Need some help analyzing these graphs...

[mannetti21]

I started from scratch this afternoon. I've got about 30 measurements saved in REW with various crossovers and sub distance settings, with and without Audyssey activated. My goal is to find the best setup with Audyssey activated and a crossover at 60Hz. I'm not quite understanding why my 60Hz and 80Hz graphs are differing the way they do. I've taken multiple measurements at 60Hz with sub distances varying from 6ft, all the way up to 14ft, and it seems that 8.5ft is the lesser of all evils at 60Hz.

First, I measured the sub response with no filters or Audyssey activated, and without the mains connected. I don't recall the sub-distance set in the AVR, but I'm not sure if that makes a difference (although I believe it was set to 14ft in AVR).

Settings: No Audyssey, Sub alone, 120Hz crossover in AVR

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Then, using the Behringer Feedback Destroyer Pro DSP1124 parametric equalizer:
Target setting: flat curve (speaker type set to: None)
70dB target level
Filter Task: match range from 15-80Hz

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Settings: No Audyssey, 80Hz crossover, sub distance 14ft

Ok, looking good so far, but then all hell breaks loose after Audyssey auto-calibration enters the equation....
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Note: Audyssey makes the following changes (unfortunately I don't recall Front distances in the non-Audyssey measurements)
Front levels -0.5dB
Sub level -4.0dB
Front distances 9.0ft
Sub distance 14ft



Settings: Audyssey, 80Hz crossover, sub distance 14ft

Still not too bad, but I really wanted to use a 60Hz crossover to take advantage of the Sierra-2's range and essentially eliminate any potential for sub localization.
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Settings: Audyssey, 60Hz crossover, sub distance 14ft

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Settings: Audyssey, 60Hz crossover, sub distance 8.5ft

Among many things, I guess I'm not understanding
1) Why am I getting such a large dip at 45Hz when switching from an 80Hz crossover to a 60Hz crossover? :dontknow:
2) Why is the activation of Audyssey introducing a rising slope from 40Hz to 80Hz in graph #4?
3) Is there something else besides distance/phase delay that can be changed to better integrate the sub/mains?

 

[Gordonj]

I would look at your sub without any "distance" in it . Since the distance setting is for alignment with your mains don't take your sub only measurements with delay. The delay is for alignment with the mains. The delay can cause phase issues. So take all your measurements of your sub with out the mains and no delay.
Then roll in your mains and look at the phase between your mains and sub. Then you can allow the program to give its input on the distance/delay.

See if the dip that you are referring to smooths out some once you eliminate the distance setting. Also, I would pay attention to the 6db bump at 90hz.

if your delay and phase are smeared then you can eq. For ever and never solve the problem(because eq adds phase as well). Make sure your speakers are in phase and the mains and sub are aligned before your eq.

Gordon

 

[ReUpRo]

Home Theater Shack has a whole sub section dedicated to REW. Folks frequently post measurements asking readers for help in deciphering them. Maybe you'll have better response there.

http://www.hometheatershack.com/forums/rew-forum/