Speaker manufacturers or box manufacturers with off the shelf drivers?

@ebm “ I am chairman of the bored “ Iggy Pop 
.... think I will go play some....

:-) enjoy the music

Why are most high end speakers manufacturers using mdf for their boxes?

because its a cheap nasty material. Its good enough though for most folks. But some manufacturers think its not good enough and they use other materials. 

if mdf is used, do you think one box that has substantial bracing performs like another box without any bracing? And what are the merits of mdf. It’s hard to understand why so many speaker manufacturers competing for sales through good sounding products would use such a material if it was a horrible choice. Does it all simply come down to cost or are there other benefits to using mdf?

mdf is a good versatile material. Its easily available, cheap and
easy to cut. A box without bracing will vibrate more. 

In your years of high end speaker building, what materials have you found that work best?

You will need a concrete box 100 inches thick all the way round. 

 I understand that you manufacture all of your own drive units.
How much of that comes into play with regards to the exceptional sound you achieve in your designs?

Zero. Off shelf drivers work fine. 

Would you say crossover design is important or you just use whichever resistors and capacitors you have on hand at the moment?

Its not that important. It can always be adjusted if you
get it wrong. 

And lastly, are you still currently developing any products that we should keep our eyes open for?

No. Not for the public. My designs will remain for personal use only. They are being developed to meet my unique requirements that the worlds finest speakers could not satisfy. There are plenty of speakers out there already for the rest of you.

If someone is an expert speaker are they also a speaker expert? 

In your years of high end speaker building, what materials have you found that work best?

kenjit-
You will need a concrete box 100 inches thick all the way round.

kenjit, you are talking about a cube of concrete 16 feet on a side, per speaker. That is 151 yards of concrete. 614,400lbs of concrete. 307 TONS of concrete. PER SPEAKER. 

Are you sure about that???

Are you sure about that???

it may need to be even thicker. Without trying it, hard to know.