I am not an engineer, but I've read a bit of the technical stuff from Altec that it is supposed to be better, to extend the high freq response etc.

When I first got my 806 drivers, I was curious what the phase plug actually looked like; and so I opened the back and remove the 'phram and looked at the phase plug, it was a piece of machined steel, with semi-circular groves, no biggie, and replaced all of the parts and button it up.

I haven't actually taken apart a radial/Tangerine phase plug driver, but the newer phase plug is a piece of molded plastic that is held in place by glue. One thing for sure, the new radial phase plug is a lot cheaper to make because it is cheaper to mold a piece of plastic than to machine a piece of metal(of course once you recovered the cost of making the mold.)

Can we actually hear a sonic difference between the two phase plug designs, I know they can measure it with instruments. I am not against the new plug, I am all for cheaper, without any performance degradation. I am just curious.