Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 408 - AVS Forum
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post #12211 of 12235 Old Yesterday, 06:13 AM
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gskinusa,

Check signal routing. Make sure you have correctly set up Soundflower and Audio MIDI Setup.

Measure another speaker close. Close means closer than 10% of the effective speaker membrane radius.

Is processing/EQ turned off?

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 #12212 of 12235 Old Yesterday, 07:18 AM
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gkinusa,

Are you certain that the UMIK mic is performing the measurements, and not the internal Mac mic?

Regards, Mike.
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post #12213 of 12235 Old Yesterday, 08:49 AM
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Quote:
Originally Posted by AV_mike View Post
gkinusa,

Are you certain that the UMIK mic is performing the measurements, and not the internal Mac mic?

Regards, Mike.
I've been burned by that multiple times. When it's happened to me the bass extension virtually disappears.
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post #12214 of 12235 Old Yesterday, 09:11 AM
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Quote:
Originally Posted by 3ll3d00d View Post
well I would have thought the notch would be at the resonant frequency of the port & that seems awfully high for PB13 Ultra! Can you give more detail about your mic & sub position?
I am using the UMIK calibrated through Cross-Spectrum and with that I am using the "narrow_band_response_0_degree.frd" calibration file. The sub is located in the back right corner on the riser. I would say it is 6 inches from side and back wall and around 8in from the side of the sofa. The ports are facing the open area (towards the screen).

Quote:
Originally Posted by markus767 View Post
gskinusa,

Check signal routing. Make sure you have correctly set up Soundflower and Audio MIDI Setup.

Measure another speaker close. Close means closer than 10% of the effective speaker membrane radius.

Is processing/EQ turned off?
I followed the instructions provided in our forums and also in the MiniDSP site to set it up. I think the soundflower is configured correctly as I could change the channels and get the corresponding signal from the speakers. I will try the speaker response and report back. The front speakers are behind the screen so may be I will do it with one of the surrounds. Just for comparison, is there a sample measurement graph for a speaker so I can know what to expect.

Regarding the EQ, yes I have that turned off (when to Audio --> Audyssey--> set it to off in Marantz).

With Soundflower, I am using the Soundflower 64 and not Soundflower 2. That is what explained in the articles so if this is not correct then I can run with the other.

Quote:
Originally Posted by AV_mike View Post
gkinusa,

Are you certain that the UMIK mic is performing the measurements, and not the internal Mac mic?

Regards, Mike.
I think I am sure. I check every time to see the input is UMIK and the output is Soundflower 64. Also, I have the laptop in the equipment room which is basically a closet within the HT room. When I am taking measurements I have the closet doors closed so I do not think the internal mic would have picked it up. I will still do that test as well when I run it tomorrow.

BTW, thank you guys for the multiple thoughts/suggestions. This gives me confidence that somehow will get the solution for this.

I am also thinking of getting a PC laptop and set up REW using that and compare. I will report back on that as well.

Thank you
-Sen
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post #12215 of 12235 Old Yesterday, 09:42 AM
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Quote:
Originally Posted by gskinusa View Post
I am also thinking of getting a PC laptop and set up REW using that and compare. I will report back on that as well.
As much as I love my macs, I have a pc laptop for REW and HCFR. Hey, a hobby is a hobby, right?

You've seen this?
http://johnr.hifizine.com/2013/02/ro...ut-workaround/

Downloadable FREE demo discs:
http://www.avsforum.com/t/1475769/de...ently-authored 

Did you really need to quote that entire post in your reply?
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post #12216 of 12235 Old Yesterday, 09:43 AM
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Quote:
Originally Posted by gskinusa View Post
I followed the instructions provided in our forums and also in the MiniDSP site to set it up. I think the soundflower is configured correctly as I could change the channels and get the corresponding signal from the speakers.
That's good. Also check the "Audio MIDI Setup" application on your Mac and make sure you're using the correct sound input and not the internal mic.

Quote:
Originally Posted by gskinusa View Post
I will try the speaker response and report back. The front speakers are behind the screen so may be I will do it with one of the surrounds. Just for comparison, is there a sample measurement graph for a speaker so I can know what to expect.
Here's a 10" woofer measured near field without any smoothing applied:



You should see a rather smooth fall-off at low frequencies.
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post #12217 of 12235 Old Yesterday, 01:47 PM
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Quote:
Originally Posted by markus767 View Post
That's good. Also check the "Audio MIDI Setup" application on your Mac and make sure you're using the correct sound input and not the internal mic.



Here's a 10" woofer measured near field without any smoothing applied:



You should see a rather smooth fall-off at low frequencies.
Thank you. I think I got the problem fixed.

Quote:
Originally Posted by LastButNotLeast View Post
As much as I love my macs, I have a pc laptop for REW and HCFR. Hey, a hobby is a hobby, right?

You've seen this?
http://johnr.hifizine.com/2013/02/ro...ut-workaround/
Thank you. Though what is being addressed in this article was not the problem I was facing, after reading it, got some ideas to tweak and I think it worked. So I guess it did solve my problem .

The rerun after I (think) fixed the problem.

Please let me know whether I got it or not.
Thank you for your help.
-Sen
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^
What do we see in those graphs? Where did you put the mic? Are those graphs smoothed?

