Quadratic Diffusers

That one looks great. I have no experience with it but... IRT diffusers, my experience is they can improve the soundstage to a remarkable degree. They added clarity & detail to my system, which was already very good. I made my own (40" X 30") and have it centered on the front wall behind/between the speakers.

Here is a link for a guy in Michigan who sells "kits", if you are so inclined.

https://www.ebay.com/itm/323062665096?hash=item4b38090f88:g:4RMAAOSwmRVfc0ra
   

Thanks folks. Two interesting options. I think I'd rather find plans and save the money on the kit by buying it all myself. If that would work out, $$ wise.

Hilde45, I am not a fan. I think if you use the proper absorption in the right places diffusers are an unnecessary expense. You can get an entire case of acoustic tiles from the Foam Factory for 25 dollars. Something like 30 tiles. They come all compressed and you will look at the mess thinking you made a big mistake. Just unpack them and walk away. 24 hours later you will have a stack of pristine tiles, they inflate like automatic balloons. I use the 4" tiles. 

@mijostyn I was already given a couple of diffusers which are doing a great job. I'm interested in adding a few more given the current evidence I have that they work. I'm thinking about a diffuser able to operate in two dimensions.

I'm using Stillpoints Aperture 2's.
Cost more, looks better.

ozzy