# Latest REW Beta & UMM-6 mic



## antoninus9 (Nov 25, 2013)

REW tells me that I do not need to calibrate the UMM-6 mic for SPL, but when I compare the SPL REW indicates with my Radio Shack SPL there is about a 10 db difference. 

1. Bad Radio Shack meter?
2. Bad UMM-6?
3. Bug in REW?


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## fusseli (May 1, 2007)

Interesting discovery. The UMM-6 should be calibrated and I would trust it over an RS SPL meter. That being said, a 10dB difference is kind of a lot...


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## Phillips (Aug 12, 2011)

Is the UMM-6 calibration file got a "SENS FACTOR" number on the first line.
Where did you purchase the mic, if from Herb Cross-Spectrum he doesn't include this line on his files.
If this is the case simply download the calibration file from Dayton's site and copy this line over to Herbs.

If it does have the line on the file, if you are using Windows as your OS check the "Mic" input in your "Sound settings" in the control panel of your laptop and check to see it is set to 33%.


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## antoninus9 (Nov 25, 2013)

I bought the mic from Parts Express, and downloaded the cal file from Dayton Audio.

Yes, it's set to 33%.

If the RS meter says 77 db, the UMM-6 through REW shows 61db. I can say from experience that the RS meter is more accurate. The sound level is closer to 80 than 60.


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## Phillips (Aug 12, 2011)

antoninus9 said:


> I bought the mic from Parts Express, and downloaded the cal file from Dayton Audio.
> 
> Yes, it's set to 33%.
> 
> If the RS meter says 77 db, the UMM-6 through REW shows 61db. I can say from experience that the RS meter is more accurate. The sound level is closer to 80 than 60.


Ok so you trust the RS meter, adjust either the mics calibration first line figure or REW SPL meter to equal the RS reading.


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## Glyptoron (Apr 20, 2006)

Hi Phillips,
To be clear, I record the Umikxxx.txt under a different name to save the original file, then I open the new file and I change the value "Sens factor" in the first line.
For example :
"Sens Factor =-5.013dB, SERNO: 7001278"
Am I right ?


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## angryht (Nov 23, 2006)

Phillips said:


> Is the UMM-6 calibration file got a "SENS FACTOR" number on the first line.
> Where did you purchase the mic, if from Herb Cross-Spectrum he doesn't include this line on his files.
> If this is the case simply download the calibration file from Dayton's site and copy this line over to Herbs.
> 
> If it does have the line on the file, if you are using Windows as your OS check the "Mic" input in your "Sound settings" in the control panel of your laptop and check to see it is set to 33%.


I am in the beginning stages of figuring out my new usb mic as well, which is also a UMM-6 mic. I got mine from Herb at Cross Spectrum Labs. I am curious about the "SENS FACTOR". How do I check to see if it's there. Do I change the file extension to .txt? When I was doing some preliminary checking, I did notice that SPL reading in REW from the UMM-6 seemed a bit higher than I would have expected. I guess I should try to compare with my RS meter. I guess I figured the mic's calibration file would have that information in it. Don't mean to hijack this thread but I thought it might be helpful here.

Oh yeah and why set the microphone input level to only 33%?


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## AudiocRaver (Jun 6, 2012)

In addition to the above, be sure both REW & RS meter are set to same averaging speed - fast or slow - and same filtering - A or C.


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## antoninus9 (Nov 25, 2013)

AudiocRaver said:


> In addition to the above, be sure both REW & RS meter are set to same averaging speed - fast or slow - and same filtering - A or C.


Good point.

I wonder what would happen if I removed the "Sens Factor =-5.013dB, SERNO: 7001278" and then imported the edited cal file into REW? I think I'll give it try. :innocent:


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## Phillips (Aug 12, 2011)

Glyptoron said:


> Hi Phillips,
> To be clear, I record the Umikxxx.txt under a different name to save the original file, then I open the new file and I change the value "Sens factor" in the first line.
> For example :
> "Sens Factor =-5.013dB, SERNO: 7001278"
> Am I right ?


If you want to make a copy of the file just right click > copy > and then rename (maybe UMIK-1 7001278 New) and then change the "SENS FACTOR *number only* so yes you are correct.

Hope this helps


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## Phillips (Aug 12, 2011)

> I got mine from Herb at Cross Spectrum Labs. I am curious about the "SENS FACTOR". How do I check to see if it's there.


I would doubt it is there.
Open the calibration file and see if it has "SENS FACTOR = xxxxx db" on the first line.
If not download the calibration file from Dayton's website and copy and paste this first line onto Herbs file (first line), then save. REW recognizes this number and adjusts accordingly.

If you have a problem attach both files (Herbs and Dayton's) and i will post the correct file back.



> Do I change the file extension to .txt?


No need to.



