EMM-1 Mic Vs Individually Calibrated Mics

[ttocs]

Sept 26, 2020 19:07:30 GMT -5 LCSeminole said:

Sept 26, 2020 18:48:46 GMT -5 LCSeminole said:

So have you done this yet?.....if so I too am curious as to what the DIP switches should be on for the 18dB gain. I've opened my UMIK-1 and see 3 DIP switches, switch 1 is "ON" or in the up position, switch 2 & 3 are "down" or I assume the "OFF" position. What combination gives the 18dB gain?

Did a little digging myself and have figured out by the table on the back of the PCB board in the UMIK-1 that to attain an 18db gain the "three" DIP switches are either set to "0" or "1". 0 being in the down position and 1 being in the up position. My UMIK-1 came preset to 12db, so I too will be giving 18db a try. I also just read in several posts(by John Mulcahy the REW software writer)on the AV Nirvana, HomeTheaterShack and miniDSP forums, that DIRAC suggests the 18db setting.

First # in the table below is "DIP SWITCH #1", Second # in the table below is "DIP SWITCH" #2, Third # in the table below is "DIP SWITCH #3". So for example, my UMIK-1 came from CSL with the 12db setting, (ie: 1 0 0)

To gain access to the PCB board, there are two small pin-holes on the bottom end of the UMIK-1. I simply used a push pin and put in one of the holes and rotated counter-clockwise, and the "Ring" that ttocs described above will come out. Now simply and gently pull on the inside edges where the "Ring" was and pull out the PCB board(remembering that there are a few wires attached to the other end of the PCB board) far enough to expose the DIP switches on one side and you'll see the table that I copied below on the other side of the PCB board. I used the push pin, that I unscrewed the Ring with, to change the DIP switch settings. Now simply do everything in reverse to put it back together. Now my UMIK-1 is set to (0 1 1), ie: 18db. I bought my UMIK-1 from CSL right before I received my XMC-1(6 or 7 years now, so this explains why my UMIK-1 was set to 12db, and why miniDSP is now setting them by default from around 2017-2018.

1 1 1 = 0db
1 1 0 = 0db
1 0 1 = 6db
1 0 0 = 12db
0 1 1 = 18db
0 1 0 = 24db
0 0 1 = 30db
0 0 0 = 36db

..............just for conversation sakes, I had my eyes dilated today at the ophthalmologist so I could get prescription reading glasses. Meaning if I can do this gain setting change with temporary blurry vision, then just about anyone can do it.

This is the custom spanner I ordered from NeptuneThinkItGetItNow instant product delivery service. Wire cutter/stripper and a couple #8 screws.


I tried 0dB but was waaaaaaay to insensitive. Tried 6dB, still too low. Set it for 12dB and am now able to measure as high as I dare. When I did the cal in the REW SPL meter tool, and used my calibrator set to 94dB, REW reported the mic is good up to 131dB, but my house isn't.

I don't have the calibration exactly right yet due to how REW "wants" the mic cal file to be used, but for the purposes of finding out what the limit is at clipping, it works. I don't know what the limit is. After getting to 107dB and things walking around I stopped. I'm satisfied.

[ttocs]

Sept 26, 2020 19:34:03 GMT -5 LCSeminole said:

Sept 26, 2020 19:29:33 GMT -5 megash0n said:

interesting. When using the calibration file... It says 18dB gain. Is this just in the file, or does it understand how these dip switches are set?
Sorry if this was mentioned already and I skimmed over it.

Not sure if this is in the file or not(I'm guessing probably not), since the actual PCB board has the three DIP switches to change the gain settings, thus I would think it would just be going by how the switches are set.

It's definitely the dip switch that is reporting the setting to REW. I tried several and wasn't using a cal file, and each time REW knew what the setting the dip switch was set for.

[megash0n]

Sept 26, 2020 20:05:25 GMT -5 ttocs said:

Sept 26, 2020 19:34:03 GMT -5 LCSeminole said:

Not sure if this is in the file or not(I'm guessing probably not), since the actual PCB board has the three DIP switches to change the gain settings, thus I would think it would just be going by how the switches are set.

It's definitely the dip switch that is reporting the setting to REW. I tried several and wasn't using a cal file, and each time REW knew what the setting the dip switch was set for.

Good info. Thank you sir. 

[ttocs]

Sept 26, 2020 20:03:21 GMT -5 ttocs said:

I tried 0dB but was waaaaaaay to insensitive. Tried 6dB, still too low. Set it for 12dB and am now able to measure as high as I dare. When I did the cal in the REW SPL meter tool, and used my calibrator set to 94dB, REW reported the mic is good up to 131dB, but my house isn't.

I don't have the calibration exactly right yet due to how REW "wants" the mic cal file to be used, but for the purposes of finding out what the limit is at clipping, it works. I don't know what the limit is. After getting to 107dB and things walking around I stopped. I'm satisfied.

What I'm finding is if I use the cal file for the UMIK, and also use an SPL meter to check the peak SPL during a REW measurement, that measurement is low by 4dB, which is the amount of offset in the cal file - actually 3.9. And if I clear the cal file and use the SPL tool to calibrate using my calibrator sounder tool, then take a measurement, the curve shows exactly what the handheld SPL meter shows for peak SPL.

Also, what's interesting is that the curve is identical. So now I might edit the cal file and take out the offset and load that as the cal file and see what happens.

[ttocs]

Sept 26, 2020 20:33:28 GMT -5 ttocs said:

What I'm finding is if I use the cal file for the UMIK, and also use an SPL meter to check the peak SPL during a REW measurement, that measurement is low by 4dB, which is the amount of offset in the cal file - actually 3.9. And if I clear the cal file and use the SPL tool to calibrate using my calibrator sounder tool, then take a measurement, the curve shows exactly what the handheld SPL meter shows for peak SPL.

