Proac using 'x' in their passive crossover this doesn't really generalise to 'typically' although I'd like to see the boards at the factory.
The devices measured by 'Ralph' and 'Shin' were 8 Ohm. We don't know whether the 16 Ohm variant is equivalent or not. At first glance putting more wire onto the coil must change things.
I used the 16ohm version.
You said 'Certainly when crossed over at 500hz and properly EQ'ed the dome has none of the charaterisitcs detractors find off putting in the ATC monitors.' which clearly wasn't a complete statement.
I don't know the details of the ATC active or passive crossover so I wouldn't comment on it. It seems to me you don't know either but are happy to jump from effect to cause and then suggest a solution.
Paul
Paul, Mike has the general idea and I think this very thread was originally much larger but got pruned back because of heated debate surrounding just what was and wasn't the correct implementation for the ATC mid.
I championed my own implementation which attempted to circumvent the obvious short comings of the drivers and ones which ATC wander quite close to in their own implementations.
The driver has a large breakup at about 4.4Khz and ATC use 3.8Khz 24db/oct slopes. The low end has the driver Fs or resonance frequency at approx 320hz and ATC use 380hz with the same 4th order slopes.
If it isn't apparent from this, then I'll just say that's cutting it fine on both counts.
My own experiments and ATC orientated build yielded better objective and subjective performance from moving further away from these issues and that was done with either steeper filtering and/or narrowing the passband away from the problems.
Driver engineering isn't quite voodoo and good common sense design in light of component behaviour applies is something you'll find in all good and particularly accurate loudspeakers. ATC isn't a special case here, at least not if linearity is an issue.
This is obviously controversial because it implies that ATC have a sub optimal implementation of a driver they themselves engineered and that I, a simple enthusiast, did it better. This was exactly why the thread turned sour all that time ago. I've long since sold the ATC's and have no further interest in debating just what is and isn't right for the driver nor do I wish to antagonise happy ATC owners.
Consider this post another opinion on how loudspeakers should be designed and file it with the thousands of others you'll find scattered around the internet.