Linkwitz Tranform filter for EQ function?

[satefan]

I have been using REW to model my desired x-overs and corrections of my DIY loudspeaker with great pleasure, especially after the 'Save Predicted as Measurement' function was added. Thanks for that again.

My active loudspeaker uses Linkwitz Transform / Asymmetric shelves for both woofer and tweeter curve optimization. It would be amazing if the EQ function would allow for configuration of a Linkwitz Transform filter.

With that added, it would turn REW in to the ultimate modelling/simulation and loudspeaker measurement tool.

I realize this might be beyond the scope of REW, but again, would be brilliant. Especially as I would be able to put the filters in my MiniDSP directly from REW.

Cheers,

Stefan

 

[John Mulcahy]

It's on the todo list (somewhere), the difficulty is the extra parameters required to specify the filter since there are two frequency and two Q values, so it doesn't fit easily in the current filters panel.

 

[jtalden]

I don't know if this addresses your situation, but FYI:

It's not difficult to just construct the filter manually in REW if you know the desired shape. I selected the MiniDSP 2X4 HD and tried to recreate the MiniDSP example Linkwitz transform response that they posted here. The normal REW auto EQ function can then be run. Setting these first 2 filters as 'manual' prevents them from being changed as REW calculates other filters.

Personally, I think it is advantageous to only use PK filters to smooth SPL response as a LS filter may lead to additional distortion if the woofer is overly strained with undesirable boost at frequencies below f6.

 

[satefan]

That is a useful approach indeed. I'll experiment with that a bit, until hopefully the LT appears in REW.

Currently I measure the FRES and Q of the speaker and define the Linkwitz transform. As the roll off of a close enclosure is very predictable, this works well. The enclosure is cilinder shaped with two 6.5 inch mid-woofers, about 11 liters. FRES is about 90hz. So i boost the roll of to extend the low end of the speaker.

Thanks for your suggestion again.

Cheers,
Stefan