The mistake armchair speaker snobs make too often

Yea, from 4K up the Vifa is fantastic and easy to use. Have them on my desk with RS 120's.  Go much below that, even in my near-field desk setup and the distortion skyrockets.  It just does not have the surface area. Hard part is a decent midrange.  I have not found one because of the efficiency problem and blending them with the woofer. Totem did well with them until the supply got short during COVID and they switched to a metal dome that IMHO is no where near as nice. 

I tried a pair of the SS, and a pair of the HDS. Both were OK, but to tame and flatten took too many parts. I have a pair of SB26 I am giving a try as they can work below 2K at reasonable levels. I tried their "ring radiator" and while it did sound clean, was a bit bumpy.  I noticed Sonas Faber is doing something similar stabilizing the dome from the front.  At least in the store, I am pretty impressed. I have used several pairs of the Seas 27 TBFC but in hind sight, I think the issues I was having was not rolling off the woofer steep enough. I had less luck with the 29TTF and the DXT. 

I am holding out hope for better AMT's.  The Mundorf is a bit pricy for me  ($1400/pair) just to play with and I have never heard one well done or seen any distortion measurements. I(distortion vs freq and spl)  Dispersion is kind of an issue with them, but that can be dealt with. The SB is a lot cheaper, but again, neither heard or seen measurements and not pocket change.  

I keep hoping for a 90 dB efficient midrange that can go 400 to 4K.  There was a lot to be said for the old "decade" monkey coffins. 40-400, 400-4K, 4K up.  The new SB "filler" dome may have some possibilities. 

Actually, depending on how the SB's work out, I am half tempted to just buy some Sonas Faber Lumina IIs, sell all my lab stuff and give Komiko woodworking a try. 

@tvrgeek Check out the Beyma AMT’s. Far cheaper and the opinion of builders I respect is they like Beyma as well or better than the Mundorfs.

However, further discussions about DIY speakers are probably best left for a place like diyaudio.com which has a very active speaker making community.

@mijostyn J. Gordon Holt wrote about activated carbon in wall filtering in Stereophile.  I built a custom listening room, four walls and floor (had to keep the ceiling without them due to thin 2X8 rafters).  You can see a description on my profile.  The carbon is contained in a four chamber, wooden 12.5" wide X 48" high compartment lining all walls and both doors.  The wall width is 16".  With 6-12" woofers, I'm not overloading the room with this design and don't require external filtering, including available activated carbon boxes on walls.

From the ad for external boxes:

Carbon technology has the same smooth frequency response starting at 40 – 60 Hz. and going through 6,500 Hz. it is a smooth low-frequency absorbing tool for absorbing unwanted low-frequency energy along the boundary surfaces in small rooms. At a maximum depth of 12″, it won’t take up much wall space and gives you lower frequency absorption down to 40 Hz.

With carbon technology, you achieve a smooth absorption curve that is smooth in rate and level with a special quality of clarity that is not offered with foam or other absorption technologies especially the building insulation types that dominate the industry. If you are looking for a more natural rate and level of absorption that does not over absorb at certain frequencies and under absorbing at others, our carbon and foam technologies will give you that linearity you need.

wrote about activated carbon in wall filtering in Stereophile.

Does he replace it every six months?? 🤣

https://en.wikipedia.org/wiki/Activated_carbon

....ah, to be a lottery winner and younger....

...and another side of this life I could be living....