Originally Posted by
Zilch
Early 4430 two-ways were made with 2421's, i.e., the equivalent of LE85's with aluminum diaphragms.
In my own testing of old LE85's I was surprised to find that they actually had better HF extension than 2426's with titanium diaphragms.
I agree with the others that the aluminum sounds sweeter, and I would have no concerns about losing HF extension.
It seems JBL switched to titanium in part because of aluminum's limitations in high-power sound reinforcement applications. Aluminum is just fine, perhaps better, even, in normal home hi-fi use.
I'll be swapping in some diamond-surround aluminum diaphragms myself to test this thesis here soon....