I was using a DEQX crossover with various crossover settings from 1.5kHz to 8kHz.
The AMT's have much more distortion then the Raal ribbons, but distortion figures don't tell everything specially when both are allready on the low side. Anything under 3% distortion does not add up much to the sound character of a driver, anything below 1% becomes almost inaudible. There is much more to a driver wich make it sound different then distortion figures. Polar pattern is much more audible for instance, and so ther are a ton of other factors. Personally I never look at distortion figures when choosing drivers unless I have to choose some low budget drivers.
I'm using Phy-Hp wide range drivers as midrange wich I only like up to 3.5kHz max. These are very nice drivers and as with all drivers they do colour the sound. The colouration of the Phy dos not match very well with the colouration of the Raal's so there is a mismatch going on. It simply sounds a bit boring and it makes the midrange sound too coloured. The Phy-AMT combination is not perfect but is makes you want to listen more and more and more to music and that's a great achievement imho.
I'm listening most of the time at low volume and want my system to have a sense of big scale dynamics on low volume. I never listen really loud, so my system isn't voiced to play loud. The Raals can play much louder then the AMT without a swet. So if you are in to playing loud most of the time I would recommend them. The AMT behave better on low volume, the do have that sense of big scale dynamics then. Maybe it's distortion after all, who knows. I'm enjoying it more and that what's counts. At least to me.
Back on topic.
I have also tried dipole tweeters but found that it is not always the best solution in a open baffle system. With dipole tweeters you need more space from the wall behind the speakers or you have to attenuate the output at least.
