@lewm It was sort of iatrogenic. The processor was doing what it was programmed to do which was make the frequency response of the speaker flat. Because of that speaker's location there was a large dip in the high frequencies that the processor was correcting. I then poured the coal into that situation with very powerful amplifiers. New processors have programmable limits to keep such an event from happening. I corrected the problem by removing the window next to the speaker and replacing that brilliance control with a 500 watt resistor and a very large heat sink.
Sowter does not make toroids. I used a 1:100 transformer successfully on the Acoustats using the same set up. It was one of their standard ESL transformers at the time. They may help design transformers to suit. I do not know yet. Using a super tweeter next to 8 foot ESLs is sonically risky. I would prefer a 6 foot ribbon out of a Magneplanar which would be less likely to call attention to itself as the radiation characteristics are the same. Above 12 kHz I think the tweeter will likely be less obvious. With the new processor I'll have four independent crossovers and I can experiment with less expensive equipment before I go to town. I can buy used Maneplanars, get new tweeters with their serial numbers then sell them. Perhaps I can get the local Magneplanar store to wrench a pair out of the company. I'll figure something out. What else is a retired guy going to do?
