Thanks for the information. The elements in my speakers are definitely 4 ohms and as you can see from the rear shot (the top one is the original from the speaker) they are called "AD5061/M4 2422 257 35511. The only number different in the one I thought would be an exact replacement is as you can see the last one; 35501 instead of 35511. I find this very strange. Almost makes me wonder if the ones in the speaker have specially made cones.
Even stranger is that when I managed to get in touch with someone at Audio Pro support who know about these old speakers he said the correct component number should be AD5061-P4S. And this is an element I can't find at all, not even a datasheet.
However, the element I wanted to change is not really broken. Mostly it sounds nice but every now and then it will get stuck and I need to turn up the volume for a short period and then they will work again. Sometimes for months.
I can indeed certify theses speakres sounds great. The bass system is made of two elements, one facing up and the other facing down. I believe ACE has something to do with controlling the relation between acoustic and electric impedance to get a flat response.