of 10749 Old 02-21-2014, 07:40 AM
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Quote:
Originally Posted by toofast68 View Post

Ok, but I think you are wrong eek.gif

At least according to the experts on this thread....or am I more confused than ever.

For diffuse field measurements (like measurements at the listening position) the mic should be pointed upward. For free field measurements (like measuring a speaker driver) the mic should be pointed at the speaker. That's why different calibration files are needed. If only one calibration file is available then point the mic in the direction the calibration file is valid for.

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post #8861 of 10749 Old 02-21-2014, 08:16 AM
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Depends on what you are trying to measure. I measure my speaker's individual responses to adjust miniDSPs. For room response I use Audyssey XT32 and use it's measurement mic pointed upwards. So it depends whether you are measuring diffuse room response or individual speakers. So we're both right.
smile.gif
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post #8862 of 10749 Old 02-21-2014, 08:30 AM
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What post are you referring to?

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post #8863 of 10749 Old 02-21-2014, 08:59 AM
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Quote:
Originally Posted by Theresa View Post

Depends on what you are trying to measure. I measure my speaker's individual responses to adjust miniDSPs. For room response I use Audyssey XT32 and use it's measurement mic pointed upwards. So it depends whether you are measuring diffuse room response or individual speakers. So we're both right.
smile.gif

 

Sooooooooooooooo confused....if I am trying to use REW to measure (forget every other reason) FR/Waterfall, etc. the GUIDE says point the MIC UP (something I got wrong earlier) no matter HOW MIC is calibrated - that is what I understand now.

 

Yes ?

 

Or if my MIC has 0 degree, then I MUST point it toward the "front" for REW type measurements.

 

Buy the way just verified from Dayton Audio direct this for everyone else benefit...for those who screwed up and bought through parts express.

 

The UMM-6 USB measurement mic is tested on-axis (zero degrees) for calibration. 

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post #8864 of 10749 Old 02-21-2014, 09:17 AM
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Point the mic in the direction it is calibrated for.

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole
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post #8865 of 10749 Old 02-21-2014, 09:18 AM
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Quote:
Originally Posted by markus767 View Post

How do other locations within the listening area look like? Is that graph smoothed?



Black = Left channel - mic at Left ear location
Green = Left channel - mic pointing forward
Orange = Left channel - mic at Right ear location






Red = Right channel - mic at Right ear location
Green = Right channel - mic pointing forward
Gray = Right channel - mic at Left ear location

All measurements with 1/24th oct smoothing and 250ms gate.

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post #8866 of 10749 Old 02-21-2014, 09:21 AM
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Without gating <300Hz? Does your software support exporting IRs?

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post #8867 of 10749 Old 02-21-2014, 09:26 AM
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Quote:
Originally Posted by markus767 View Post

^
Without gating <300Hz? Does your software support exporting IRs?

Yes, but id have to remeasure everything. You will just have to trust me that removing the gate entirely doesn't change anything in the bass region more than 1db.



Here is an older measurement. (both channels driven, mic pointed forward)

Black = no gate, no smoothing
Red = 250ms gate, 1/24th oct smoothing

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post #8868 of 10749 Old 02-21-2014, 09:34 AM
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Originally Posted by jim19611961 View Post

Yes, but id have to remeasure everything.

What? You can't/didn't save those measurements??

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post #8869 of 10749 Old 02-21-2014, 09:36 AM
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The software doesnt save IR data unless you ask it to. The graphs are what is saved with whatever parameters you apply. Omnimic works very differently than REW.

edit: Even when you DO ask it to, it only saves one sweep of one short sine wave. It doesnt average several long sine sweeps together over time like REW does. So, the IR data is of limited value.

Omnimic is designed to work in real time. While this has advantages, it has disadvantages also.

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post #8870 of 10749 Old 02-21-2014, 09:40 AM
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Quote:
Originally Posted by markus767 View Post

^
Point the mic in the direction it is calibrated for.

Ok, this this goes against what AustinJerry posted 1540 posts ago :eek:

 

Not trying to cause trouble, just trying to understand.

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post #8871 of 10749 Old 02-21-2014, 09:46 AM
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Originally Posted by toofast68 View Post

Ok, this this goes against what AustinJerry posted 1540 posts ago eek.gif

Not trying to cause trouble, just trying to understand.