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 #12219 of 12235 Old Yesterday, 02:53 PM
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Quote:
Originally Posted by markus767 View Post
^
What do we see in those graphs? Where did you put the mic? Are those graphs smoothed?
I apologize for not providing the details.

The first one is the near field measurement of the subwoofer with the mic an inch from the middle of the subwoofer. The different measurements in it represent the 1 port closed, 2 port closed and all ports closed (sealed) modes.


The 2nd image is with the mic in the main listening position and measurement taken with all ports closed (sealed) in the sub and no audyssey applied.


The last one is same as 2nd but with the audyssey applied.


All are without any smoothing applied.

I hope this helps.
Thank you
-Sen
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post #12220 of 12235 Old Yesterday, 02:59 PM
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^
Looks plausible.

As said before for a near field measurement put the mic <10% of the membrane radius. For your sub this is about 1/2".

If you use a very slow sweep (1M) does the response change significantly?

Markus

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post #12221 of 12235 Old Yesterday, 03:02 PM
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Quote:
Originally Posted by markus767 View Post
^
Looks plausible.

As said before for a near field measurement put the mic <10% of the membrane radius. For your sub this is about 1/2".

If you use a very slow sweep (1M) does the response change significantly?
Sorry, I meant to type half an inch but somehow typed it as an inch. I am not sure about the slow sweep. I will look in to that and once I take the measurement will provide that detail as well.
Thanks
-Sen
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post #12222 of 12235 Old Yesterday, 03:06 PM
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post #12223 of 12235 Old Yesterday, 03:11 PM
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Thank you very much. I was just trying different searches on it . I will have it run tomorrow and provide the details. Just for me to understand what I will be seeing when I do this, can you provide some thoughts what I should look for. Should the measurement remain the same as the near field one that I have measured? or should I expect something different?.

Thank you for your time.
-Sen
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post #12224 of 12235 Old Yesterday, 03:17 PM
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You get a better signal to noise ratio with longer sweeps. It should look very similar to your last graphs.

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 #12225 of 12235 Old Yesterday, 03:41 PM
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Can someone tell me what I did and how to fix it?
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post #12226 of 12235 Old Yesterday, 05:00 PM
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Perhaps you accidentally entered a file name in the soundcard calibration box? This box should be empty.

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Originally Posted by AustinJerry View Post
Perhaps you accidentally entered a file name in the soundcard calibration box? This box should be empty.

I will check that out.

Is entering the mic cal a one time thing?

By me having both the sound card and the mic cal the same, would this effect measrurements?
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post #12228 of 12235 Old Yesterday, 06:52 PM
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BTW......thanks Austin, you helped me a bunch getting everything set up awhile ago. I am finally getting around to taking measurements and using them to EQ my subs with the Mini-DSP.
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post #12229 of 12235 Old Yesterday, 07:14 PM
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I will check that out.

Is entering the mic cal a one time thing?

By me having both the sound card and the mic cal the same, would this effect measrurements?
Generally, once you enter the mic calibration file in the Preferences area, the file will stay configured. However, as mentioned in the previous post, when using a USB mic, a Soundcard calibration file is not required. The soundcard calibration and the mic calibration are two completely different things.
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post #12230 of 12235 Old Yesterday, 11:13 PM
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Just got my Umik-1, and finally getting back into taking some measurements. It's been a fairly epic stuggle for me to get REW working (partly documented on my previous post here), so I'm very excited to get going with this.

While I was in the process of figuring out what was going on with the screwy results I was getting form my previous mic, I couldn't resist taking a couple steps into the room treatment thing. I've not got 4" panels hitting two of the sidewall 1st reflections and then I made 2" clouds above as pictured here:



I didn't notice too much change after putting up the sidewall panels, but after putting up the clouds I thought I noticed a big different. More or less as one might expect, I felt the soundstage was more pronounced, and at least a couple times I actually got up to make sure I did leave my receiver in PLII since it sure sounded like the center channel just had to be on.

Since my mic now seems to be working properly, just now I measured the MLP with the clouds up and then again with the clouds down. Here is that result:



I'm seeing very little difference. This makes me wonder if:

a. There's not actually much difference and my perception is due to confirmation bias.

b. I shouldn't expect to measure a difference in the frequency response from this change.

c. There is actually a difference in the graphs I'm not picking up on.

Also, how does the graph look to people? Of course I know it's not great. I've still got four sheets of Owens Corning 703 to use up, and I'm feeling pretty motivated ot make more absorption panels, if it would make a difference. Here is my family room / listening area:



I really appreciate any help in moving forward here!
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post #12231 of 12235 Old Today, 12:07 AM
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Graph looks plausible. Could you upload the .mdat?

The cloud reduces the ceiling reflection so you have to look at graphs that show how the sound field behaves over time.

Markus

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^
Graph looks plausible. Could you upload the .mdat?

The cloud reduces the ceiling reflection so you have to look at graphs that show how the sound field behaves over time.
I hope I'm doing this right. Please let me know if you have any problem reading these. Thank you.

https://dl.dropboxusercontent.com/u/...oud%20off.mdat

https://dl.dropboxusercontent.com/u/...ouds%20on.mdat

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Thanks but you've linked two times the same measurement?

Markus

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^
Thanks but you've linked two times the same measurement?
Oops. I edited it above.
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post #12235 of 12235 Old Today, 01:29 AM
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Without absorber:



With absorber:

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