Which material sounds better for speakers construction? Wood, Ply or MDF?

@ctsooner Magico’s as he’s lifted the treble to make them sound more open on top

Listen, you can like what you like, I am not about to get into a Magico dirt fight again, but some basic diligent of facts, not opinions, are needed.
It is actually the Vandersteen highs that are pronounced, not Magico (Plenty of measurements all over the place of current production models – you can start with Stereophile S5/Model 7). Vandersteen enclosures use of CF is minimal; they use a layer or 2 to basically veneered MDF. Vandersteen “CF” enclosures ring plenty; it is his pure MDF enclosures that are inert but, as the case with many “inert” cabinets, they are over-damped, again just look at measurements. Magico S5 THD measurements are the lowest ever measured at the NRC; rest assured, it will not be the case if they “ring”. Try listening with your ears, not your eyes, just because something is made out of metal, does not mean anything; does your car rings?

"Wasn't there a company making cabinets out of cast concrete?"

Maybe you are thinking of different brand, but early Hales speakers had concrete baffles. Paul Hales switched to MDF because of economy in creation and exporting the heavy speakers. I came across an Asian manufacturer making cabinets out of vases. They were trying to find US distribution. Nice people; I hope they didn't struggle too much before quitting the impossible mission of marketing it to US audiophiles.

MDF, if anything is ultimately practical and established. I have not heard a wood box speaker using Scanspeak drivers as good as what YG has achieved, and I welcome the variety and pioneering as MDF is not some panacea. 

RV is a measurement and science based engineer, I can assure you that the 7 cabinet is superior to the 5a in every way.
impossible to overdamp a passive component like a cabinet - you want to hear the Stradivarius or the cabinet ?
the 7 cabinet is a mdf  cabinet within a mdf cabinet with constrained layer damping ( he collaborate s with Michael at HRS, so my guess is that is is HRS supplied ( and you just know they are serious engineers ) and CF wrap cooked in an Autoclave.
in a previous working life I dabbled in advanced composite structures... running arguably some of the most advanced high technology composite shops on the planet- simple stuff like the Hubble optical bench, F-22 wings, 787 fuselage.....
easy stuff...
i can assure you it is more than veneer
now from a musical perspective, while I loved my 5a for many many musical years, the 7 mk 2 are lightyears on....

enjoy....

cueing up some late nite Sunday massed chorale..... perfect for a prayer of discernment....

i checked w RV
he invented the trade secret constrained layer damping material used in Treo up thru model 7 and it’s initial use predates HRS.

motion into heat
simple to say
not so easy to do at the correct range of frequencies.....

i should probably disclose i use a bunch of Vandersteen and HRS products......