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More => Old Versions => JRiver Media Center 20 for Windows => Topic started by: luckyaua on May 08, 2015, 01:33:07 pm

Title: DSP Analyzer and db level. ISSUE
Post by: luckyaua on May 08, 2015, 01:33:07 pm
I think there is an issue with level of DSP analyzer:
if i play a -20db sine wave stereo track the draw level of the curve left and right channel is the same and the total level (orange curve) is +3db so it's ok but the level reported in db on the upper left corner is the same for all curve (-23db) why?
the level of total curve should be -20db!!

So another question...i believe that each horizontal line represent a 3db increment and the scale is 50Db (from 0 to -50db) but it seem referred to a single channel level not for the total level infact if i play a 0db sine wave the yellow and blu lines are at the top instead the orange is over the  range...why?

at the end i think that is useful to have a db label for level on the left axis. ;)
Title: Re: DSP Analyzer and db level. ISSUE
Post by: luckyaua on May 09, 2015, 11:25:30 am
nothin 4 me? ?
Title: Re: DSP Analyzer and db level. ISSUE
Post by: mwillems on May 09, 2015, 12:32:43 pm
The 3dB issue is a common issue with sine wave test clips. A "-20dB sine wave" could be a -20dB RMS sine wave or a -20dB peak level sine wave.  If it's a -20dB peak sine wave the analyzer would correctly show a -23dB RMS level as the RMS level of a sine wave is 3dB lower than its peak.

Title: Re: DSP Analyzer and db level. ISSUE
Post by: luckyaua on May 09, 2015, 12:55:55 pm
ok but if the 3 curves are rappresented with left and right same level and both + 3db i think that alspo the level repsented with number (top left) must show same level for left/right and +3db fot both but the tree value is the same!?!?!?
this is the screenshot for a 100Hz sine wave art -20db.
(http://i59.tinypic.com/2v0292p.jpg)
Title: Re: DSP Analyzer and db level. ISSUE
Post by: blgentry on May 09, 2015, 08:11:52 pm
Maybe the overall volume level is an average of left and right?

Brian.