Wilson's new speaker the Sasha is coming.

Dgad,

"Not sure if you are a Magico or YG fan"

I am neither. In fact I never heard them, but after reading Wilson spin, maybe I should. I was interested in a new loudspeakers, and having heard and liked the Sophia, I thought I will do some more investigating to Wilson other offering. I must say, as an engineer (Mechanical), I was mortified by some of the nonsense I read on Wilson web site. Regardless of how good the sound is, I can see now from where the high-end gets its “bad rap”. BTW, the functionality of a loudspeaker enclosure is completely opposite to a musical instrument one. A musical instrument enclosures role is to vibrate and amplify sound a loudspeaker enclosure need to do the as “quiet“ (but rigid) as possible.

Wilson employs a post-grad mechanical engineer, along with an electrical and acoustical engineer -- again, both post-grad degrees. I can assure you that neither of these credentialed engineers are "mortified" about revealing this aspect (just one of several) of Wilson's science. You are absolutely correct: a loudspeaker enclosure needs to be as quiet and rigid ass possible. X-material does these two things in combination far better than any tested material to date. The science indeed clearly supports this claim.

Mr Johnmaxx, thanks for joining in. So if aluminum is not a serious contender for speaker enclosures how do you explain the excellent decay plot on the YGA (http://stereophile.com/floorloudspeakers/yg_acoustics_anat_reference_ii_professional_loudspeaker/index4.html) and the hardly adequate one’s on the Watt (http://stereophile.com/floorloudspeakers/607wilson/index4.html)

With all due respect Mr Johnmaxx, to suggest that a phenolic resin is stiffer then aluminum is ridicules. Whatever flavor of phenolic you are using the Young modules of what is basically a polymer resin, is much lower than Aluminum or steel. You seems to be confusing strength with stiffness. A sq inch of X material, might be heavier and “stronger“ then a sq inch of aluminum, but it will not be stiffer and it will also have a much higher damping ratio. That is basically what your plots are showing. The X material is very good at storing energy. So is MDF. It says nothing of its “stiffness”. Where the aluminum, can be easily damped, the phenolic resin Young modules (stiffness) can’t be change. Aluminum is indeed a great material for loudspeaker enclosure since you get excellent strength-to-weight ratio, stiffness and a very easy material to damp due to low energy storage (That is why it looks like a “train wreck” in you plots. It releases all the energy out instead of storing it). Especial if used as a constrained layer construction, which IMO will be the best way to go.