I have a pair of what looks like 4205 hf drivers but the magnet assembly looks different than any I've seen. It is just as heavy but thinner and a little bigger in diameter than the one's you usually see. Did they make these with ferrite magnets in the later years or has someone put something wierd together that actually works well. They sound fine. Also ,Would I be wrong if I said the 4205 was the professional series version of the 077 ? Thankyou And Help..Jay