Implications of UMIK-1 shipping with -18dB gain? - Home Theater Forum and Systems - HomeTheaterShack.com

 
Thread Tools
post #1 of 2 Old 06-02-15, 06:02 PM Thread Starter
Senior Shackster
lovingdvd
 
Join Date: Jan 2007
Posts: 246
Implications of UMIK-1 shipping with -18dB gain?

I received my UMIK-1 mic last week and was a bit surprised to see that, as REW identified it as -18dB. I've read elsewhere that it seems that new UMIK-1 mics are being shipped with -18dB gain instead of -12dB gain.

What would be the advantage for them to want to make this change to -18dB? And what implications does this have for use with REW? Are there any changes in the REW preferences or setup/settings I should use to compensate for this difference?

I am having difficulties trying to measure at high SPL without clipping, whereas it seems others can measure at higher SPLs without clipping that are using the mic with -12dB. Is this related to the -18dB gain on my mic?

I run my sub "hot" - about +10 dB over what would be a flat FR with the rest of the system. As such, I can't seem to take any measures much past 80dB without REW saying it ran out of headroom and warning me about clipping.

In particular I want to see how loud I can play my sub and speakers without introducing much distortion, and to see at what point the distortion starts to ramp up. Sub dB at reference is like 105dB or 115dB right? Doesn't seem like I could even get close to measuring at those levels without clipping. How can this be done?

Thanks!
lovingdvd is offline  
Sponsored Links
Advertisement
 
post #2 of 2 Old 06-04-15, 03:59 PM
REW Author
 
JohnM's Avatar
John
 
Join Date: Apr 2006
Location: UK
Posts: 6,707
Re: Implications of UMIK-1 shipping with -18dB gain?

The mic sensitivity was increased to improve signal to noise ratio at normal measurement levels - I think Dirac were keen that was done to get good correction results with Dirac Live. There are no implications for REW, the sensitivity figure in the mic's cal file takes account of the gain setting.

The max input level before clipping for an 18 dB gain mic is 100 dB, give or take a dB. Make sure the input volume is set to the 0 dB level for the mic - for Windows 8 that is normally 52%, you can toggle the windows volume control display between % and dB by right clicking on it. If you have the input volume set to 100 you will clip very easily as that is applying 24 dB of digital gain.

If you want to measure levels over 100 dB you will need to open the mic and change the gain settings, then adjust the sensitivity figure in the cal file accordingly. It is probably not necessary though. To measure the power level that starts to cause significant distortion on your sub you are best using the CEA-2010 test signal, it was designed for that purpose - see the help - and use the RTA to check the result.
JohnM is offline  
Reply

Bookmarks

Tags
18db , gain , implications , shipping , umik1

Quick Reply
Message:
Options

Register Now




PLEASE COMPLETE ALL REQUIRED FIELDS BELOW... THANKS!

REQUIRED FIELDS ON THIS PAGE
YOU MUST COMPLETE ALL OF THESE

Username
Password
Confirm Password
Email Address
Confirm Email Address
Random Question
Random Question #2




User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
PLEASE READ BELOW PRIOR TO ENTERING AN EMAIL ADDRESS!

ATTENTION!

YOU MUST ACTIVATE YOUR ACCOUNT!

Activation requires you reply to an email we will send you after you register... if you do not reply to this email, you will not be able to view certain areas of the forum or certain images... nor will you be able download software.

AN INVALID EMAIL ADDRESS WILL CAUSE YOUR ACCOUNT TO BE DELETED!

See our banned email list here: Banned Email List

We DO NOT respond to spamcop, boxtrapper and spamblocker emails... please add @hometheatershack DOT com to your whitelist prior to registering or you will get nowhere on your registration.


Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML is not allowed!
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


For the best viewing experience please update your browser to Google Chrome