# does anyone know?



## nineballg (Jan 19, 2008)

i've never calibrated my system with an spl before so bare with me.
i was planning to get an audio test cd and play each channel one at a time using the different frequencies on the cd to get my readings on my spl meter and then make the proper adjustments on my eq to make sure all my db matched at each frequency.
is this method going to work or do i need analyzers and such equipment to do this.
i dont know how to use computer graphs and microphones etc.

also, i'm calibrating my system for blu ray audio via the analog outputs to multichannel inputs on my processor.
i know they make new hd "video" calibration discs but i need "audio". do they make a new blu ray calibration audio test cd, or will i have to get the older audio test cds?

thanks


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## brucek (Apr 11, 2006)

> is this method going to work or do i need analyzers and such equipment to do this.


You can use the manual method (see our download site) or you can use a free program called REW.

brucek


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## Wayne A. Pflughaupt (Apr 13, 2006)

Yeah, manual plotting - we used to do it all the time. Before John's REW program it was the only way. 

The best method for manual measurements is to use sine wave test tones between 20-120 Hz, which you can find at the link brucek provided (of course, you can opt for lower and higher end points if you need). The best way will be to use 1/6-octave intervals between the tones. The Excel Workbook you can download at that link will get you a graph like the one below; if that's to complex you can always manually plot response on graph paper. Page 2 of the BFD Guide describes how to take manual measurements.










Regards,
Wayne


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## nineballg (Jan 19, 2008)

i've seen and heard the term 1/3 octave and 1/6 octave used.
what does that mean. what is the difference.

thanks


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## Wayne A. Pflughaupt (Apr 13, 2006)

Every doubling or halving of a given frequency is one octave. For instance, at a reference point of 1000 Hz: 2000 Hz would be one octave higher, 500 Hz would be an octave lower.

There are ten octaves in the frequency spectrum between 20 Hz - 20 kHz. Starting at 20 Hz, the one octave intervals would be centered at (using some rounding): 20 Hz, 40 Hz, 80 Hz, 160 Hz, 320 Hz, 640 Hz, 1200 Hz, 2400 Hz, 5000 Hz, 10,000 Hz, and 20,000 Hz.

One-third octave intervals would add two additional frequency points for each octave: *20 Hz*, 25 Hz, 32 Hz, *40 Hz* 50 Hz, 63 Hz, *80 Hz*, etc. You might note that these are the center frequencies you will see for the sliders of a typical 1/3-octave graphic equalizer.

Likewise, 1/6-octave spacing will divide an octave into six intervals, adding a frequency stop between each of the 1/3-octave centers. The graph in my previous post shows 1/6-octave spacing between 16 Hz - 160 Hz. 

Hope this helps.

Regards,
Wayne


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