Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 735 - AVS Forum | Home Theater Discussions And Reviews
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post #22021 of 22041 Old 03-21-2017, 10:01 PM
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Originally Posted by David Varner View Post
I will do that same test tomarrow with screenshots. The only thing different is out mics. I'm using the latest version of REW and Windows 10. I was not paying attention to the input dBFS when I was changing Windows mic levels. I also see you are using Z weighted I used C. I do understand the differences but I used C because my SPL meter only does A or C. I'm not drawing a conclusion yet.

That is perplexing how your input levels are changing but your db measurements are not. Hmmm.

I find it odd that REW automatically adjusts my mic to a default parameter in Windows mic properties every time I open the program.

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Are you commenting on a post that I removed after I discovered I was using Z weighting, which obviously was an error?
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post #22022 of 22041 Old Yesterday, 02:20 AM
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Originally Posted by AustinJerry View Post
my SPL meter was set to "Z" weighting, whatever that is
z weighting is basically a flat response, i.e. no adjustment applied - https://www.noisemeters.co.uk/help/f...-weighting.asp

what sort of pink noise are people using? full bandwidth or band limited? if band limited, which band?
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post #22023 of 22041 Old Yesterday, 05:09 AM
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Originally Posted by 3ll3d00d View Post
z weighting is basically a flat response, i.e. no adjustment applied - https://www.noisemeters.co.uk/help/f...-weighting.asp

what sort of pink noise are people using? full bandwidth or band limited? if band limited, which band?
I am using speaker cal not full bandwith.

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post #22024 of 22041 Old Yesterday, 05:31 AM
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I am using speaker cal not full bandwith.
I would expect an SPL meter to measure that accurately
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post #22025 of 22041 Old Yesterday, 05:48 AM
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Yes I am going to try a couple of other things. I was going to order a umik-1 and compare but cross spectrum labs is out of stock

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post #22026 of 22041 Old Yesterday, 06:54 AM
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Originally Posted by PlasmaPZ80U View Post
So I measured my impulse response of all 5 speakers and sub, Room Correction off, bass management off, speakers 15-20,000Hz and LFE channel 15-300Hz with acoustic timing reference set to right surround speaker as it is closest to MLP. I left the speaker and sub distances at where YPAO set them, which is:

FL 7.2ft
FR 5.8ft
CC 6.2ft
SL 4.6ft
SR 4.4ft
SW 6.4ft (was 8.4ft before sw dist tweak but set at 6.4ft during these measures)

https://drive.google.com/file/d/0B2P...ew?usp=sharing (mdat file)


Issue is FL, FR, CC all are before 0ms and SL and SR are at 0ms. Why is that considering YPAO set these distances/delays and they are very close/matching tape measured distances?
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Originally Posted by PlasmaPZ80U View Post
I was trying out ETC graphs for the first time and they look terrible with FL and SR in particular...Also, can Audyssey XT32 help any of this with its FIR taps and indirectly too by smoothing out some nasty peaks and dips in the low to mid frequencies?
Three acoustical issues that room correction can?t correct.

Post your .mdat file.
See file linked above
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post #22027 of 22041 Old Yesterday, 07:36 AM
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Commence beating on me if I'm posting a duplicate question or posting in the wrong area! The REW 101 Guide recommends measuring Center+Sub along with L+Sub and R+Sub separately so that the effect of each speaker on overall bass response is known. Why then does it instruct us to measure L+R+Sub and not L+R+Center+Sub? Is it because we're excluding the LFE channel and bass management routes summed-mono only to left and right channels?

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post #22028 of 22041 Old Yesterday, 07:54 AM
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Originally Posted by 1_sufferin_mind View Post
Commence beating on me if I'm posting a duplicate question or posting in the wrong area! The REW 101 Guide recommends measuring Center+Sub along with L+Sub and R+Sub separately so that the effect of each speaker on overall bass response is known. Why then does it instruct us to measure L+R+Sub and not L+R+Center+Sub? Is it because we're excluding the LFE channel and bass management routes summed-mono only to left and right channels?
I suspect because REW is limited to sending a measurement signal to only two channels at a time. L+R+C+subs would require a simultaneous signal to three channels.
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post #22029 of 22041 Old Yesterday, 08:31 AM
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Based on recent conversations regarding using REW for time-alignment, I created the attached brief procedure for review. Once the draft has been finalized, I would like to add it ito the REW Guide as a new section. Please review and comment.
Again thank you so much for your dedication.

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post #22030 of 22041 Old Yesterday, 11:41 AM
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Has anyone done the acoustic timing reference using a Mac with HDMI?

So, I got a new-to-me Mac laptop and it has a Thunderbolt connection and I already have the Thunderbolt to HDMI adapter.

I followed the instructions here (which are Markus', I think).

When I take a measurement using the Center for one of the subs I get approx. 5ms. But I seem to get almost the same value no matter which sub I measure. They vary from 4.9 to 5.2 ms. It was just a quick&dirty set of measurements to try out a feature I'd never used before.

Before I attempt a more rigorous measurement I'd like to hear from any of the graduates of the School of Hard Knocks with an experience here. Tips and tricks vastly appreciated.
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post #22031 of 22041 Old Yesterday, 11:44 AM
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Originally Posted by artur9 View Post
Has anyone done the acoustic timing reference using a Mac with HDMI?

So, I got a new-to-me Mac laptop and it has a Thunderbolt connection and I already have the Thunderbolt to HDMI adapter.

