New Open Back top-end project

tajanes

 A couple of comments at Iowa; my OB could use more high-end air, and focus on response at 15 degrees when setting up filters.   So… 

thought I’d give a try matching the bottom-end Beymas (2x12s) with a Celestion (6.5) concentric coax on my open back project.  I will continue to bi-amp and use minidsp for the cross between bass and top unit (and low-shelf for low-end), but will be building filters for the coax after measuring.  Looking at implementing a notch filter to address the rise in the mid around 4800 and let it roll-off and then see what options I may have for the tweeter (compression horn driver).  I'd like to get away with a notch filter only on the mid, and fitting slope order of the tweeter (as presented in an old David Weems speaker design book) as high as possible (but may need a LP on the mids as well).  

A couple days building OB units, guessing weeks on the filters…  If anyone has had success / experience with this mid-tw filter setup all suggestions welcome.

 

Andy

BTW found a good source on line for ¼ self -adhesive felt (12x12) sqrs...

https://www.zoro.com/zoro-select-felt-sheet-f26n-14-in-t-12-x-12-in-2huv7/i/G2002524/

jhollander

My comment would be to watch the dip in the tweeter response and move off axis until it goes away.  Design your filter at that point then move back on axis to see if the mid behaves.  Coax off axis, OB, plus box resonance you are making for a challenging build