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Latest REW Beta & UMM-6 mic

8K views 35 replies 11 participants last post by  panson 
#1 ·
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?
 
#3 ·
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%.
 
#7 ·
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%?
 
#4 ·
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.
 
#11 ·
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.
 
#15 ·
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)?
 
#18 ·
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.
 
#19 · (Edited)
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?
 
#21 ·
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?
 
#24 ·
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.
 
#25 ·
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 )
 
#31 ·
This was the method I used to adjust mine:
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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