The Audyssey mic, consumer or Pro, IS calibrated on the 90° axis, therefore pointing it at the ceiling is the correct orientation. Unless you are measuring a speaker on the ceiling. wink.gif

Mics purchased from Parts Express are calibrated on the 0° axis and need to be pointed AT whatever is being measured. This is unsuitable for some/many measurements being done here on this thread. The same mics, when purchased from Cross Spectrum, have calibration files for 0°, 45° and 90°, so users load the appropriate file for the particular measurement being done.
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post #8872 of 10749 Old 02-21-2014, 09:48 AM
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The Audyssey mic, consumer or Pro, IS calibrated on the 90° axis. Therefore pointing it at the ceiling is the correct orientation.

 

Ok, so maybe this is why we (or I) am confused.

 

yes got that for the Audyssey Mic supply with the AVR

 

I am asking about the USB MIC that I (we) are using to measure FR, etc.

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post #8873 of 10749 Old 02-21-2014, 09:55 AM
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Damn...I've been using my UMC-1 mic with it pointing up as I thought it should be the same as my Audyssey mic. I only have one calibration file for it so I'm thinking that I may need to point it towards the speaker(s) next time I do some measurements. redface.gif

I'd just run through a batch of left + sub, centre + sub & right + sub measurements having finally go my matching MK MP150 centre speaker (and spent yesterday installing a special TV lift so that the centre can hide behind the TV when not in use cool.gif). I was mostly just playing around with checking sub distance settings (ended up back at the Audyssey ones anyway) and different crossovers.

I was feeling pretty pleased with the results and that it sounds really good as well, but I've made another 'school boy' error: I ran Audyssey without the TV in place above the centre, so it may make some difference (I've measured with the TV at different heights and there is an impact on the response, so it makes sense to do the Audyssey set up and any fine tuning with the TV fully raised as it will be for 'serious' viewing.

Oh well, here are the results for today anyway. I still need to add stuffing to my home built subs, but the TV lift took longer than I thought so the subs haven't been touched this week while I've been off work. frown.gif

I've shown the left and right (both measured with the subs) and then the centre and left (again both with subs). The centre has a bumpier response between 100-200Hz possibly due to the TV now being above it. The left and right responses seem better than my previous attempts too, so things are getting better. smile.gif




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post #8874 of 10749 Old 02-21-2014, 10:03 AM
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Quote:
Originally Posted by toofast68 View Post

Ok, so maybe this is why we (or I) am confused.

I know where my bet would be placed. biggrin.gif
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post #8875 of 10749 Old 02-21-2014, 10:05 AM
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Quote:
Originally Posted by jim19611961 View Post

The software doesnt save IR data unless you ask it to. The graphs are what is saved with whatever parameters you apply. Omnimic works very differently than REW.

edit: Even when you DO ask it to, it only saves one sweep of one short sine wave. It doesnt average several long sine sweeps together over time like REW does. So, the IR data is of limited value.

Omnimic is designed to work in real time. While this has advantages, it has disadvantages also.

Sounds confusing. Maybe it's time to upgrade to REW? Works in real time too and generates plots that are more in line with what we're used to wink.gif


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post #8876 of 10749 Old 02-21-2014, 10:06 AM
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Quote:
Originally Posted by markus767 View Post

^
I'd say the difference at high frequencies is quite significant. Here's my EMM-6:




And mine

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My Equipment

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Rega - DAC
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post #8877 of 10749 Old 02-21-2014, 10:10 AM
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Quote:
Originally Posted by markus767 View Post

Sounds confusing. Maybe it's time to upgrade to REW? Works in real time too and generates plots that are more in line with what we're used to wink.gif

I have REW. And sometimes import into it. I just cant measure with REW (no PC hooked up to main system)

Edit: If there is something specific you want to see, I might be willing to create IR files for you to look at smile.gif

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Originally Posted by pepar View Post


I know where my bet would be placed. biggrin.gif

 

Ok I will be the bad guy....ALWAYS POINT YOUR MIC AT 90 DEGREES TO MEASURE FR USING REW

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post #8879 of 10749 Old 02-21-2014, 10:37 AM
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Ok I will be the bad guy....ALWAYS POINT YOUR MIC AT 90 DEGREES TO MEASURE FR USING REW

AND BE SURE TO LOAD THE 90° CALIBRATION FILE.

smile.gif
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post #8880 of 10749 Old 02-21-2014, 11:09 AM
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Quote:
Originally Posted by Kelvin1965S View Post

Damn...I've been using my UMC-1 mic with it pointing up as I thought it should be the same as my Audyssey mic. I only have one calibration file for it so I'm thinking that I may need to point it towards the speaker(s) next time I do some measurements. redface.gif
For sub + mains integration work it doesn't really matter as the differences occur at high frequencies.
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