# UMIK - linux/Java install



## grokaudio (Feb 11, 2013)

So a couple of questions.

I recently got my UMIK - and installed REW.

Going through the setup - I have a few general questions.

I currently have amd64 system - Ubuntu 12, and HDMI on motherboad with an old altec lansing system attached (SUB and two satellites - amplifier in the sub and independent volume control)

I noticed once UMIK plugged in and REW started, that I was unable to switch the input to the UMIK as microphone input without error. 
Which seemd ok - once I figured I could leave the Mic input as default and all is ok.

So here are my questions..


Should I get an HDMI cable to connect to UMIK instead of the Regular USB?
Should I set the computers input for the mic to high levels or lower 
my sensitivity on the calibration file from minidsp ~ -7.6 dB does that change the recommended between -12 and -24db when setting the soundcard levels (right now i'm at about -18db)
SPL meter - after setting this I got a message saying max measurement is about 86 db - if I need higher - lower the sensitivity of input. 
Is 86 ok - how do change input sensitivity
Since Im planning on measuring raw drivers how do I set up the sense resistor give above so I can take T/S and impedance sweeps
Also - how can I test whether the mic is either set up right or the calibration files are accurate

PS thanks I'm sure i'll have more and looking foraward.

Both are great products (REW and UMIK)


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## JohnM (Apr 11, 2006)

grokaudio said:


> Should I get an HDMI cable to connect to UMIK instead of the Regular USB?


UMIK is a USB device, connect it to a USB port.


> Should I set the computers input for the mic to high levels or lower


Are you referring to the computer's own mic input? You would not be using it with UMIK.


> my sensitivity on the calibration file from minidsp ~ -7.6 dB does that change the recommended between -12 and -24db when setting the soundcard levels (right now i'm at about -18db)


Ignore the level warning messages if you are using a USB mic, but it would be unusual to see -18dB from UMIK as that would typically mean SPL of more than 100 dB. Are you sure the UMIK has been set as the default audio input in your OS settings?


> SPL meter - after setting this I got a message saying max measurement is about 86 db - if I need higher - lower the sensitivity of input.


Would be difficult to achieve with UMIK unless a lot of gain ws being applied to the UMIK signal in the OS, seems wrong.


> Is 86 ok - how do change input sensitivity


No, it is not OK, but I don't know anything about audio system settings on Linux, sorry.


> Since Im planning on measuring raw drivers how do I set up the sense resistor give above so I can take T/S and impedance sweeps


You can't use UMIK for this, driver measurements are electrical connections only and require a stereo line input and a line or (preferably) headphone output configured as shown in the help.


> Also - how can I test whether the mic is either set up right or the calibration files are accurate


To test cal file accuracy you would need a reference measurement from a device with known characteristics. To check whether the setup is right post a measurement file for us to look at.


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## grokaudio (Feb 11, 2013)

I've got some screenshots if it would help?

Mic - current placement of microphone
Original error - when selecting the UMIK instead of leaving default device (notice it says 12DB Gain)
OS input - shows the default device as UMIK 1 
Levels - was using the woofer - shows levels and Mic input to achieve
Sound Calibration - shows levels and Mic input to achieve

Overwrote the 86DB screenshot on the SPL - I'll try and post later.


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## grokaudio (Feb 11, 2013)

All,

Ok - I figured I would reset all calibrations (except for the MIC) - I checked levels, Did not calibrate spound card, and ran a SPL. Is this to be expected - I only need assistance with the Sound card calibration at this time.

Michael

:help:


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## JohnM (Apr 11, 2006)

Looks like a soundcard loopback measurement with mic cal applied to it (which would not be appropriate as the mic is not in the measurement path).


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## grokaudio (Feb 11, 2013)

I've attached current sound card calibration - can someone confirm it is ok??

I still need some assistance on my 86dB umik measurement - anyone willing to chime in?


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## JohnM (Apr 11, 2006)

Soundcard measurement looks fine, but you would not use a soundcard calibration with the UMIK. When you did the SPL calibration what did your external meter show as the SPL?


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## grokaudio (Feb 11, 2013)

John,

Thanks for the reply. I went through the trouble to do sound-card calibration, since I will be taking T/S Impedance and Driver frequency response measurements and though I would need it to improve the impedance measurements... Once I have the speakers built, I'm sure the rest of REW and UMIK will come in handy.

As screenshots showed above - I used the analog line out/line in (not headphone) for the sound-card calibrations

2 quick questions
1. For impedance measurements, I'm planning on using line out/line in (same as used in sound-card calibration) what value resistor (33, 100 or 1K) - I currently have a 100 Ohm sense resistor - (measures 99.38) 
2. Since I am making the sense resistor connectors - which of the three prongs inside a bare 1/8th stereo jack are right and left.

2 Quick Comments
1. I've noticed some differences between documentation (Online help and the latest 5.13 beta help)

2. It may help to have UMIK specific help files - I'm sure it would be more work on your end, but it may save some time fielding the hapless questions like mine.

Thanks again

Michael


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## JohnM (Apr 11, 2006)

If you have a headphone output that would work better for T/S measurements, as the output stage has more drive capability. A line out would typically need a higher sense resistor than 100R. 

The tip of a stereo jack is the left channel.

The online help is for the V5.00 release version, for the beta version use the help within the program.


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## grokaudio (Feb 11, 2013)

John,

Thanks - are 1 Watt sense resistors acceptable, should they be lower, what do you recommend??

I was considering this as a (close to 100 Ohm) RWR81S1110BRB12 Resistor - Wirewound 111 Ohm 0.1% 1W ±20ppm/C 0.01% Ceramic Hi Temp Sil AXL Thru-Hole 

Michael


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## JohnM (Apr 11, 2006)

There is some useful info on the setup for impedance measurement in this thread.


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## grokaudio (Feb 11, 2013)

Thanks John,

Just what I was looking for!


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## grokaudio (Feb 11, 2013)

Been reviewing the impedance rig and impedance measurement graphics from the help files.

I have a 2 quick questions 
1. the speaker connection - For impedance measurements - looks like the on connection is to ground - is that correct?

2. Can the same wiring be used for both so the Rleads and Rsense can be easily measured?

Attached Graphic - mine (which green can be removed depending on 1 Above) 
Attached Graphic - helpful 1/8 th stereo plug found here: http://4.bp.blogspot.com/-g9z8wsTGr6A/UBWIHEx9LkI/AAAAAAAAAhw/1KsR__gjVnI/s1600/Stereo_Pin_Plug.jpg
Attached Graphic - Impedance Measurement from REW help file


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## JohnM (Apr 11, 2006)

Yes, that looks fine.


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## grokaudio (Feb 11, 2013)

Thanks John!

Attached Impedance rig based on above. I take it the points I indicated for measuring Rleads is correct - can you verify???

Michael


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## JohnM (Apr 11, 2006)

To measure the leads resistance join together the points that will attach to the driver.


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## grokaudio (Feb 11, 2013)

John,

I should have been more specific. Do you measure only from the headphone output (right channel tip) to where it attaches to the driver (A to B above drawing) OR do we also include driver to the sound input right channel tip as well?

If I'm also including the ground - is that measured as well???


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## JohnM (Apr 11, 2006)

To measure the lead resistance you want everything in the circuit that will be present when you measure a drive unit, think of it as measuring a drive unit that has zero resistance.


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## grokaudio (Feb 11, 2013)

Thanks John!!!


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