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 28th September 2019, 10:43 AM #991 wesayso   diyAudio Member     Join Date: Jul 2007 This is a RePhase exercise right? Not a real null in the mains, just a virtual one done by EQ, right? __________________ Use Science to design your speakers and they will sound like a piece of Art...
BYRTT
diyAudio Member

Join Date: Dec 2009
Not shure but could imagine phase of that dip maybe can be a little wild, what i mean is its not pure linear phase and not pure minimum phase but a mix of both, guess a chance to repair that then into REW you need to divide a carefull alligned measured line array IR with textbook target of a carefull alligned target curve IR, to ignore HF stopband from measured IR then filter the two IR before the divide command for example 1/1 at 125Hz and export that as frd file, then over in Rephase use whatever mix of minimum phase and linear phase filters it takes to get that hump flat as pancake in both the amplitude and phase domain, below should be some pointers

Attached Images
 1060.png (60.8 KB, 280 views)

fluid
diyAudio Member

Join Date: Jan 2009
Quote:
 Originally Posted by wesayso This is a RePhase exercise right? Not a real null in the mains, just a virtual one done by EQ, right?
No the null is real, it appears in the averaged measurement and DRC does not try and correct it.

These images show it, 6 cycle FDW to clean up the phase and unwrapped to see the cliff more clearly. The exercise part is combing the real corrected measurement with pure impulses to represent a perfect sub.

Quote:
 Originally Posted by BYRTT below should be some pointers
I'll have to read that one a few times to understand it I don't think it can be corrected electrically, but needs a combination of absorption and mitigating with the sub channel if possible. I have had no success with dividing impulses before, it always sounds wrong somehow.
Attached Images
 Average no EQ.jpg (101.0 KB, 536 views) Flat test unwrapped phase.jpg (93.4 KB, 283 views)

fluid
diyAudio Member

Join Date: Jan 2009
Some progress has been made in the physical world

Pile of Glass fibre batts

Pile of MDF

MDF cut for sub cabinets and absorber frames

Attached Images
 IMG20190906160416.jpg (447.3 KB, 243 views) IMG20190906160433.jpg (411.7 KB, 245 views) IMG20191006173818.jpg (361.7 KB, 240 views) IMG20191006173830.jpg (395.1 KB, 241 views)

 6th October 2019, 02:33 PM #995 wesayso   diyAudio Member     Join Date: Jul 2007 Big plans! __________________ Use Science to design your speakers and they will sound like a piece of Art...
 6th October 2019, 03:58 PM #996 nc535 diyAudio Member   Join Date: Apr 2011 plans for big subs? __________________ My Synergy Corner Horns and Bass Bins http://www.diyaudio.com/forums/multi...bass-bins.html
fluid
diyAudio Member

Join Date: Jan 2009
Quote:
 Originally Posted by wesayso Big plans!
I should end with 3 panels 560 x 2260 x 180 (whd) and 5 panels 430 x 2260 x 150

That's what I got out of two bags of glass fibre and three sheets of MDF

Quote:
 Originally Posted by nc535 plans for big subs?
Roughly 500 x 500 boxes for the 15" drivers, reasonable compromise between size and efficiency

 6th October 2019, 10:16 PM #998 DonVK   diyAudio Member     Join Date: Jan 2017 Location: Ottawa Are those panels for your null? or general room treatment?
 7th October 2019, 01:05 AM #999 fluid   diyAudio Member   Join Date: Jan 2009 The original idea was for corner traps and first reflection control. Having measured, the ETC shows less early reflections than I thought but a few bass nulls, so I will try to see if I can reduce the front wall null enough to be dealt with by other means.
fluid
diyAudio Member

Join Date: Jan 2009
Here are some progress shots of the absorbent panels, one completed so far

Basic frame with backing fabric attached (excuse the perspective the divider is in the middle of the frame)

Filled with fibreglass insulation

Front fabric attached

In room next to array for scale, even with no bracing these things are awkward to move around.

Attached Images
 IMG20191018130140.jpg (438.4 KB, 159 views) IMG20191018130646.jpg (510.9 KB, 156 views) IMG20191018135911.jpg (461.4 KB, 156 views) IMG20191018140310.jpg (320.8 KB, 157 views)

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