> When I was doing some preliminary checking, I did notice that SPL reading in REW from the UMM-6 seemed a bit higher than I would have expected. I guess I should try to compare with my RS meter.


Do the above first then compare with your RS meter. Make sure that they are both set to c weighting slow as said posted below.



> I guess I figured the mic's calibration file would have that information in it. Don't mean to hijack this thread but I thought it might be helpful here.


No worries



> Oh yeah and why set the microphone input level to only 33%?


That is Windows default setting.


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## Phillips (Aug 12, 2011)

AudiocRaver said:


> In addition to the above, be sure both REW & RS meter are set to same averaging speed - fast or slow - and same filtering - A or C.


Thanks for that good point.


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## angryht (Nov 23, 2006)

Phillips said:


> . . .


Thank you!


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## Phillips (Aug 12, 2011)

antoninus9 said:


> Good point.
> 
> I wonder what would happen if I removed the "Sens Factor =*-5.013*dB, SERNO: 7001278" and then imported the edited cal file into REW? I think I'll give it try. :innocent:


It would be easier just to change the figure (highlighted above) but your decision.


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## JohnM (Apr 11, 2006)

antoninus9 said:


> REW tells me that I do not need to calibrate the UMM-6 mic for SPL, but when I compare the SPL REW indicates with my Radio Shack SPL there is about a 10 db difference.
> 
> 1. Bad Radio Shack meter?
> 2. Bad UMM-6?
> 3. Bug in REW?


Probably number 3 - I don't have a UMM-6 so can't verify the cal figures and gain settings, and the behaviour may vary depending on which OS you are running. There was a 10 dB tweak in UMM-6 levels in beta version 16 following previous reports of a discrepancy, are you running the latest beta version (17)?


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## antoninus9 (Nov 25, 2013)

Yes, I'm on Beta 17 because after having read the list of fixes/enhancements I assumed the UMM-6 fix would be needed.

Do you want me to revert back to the official release and test it?


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## JohnM (Apr 11, 2006)

No, stick with beta 17. Easiest is to edit the cal file sensitivity figure to change it to -15.013, that should add 10 dB to the REW SPL meter readings. What OS are you running?


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## angryht (Nov 23, 2006)

Here's what I did. I downloaded the calibration file from Dayton and copied the first line with the Sens Factor to the top of the CSL calibration file. Then I compared the reading with my Radio Shack SPL meter and it was off. By off I mean it was reading about 4 dB lower than the SPL meter. Then I remembered that the SPL meter needs corrections at certain frequencies (it's the 33-2050). I noticed that there is not a correction at 1000 Hz. So, I played that tone and compared the REW SPL meter to the RS SPL meter. I had to change the Sens Factor from about -17.### to about -20.###. Now they match at 1000 Hz. My question is: Does this approach make sense? I am still not sure why the calibration from CSL doesn't include adjusting the Sens Factor but I think I read that Herb did not think it was worth the effort, which is probably fine since we are more interested in changes (relative) in FR and not necessarily absolutes.


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## antoninus9 (Nov 25, 2013)

Hi JohnM,

My OS is Windows 8.1, 4 GB RAM, 120 GB SSD, AMD quad core A6 APU. It has a SoundBlaster X-Fi Elite Pro installed with the latest drivers, but at the moment I'm using the AMD HD Audio HDMI output with ASIO4All. It's a dedicated HTPC so the only other apps I use are MediaMonkey and J. River. 

I just edited the cal file per your recommendation. The results were RS meter 70, REW 55. Both set to C weighting and slow response. The UMM-6 is set to 33% in Windows sound settings.

I would have expected a significant change, but basically nothing happened. Perhaps the problem is somewhere in the setup?


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## angryht (Nov 23, 2006)

I noticed that in order for REW to recognize a change in the Sens Factor I had to close and restart it.


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## antoninus9 (Nov 25, 2013)

I rebooted three times. No change. I don't think REW is recognizing the cal file. This may also explain why the eq changes it recommends are inconsistent with the readings from my old spectrum analyzer.

Does the file have to end in".cal" or is ".txt" acceptable?


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## angryht (Nov 23, 2006)

I thought it had an extension .frd? But I'd have to double check.


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## Phillips (Aug 12, 2011)

TXT or FRD is fine.

Change the SENS FACTOR number then import again, this will update the settings in the calibration file for REW to recognize.


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## ermesy (Jun 11, 2013)

Hi all - this is my first post. I'm thinking of getting started with REW to treat my room but first I need the UMM-6 USB mic. I see its specs claim a frequency range of 18Hz to 20000Hz but I also see an Amazon customer saying he was advised by Dayton Audio that this mic will "not measure frequencies below 200Hz"!
Surely there's been a miscommunication somewhere?
So my first silly question for this forum is : will this mic measure 200Hz and below i.e. 18Hz to 200Hz and all the way to 20000Hz? I'm 99% certain it will but just want to be 100% before I shell out the coin.
I emailed Dayton Audio with this same question but never received a reply.

