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Help me make sense of these REW graphs...

587 Views 1 Reply 2 Participants Last post by  jim19611961
I started from scratch this afternoon. I've got about 30measurements saved in REW with various crossovers and sub distance settings, with and without Audyssey activated.

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

subalone.jpg 61k .jpg file

Then, using DSP1124:

Target setting: flat curve (speaker type set to: None)

70dB target level

Filter Task: match range from 15-80Hz

subaftereq.jpg 60k .jpg file

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

noaudy80hzsub14ft.jpg 69k .jpg file

Ok, looking good so far, but then all hell breaks loose after Audyssey auto-calibration enters the equation....

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

mainsandaudy80hz.jpg 66k .jpg file

Settings: Audyssey, 60Hz crossover, sub distance 14ft

60hz14ft.jpg 64k .jpg file

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

mainsandaudy60hz8.5ft.jpg 69k .jpg file

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.

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?


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For starters, most measuring in the bass region either use no smoothing, or mild smoothing (1/24th octave). 1/6th octave is too much.

Since sound doesn't become directional till 80-100hz, you have flexibility to where you crossover. I would use whatever in the 40hz-80hz area gives the smoothest response.
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