Martin,
This might be a solution for you, got a pair of 44's last year (reading from here to see what the fuss is about)only to find both tweeters gubbed, :doh:
after checking the going rate for the HF2000's, no way am i gonna drop £150 to £200 for a pair,
so i lashed up a fix with some Wharfedale Purple tweeters i had kicking around. both measured 4.5 ohm and working a treat,
not my main speakers but i must enlarge the magnet hole to drop them in someday, the outside diameter is perfect btw. :)
Pulled them out to take a couple of shots to let you see what i mean, note they sit on ipad packing to have them firing slightly downwards to give time alignment, sounding lovely as i type. :D
http://imageshack.us/a/img7/1596/002izc.jpg
http://imageshack.us/a/img801/7223/004sri.jpg

