Hi Tom,
To the point of Seas, Vifa etc. could do "it". We tried for years without success working with the best. It’s not so easy as it might appear.
That is very interesting. Seas and Vifa were some of the very best at the time indeed. I have no doubt at all that is not easy, but I just thought if someone like Seas or ScanSpeak (since Vifa was taken over by SS) were serious enough about it, maybe they could make some very good concentric drivers. The challenge is in the motor design as well as doppler affect of each driver modulating each other. Based on what I read online and what are available off the shelf parts, it seems like the speaker design industry more or less has given up on time-coherent design. With exception for some very few drivers, most drivers has to be designed with at least 12db roll off. For example, Accuton is a very reputable driver makers, but if you use their drivers, you almost have to go with 12db or 24 db roll off. As for Seas and ScanSpeak, with their portfolio of products, only a few drivers can be implemented with first order.
Another things I found interesting is that almost all of Thiel designs use aluminum drivers. To the best of my knowledge, there is no off the shelf aluminum drivers on the market today can be implemented using first order filter because of their inherent break up at high frequency. So you pretty much have to use higher order filter to suppress the break up. So how Thiel did it with first order using their aluminum drivers must require some unique engineering. I think the "wavy mid range" driver of the CS2.7 is one way to minimize the break up. As for the CS2.4, I am just guessing but the mechanical of the rubber surround was meant to solve the break up problem, and whatever it is, it really works.
Hm..., this whole big planet that there is nothing like Thiel? To borrow a phrase from the movie "Contact" which was based on Carl Sagan book, "this whole big universe and our planet is the only source of life? What a waste of space."
