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Discussion Starter · #1 ·
I have finally made my first few full range plots of my system. First, thanks to all who did such a great job with the software and the help files. This is a great boost to improving our audio experience.

I am using an ECM 8000 on my Home Theater PC. I calibrated the audio card and have attempted to follow the directions as best I could. Following is a plot, actually it is 4 plots, made while I made changes to the mid range crossover settings on my system. Pretty neat to see the effect of just changing the mid range.

However, I have two main questions. When I set the system up, the volume calibration was set to 75 dB. However, I notice the plot rarely reaches 75 dB. Only a few bass peaks reach that decibel level. Why is the plot not 'centered' around 75 dB, Is that something I am doing wrong? Second questions relates to the high frequency roll off starting around 6 kHz. This is where my tweeter crosses over. Is that a measurement problem, a room problem or another mistake in setting up the software on my part? In my search of the forum, I noticed many of the full range plots exhibit the same high frequency roll off. I am trying to understand the process better. Thank you for your help.

 

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Discussion Starter · #3 ·
Wayne, thank you . I guess this is a rather normal plot then, other than the mid range variations I induced.
 

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Discussion Starter · #6 ·
I have taken measurements both with and without the generic mic calibration file. With the calibration, the dropoff is even worse. I will take some nearfield tests to determine if my reflection point absorbers are having too great an effect and attenuating the high frequencies excessively.

I am now pointing the mic directly at the speaker being measured. Pointing the mic vertically again shows a bigger rolloff in the high frequency range.

Thank you guys for taking the time to entertain my questions. I find I sometimes need to understand how something works rathen than just follow directions without knowing the basis for the instructions.
 
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