I followed the instructions here (which are Markus', I think).

When I take a measurement using the Center for one of the subs I get approx. 5ms. But I seem to get almost the same value no matter which sub I measure. They vary from 4.9 to 5.2 ms. It was just a quick&dirty set of measurements to try out a feature I'd never used before.

Before I attempt a more rigorous measurement I'd like to hear from any of the graduates of the School of Hard Knocks with an experience here. Tips and tricks vastly appreciated.
Did you read the very first sentence on that page?
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post #22032 of 22041 Old Yesterday, 11:46 AM
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The timing reference isn't for measuring subs, it's for measuring mains.
So let's see those quick and dirty measurements.

Michael

Did you really need to quote that entire post in your reply?
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post #22033 of 22041 Old Yesterday, 11:48 AM
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Originally Posted by markus767 View Post
Did you read the very first sentence on that page?
As opposed to married speakers?

I guess you may need to be more specific (for artur, anyway).
Michael

Did you really need to quote that entire post in your reply?
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post #22034 of 22041 Old Yesterday, 11:54 AM
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The timing reference isn't for measuring subs, it's for measuring mains.
So let's see those quick and dirty measurements.

Michael
Sure you can (and should) measure subs with a timing reference as long as the acoustic timing reference itself is coming from one of the satellites.

Markus

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post #22035 of 22041 Old Yesterday, 02:26 PM
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Originally Posted by AustinJerry View Post
Are you commenting on a post that I removed after I discovered I was using Z weighting, which obviously was an error?
I was not aware I didn't know if you were doing that for a reason or not. Anyway here is the screenshots of me adjusting the mic volume on my UMM-6 while generating pink noise. I thought it increased my SPL reading when I increased the mic level but it actually does the opposite.

Measurement were taken at -25db on the pre pro with YPAO enabled 7ft away.
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post #22036 of 22041 Old Yesterday, 03:26 PM
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Originally Posted by David Varner View Post
I was not aware I didn't know if you were doing that for a reason or not. Anyway here is the screenshots of me adjusting the mic volume on my UMM-6 while generating pink noise. I thought it increased my SPL reading when I increased the mic level but it actually does the opposite.

Measurement were taken at -25db on the pre pro with YPAO enabled 7ft away.
Again, here is what I see, and there are differences from what you posted. First of all, my mic level can be varied from -31dB to +24dB. From your screenshot, it seems that your lower level is 0dB. Second, when I vary the mic level, the input level seen by REW indeed varies by the expected amount. The input level is shown as a horizontal meter with readings in dBFS. Yet, when the input level varies, the mic reading is consistent at ~82dB. This is exactly what I would expect, because the level of the Speaker Cal Pink Noise is consistent at -12dBFS, i.e. it's level is not controlled by the mic input level. So, from my perspective, my mic is working as designed.

No, what is peculiar about the results you posted is that your measured level went from 94dB to 105dB, yet the signal generator level remained unchanged at -12dBFS. Something is wrong there. Did you actually perceive a change in the Pink Noise output level when you varied the mic level and, if so, would you not have felt that this was strange? Perhaps you can re-run the test, paying close attention to the Pink Noise output level--it should not change.

BTW, my measurements were taken near-field, i.e. the tip of the mic is 1" from the speaker. Not sure this would make any difference.
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post #22037 of 22041 Old Yesterday, 04:37 PM
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Originally Posted by AustinJerry View Post
No, what is peculiar about the results you posted is that your measured level went from 94dB to 105dB, yet the signal generator level remained unchanged at -12dBFS. Something is wrong there. Did you actually perceive a change in the Pink Noise output level when you varied the mic level and, if so, would you not have felt that this was strange? Perhaps you can re-run the test, paying close attention to the Pink Noise output level--it should not change.
I just did the same test again while moving the mic properties level up and down there is no perceived change in the PN signal. I even verified it with my handheld SPL meter and my ears. Also the input level changes accordingly to the level change your mic properties. Mine does not. Increased the mic by 20db and my input went from 25dBFS to 55dbfs a 30db change instead of the 20db i raised the mic input level. Nothing makes sense here about my microphones behavior. It seems to measure well but I am not sure if this SPL issue is specific to the UMM6 or just my UMM6.
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post #22038 of 22041 Old Yesterday, 06:47 PM
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Originally Posted by markus767 View Post
Sure you can (and should) measure subs with a timing reference as long as the acoustic timing reference itself is coming from one of the satellites.
Doh! about the 1st sentence on the page. My bad, sorry.

I was attempting to use the center as the ref for my subs. More to learn the feature than anything else.

I'll have to try again when time permits but IIRC what I saw was that neither dropdown offered anything other than LEFT and RIGHT. This is on 5.19, which I just downloaded to try this out.
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post #22039 of 22041 Old Yesterday, 06:50 PM
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Originally Posted by LastButNotLeast View Post
So let's see those quick and dirty measurements.

Michael
Nah. I was using the Mac's built-in mic because I was more interested in how the HDMI stuff worked. The measured response was interesting to say the least.
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post #22040 of 22041 Old Yesterday, 07:10 PM
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Nah. I was using the Mac's built-in mic because I was more interested in how the HDMI stuff worked. The measured response was interesting to say the least.
You are using a built-in mic for REW?
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post #22041 of 22041 Old Today, 05:50 AM
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You are using a built-in mic for REW?
Just to learn more about how the HDMI OUTPUT feature was configured. Not for any actual measurements.

I'll do it "for realz" when more time permits.
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