Also, what's interesting is that the curve is identical. So now I might edit the cal file and take out the offset and load that as the cal file and see what happens.

Yep, that works. I edited a copy of the cal file for the UMIK-1 that I bought directly from miniDSP. I changed the "Sens Factor = " from the 3.9xxxdB to 0.0dB since what I was measuring was almost exactly a 4dB offset. So now the legit cal file is being used.

I am guessing that the Sens Factor is an offset for the 18dB dip switch setting. Everything I was measuring was off by 4dB, including the number that first pops up when using the calibration in the SPL meter tool in REW.

So as LCSeminole brought up, and I verified by searching miniDSP posts by the miniDSP moderator, they began using the 18dB setting a few years ago because so many folks had clipping errors in Dirac. Maybe this can help others sort some things out. Otherwise, I suggest they use the EMM-1, which is close enough, or put another way, the difference between my EMM-1 and both of my UMIK-1 mics is about the same as running the same sweep with the same settings and mic multiple times and getting slightly different results. A dB here or there kind of thing.

[AudioHTIT]

Looks like there’s another selection for the calibrated mic quiver.

www.minidsp.com/products/acoustic-measurement/umik-2 — Webpage

www.minidsp.com/images/documents/Product%20Brief%20-%20UMIK — Specs

www.minidsp.com/images/documents/miniDSP%20UMIK-2-User%20Manual.pdf — Owner’s manual

[ttocs]

AudioHTIT you read my mind! Perfect, thanks!

To go along with that info is something I didn't ever look at closely before today. The spec for Max SPL kinda goes unnoticed that it's rated at the 0dB Gain setting, which miniDSP doesn't "advertise" that the mics are not set to from the factory.

From minidSP about the UMIK-1:
Resolution & Sample rate: 24bit ADC @ 48kHz
Max SPL for 1 % TDH @ 1kHz: 133 dB SPL @odb gain setting

The other thing to notice is the Res and Sample rate. With some folks wanting Dirac on the G3P to be able to use higher rates, the UMIK-1 is only rated to 48kHz. However, the UMIK-2 solves that limitation on their end with the new higher spec of: 32bit 44.1~192kHz, albeit with a lower Max SPL rating.

[ttocs]

If you have multiple mics and would like them to measure close to identical, it's possible to make a cal file for the one(s) you want to alter. And, it's not very difficult to do.

There are a number of reasons for using multiple mics. One that I've done is to setup 3 mics in the three main seating locations, Left, MLP, and Right. This has allowed me to make numerous measurements while changing other aspects of system setup to quickly assess whether the changes are of benefit or not with regards to seat to seat variation.

I've only scratched the surface so far with Cal Matching, but it's pretty cool how it works! So I'll be suggesting this to be one of the topics for the next REW ZOOM Conference coming up soon.

[ttocs]

marcl you'll need to create a Aggregate Device to combine multiple mic elements to be seen as one device. Aggregate Device is what macOS calls it, I don't know what this would be called in a PC.

[marcl]

May 18, 2023 11:14:39 GMT -5 ttocs said:

marcl you'll need to create a Aggregate Device to combine multiple mic elements to be seen as one device. Aggregate Device is what macOS calls it, I don't know what this would be called in a PC.

Thanks I'm working on it but doesn't seem to be a way to do it in Win 10 ... despite several search results giving steps that are impossible to execute.  One said ASIO4ALL could do it but as far as I can see it only shows one or the other selected stereo mic channels.

[ttocs]

May 18, 2023 12:09:29 GMT -5 marcl said:

May 18, 2023 11:14:39 GMT -5 ttocs said:

marcl you'll need to create a Aggregate Device to combine multiple mic elements to be seen as one device. Aggregate Device is what macOS calls it, I don't know what this would be called in a PC.

Thanks I'm working on it but doesn't seem to be a way to do it in Win 10 ... despite several search results giving steps that are impossible to execute.  One said ASIO4ALL could do it but as far as I can see it only shows one or the other selected stereo mic channels.

Ahhhh, then maybe those 2 mics are really just 1 mic after all, which makes sense.

All of my mics have "2" channels when I look at how they're setup in the OS and REW.

Go to REW Preferences, Input, Microphone, and to the right of Microphone will be a drop down box with L or R, these are the channels of a single microphone.

So try doing this, click the checkbox for Virtual Balanced Input and see if you can "tie" both channels to be used concurrently.

edit: I've never tried this, so I don't know how this works.

[ttocs]

May 18, 2023 13:36:44 GMT -5 ttocs said:

May 18, 2023 12:09:29 GMT -5 marcl said:

Thanks I'm working on it but doesn't seem to be a way to do it in Win 10 ... despite several search results giving steps that are impossible to execute.  One said ASIO4ALL could do it but as far as I can see it only shows one or the other selected stereo mic channels.

Ahhhh, then maybe those 2 mics are really just 1 mic after all, which makes sense.

All of my mics have "2" channels when I look at how they're setup in the OS and REW.

Go to REW Preferences, Input, Microphone, and to the right of Microphone will be a drop down box with L or R, these are the channels of a single microphone.

So try doing this, click the checkbox for Virtual Balanced Input and see if you can "tie" both channels to be used concurrently.

edit: I've never tried this, so I don't know how this works.

edit2: I just noticed that there's another checkbox for Multiple Inputs, so you might want to also try that.

All of this is with the non-Pro version of REW.