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RE: Apogees and ethics - comments

As I pointed out, the BG eperience made me agnostic about pure corrugated Al and kapton or what have you backing. Given stronger magnets, the current capacity of the ribbon becomes a non-issue, leaving you with tensile strength and mass minimization. Al foil is not what you want for tensile strength, so minimum mass is actually achieved with polymer diaphragms once you have a threshold magnetic strength.

I think the Scintilla tweeter(s) are where they are for coaxial symmetry as an inversion of the MTM coax we keep discussing. Achieves the same goal, and with their high XO are going to produce the multiple lobing you speak of - which is a nearly as good way of getting a broad sweet spot and an approximation of good lobing.

I think the reversed backwave - making the tweeter a bipole - is a deliberate choice similar to what Nudell did in his IRS by sealing the backs of his EMITs and putting an extra set on the back of his speakers. Swans also do the same with their flagship, and a few DIYers have done so with their neo3 PDRs. Note also that Revel (a harman co.) do their back tweeters in bipole phasing. I don't really know how to weigh these against each other. I would assume that the results achievable in side by side and coax end up being similar. Later mids and tweeters were not made that way at Apogee. The TMT though, allows you to tap the magnetic flux near the sides where it can be stronger at the edge closer to the front (and back) of the magnet structure, by doubling up and placing at the edges, the tweeter ribbons can be made narrower and run at lower output per each - thus reducing the torsioning problems - which I think is the weakest point in the side by side Apogees.

I agree that you would prefer to have the tweeter away from the bass in order to get less IMD, but then, if you have a two way, you can still have physical isolation of the center tweeter from the flanking bass ribbons, That way you get your MTM. The tweeters would be in a dipole null so you should not have much of a problem with airborne imd.

Quite frankly, the bass freq need to carry so much energy that I would prefer to have even 150hz away from the mids, not to speak of real bass below 100hz. You so don't want them together in the same structure - definitely not on the same diaphragm.


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