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Discussion Starter · #1 ·
Hello,

The following is a graph taken using REW. I am using a SVS SB12PLUS with a crossover at 80HZ. Main speakers are disconnected. Loaded correct Radio Shack Meter calibration and completed soundcard calibration which looked good (using Behringer UC 202). I check my AVR and made sure it was setup in stereo and all DSP/boosts/trims are shut off. I feel I followed all of the directions and need some additional advice. Thanks in advance for you input.

Why is the sub db level significantly higher than my target 75 db which was setup? It appears to following the curve at a higher db level.
What are your thoughts regarding the graph? I know I can play around with sub placement a bit? I also can smooth out the null a bit 27HZ by increasing the crossover to 100HZ on my AVR.
It also appears I have some noise in my PC soundcard with the steep increase at 18HZ after sub rolloff begins. Is this the case based on your experience?
Based on the graph...Is there a specific peak I should tame with my subs PEQ before running audyssey to further smooth out the response?

80hz crossover graph for posting.jpg
 

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Why is the sub db level significantly higher than my target 75 db which was setup? It appears to following the curve at a higher db level.
You likely forgot to run the Calibrate SPL routine after you ran the Check Levels routine.

What are your thoughts regarding the graph?
It's fine - nothing more for you to do.

It also appears I have some noise in my PC soundcard with the steep increase at 18HZ after sub rolloff begins. Is this the case based on your experience?
Yes, as the frequency gets below ~20Hz the large calibration boost required for Radio Shack meters amplifies any noise and it appears as signal in the response plot. It is not - it's just noise and identified usually by the sharp dip and rise at low frequencies that you have observed.

Based on the graph...Is there a specific peak I should tame with my subs PEQ before running audyssey to further smooth out the response?
No.

brucek
 

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Discussion Starter · #3 ·
bruceK....

Thanks for your comments and the information on this site provided by you and other members. It is trully appreciated.

I am pretty sure I ran the calibrate SPL routine and clicked the appropriate finish button. I did read on other postings where you then recommend the clicking of the apply button in the IR window. I do not recall doing this and it may be where the issue resides.

I will let you and the forum know if I need additional assistance. Thanks.
 

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where you then recommend the clicking of the apply button in the IR window.
That's only when you want to modify the gating window, or change a cal file that was used for a measurement. It's not normally used.

Generally, if you set the Check Levels routine up at 75dB and then run the Calibrate routine (which sets the REW SPL meter at the same 75dB), your trace will be fairly close to the 75dB target. Of course, REW can only set that level as a response to the pink noise that it uses and the upper and lower limits of bandwidth that the pink noise is set to, so it's never perfect. It's only level though, and matters not. It's the overall response that matters.

brucek
 
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