Thanks guys.


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## EarlK (Jan 1, 2010)

ermesy said:


> Hi all - this is my first post. I'm thinking of getting started with REW to treat my room but first I need the UMM-6 USB mic. I see its specs claim a frequency range of 18Hz to 20000Hz but I also see an Amazon customer saying he was advised by Dayton Audio that this mic will "not measure frequencies below 200Hz"!
> Surely there's been a miscommunication somewhere?
> So my first silly question for this forum is : will this mic measure 200Hz and below i.e. 18Hz to 200Hz and all the way to 20000Hz? I'm 99% certain it will but just want to be 100% before I shell out the coin.
> I emailed Dayton Audio with this same question but never received a reply.
> ...


Yes the info relayed from that Amazon customer is silly ( if accurately presented within your quote ) .

Simply, I suggest that you buy a calibrated UMM-6 ( or UMIK-1 ) from CSL . 

Herb creates an accurate ( individual ) calibration file for each mic ( & I trust that it is more accurate than what's available from Dayton Audio's website ) .

* UMM-6 from CSL * 

:sn:

PS ; ( That is all the detail I'm willing to go into here / maybe others will help answer other questions should you have more )


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## ermesy (Jun 11, 2013)

Cheers Earl. Sadly, CSL doesn't ship outside the U.S. so it looks like Parts Warehouse here I come!


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## Phillips (Aug 12, 2011)

ermesy said:


> Cheers Earl. Sadly, CSL doesn't ship outside the U.S. so it looks like Parts Warehouse here I come!


Have you been in contact with Herb?

Where did this info come from?


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## panson (Nov 24, 2011)

Are UMM-6 and UMIK-1 identical? Same thing different names?


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## ermesy (Jun 11, 2013)

No idea, Panson but I've just ordered the Umik as it got a good rap here and will work easily with REW. Oh, and the fact that Dayton Audio didn't bother answering my query on the UMM left me a little miffed, too!


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## panson (Nov 24, 2011)

I got my UMIK recently. It is nice mic. However the cal file does not give me "correct" sensitivity factor. It was about 5 dB lower than references (SPL meter and mic calibrator).


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## angryht (Nov 23, 2006)

panson said:


> I got my UMIK recently. It is nice mic. However the cal file does not give me "correct" sensitivity factor. It was about 5 dB lower than references (SPL meter and mic calibrator).


This was the method I used to adjust mine:


angryht said:


> Here's what I did. I downloaded the calibration file from Dayton and copied the first line with the Sens Factor to the top of the CSL calibration file. Then I compared the reading with my Radio Shack SPL meter and it was off. By off I mean it was reading about 4 dB lower than the SPL meter. Then I remembered that the SPL meter needs corrections at certain frequencies (it's the 33-2050). I noticed that there is not a correction at 1000 Hz. So, I played that tone and compared the REW SPL meter to the RS SPL meter. I had to change the Sens Factor from about -17.### to about -20.###. Now they match at 1000 Hz. My question is: Does this approach make sense? I am still not sure why the calibration from CSL doesn't include adjusting the Sens Factor but I think I read that Herb did not think it was worth the effort, which is probably fine since we are more interested in changes (relative) in FR and not necessarily absolutes.


You would need to get the initial sensitivity factor from MiniDSP. It seemed to work for me and nobody said I was off-base.


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## Glyptoron (Apr 20, 2006)

_nobody said I was off-base._
and nobody will tell Greg !
John himself speaks of this change. 
Anyway, you can still go back and put the original value.
http://www.hometheatershack.com/forums/rew-forum/72057-latest-rew-beta-umm-6-mic-2.html#post666520


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## JohnM (Apr 11, 2006)

panson said:


> Are UMM-6 and UMIK-1 identical? Same thing different names?


No.


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## AustinJerry (Apr 2, 2010)

panson said:


> Are UMM-6 and UMIK-1 identical? Same thing different names?


Adding to John's answer, the two mics are made by different companies. The UMM-6 is made by Dayton Audio, and the UMIK-1 is made by MiniDSP. I have both mics and have run REW measurement comparisons of the microphone responses, and I can find no measurable difference in performance. It is quite possible that the internal electronic could be the same.

So which one is better? In my opinion, the UMIK-1 is physically a bit more robust. I dropped my UMM-6 on a carpeted floor, and the barrel snapped in two, which leads me to conclude that it is slightly more fragile. Otherwise, I see no significant difference. Either mic will be fine for REW use.


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## JohnM (Apr 11, 2006)

AustinJerry said:


> It is quite possible that the internal electronic could be the same.


They aren't, MiniDSP did the board design for their UMIK-1.


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## panson (Nov 24, 2011)

Might be same acoustic, different electronic.


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