The gaffa tape holding my tweeters in their little plastic spheres was a bodge and only temporary so I could see if isolating the tweeters had any merit. Even with that far from ideal bodge it was clear from the first ten seconds that it was a winner. Since then the tape started to come unstuck and I got fed up pushing it back on.
So the next stage was considered and implemented. This is still not the final thing but gives me an idea on how suitable butyl rubber will be to attach the tweeter to the enclosure. I cut out a donut of wheelbarrow inner tube just wide enough to overlap the enclosure and with a hole in the centre that just fits around the edge of the surround.
![Image](https://i.imgur.com/Idysua2.jpeg)
I then proceeded to add some 3mm thick plastic to the tweeter to make it circular and give a bigger area to stick the butyl rubber to. None of this is seen as the butyl rubber ring very conveniently covers everything right up to the tweeter's surround.
![Image](https://i.imgur.com/DQoFtqE.jpeg)
So now the parts were made I had to adhere the rubber ring to the enlarged face plate and the spherical enclosure. This went rather well and looks much better than the gaffa tape effort
![Image](https://i.imgur.com/hX7qF5v.jpeg)
Well it not only looks better but sounds better too. The gaffa tape was a poor solution but this butyl rubber ring has well and truly done the business. These are the best performing speakers I have heard (not that I have heard loads).
I just need to think now of how to blend the edge of the butyly rubber smoothly into the sphere without any edges and the re radiation that brings. Geoff's miĺiput suggestion is under serious consideration but as are other options.