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Author Topic: what difference fullcale and 1/3octave?  (Read 1371 times)

changmin lee

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what difference fullcale and 1/3octave?
« on: September 12, 2016, 02:09:08 am »

hello~


i use sys tune.



i have a question.



what's difference full scale and 1/3 octave?



why does it look difference?
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Lee Buckalew

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Re: what difference fullcale and 1/3octave?
« Reply #1 on: September 12, 2016, 06:49:37 am »

hello~


i use sys tune.



i have a question.



what's difference full scale and 1/3 octave?



why does it look difference?

This is not a difference of full scale vs. 1/3 octave.  That is mixing up 2 different ideas.  Full scale relates to magnitude of signal (level), while 1/3 octave relates to resolution of signal.  Full scale could be thought of as full level, right at the boundary between maximum level and clipping.  1/3 octave has to do with the width, in frequency, of each measured area.  1/3 octave centers roughly align with the center frequency points on a 1/3 octave graphic equalizer.

The upper section of your screen shot shows a continuous resolution while the lower section shows a 1/3 octave resolution.  Systune allows you to select the resolution at which you look at the measurement in the windows. 

Lee
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Lee Buckalew
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Nicholas C. Ames

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Re: what difference fullcale and 1/3octave?
« Reply #2 on: September 13, 2016, 01:27:03 am »

Hi, I'm new to the forum, but I have a lot of experience with both Smaart v7 & 8 and SysTune Pro.

What you're describing in SysTune, is in Spectrum, you can choose either "Full" or 1/1 thru 1/96 octave banding. What "Full" means, in this context is, the "full" FFT (raw, unbanded FFT data).

This means that you are choosing to view the full unbanded FFT, and as such, viewing pink noise on such a display will show it having downward tilt from left to right, as a result of pink noise being equal energy per OCTAVE, not equal energy per FREQUENCY. Since you have chosen, by selecting "Full", to NOT apply octave banding to the data, an acoustic measurement taken in the traditional way, using pink noise, will show a spectral tilt that is lower on the high end and higher on the low end than a conventional fractional octave banded measurement.(like an RTA) This would be the same thing as choosing "Log" in Smaart when in RTA mode.

A more "conventional" RTA style measurement can be accomplished in SysTune by instead choosing one of the fractional octave bandings 1/1 thru 1/96. Alas, this is but one way to see the incoming data on your measurement channel in SysTune. The real power of the program, in my opinion, is it's awesomely stable (when using periodic noise) Transfer Function measurements and the ability to overlay IRs. Virtual EQ and Delay Analysis are also awesome tools that have taught me a lot in the last couple years.
« Last Edit: September 13, 2016, 01:30:36 am by Nicholas C. Ames »
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